EARTHQUAKE NOTES

Vol. XXIII



September-December 1952

Nos. 3 and 4

M1CROSEISMS AND OCEAN WAVES by J. E. Dinger The field experiments conducted by the Naval Research Laboratory during the past several years have never produced data which could be interpreted as giving evidente that microseisms are generated under a hurricane which is over remote deep-water areas. The data, however, could be given a logical interpretation.if the water waves over relatively shallow water were assumed to play a role in the generation of microseisms. This is the same idea investigated in the past by Longuet - Higgins, Darbyshire, and others. In an effort to obtain additional data as to what correlation, 1f any, exists between storm-generated water waves and microseisms, two wave gages were installed by the Naval Research Laboratory at Cocoa Beach, Florida, through the cooperation of the Beach Erosion Board and the University of California. These gages were of the pressure-sensitive type; the one was similar to the type developed by Woods Hole and used quite extensively by the Beach Erosion Board and the other was developed by the University of California. These gages were in water depths of about 28 and 46 feet. A single horizontal component seismograph was placed on the grounds of the U. S. Navy Underwater Sound Reference Laboratory at Orlando, Florida. This location was approximately 50 miles inland from Cocoa Beach and therefore can be considered isolated from local surf vibrations which can causé high seismic noise near the shore.

The simultaneous data of microseisms and water waves obtained during two hurricanes of the 1951 season are of interest in that the paths of the stoms were radically different, Figure 1 shows the paths of the two storno "Easy" and "How."

80•

1 60•

70•

40•

00•1 6-0600

WASHIVON l

PT.10-1700

O CT. 5-1700

aas 6-0600 ocs 6- 1700

CHAP2t.

PT.10- 0300

OCT. • - 0800

IS 0*

OT. 3 - 700 OCT. -00 00

COCOA

RLA/100 , • BEAMI OCT. 241700

HOW

PT B-1700 EPT. s - 0500

S EPT. 5 - 1700 PT. 5-0600

700

Os00

GRAXIA■■Arm

PT. P- 1700

Wi T-0500

s le-aso

EASY 15-1700

SEPT 6-0500

6 . d>

so•

50•

Figura 1. Map Showing Paths of Hurricanes 'Easy and 'How'.

"Easy" followed a path which was well out over deep water during its entire path (except near its end when it moved over the Banks of Newfoundland). Its narest approach to Florida was about 650 miles. Hurricane "How" generated in the Gulf of Mexico and

-22rapidly moved across Florida and entered the Atlantic with the center going slightly to the south of the wave recorder location. Both of these stoms produced high waves on Florida 'hut the character of the waves was considerably different and the microseismic activity was greatly different. These two stoms therefore provide an interesting comparison. HURRICANE EASY — SEPTEMBER,195I

PERIOD OF WATER WAVE AT COCOA BEACH, FLA.

5—

HEIGHT OF WATER WAVE

23-

COCOA BEACH, FLA.

AMPLITUDE OF MICROSEISMS T5-5 Som. Pon I

9

1\1

°BLANCO, FLA.

A

WASHINGTON D.0

1200

1200

B SEPT.

9 SEPT.

1200 10 SEPT.

loo II SEPT.

1200 12 SEPT.

Figure 2. Microseismic and Water Wave ActivIty During Hurricane ° Easy'.

Figure 2 gives results of the simultaneous recordings of microseisms and water waves throughout the period hurricane "Easy" was in existence. The wave gage data were analysed by the Beach Erosion Board to give the significant wave height and period plotted as curves C and D respectively. A measure of the amplitude of the microseisms was obtained by measuring the area enclosed by the envelope of the microseisms over a 15-min. interval, an interval being used every two hours and in some nerts of the curve every hoor. The relative position of curves A and B has no significance as the two curves have been shifted with respect to each other. However, the value of the arbitrary units for A and B is closely the same. The sharp increase in both wave height and period as shown in curves C and D on the morning of September 8 accompanied the arrival of the swell from "Easy." Data from a Beach Erosion Board gage at Cape Henry and a report from Weather Ship H, several hundred miles east of Charleston, N. C., also gives added evidente that the wave activity shown by curves C and D on September 8 is associated with the arrival of swell from "Easy." The microseisms as recorded at Orlando on September 8 and 9 show some increase in amplitude at approximately the same time as the maximum wave activity at Cocoa Beach. This increase in amplitude was not at all pronounced, in fact this particular period of microseisms normally would not have received any attention as being an indication of anything unusual. The record was too erratic to permit an analysis of the most pronounced period. The slight increase in microseisms during the wave activity can be interpreted as being associated with the swell and in no way representing microseisms from under the storm for these reasons: (1) no simultaneous increase in microseisms occurred in Washington, and (2) microseisms generated under the storm should also have shown increased activity before the arrival of swell. According to the Miche-Longuet-Higgins theory a standing wave pattern is required to transfer the water wave energy to.microseisms. A standing wave pattern can conceivably be established upon reflection of the incoming swell by a sufficiently steep coast. The low level of microseismic activity during the swell from "Easy" would indicate, if the MicheLonguet-Higgins theory is of importante, that the reflected wave energy along the Florida coast is very small. Because of the very gradual slope of the shore along Florida one would expect low reflections; one author stating that reflection from a 1/10 slope is negligibly small.

— 23 — One indisputable statement on the basis of these data, which is not subject to inter pretation, can be made regarding "Easy," namely; an intense hurricane completely over deep water and about 600 miles distant did not produce microseisms on the continent (by any method) which positively indicated the existence of a hurricane. HURRICANE HOW — OCT 12 II



2

cic> .50

.25 Figure 2 10 Period

1

10

100

Frequency

The vertical seismometer is a 2+ pound mass supported by a primary spring. The spring is 2 inches in diameter and has approximately fourteen turns. The diameter of the spring wire is 0.075 inch, The upper attachment of this spring is fastened to a boom. This boom can be raised or lowered to compensate for any drift in the spring. The mass is a brass plate three by five inches by one-half inch high. This mass is hinged to the base on one of its three inch edges. The free end of the mess is used as the center plate of a three plate condenser. A plate above the one below are fixed to the base of the seismometer. This three plate capacitor serves a double purpose. It is the detecting element and the damping element. To change the damping, one changes the spacing of the air gap between the condenser plates. The accompanying change of electrical capacitance is compensated for in the amplifier unit. The period of this instrument may be changed by the device described as follows. A fiber attached to the mass at about its center is also attached to a support about two inches behind the hinge line of the mess. The tension on the fixed end of the fiber may be varied. If the mass is deflected downward this fiber causes a downward pull on the mess acting in an opposite sense to the restoring force of the main spring. It is possible to make this downward component of force equal in magnitude to the restoring force of the primary spring. When the above statement is true, the seismometer is aperiodic. Practically, uithout thermostating, a usable period of eight to ten seconds may be obtained, without much trouble. The tension on the fiber is caused by loading a platform with weights. Increasing the weights on this platform increases the period of the instrument until it becomes unstable. The horizontal seismometer does not require that its mass be supported against the

action of gravity, hence does not require as heavy a spring as the vertical unit. Much

of the spring action in this horizontal unit is due to its hinges. The primary spring is about three-fourths inch long and wound on a one -half inch mandrel. The fixed end of this primary snring may be moved back and forth as required to compensate for drift.

The horizontal seismometer is essentially an inverted pendulum. The maas is not simple and is made of four parts somewhat in the shape of an open-ended box. The two sides of this box are hinged to the base on their lower end. The top of the box is hinged to the upper ends of the two sides. This top forms a platform upon which weights may be placed with a subsequent change of period. The fourth member of the mass is a plats attached to the platform and projecting down from it. This plate is the center plate of a three plate condenser. The two outer plates of this three plate condenser are rigidly attached to the base. Detection and demping are identical to those in the vertical seismometer.

-28— The amplifier and servo —mechanism. — As previously mentioned detection of ground motion is made by the three plate condenser. This three plate condenser forms two double plate condensers. The center plate is kept at ground potential. Each of these two plate condensers is part of the frequency determining parameters of a vacuum tube oscillator. If the middle plate is moved towards one of the fixed plates, the capacity between this fixed plate and the center plate is increased. The capacity between the other fixed plate and the center platé is decreased. The frequenties of the two vacuum tube oscillators would tend to be changed, one lowered and one increased by this motion of the center plate. Because, however, of an interlock introduced between these two oscillators this frequency change does not occur. The phenomenon that takes place is a change of phase between the a. c. voltages of the two oscillators. Signals from these two oscillators are fed into a phase-detector circuit. A change of phase is converted into a d. c. push—pull signal. This letter signal is applied to the grids of two tubes used to drive the galvanometer and also applied to the control tubes of the servo—mechanism. There are five controls and one test button on this amplifier. The first control is a padding condenser; the need for which is described in connection with the demping device of the vertical seismometer. (There are tuned circuits in the amplifier and the oscillators' frequency must be maintained at a fixed value.) The second control is a gain control. A potentiometer controls the amount of interlock between the two oscillators. The greater the interlock between the oscillators the smaller will be the change of phase that takes place for a specific small deflection of the center plate of the three plate transducer. Theoretically, if the oscillators are completely unlocked, the gain is infinite. Actually, this condition cannot be realized. A magnification of about 100,000 is possible with this circuit. It is possible to introduce the equivalent of a test impulse by electrical means. An electrostatic charge is introduced between one of the fixed plates and the movable plats. The amount of deflection of the movable plate is related to the voltage between the fixed plate and the movable plate. The size•of this voltage is regulated by the third control. A test button, when depressed, applies this test voltage. Time marks are indicated on the seismogram by a momentary deflection of the writing point. The fourth control regulates the size of this deflection. For the galvanometer to operate linearly, the current through it should be a certain value when the galvanometer is not deflected. (This value depends on several parameters.) The fifth control regulates this current. The size of this current is indicated on a milliammeter. Changes in temperature will cause this instrument to drift, This will cause a permanent displacement of the galvanometer. This permanent displacement needs to be corrected and is done by a servo—mechanism which redeives its control signal from the output of the phase detector. This servo—mechanism moves the fixed support of the primary spring of the seismometer as required. There is a flexible shaft coupling between the servo—mechanism in the amplifier chassis and the-seismometer. The seismogram is a cotposite record of the three components of motion. The recording paper is ten inches wide and the writing points are three inches apart. The paper speeds are one, two, fout, and eight millimeters per second. Speeds less than one millimeter per second could be furnished on special request. The speed may be changed by a small lever on the side of the recorder. The length of the recording paper is 1800 feet. This is enough to last for six days at one millimeter per second. The paper drive is powered by a 110 volt 60 cycle a. c. synchronous motor. The galvanometers are all identical. Each is built out of magnetic iron and is ruggedly constructed. The principle of operation of each galvanometer is as follows. An armature made of magnetic materie' is pulled into a magnétic pole when this polo is energized. The amount of deflection is a function of the energizing current. The deflection in the opposite direction is accomplished by energizing a different magnetic circuit on the opposite side of the armature. This is called a variable reluctance device. The deflecting force on the armature is not linear with the current through the energizing coils. The current through these coils is supplied by a vacuum tube. The current from this tube is not linear with respect to the voltage applied to the grids of these tubes. However, thé combined performance of the galvanometer and driving tubes, grid voltage versus deflection of the writing point, is a linear function. Ink is supplied to the writing point of the galvanometer from a plastic reservoir through a flexible plastic tube and a piece of stainless steel tubing. The writing point itself is made of stainless steel. The level of the ink in the reservoir is below the level of the writing point and only as much ink as is needed to wet the paper is.drawn from the point, The recorder may be placed as far from the seismometer and amplifier as might be desired. The only prerequisite is that the impedance (essentially the d. c. resistance) of the lines running between the amplifiers and the recorder be kept low compared to the 12,000 ohms impedance on each galvanometer, Three lines are required for each channel.

- 29 EARTHQUAKES IN THE REEF-HEARING REGIONS OF THE ILLINOIS BASIN by Ross R. Heinrich One of the interenting questions about the seismicity of the interion or "stable province" of the North Americah continent is: What is the tectonic significance of the minor earthquakes which occur in the Illinois Basin? Earthquakes that have epicenters in the northern portions of this basin are not comron, perhaps twentyfive are listed in the ordinary historical sources, and they have generally been slight in intensity. The southern borders of the basin have shown the most seismic activity in Illinois, Missouri, Kentucky, and Indiana. Within the basin itself som éarthquakes have been associated with the DuQuoin flexure in the vicinity of Centralia, Ill. 11 There has been a real scarcity of data on earthquakes in the northern part of the basin. Two recent earthquakes furnish sone information on this subject and serve to point out the importante of localizing the centers of small earthquakes in this region of relatively low seismicity. September 19, 1951.—An earthquake, with center in Madison County, I11., occurred at 20h 38m 43s local C. S. T. The shock was recorded at the St. Louis and Florissant seismograph stations at epicentral distances of 19.6 and 25 miles respectively. The shock was quite noticeable in Madison and St. Clair Counties, 111., and in the City and County of Saint Louis, Mo. It was particularly strong in Collinsville, Edwardsville, Alton, and Wood River, January 7, 1952.--A slight earthquake occurred at 16h 21m 05s C. S. T. in eest-tentral Illinois near the DeWitt -McClean County line. The shock located from the epicentral distances of 136 miles for Florissant•and 141.5 miles for St. Louis, was feit by only a few observers in Osman, Rankin, and Monticello, These epicenters lie in the zone which borders the north and northwest sides of the Illinois Basin where that feature unites with other regional structures—the Ozark dome near St. Louis and the LsSalle anticline near Bloomington, Of related interest is the foet that both of these epicenters were in the belt of reefbearing low-clastic sediments of Middle Silurian age which have been the object of much recent exploratory work for petroleum. This reef-bearing belt stretches northeast-southwest across Illinois along the line connecting the two epicenters. The epicenter of September 19 is near but west of the famous Marine Pool in Madison County, I11., discovery well for reef production in Illinoi9 2 ) The January 7 epicenter is near and southwest of the reefs of the Gibson City, area." ) The interest in the Marine Pool is indicated in the statements of Lowenstam that "The Marine Pool structure, as shows on top of the Silurian„does not resemble a normal deforma tional structure in Illinois" for although "the structure at Marine is an elongate dome trend ing northeast-southwest," "the horseshoe-shaped Marine structure is primarily an expression of reef topography." It seems to the writer that the apparent epicentral association of these and other slight earthquakes with certain structural alignments in the Illinois basin may be of real tectonic significance. *** THE FAYETTEVIIJF SEISMOGRAPH STATION by James E. Case The Fayetteville seismograph station was established in August 1951, as a cooperative project between the University of Arkansas and the United States Coast and Geodetic Survey. It is located about 2.5 miles northwest of the university campus in Fayetteville. The coordinates are 36 ° 05.46' north latitude, 94 ° 11.47' west longitude, elevation 1325 feet (404 m.). The seismometer and recorder are housed in separate units which are nearly 500 feet apart and are located in the extreme northwest corner of the permanent pasture of the university farm. The area is very quiet since there are no nearby bodies of water, tall structures, waterfalls, heavy traffic, or other generators of short-period microseisms. The narest rood parallels the west side of the pasture about 600 feet west of the seismometer housing. It is lightly traveled. (1) Heinrich and Frank. Earthquake Notes, vol. X, no. 3, 1938. (2) Lowenstam and DuBois. Illinois Geological Survey, Report of Investigations, no. 114, 1946. (3) Lowenstam. Illinois Geological Survey, Report of Investigations, no. 145, 1949.

- 30 The seismometer rests on a concrete pier 3 feet vide by 5 feet long, allowing room for additional instruments. The pier was built on the dense Boone limestone of lower Mississippian Age. An insulated concrete shell was constructed around the pier leaving a fourinch air space between the shell - walls and the aides of the rectangular pier. A heavy insulated cover fits over the shell and pier. The whole shelter was streamlined with backfill from the initial excavation to bedrock. To protest against curious cows in the pasture, a fence enclosing 1200 square feet was built around the seismometer housing. From the seismometer to this fence, the laad wires are carried by poles only 1 foot high. The poles are of standard height from the fence to the recording building near the gravel road. This building contains five rooms: a radio-clock room, recorder room, darkroom, and two storage rooms. The piekup equipment consists of a Benioff small model vertical recording seismometer. Its free period is 1.5 sec. and its demping ratio is 12:1. It operates a Lehner and Griffith galvanometer which has a free period of 0.5 sec. Tests have been made, using an electromagnet on a make-break circuit, to deternine the first motion orientation of the system as it.appears on the record. The system wires have been polarized so that trace up on the record, reading from left to right and from top to bottom, indicates a compressional movement of the ground. The system is operated at a very high sensitivity due to the quietness of the area. Peak magnification is attained for waves whose periode are around 0.7 sec. The recorder is a Sprengnether Series D-H. The galvanometer and recorder rest on piers which are about 2.5 feet apart. The galvanometer pier is 6 feet long and 1 foot wide. It projects 4.5 feet from the ground. The recorder rests on a pier 1.5 feet wide and 8 feet long. The extra pier space is in anticipatiort of horizontal components, amplification systems, and recorders when such instruments can be obtained. Time breaks are impressed on the record by signals from an IBM clock that is enclosed in an insulated box. Clock time is read from the beginning of the time breaks. The temperature within the box is held at 30 ° Centigrade by a thermostatically controlled heating unit. Time signals are received over a Hallicrafter SX-43 radio. The routine of station operation is as follows: Bach day the observer leaves the University campus around 4:30 p. m., C. S. T. and arrives at the station about 4:45. After readying the chemicals for use in developing the exposed record, he impresses the correct time on the record with a telegraph key which offsets the light source that writes the trace. The records are then changed, and the process is timed so that the first time break that appears on the new record is 5:00. The exposed record is then developed and given a partial wash. After time corrections have been placed on the new record, the bid one is taken to the Department of Geology for interpretation and a final wash. The total time at the station is about 30 minutes. The daily readings are sent to the Coast and Geodetic Survey by train which leaves Fayetteville at 8:00 p. m., so that nearly three hours are allowed for interpretation. A quarterly seismological bulletin is being published by the Department of Geology. The first issue of-the bulletin appeared in April 1952; this and .subsequent issues are being distributed to all institutions desiring copies for their information. A sample reading from the bulletin follows: Date June 24

i

Phase iP

ePP

Time (GCT) h m s 16 41 00 14 43 58

Period T Trace Amp. (sec.) (mm.) 1.0 1.3 1.9

1.5C 1.0- 1.6-

Remarks C&GS*-16-29-02 462°N, 154 °E. Kurile Islands.

C following the trace amplitude indicates a compressianal type wave; D would meen a dila tation. The asterisk following the reference authority, C8:0S*, indicates that Fayetteville was credited with helping establish the data on the Coast and Geodetic Survey epicenter cards. This may be helpful to the person doing research in that he will know Fayetteville readings for the earthquake are valid. There are several problems which must be solved before the station can be classified as truly satisfactory. Great damage is done to the record when electrical stoms set up inductances around the unshielded wires from the seismometer to the recorder. At times nearly four hours of record are rendered useless. The writer feels that the Fayetteville station can be of genuine value to seismology in the coming years. This statement is made upon considering the great sensitivity which the quiet location allows. It is also based on the hopeful assumption that the scientists of long experience in the field of seismology will continue to give their encouragement and aid to the development of the station as they have done since its installation.

- 31 Dr. George V. Cohee, chairman of the Department of Geology at the time of installation, was designated station director, and the writer was appointed observer. Dr. J. Norman Payne, present chairman of the Geology Department, is now station director. Dr. Dean S. Carder of the Coast and Geodetic Survey has acted as advisor to the station since he installed the instruments in August 1951, and his•instructions regarding station maintenance and record interpretation have been most important in the success of the station. Note. --James Case is a geophysics major at the University of Arkansas, Class of 1953. He has had no formal training in seismology, yet his diligence in keeping the station in first -class operating condition and his expertness in recognizing and reporting seismic events from the record are largely responsible for the preeminent role of the Fayetteville station in the epicenter program of the Coast and Geodetic Survey. - -DSC. ***

SYMPOSIUM ON EARTIQUAKE AND BLAST EI.NbCT ON STRUCTURES The symposium was held on June 26, 27, 28, 1952, at the University of California, Los Angeles, Calif., onder the joint sponsorship of the Earthquake Engineering Research Institute and the University. The Institute, incorporated in California in 1949, is a small nonprofit organization of engineers and scientists active in earthquake engineering, dedicated to serve the public welfare in the field of engineering seismology. A major objective of the symposium was to expedite the cross-flow of knowledge gained in recent years in investigating the effects of earthquakes and air blasts on structures, and the problems of structural design. Byerly, Housner, and Neumann discussed the mechanics of earthquakes, measurement of energy, earthquake risk, nature of ground motion, geological factors, and other basic features of the earthouake problem. Housner and Neumann advanced new concepts of earthquake intensity. Blast loads on buildings, obtained largely by empirical methods, were discussed by Bleakney, Marritt, and Reines. Methods of analysing structural response to earthquake and explosion forces were outlined by Jacobsen, Newmark, and Housner, Ulrich and Carder covered factors controlling structural vibrations. Building codes and aseismié design, including tests on structural mombers, were covered by Rinne, Bolin, Andrus, and Johnston, while Engle, Binder, Miller (A. L.) and others discussed the engineering lessons learned in some of the stronger shocks of the Pacific coast. Smith (S. B.), Anderson (B. G.), Bowman, and Wilbur gave parallel talks on bomb blast effects. Panel discussions on earthquake codes and structural design practices, led by H. W. Bolin and Paul E. Jeffers ended the three -day meeting. Participants included Andrus, Degenkolb, Rinne, Blume, Bowen, Derrick, Saph, and Taylor. The proceedings of the meeting may be purchased for $5.00 by addressing Prof. C. Martin Duke, Department of Engineering, University of California, Los Angeles, or Prof. R. W. Clough, Secretary, Earthquake Engineering Research Institute, Department of Engineering, University of California, Berkeley. Professors Duke and Feigen also have in preparation a summary of the symposium. The Proceedings includes luncheon and other talks by Wilbur, Heron, and Roberts. The speakers at the symposium represented practically all of the major engineering and scientific organizations throughout the country interested in earthquake and blast research, including private engineering consultants and contrac tors as veil as research units in many Federal agencies. --Frank Neumann. ENGINEERING SEISFOLOGY DISCUSSED AT CHICAGO MEETING It is reported that 59 American and foreign engineering groups participated by holding meetings in connection with the Centennial of Engineering held in September at Chicago, Ill. This occasion marked the one-hundredth birthday of the formal organization of the American Society of Civil Engineers, America's first professional engineering society. It probably saw more prominent engineers in one place at one time than had ever been the case before. The American Meteorological Society and the American Geophysical Union held a joint meeting on this occasion, including, on the afternoon of September 11, a symposium on Seismology As It Applies To The Design of Structures. Captain E. B. Roberts of the Division of Geophysics, U. S. Coast and Geodetic Survey, acted as Chairman and introduced the meeting with a statement on where we stand in engineering seismology. The symposium included the following six papers: The Nature of Destructive Earthouake Mations, by Frank Neumann. A Review of Factors Affecting Structural Response, by L. S. Jacobsen. Building Code Provisions for Aseismic Design, by J. E. Rinne. Aseismic Design of Elastic Structures Founded on Firm Ground, by L. E. Goodman. Rational Analysis of Earthquake Distortions in Structures, by E. Cohen. Visible Earthquake Effects and Practical Corrective Measures, by H. M. Engle.

- 32 This brief program brought together a variety of viewpoints and opinions and outlined remarkably well the extent of engineering thinking of today in this rapidly developing field. It is hoped that the majority of these papers will be published for more general consumption by the American Society of Civil Engineers. --Elliott B. Roberts THE COMMERCE BUILDING LOBBY SEISMOGRAPH RECORDING STATION OF THE U. S. COAST AND GEODETIC SURVEY by Roger M. Wilson In 1951 the Chief of the Division of Geophysics of the U. S. Coast and Geodetic Survey proposed to Rear Admiral R. F. A. Studds, Director, U. S. Coast and Geodetic Survey, that the installation of an ink-writing seismograph recorder in the main lobby of the Department of Commerce Building would provide an exhibit of lastring interest to the public and of genuine scientific value. This suggestion was in turn referred to the Secretary of Commerce and approved in principle. Early in 1952 the author was assigned the talk of arranging and directing such an instrumental installation. It was placed in operation September 29, 1952. The recorder is a two-speed (15 or 30 mm/min.) drum recorder with matching pen galvanometer mounted on an integral cast alumánum bracket. The pitch of the recorder lead screw was made 6.5 threads per inch so as to give as open a record as possible yet allow continuous operation over weekends without servicing. The pen galvanometer is of a new design which employs teut upper and lower suspensions and does not use ring jewels or other bearings. It is fitted with a three-inch Brush pen. The instruments were manufactured by the Surveyor Service Company, Inc., of Silver Spring, Md. The recorder and control box are mounted in a mahogany and plate-glass case which was huilt in the Instrument Division of the U. S. Coast and Geodetic Survey. It contains a drawer for paper, ink, and miscellaneous supplies. Three display panels were prepared by the Geographic Branch of the Chart Division, U. S. Coast and Geodetic Survey. They include brief descriptions of the equipment and three typical seismograms in addition to pictorial illustrations of the éarthquake menace and engineering and scientific seismology. A terminal box was mounted behind the recorder case and an 8 -wire cable about SOO feet long was run from it to the Seismological Laboratory. This provides the five necessary conductors plus three spares. The seismometer is a Wilson -Lamison short-period vertical located in the Gravity Room which is near the Seismological Laboratory in the basement of the Commerce Building. An

auxiliary cover has been provided and very little artificial disturbance is discernible on the records. The galvanometer is a General Electric Catalog No. 32C231G11 instrument with a period of 1.7 seconds.

The general system of operation is identical to that of previbus Coast and Geodetic Survey split -beam amplifier installations.kl, It was required that the visible recorder which has been operated for the past several years in the office of the Chief, Division of Geophysics, be continued in operation. In order to accomplish this with the minimum equipment, a special two -channel split -beam amplifier was built in the Laboratory. The first stage is identical to previous units but the second stage consists of two complete amplifier stages with the grids and plates connected in parallel and the cathodes connected to separate control and pen circuits. Thus both recorders are operated from one seismometer and galvanometer without loss in sensitivity or response and with no interaction. The existing power supply was modified slightly to furnish the additional current required to operate the second recorder. The lobby recorder is now writing excellent records. The pen galvanometer period was purposely adjusted to 1.5 seconds at which value it acts in conjunction with the other resonant elements of the system to give a filtering action which almost completely suppresses disturbances produced by machinery and traffic, but enhanées the recording of P and P' phases of earthquakes and gives fairly good records of the S and L phases of many qmakes. The efficiency of this seismograph may be appraised by observing the frequency with which the Washington station is reported on the Preliminary Determination of EDicenter and Supplement cards distributed by thé Coast and Geodetic Survey. (1) Wilson, Roger M., and Burgess, L. R. A Highly Stable Cathode-Coupled Amplifier for Seismic Recording, Bull. Seis. Soc. Amer., vol. 42, no. 4, 1952.

- 33 -

- 34 EARTHQUAKES FOR 1952 IN RETROSPECT by L. M. Murphy

The year 1952 was characterized by an unusually high frequency.bf earthquake swarms occurring in both active and semi-active seismic areas of the world. The two greatest earthquakes of the year, one of magnitude 8-k off Hokkaido, Japan, the other near the southeest coast of Kamohatka, and also the destructive southern California shock of July 21 were followed by hundreds of aftershocks with relatively high magnitudes. Other seismic regions experiencing prolonged earthquake activity included Mt. Etna, south coast of Hawaii, Kurile Islands, off east coast of Honshu, and New Britain. Minor swarms frequented the somewhat inactive áreas of the Sante Cruz Islands and off the coast of Oregon on two occasions. .

The summary of world earthquake casualities--200 killed, 1200 injured, and 10,000 buildings damaged or destroyed - -indicate an unusually safe year. Many single shocks mentioned in seismic history, for instante the 1906 California shock that killed 700 and damaged property valued at $90,000,000, have caused much greater devastation. In the United States where the people are generally speaking not earthquake conscious, nearly 15% of the fatalities and 50% of the property damage reported during the year resulted from shocks in this country. Ever since the disastrous seismic sea wave of April 1, 1946, seismologists have been very conscious of the possible repetition of such a catastrophe. It was not until November 4 the date of the major earthquake off Petropavlovsk, Kamchatka, that the seismic sea wave warning system painstakingly developed and maintained for six years by the U. S. Coast and Geodetic Survey received its first major test. Needless to say the system operated very satisfactorily providing ample time to evacuate areas of the Pacific that were in danger of being inundated. Some damage was reported on the islands and the low coastal areas of the Pacific. At Hilo, a recently completed $13,000 boathouse was demolished, barges ware torn from moorings, and highways flooded. Tide gages recorded such wave heights as 8 ft. at Attu, 7-3/4 ft. at Hilo, 8 ft. at San Francisco (outer coast) and 3- ft. at Golden Gate Bridge, 61 ft. at Callao, Peru, about the same in Chile, and 2/3 ft. on New Zeeland. Along the east coasts of the Japanese Islands a 10-foot sea wave resulting from the March 4 earthquake devasted the low coastal areas but caused only a few fatalities, proba bly due to the very efficient warning system in effect throughout the country. Small waves were recorded as far away as Wake, Guam, and the west coasts of North and South America. On July 21 many people in California, especially in Kern County, believed that a long expected repetition of the great San Francisco earthquake had occurred. Fortunately after the major rumblings had ceased, the shock was found not to be of such gigantic proportiona and had not centered near a large urban area. Property damage totaled $10,000,000 and 11 ware killed. The greatest damage occurred in Tehachapi and Arvin, with extensive damage in other nearby towns. Landslides raised havoc with many highways and severely damaged four tunnels of the Southern Pacific Railroad to the extent of $1,000,000. Three of the tunnels have since been converted into open cuts. Fire destroyed a multi-million dollar refinery in Bakersfield. Destruction of buried'irrigation pipes on ranches and loss of electric power caused untold agricultural losses.

The location of the major shock according to Pasadena is 35°00' north, 119°02' west and the tentative magnitude 7.7. The strongest aftershock near Bakersfield on August 22 killed two. The estimated total damage was $50,000,000 for the entire series of shocks which continue to be recorded daily (as of January 1) with magnitudes as great as 4. In the eastern United States, Burlington, Vermont, experienced a shock on January 29 strong enough to crack concrete pavement and cellar walls. On June 20 a slight tremor neer Zanesville, Ohio, was felt over an area bounded by Athens, Chandlersville, and Columbus. A similar tremor on August 24 in the central Mohawk Valley along Klock's Fault was feit strongest in Gloversville and Canajoharie, New York. Other minor shocks ware reported at Birmingham, Alabama, February 6; Reelfoot Lake, Tennessee, February 20; Charlottesville, Virginie, September 10; and Poughkeepsie, New York, October 8. The El Reno, Oklahoma earthquake of April 9, relt over saven States from Texas to Iowa, seemed to parallel the Nemaha Fault which extends from Oklahoma City to Omaha. Reports of minor damage ware received from a few towns near the epicenter. Additional week aftershocks followed on April 16, July 16, and August 14. Other slight shocks ware as follows: in Nevada at Reno, May 9; Boulder City and Las Vegas, May 24; in Missouri at Risco, Malden, and Perm, May 28; in Tennessee at Dyersburg, July 16 and October 17, and Johnson City, June 11; in Colorado at Antonito, October 7; in Oklahoma at Wewoka and Holden ville, October 9; and in Arkansas at Blytheville, December 25.

-35— In the Rocky Mountain region en intensity V shock rocked Niarado, Heron, and Eureka, Montana, on April 1. Tremors of local interest were: in the same State, Niarado and Helena, February 12 and 27; Moiese, April 14, and Townsend, May 29; in Utah at Santaquina, July 21; Salt Lake City, July 23; and Lehi and American Fork, September 28; in Arizona, near Tucson, October 22; and in New Mexico at Cimarron, August 3, and Los Alamos, August 17. Along the west coast there were the usual number of minor earthquakes in California and two in Washington which were felt in Spokane on March 4 and in Seattle on July 27. Two slight tremors were reported ir•anada, one at Banff, Alberta, on March 3 and the other near Quebec City on October 14 was feit at Ste. Anne de Beaupre, Three Rivers, Montreal, and northern Heine. The countries of Central and South America experienced their usual number of minor earthquakes with only a few worthy of comment. In the Colombian earthquake of April 19, buildings were cracked in Arboledas and Cucutillas, and a cathedral was damaged in Pamplona. A magnitude 7 shock oentered neer San Juan, Argentina, on June 11, killing 2, injuring 150, and shaking the cities of Santa Lucia, Desamparados,and Concepcion. At the end of the year, December 30, 26 facilities were reported in the area around the Irazu Volcano, in eest-tentral Costa Rica. From June 26 to July 3, a series of more than 30 earthquakes caused a few injuries and collapse of old stone buildings on Sao Miguel Island, Azores. Another series beginning October 28 near Anse -a -Veau, Haiti, killed 6, injured 50, and extensively damaged many weak structures. On the continent, Turkey was again visited by two danaging shocks --not because of their intensity but due to exceptionally poor building construction. In the province of Erzurum, January 3, property was severely damaged in 17 villages and 16,000 were made homeless. About 90 were killed and hundreds injured. On October 22 there were 18 more fatalities, 40 were injured, and extensive property damage occurred in the Adana area. In It.aly on the slopes of Mt. Etna, three were killed at Sante Vinerina and Zaffarano and rich vineyards ware laid waste by the strongest of several shocks on March 19 that began March 2. The strongest earthquake in recent years struck Ludwigshafen, Germany, on February 24, being felt as far away as Frankfort and Stuttgart. A rockburst in a mine at Johannesburg, South Africa, set off by a July 4 earthquake killed 7 minors. Similar bursts have frequently been reported in gold mines at Kirkland Lakes, Ontario, Canada. The Japanese earthquake of March 4, off Cape Erimo, Hokkaido, previouply referred to in discussing seismic sea waves, killed 60 and injured nearly 600. About 7,000 buildings were destroyed or damaged by the earthquake and sea waves. Fortunately the United States occupation forces responded immediately with relief supplies flown in by military aircraft. A series of 100 aftershocks during the following week added to the devastation of the area. A magnitude 7 shock on July 17 killed 3 and injured 100 in the vicinity of Osaka. Additional slight shocks in the Far East were reported in the Philippines at Camiguin, March 20; in Formosa at Hualein, January 1, and Taipeh, June 20; in Assem, January 16; and in the Tokyo Bay area, May 8. In the Hawaiian Islands a light tremor shook most of the islands on April 7. A magnitude 6 shock on May 23 caused landslides and falling rocks along the Mokuauteoweo crater, cracks along the highway between Napoopoo and Kailua, and damage to water tanks around Kona. ***

HAROLD E. McCONB Mr. Harold E. McComb, former Chief of the Geomagnetism Branch, Division of Geophysics, Coast and Geodetic Survey, died on October 11, 1952, at George Washington University Hospital, Washington, D. C., after a brief illness. His death terminated a career of 43 years service with the Coast and Geodetic Survey. Born in Wilsonville, Nebraska, on November 25, 1886, Mr. McComb was educated at the University of Nebraska receiving B. S. and M. A. degrees from that institution. He entered on duty with the Coast and Geodetic Survey on May 25, 1909, as magnetic observer. In July 1918, he enlisted in the U. S. Army and in September of the same year received a commission in the U. S. Naval Reserve. He returned to. duty with the Coast and Geodetic Survey on October 11, 1919, and was in charge of the Honolulu Magnetic Observatory for a period of more than 3? years. In 1927 he returned to the States where he served with the Bureau until taken ill in August just prior to his scheduled time of retirement on August 31, 1952.

-36During his long years of Government service, Mr. MbComb made outstanding contributions in the field of geophysics. He improved instruments and methods for making magnetic observations in the field and at magnetic observatories. Notable among his achievements were the tilt -compensation seismometer, the helical spring accelerometer, and the portable shaking table. He designed these basic instruments in geophysical research and supervised their construction. Mr. McComb was the recipient of many awards, the most recent one being the Department of Commerce Exceptional Service Award for outstanding service. He served as author of numberous articles and monographs including more than thirty scientific papers on geonagnetism and seismology. Mr. McComb served as Chairman of the Eastern Section in 1938 and was a frequent contributor to Earthcuake Notes. At the time of his death he was Chairman of the Committee on Observational Techniques of the International Association of Terrestrial Magnetism and Electricity. He maintained active membership in many scientific societies including the American Association for the Advancement of Science, Seismological Society of America, American Geophysical Union, Washington Academy of Science, Philosophical Society of Washington, and Society of Signa Xi.

*** FRANKLIN P. UIRICH Mr. Franklin P. Ulrich, Chief of the Seismological Geodetic Survey, San Francisco, died suddenly of haart hom and educated in the east, he was more widely known major part that he played in building up an engineering engineers.and university scientists.

Field Survey, U. S. Coast and failure on July 2, 1952. Although on the west'coast because of the seismological program among the

Mr. Ulrich was born October 26, 1891, in Schenectady, New York. He attended the public schools in that city and graduated from Union College with a B. S. in engineering in 1913. After a brief period of employment with the New York State Engineering Department he joined the Coast and Geodetic Survey where he was assigned to magnetic and seismological observatories at Tucson, Ariz., and Sitka, Alaska. In 1933 he took charge of the newly organized Seismological Field Survey in San Francisco. The network of strong-motion stations under Mr. Ulrich's supervision was expanded from an initial array of three to a total of 56 stations in the western United States and 7 in Central and South America. Because of his unlimited energy and great popularity he was frequently callod upon to give seismological talks before engineering societies, fraternal and civic clubs, and many educational institutions. Through the years he was a frequent contributor to technical journals and was active in many scientific organizations of which a few ware Seismological Society of America, Eastern Section, Structural Engineers ASsociation of Northern California, Pacific Coast Building Officials Conference, American Geophysical Union, American Society of Civil Engineers, and Advisory Committee on Engineering Seismology. *** NOTES ON PEN-RECORDING SEISMOGRAPHS by Roger M. Wilson and John J. McCue It is quite feasible to adjust the resonant neriod of a pen galvanometer over a considerable range by changing the positions of inertia weights on two 5-inch radial arms attached to the moving system. This method was used to adjust the period of the pen-galvanometer of the new Commerce Building lobby installation to the desired 1.5 seconds. A very interenting method of improving the operation of a pen recorder is descrihed by Ronald L. Ives in an article entitled "Continuons Recorder Keep-Alive Circuit," in Electronic; volume 25, number 11 (November 1952). The system is now being tested by the Coast and Geodetic Survey at Washington, but it is too early to make any report on the results obtained. Some visible seismograph recorders use pens made by the Brush Development Company for use with their well-knots; recorders. These pens have capillary glass tips which are prune to chipping or breaking when used with drum seismograph recorders. The Coast and Geodetic Survey is now using a Brush pen with a tip made from a 27 gauge 5/8-inch length B-D Yale stainless hypodermic needle. The broken glans tip was removed by dissolving the cement with alcohol, then heating over a soldering iron while pulling with tweezers. The new steel tip was cementerf in place with stick shellac using a small electric soldering iron as a source

- 37 of heat. The capillary tubing of the hypodermic needle was cut with a fine file, held in a small pin vice for beisding and grinding, rough ground on a dry oilstone, and the point finished on a hard Arkansas stone. The altered pen is giving excellent results at this time and appears quite promising. It has been in use for such a short period that it is impossille to make any estimate of its service life or general long-term performance. ***

STATION NOTES Mr. Gerald Shea has reactivated his privately operated station at Terre Haute, Ind. At the present time Mr. Shea is not publishing his results but makes them available to the U. S. Coast and Geodetic Survey. Prof. E. C. Jacobs, director of the Burlington, Vt., seismograph station, has installed a visible-recording seismograph (vertical component) manufactured by the Sprengnether Instrument Company. Preliminary results indicate that Professor Jacobs has greatly increased the efficiency of his station. Word was recently received that four geophysical companies of Houston, Texas, have donated $25,000 for the establishment of a seismograph station at Rice Institute. The companies making the gift mere General Geophysical Company, Independent Exploration Company, Robert H. Ray Company, and Seismic Exploration, Inc. These geophysical companies feel that the establishment of such a station at Rice Institute will be of definite value in fundamen tal research and will contribute to the solution of geophysical problems. It is expected in the near future that the Washington Square Branch of New York University will install a seismograph under the supervision of the Geology Department. A French scientific mission to Kerguelen Island in the South Indien Ocean is erecting a seismograph station under the supervision of N. Baltenberger. For the present a GrenetCoulomb vertical seismometer is being installed. Even before the station is completed arrangements haye been made whereby seismograph interpretations are to be wired to the French Embassy in Tananarive. The Embassy will make the data available to Rev. Charles Poisson who will relay the information to the U. S. Consul in Tananarive for transmittal to the State Department in Washington. These interpretations will be made available by the U. S. Coast and Geodetic Survey through the medium of the seismographic data sheets distributed weekly to interested organizations. The address of the station is Missions Australes, Ile de Kerguelen (Terres Australes et Antarctique Francaises). The Rev. Charles Deppermann, S. J. has re-established the Jesuit seismograph station at Baguio, Philippine Islands, after it suffered total loss as a result of World War II. He is now operating the following Sprengnether seismographs: Short-neriod vertical, two shortand long-period horizontals, and two visible recorders. The first seismological bulletins begimning July 1952 were recently distributed. The Pakistan Government with the assistance of UNESCO is establishing a network of five seismograph stations. Two stations, Quetta and Lahore, have already commenced operation. Quetta is located 30 ° 12.5' north, 67° 02.1' east and has been equipped with two Milne-Shaw horizontal seismographs and three components of the Sprengnether instruments. Future installations consist of a portable Wilmore seismograph, Wenner accelerometers, and refraction shooting unit. The coordinates of Lahore are 31 32.6' north, 74 19.7' east and the instruments are two Milne-Shaw horizontal components. Probable locations for the additional stations are Chittagong, Drash, and Karachi.

°

°

In the United States the U. S. Coast and Geodetic Survey has installed ar outpost station about 2 miles from the old station at Boulder City, Nev. The two stations at Overton, Nev., and Pierce Ferry, Ariz., were discontinued July 1952. The Overton equipment has been installed at the University of Minnesota, Duluth Branch, and will he operated under the direction of Professor Harold Hanson.

-38MIES AND REGDLATIONS OF THE EASTERN SECTION OF THE SEISMOLOGICAL SOCIETY OF AMERICA (Adopted in 1936, revised in 1939, 1946, and 1952) Section 1-4he Constitution of the Seismological Society of America provides for the authorization of sections of the Society, prescribes in general how sections shall be organized, and states how such sections shall be related to the Society. The following Rules and Regulations shall serve only as a guide to the officers of the Eastern Section and its Executive Committee in the execution of their duties. Officers Section 2--The Constitution of the Seismological Society of America specifies that a Section shall have an Executive Committee consisting of five members of the Society, four of whom shall be officers of the Section; namely, a Chairman, Vice-Chairman, Secretary, and.Treasurer. These officers and the other member of the Executive Committee shall be elected at the annual meeting of the Section, for a term of one year beginning the first of July following their election, or beginning 30 days following their election, if the annual meeting is held after July 1, in which case it is understood that the term of office shall not extend beyond July 1 of the following year unless the annual meeting is again delayed. No member shali hold the same office for more than three years in succession except the Secretary and Treasurer who may be elected to succeed themselves indefinitely. Section 3 —The Chairman shall preside at meetings of the Section and of the Executive Committee. He shall appoint all necessary conmittees after consultation with the Executive Committee, except that in the case of the Editorial Committee the Chairman of that Committee shall also be consulted. In absence of the Chairman, his duties shall be performed bv the Vice-Chairman. In the event of the office of the Chairman betoming vacant, the Vicr;Chairman shali become Acting Chairman for the balante of the unexpired term of the Chairman. In the absence of both Chairman and Vice-Chairman, the duties of the Chairman shall be performed by the fifth member of the Executive Committee, or in his absence by the Secretary, or in the absence of both, by the Treasurer. The Secretary Section 4 -The Secretary shall conduct the general correspondence of the Section and of the Executive Committee; keep in touch with the Chairman and other members of the Executive Committee in regard to matters of policy not provided for in the Constitution or in the Regulations; prepare notices of appointments of committees (excepting those appointed during and for the period of the annual meeting) for the signature of the Chairman; shall present to the Chairman inenediately before each session of the =val meeting a memorandum covering the items of business to be acted upon at that session; keep the minutes of all Section meetings and meetings of the Executive Committee, and prepare the minutes of the annual meeting for publication; notify the membership of the time and place of all Section meetings; prepare and mail to the membership programs of all meetings. He shall notify new members of the Executive Committee of their election. Prior to December 1, of each year, he shall obtain from the Treasurer the membership list mentioned in Section 5 of the Rules and Regulations, and article XVII of the Constitution ok the Society, and forward it to the Secretary of the Seismological Society of America. At the expiration of his term of office, he shall turn over to his successor, as Secretary, all Section records in his possession. If the office of Secretary becomes vacant, the Executive Committee shall elect a person to fili out the renainder of the unexpired term. -

The Treasurer Section S -The Treasurer shall, under the direction of the Executive Committee, have charge of the funds of the Section. Within two weeks after the date of his induction into office he shall prepare a budget for the term of his office, which shall be submitted through the Secretary of the Section to the Executive Committee for consideration; shall make disbursements in accordance with the budget as approved, with a tolerante of five percent (5%), or as otherwise authorized by the Executive Committee. If, due to unforeseer circumstances, the election of his successor is delayed so that the term of office of the Treasurer is extended beyond the period normally expected, a supplemental budget to cover the period in excess of his normal term of office may be submitted to the Executive Committee, subject to the same conditions, limitations, and restrictions as the•regular budget. He shall keep a record of members and subscribers to Earthquake Notes showing dates of receipts of dues and subscriptions and a record of all miscellaneous receipts. For the Executive Committee he shall act on all applications for membership in the Section, subscriptions to Earthquake Notes, and resignations from the Section; make all necessary changes in the mailing list, and keep a register of members showing dates of affiliation with the Section, transfers, resignations, deaths, etc., and shall include a.tumMary of such natters in his annual report to the Section. On the membership list which it is required -

-39— shall be submitted to the Secretary of the Society on December 31 of each year (Article XVII, Section 7, Constitution of the Society), through the Secretary of the Section, it shall be indicated after each name on the list whether the individual or organization is a member (as provided in Sections 4 and 5, Article XVII, Constitution of the Society), or is a subscriber to Earthouake Notes. Necessary information for the compilation of this list shall be obtained in advance from the latest available list of members of the Section. On or before December 15 of each year he shall report to the Executive Committee, through the Secretary, the standing of all individuals and organizations on the mailing list of the Section. He shall send ,out dues notices before January 20 of each year and collect the annual dues; shall pay all vouchers covering proper expenditures which have been approved by the Secretary acting for the Executive Committee and which are in accordance with the budget; Shell make petty disbursements for necessary postage, etc.; shall keep a journal showing dates of all receipts and disbursements of all funds of the Section (and of all funds of the Society which he may be obliged to handle); shall advance funds to officers, committees, or members only in accordance with the budget and regulations or on authorization of the Executive Committee acting through the Secretary; and shall subtuit an annual report at the first business session of the annual meeting, such report to cover the period from the date of the last annual report of the Treasurer to date of audit of his records. At the expiration of his term of office, he shall turn over to his successor as Treasurer all Section funds, accounts, documents, records, etc., in his possession, together with a complete statement of the condition of the Treasury from the date of the last approved annual report to such date of expiration of office. He shall also notify the Secretary of the Section of such transfer of accounts, funds, etc. If the office of Treasurer becomes vacant, the Executive Committee shall elect a person to fill out the renainder of the unexpired term. The Executive Committee Section 6--The Executive Committee shall have general charge of the affairs of the Section. The Chairman may call a meeting of this Committee at any time during his term of office that he can ohtain a quorum for the transaction of business. Three members shall constitute a quorum provided one is the Chairman or other officer acting for or on behalf of the Chairman. At other times the members of the Executive Committee may transact any item of business by mail, through the Secretary, and any member of the Executive Committee may at any time offer suggestions to the Committee through the Secretary relative to meetings, programs, policies, etc. As of September 1 of each year the Executive Committee shall decide upon a budget covering the period from that date to August 31 of the following year. The Executive Committee shall also act on all supplementary budgets for expenses not covered by the regular annual budget. On or before March 1 of each year, the Executive Committee shall act'upon the Treasurer's report of the standing of individuals and organizations on the mailing list. Unless contrary action is taken, those individuals or organizations more than one-half year in arrears in payment of dues or subscriptions to Earthcuake Notes shall be removed from the mailing list. Other Committees Section 7 - -Auditing Committee. A conmittee consisting of two members of the Society shall be appointed at least six weeks in advance of the annual meeting to audit the accounts of the Treasurer. This Committee shall prepare a report of such audit for presentation at the next annual meeting of the Section. Membership Committee. A comnittee consistimg of three or more members or associate members, the Chairman of which shall be a member of the Society, shall be appointed not later than September 1 of each year for the purpose of hringing to the attention of these interested in seismology the advantages of membership in the Society and the Section. Editorial Committee. There shall be an Editorial Committee consisting of three members or associate members of the Section, the Chairman of which shall be a member of the Society and he shall serve as the Editor of Earthouake Notes, and proceedings of the meetings. It shall be the duty of this connittee to read and review all copy intended for these publications at the discretion of the Chairnan of the Editorial Committee. The Chairman of the Editorial Committee shall assume responsibility for the publication and the text of Earthouake Notes. He shall be responsible to the Executive Committee for the publication and text of such publications.

-40Meetings Section 8 - -There shall be an annual meeting of the Section each calendar year, held preferably between April 1 and June 30, at such time and place as may be arranged by the Secretary acting for and with the consent of the Executive Committee. The order of business of the first session of the annual meeting shall be as follows: (1) Reading of the minutes of the last meeting, (2) reports of officers, (3) report of Auditing Connittee, (4) appointment of Nominating Committee for the five menbers of the Executive Committee, (5) appointment of Resolutions Committee, (6) reports of Standing or Special Comnittees, (7) unfinished business, (8) new business, and (9) presentation of papers. The order of business at the second session or third session of the annual meeting shall be as follows: (1) report of the Nominating Committee, (2) effection of the Executive Committee, (3) report of the Resolutions Committee, (4) unfinished business, (5) new business, (6) presentation of papers, and (7) adjournment. Amendments Section 9 -These rules and regulations of the Section may be amended by a two-thirds vote of those mombers present at the last session of an annual meeting provided that the proposed amendment is presented formally at the first session of the same annual meeting. -

***

OFFICERS OF THE

EAST~i

SECTION

CHAIRMAN

L. M•. Murphy, U. S. Coast and Geodetic Survey, Washington. VICE CHAIRMAN

Daniel J. Linehan, S. J., Weston College, Weston, Mass. SECRETARY

V. J. Blum, S. J., St. Louis University, St. Louis,

¥~.

TREASURER

Dean S. Carder, U. S. Coast and Geodetic Survey, Washington. FIFI'H MEMBER OF THE EXECUTIVE COMMITTEE

Ross R. Heinrich, St. Louis University, St. Louis, Mo.

CHAIRMAN OF THE EDITORIAL COMMITTEE

L. M. Murphy, U. S. Coast and Geodetic Survey, Washington. Ed~d J. Walter, John Carroll University, Cleveland, Ohio. Ross R. Heinrich, St. Louis University, St. Louis, Mo.

EARTHQUAKE NOTES is pUblished by the Eastern Section o£ the Seismological Society of America. Subscription $1.50 per year to members and those subscribers belonging to the Seismological Society of America, $2.00 per year to all other subscribers. Price o£ individual copies $0.50 each. Remittances should be made payable to D. S. Carder, Treasurer. Orders for back numbers and changes o£ address should be sent to the Chairwsn of the Editorial Committee.