PROGRESS REPORT ON SELECTED 

GEC^HYSICAL ACTIVITIES OF THE 

UNITED STATES; 1973-76

A QUADRENNIUM OF 

COOPERATION AND PROGRESS

GEOLOGICAL SURVEY CIRCULAR 763

/WENT
PROGRESS REPORT ON SELECTED 

GEOPHYSICAL ACTIVITIES OF THE 

UNITED STATES, 1973-76

A QUADRENNIUM OF COOPERATION 

AND PROGRESS

Edited by James N. Jordan, U.S. Geological Survey, 

and Kendall L. Svendsen, National Oceanic and 

Atmospheric Administration

GEOLOGICAL SURVEY CIRCULAR 763

FOR PRESENTATION TO THE HL PANAMERICAN CONSULTATION ON GEOPHYSICS, QUITO, ECUADOR, AUGUST 15-20, 1977

SUBMITTED BY THE UNITED STATES 

MEMBER OF THE COMMISSION ON GEOPHYSICS OF THE PANAMERICAN INSTITUTE OF GEOGRAPHY AND HISTORY, 

A SPECIALIZED AGENCY OF THE ORGANIZATION OF THE AMERICAN STATES

1977
United States Department of the Interior

CECIL D. ANDRUS, Secretory

Geological Survey

V. E. McKelvey, Director

Library of Congress catalog-card No. 77-600026

Free on application to Branch of Distribution, U.S. Geological Survey, 7200 South Eads Street, Arlington, VA 22202
Preface

This report contains information on some of the United States 

activities of interest to the Commission on Geophysics and its 

committees. More detailed information may be obtained from the 

journals of the various professional societies concerned with the 

areas that are of interest to the Commission both those activities 

solely within the United States and those joint projects that 

involve U.S. and Latin colleagues in the hemisphere. In particular, 

refer to the U.S. National Report (1971-74) to the International 

Union of Geodesy and Geophysics in Reviews of Geophysics and Space 

Physics, American Geophysical Union, v. 13, no. 3, July 1976. 1 

Of special note among the many contributors to this report, we 

would like to cite the following: Margaret Ann Shea of AFGL; 

George W. Wetherill, L. Tom Aldrich of CIW/DTM; Ellis Krinitzsky 

of USA/COE; Stephen E. Patchett, Roman Geller of DMA/IAGS; George P. 

Woollard of HIG; Gilbert D. Mead, Richard J. Allenby of NASA; Boyd E, 

Olson, Robert H. Higgs of NAVOCEANO; Rutlage J. Brazee, Kendall L. 

Svendsen, Paul'J. Grim, J. Bruce Grant, Harris B. Stewart, Jr., 

Jerry L. Coffman, Jeffrey P. Calebaugh, Mark G. Spaeth, Raymond 0. 

Conkright of NOAA; Lauriston R. King of NSF; Tom Simkin of SI; 

John S. Derr, Waverly Person, Carl W. Stover, Albert M. Rogers, Jr., 

Stanley Brockman, Charles Knudsen, Walt W. Hays, M. Dean Kleinkopf, 

Eugene B. Fabiano, John D. Wood, James Jordan of USGS.

James N. Jordan 

Kendall L. Svendsen

*Use of brand names in this report does not constitute endorsement 

by the U.S. Geological Survey.
U.S. NATIONAL SECTION 

COMMISSION ON GEOPHYSICS 

PAN AMERICAN INSTITUTE OF GEOGRAPHY AND HISTORY

National Member

Mr. James N. Jordan 

U.S. Geological Survey

Alternate National Member

Mr. Kendall L. Svendsen

National Oceanic and Atmospheric Administration

Committee on the Solid Earth 

Active Member

Dr. Peter L. Ward 

U.S. Geological Survey

Alternate Member

Dr. M. Dean Kleinkopf 

U.S. Geological Survey

Committee on Oceans and Atmospheres 

Active Member

Mr. Nels E. Johnson

National Oceanic and Atmospheric Administration

Alternate Member

Dr. Jose Colon

National Oceanic and Atmospheric Administration

Committee on Solar-Terrestrial Physics 

Active Member

Ms. Margaret Ann Shea

Air Force Geophysics Laboratory

Alternate Member

Mr. Raymond 0. Conkright

National Oceanic and Atmospheric Administration
ORGANIZATIONS CONTRIBUTING TO THIS REPORT

Air Force Geophysics Laboratory (PHE) 

Space Physics Division 

Hanscom Air Force Base 

Bedford, MA 01731

Department of Terrestrial Magnetism 

Carnegie Institution of Washington 

1541 Broad Branch Road, NW 

Washington, DC 20015

Waterways Experiment Station 

Corps of Engineers 

Department of the Army 

P.O. Box 631 

Vicksburg, MS 39180

Defense Mapping Agency

Inter American Geodetic Survey

Drawer 934

Fort Clayton, Canal Zone

Office of Earthquake Studies 

U.S. Geological Survey 

Federal Center, Box 25046, Stop 968 

Denver, CO 80225

Office of Earthquake Studies 

U.S. Geological Survey 

Stop 905, National Center 

Reston, VA 22092

National Center for Earthquake Research 

U.S. Geological Survey 

345 Middle field Road 

Menlo Park, CA 94025

Office of Geochemistry and Geophysics 

U.S. Geological Survey 

Federal Center, Box 25046, Stop 964 

Denver, CO 80225

Hawaii Institute of Geophysics 

University of Hawaii at Manoa 

2525 Correa Road 

Honolulu, HI 96822

Geophysics Division

Goddard Space Flight Center

National Aeronautics and Space Administration

Greenbelt, MD 20771

Atlantic Oceanographic and 

Meteorological Laboratories 

15 Rickenbacker Causeway, Virginia Key 

Miami, FL 33149

Environmental Research Laboratories 

National Oceanic and Atmospheric 

Administration 

Boulder, CO 80302

National Geophysical and SolarTerrestrial Data Center 

Environmental Data Service 

National Oceanic and Atmospheric 

Administration 

Boulder, CO 80302

National Weather Service (W13)

National Oceanic and Atmospheric

Administration

8060 13th St.

Silver Spring, MD 20910

Director

International Decade of Ocean 

Exploration Program 

National Science Foundation 

Washington, DC 20550

Latin American Cooperative Science

Program

Office of International Programs

National Science Foundation

Washington, DC 20550

Magnetic Division (Code 3520) 

U.S. Naval Oceanographic Office 

Bay St. Louis, MS 39522

Technical Director (Code 02) 

U.S. Naval Oceanographic Office 

Suitland, MD 20373

Division of Petrology and Volcanology 

National Museum of Natural History 

Smithsonian Institution 

Washington, DC 20560

VI
CONTENTS

Page

Solid earth geophysics ........................................ 1

Earthquake studies ......................................... 1

U.S. earthquake damage statistics (1973-1976) ........... 1

National Earthquake Information Service ................. 1

Intensity surveys ....................................... 5

Seismological data services of the National Geophysical

and Solar-Terrestrial Data Center .................... 5

Engineering applications ................................ 5

Induced seismicity ................................... 5

Seismological and geological review of nuclear

reactor sites ..................................... 7

Strong-motion program ................................ 9

Earthquake hazards ...................................... 13

Prediction of seismic and volcanic activity ................ 13

Earthquakes ............................................. 14

Volcanic eruptions ...................................... 15

Geophysical exploration .................................... 15

Geomagnetism ............................................... 17

Operations .............................................. 17

Data services ........................................... 17

Heat flow .................................................. 19

Volcanology ................................................ 19

Marine geophysics .......................................... 19

International Decade of Ocean Exploration and

International Phase of Ocean Drilling ................ 19

Cooperative Investigation of the Caribbean and Adjacent 

Regions and Intergovernmental Oceanographic Commission 

Association for the Caribbean and Adjacent Regions ... 19 

Nazca Plate Project ..................................... 20

Other activities ........................................ 20

Scientific Event Alert Network ............................. 21

Earth structure studies by the Department of Terrestrial 

Magnetism/Carnegie Institution of Washington and various 

groups in Latin America ................................. 22

Anelasticity ............................................ 22

Seismicity .............................................. 22

Explosion seismology .................................... 22

Electrical conductivity in the Andes .................... 22

Defense Mapping Agency/Inter-American Geodetic Survey

geophysical activities in Latin America ................. 23

National Aeronautics and Space Administration geophysical

projects in Latin America ............................... 23

Oceans and Atmospheres ........................................ 23

International Decade of Ocean Exploration .................. 23

Living Resources Program ................................ 23

Seabed Assessment Program ............................... 25

Tsunami Warning System ..................................... 25

Solar-terrestrial physics ..................................... 26

Data bases ................................................. 26

Catalog of possible collaborators .......................... 28

Other activities ........................................... 29

Progress in the science .................................... 30

VII
Page

Special projects of the PAIGH involving the U.S. Member of the

Commission on Geophysics ................................... 30

Geomagnetism projects ...................................... 30

Latin American-United States cooperative work in

geomagnetism ......................................... 30

Site planning for geomagnetic facility in Costa Rica .... 31

Latin American-United States cooperative work in

geomagnetism Phase Two .............................. 31

Preparation of a catalog of principal facts for gravity 

stations and gravity anomaly maps on a. common scale 

for Latin America ....................................... 32

Seminar on seismic and volcanological risk ................. 33

lonogram scaling course .................................... 33

ILLUSTRATIONS

Page

FIGURE 1. Map of NEIS seismograph network .................... 4

2. Earthquake report questionnaire .................... 6

3. Map locating major CE (Corps of Engineers) 

projects and reservoirs instrumented for 

microearthquake monitoring ...................... 7

4. Map of nuclear power reactors in the United

States .......................................... 8

5. Map of United States accelerograph network,

September 1976 .................................. 9

6. Map locating Central America strong-motion

stations ........................................ 10

7. Map of Latin America and Caribbean strongmotion accelerographs ........................... 11

8. Map locating large-magnitude and destructive

earthquakes in Middle America ................... 13

9. Contour map of United States showing horizontal acceleration (percent of gravity) 

in rock (with 90 percent probability of not 

being exceeded in 50 years) ..................... 14

10. Map locating project MAGNET surveys, southern

PAIGH area, 1973-1976 ........................... 18

11. Map of JOINT-II area showing hydrography

lines forming the JOINT-II research grid ........ 24

12. Map of reporting stations of the Tsunami

Warning System .................................. 27

13. Map locating solar-terrestrial physics

stations ........................................ 28

TABLES

TABLE 1. Significant earthquakes of the United

States, 1976-1976 ........................

2. Organizations with more than 10

accelerographs ...........................

3. Significant accelerograph records, 1973-1976

4. Tsunami activity, 1973-1976 .................

Page

10

11

26

VIII
PROGRESS REPORT ON SELECTED

GEOPHYSICAL ACTIVITIES OF THE

UNITED STATES, 1973-76

Solid earth geophysics

Earthquake studies 

UcS. earthquake damage statistics (1973-76)

A number of damaging earthquakes struck the 

United States in this quadrennium. Some of 

these appear to have been rare events, causing 

minor damage in Minnesota, Florida, Pennsylvania, New Jersey, Tennessee, Georgia, Nebraska, 

Alabama, and Kentucky. Damaging earthquakes 

also struck Alaska, Hawaii, California, Idaho, 

Illinois, South Carolina, Montana, Wyoming, New 

York, New Mexico, Arizona, and Oregon. The most 

significant events are listed in table 1.

National Earthquake Information Service

This activity was transferred to USGS (U.S. 

Geological Survey) in September 1973 from NOAA 

(National Oceanic and Atmospheric Administration), where it had been known as NEIC (National 

Earthquake Information Center). In August 1974 

the office was moved from Boulder about 32 km 

south to Golden, Colo. The PDE (Preliminary 

Determination of Epicenters) and WWSSN (Worldwide Standardized Seismograph Network) programs 

are now under USGS; historical data services are 

provided by NOAA EDS (Environmental Data Service). Thus, hypocenters are computed and published by NEIS, but hypocenter data-file services such as searches and selective listings 

are provided by EDS. Likewise, the WWSSN is 

administered and serviced and its quality controlled by USGS, but the network seismograms are 

are microfilmed and copies are provided to the 

users by EDS. James F. Lander is now responsible for the EDS seismic data services; his 

former position with NEIS in now filled by 

Waverly Person.

Many of the tsunami-warning observatories 

have also changed authority. Guam, Mariana 

Islands, Newport, Wash., and San Juan, P.R., 

are now in USGS, while Honolulu, Hawaii, and 

Adak and Palmer, Alaska, are still in NOAA. 

All of these observatories still cooperate 

closely in the tsunami program. Nine stations 

in the U.S. Network are telemetered to Newport 

Observatory, Wash., providing rapid data at 

Newport and for the Tsunami Warning System 

in Honolulu, from an area covering the 48 contiguous United States. The specific stations, 

in addition to Newport Observatory, are Albuquerque, N.M., Dugway, Utah, Kanaka Peak, 

Calif., Glamis, Calif'., Large Aperture Seismic Array stations (Montana), Gold Mountain, 

Wash., Liberty all, S.C., Potsdam, N.Y., and 

Glen Canyon, Ariz.

The U.S. Network of seismographic stations 

has expanded to both coasts in the past 4 

years. Figure 1 shows the participating stations that are now telemetered to Golden and 

recorded in real time on develocorders and helicorders. The stations that cooperate by sending readings by telephone for significant events 

are also shown. This network is still expanding, and state-of-the-art digital telemetry 

units are gradually replacing the older FM 

systems.

The NEIS continues to publish the PDE, EDR 

(Earthquake Data Report), and PDE Monthly Listing. Other publications are an annual report 

(Coffman and Stover, 1976) and quarterly reports on U.S. earthquakes (Stover and others, 

1976a, b, c; Simon and others, 1976, 1977). 

The service was interrupted temporarily in 

1975 during a change to a new and very different 

computer. Some recovery in schedule has since 

been made, but the computer has just recently 

been changed again. USGS is now utilizing a 

commercial computer service while the entire 

system is being rewritten for the new Honeywell 

Multics computer. PDE monthly listings are now 

(June 30, 1977) published through July 1976 and 

the publishing program is being accelerated. 

More up-to-date PDE's are available through a 

bi-weekly series of publications. When the new 

system is completely operational, events should 

be published within 2 weeks of their occurrence.

Over the last 4 years, the amount of data 

coming to NEIS by both telegrams and air mail 

has increased significantly. In addition, another mode of data input has been initiated: 

direct computer link. At present, data from 

Canada and some other countries are obtained by 

having NEIS call the remote host computer and 

copy a data file to a cassette tape in the 

standard telegraphic format. Another mode, to 

be initiated this year, is to have observatories 

in the United States call the NEIS computer using a toll-free WATS line and enter the data 

directly. Advantages of this latter system 

are that the contributing observatories can 

check their data to assure accuracy, locate hypocenters and determine magnitudes using USGS 

computer programs, and search current and historical files, all at no cost to the observatory. 

As hemisphere telephone service improves, it may 

become practical for neighboring countries to 

use such services.

In the meantime, hemisphere nations that do 

not report to NEIS are encouraged to work out 

arrangements for contribution of data telegraphically over the U.S. State Department AUTODIN 

circuit.
Table 1. Significant Earthquakes of the United States, 1973-1976

[Leaders ( ) indicate no data. PAS, Pasadena; 

BLA, Blacksburg; TUL, Tulsa;

BRK, Berkeley; SLM, St. Louis Un

SHA, Spring Hill]

Date Origin time Lat Long 

(UTC)

Hr Min S

Location Depth 

(km)

Magnitude 1

USGS Other

1973

Feb. 21 14 45 57.3 34.1 N. 119.0 W. Southern California 

Apr. 26 20 26 28.0 19.9 N. 155.1 W. HawaiiJune 15 01 09 04.2 45.32 N. 70.91 W. MaineJuly 1 

Nov. 30

13 33 34.6 57.8 N. 137.3 W. Off coast of southeastern Alaska. 

07 48 41.2 35.80 N. 83.96 W. Tennessee -

8 5.2 5.9 PAS Seve

ap

dam

Ox

San 

Ob

50 6.1 6.3 PAS Eleve

6.2 ML $5

th

12 4.8 mb Maxim

in 

Rh

Ver

Mai

Qu

Mag

33 6.7 6.7 PAS Minor 

6.1 mb in 

3 5.6 mb Minor 

are

gia

So

We

(B

1974

Feb. 15

Apr. 20

Aug. 2

Nov. 11

13 33 49.2 36.5 N. 100.7 W. Texas Panhandle

region.

03 00 09.3 46.76 N. 121.52 W. Washington08 52 09.8 33.87 N. 82.49 W. Georgia -

05 17 51.0 51.6 N. 178.1 W. Andreanof Islands,

Aleutian Islands.

24 4.5

5 4.8 mb

4.9 ML

1 4.3 mb

68 5.8 mb

Maxi

Kan

De

de

Ala

Felt 

Sligh

St

No

Ca

4.

Mino
1975

Feb. 2

Feb. 4

Feb. 22

Mar. 28

May 18 

June 7

June 30

July 8

July 9

Aug. 1

Aug. 2

Sept. 24

Nov. 29

08 43 39.1

01 32 52.1

08 36 07.4

02 31 05.7

15 42 59.1 

08 46 22.4

18 54 13.4

09 37 27.3

14 54 15.1

20 20 12.9

10 18 17.9

17 19 37.2

14 47 40.4

53.1 N.

48.2 N.

51.4 N.

42.06 N.

63.17 N. 

40.57 N.

44.75 N.

29.46 N.

45.67 N.

39.44 N.

53.39 N.

25.15 N.

19.3 N.

173.5 E. Near Islands, Aleutian

Islands.

114.1 W. Montana 

179.4 W. Andreanof Islands,

Aleutian Islands.

124.14 W. Near coast of northern

California.

110.61 W. Yellowstone National

Park , Wyo .

113.35 W. Gulf of California -

96.04 W. Near Morris, Minn. 

121.53 W. Oroville, Calif. 

161.49 W. South of Alaska 

109.26 W. Gulf of California 

"ICCr*TA7 HI a T.T :a -i -i _ ____ _ _

10

48

5

106

21

7

33

10

15

33

33

5

7.6

6.1 mb

4.6 mb

5.0 ML

6.5

6.3 mb

6.0-

6.1 ML 

5.4 mb

5.7

5.4 mb

5.9

6.5

4.6 mb

5.6

6.0

6.2 mb

5.7

7.1

7.5 PAS

7.4 BRK

6.4 BRK

6.0 PAS

6.2 PAS

5.2 ML

BRK

6.1 BRK

 

 

5.7 ML

BRK

5.7 BRK

5.8 BRK

7.2 PAS

Fifte

She

on 

Minor 

Kal

Tre

Lak

Felt 

$1 mi

T? 1 4- r e JLH- .

Damag

Del

Felt. 

Felt.

Felt. 

Damag

Felt 

 

Tsuna

mil

1976

Jan. 5

Feb. 4

Mar. 25

Apr. 13

Nov. 26

06 23 32.9

00 04 58.1

00 41 20.5

00 47 17.1

11 19 23.1

35.84 N.

34.66 N.

35.60 N.

45.22 N.

41.35 N.

108.34 W. New Mexico 

112.50 W. Western Arizona 

120.77 W. Washington-Oregon

border region.

125.77 W. Off coast of northern

California.

25

12

15

15

33

5.0 mb

4.6 ML

4.9 mb

5.1 ML

4.9 mb

3.3

4.5 mb

4.8 ML

6.8

5.2 ML

PAS

5.0 mb

SLM

 

6.1 ML

BRK

Sligh

Gal

New 

Sligh

Pau

Val

Moh

Pin

dam

Sligh

Fel

Ill

Mis

Sligh

Ore

Dal

in 

ing

Felt 

1 AII magnitudes MS unless otherwise stated.
128° 124° 120° 116° 112° 108° 104° 100° 96° 92° 88° 84° 80° 76° 72 « 68° 64°

Berkeley and 

Menlo ParkNets

--T---- CANADA

UNITED] STATES J

BDW

'-/Salt Lake City 

Net \ *LAR

San Diego Net A ~~XN TUC , SNM Net \ A LUB

Cooperating stations 

Telemetry mode 

26°- Digital 

FM

30°-

22°-

FIGURE 1. NEIS seismograph network; abbreviations as in Covington (1974). Networks cited 

indicate a central recording station from 

which one or more stations may be used by the 

NEIS network. AAM, Ann Arbor, Mich.; AGM, 

Allagash, Maine; ALG, Albuquerque, N. Hex.; 

AMG, Americus, Ga.; ANl, Anna, Ohio; ARN, 

Arnold Ranch, Calif.; ATL, Atlanta, Ga.; BAV, 

Blackburg, Va.; BDW, Boulder, Wyo.; BEI, Bear 

River Range, Idaho; BFW, Baw Faw Mountain, 

Wash.; BGO, Bowling Green, Ohio; BLO, Bloomington, Ind.; BMN, Battle Mountain, Nev.; 

BNH, Berlin, N.H.; BNY, Binghamton, N.Y.; 

BRK, Berkeley, Calif.; BUT, Butte, Mont.; 

CBN, Corbin, Va.; CHC, Chapel Hill, N.C.; 

CHI, Chicago-Loyola, 111.; CLE, Cleveland, 

Ohio; COR, Corvallis, Oreg.; CPO, Cumberland 

Plateau, Tenn.; DBQ, Dubuque, Iowa; DCU, Deer 

Creek, Utah; DON, Dongola, Mo.; DUG, Dugway, 

Utah; ELC, Elco, 111.; ELK, Elko, Nev.; 

EMM, East Machias, Maine; EPT, El Paso, lex.; 

FAV, Fayetteville, Ark.; FHC, Fickle Hill, 

Calif.; FVM, French Village, Mo.; GCA, Glen 

Canyon, Ariz.; GLA, Glamis, Calif.; GLD, 

Golden, Colo.; GMW, Gold Mountain, Wash.; 

GOL, Golden, Colo.; GPD, Green Pond, N.J.; 

HBF, Harts Bluff, S.C.; HBV, Harrisonburg, 

Va.; HHM, Hungry Horse, Mont.; HID, Hammer 

Butte, Idaho; HKT, Hockley, lex.; INY, Ithaca, 

N.Y.; JAS, Jamestown, Calif.; JCT, Junction

City, lex.; JSC, Jenkinsville, S.C.; KNB, 

Kanab, Utah; KPK, Kanaka Peak, Calif.; KIT, 

Kermit, Tex.; KTZ, Kutztown, Pa.; LAC, Landers, 

Calif.; LAO, LASA array, Mont.; LAR, Laramie, 

Wyo.; LDM, Libby dam, Montana; LEK, Lexington, 

Va.; LEX, Lexington, Va.; LUB, Lubbock, Tex.; 

MCW, Mt. Constitution, Wash.; MHK, Manhattan, 

Kans.; MNM, Minneapolis, Minn.; MNV, Mina, 

Nev.; MRG, Morgantown, W. Va.; MSO, Missoula, 

Mont.; NED, Newark, Del.; NEW, Newport, Wash.; 

NMC, Nine Mile Canyon, Calif.; ORT, Oak Ridge, 

Tenn.; PEC, Perris, Calif.; PNO, Pendleton, 

Oreg.; POW, Powhatan, Ark.; PRM, Parsons 

Mountain, S.C.; RMU, Rainbow Monument, Vt.; 

ROL, Rolla, Mo.; SCP, State College, Pa.; 

SEA, Seattle, Wash.; SHA, Spring Hill, Ala.; 

SLM, St. Louis, Mo.; SNM, Socorro, N. Mex.; 

TNP, Tonopah, Nev.; TUC, Tucson, Ariz.; 

TUL, Tulsa, Okla.; UWM, Milwaukee, Wis.; 

WCN, Washoe City, Nev.; WES, Weston, Mass.; 

WKR, Work Ranch, Calif.; WNC, Wilmington, 

N.C.; WPM, White Pine, Mich. NETWORKS: 

Berkeley and Menlo Park, Calif.; Connecticut; 

Idaho; Kermit, Tex.; Las Vegas, Nev.; Los 

Alamos, N. Mex.; Massachusetts Institute of 

Technology; Nevada; New York; Pasadena, Calif.; 

St. Louis, Mo.; Salt Lake City, Utah; San 

Diego, Calif.; Seattle, Wash.; South Carolina; 

Weston, Mass.
Intensity surveys

The intensity and (or) damage data for U.S. 

earthquakes are collected, in general, by means 

of a mail canvass using the "Earthquake Report" 

questionnaire (fig. 2). The canvass is made using a computer file of addresses of postmasters, 

government employees, police headquarters, and 

so forth, which is searched for the addresses 

located in the area affected by the earthquake. 

The line printer used this list to address the 

questionnaires; they are then mailed. When the 

size of the earthquake warrants it, a field 

survey of damage is made by a geophysicist and 

(or) engineer, and the data are incorporated 

with the mail canvass and used in compiling the 

intensity report. Figure 2 is the questionnaire now in use by USGS. It is designed for 

computer evaluation and for use in automated 

isoseismal mapping.

The intensity data collected by the method 

described above are published in the report on 

U.S. earthquakes (Stover and others, 1976a, b, 

c; Simon and others, 1976, 1977), which consists 

primarily of two sections. The first is a tabular listing of earthquakes, in chronological 

order by State, consisting of the following 

basic information: date, origin time, hypocenter, magnitude, maximum intensity, and the computation source of the hypocenter. The second 

sections consists of seismicity maps, isoseismal 

maps, and detailed descriptions of damage and 

feld data. These data, along with strongmotion, tsunami, and water-well-fluctuation 

data, are also included in the annual publication "United States Earthquakes," published 

jointly by USGS and NOAA. In addition to the 50 

States, this publication contains data from the 

Panama Canal Zone, Puerto Rico, and the Virgin 

Islands (Coffman and Stover, 1976).

Seismological data services of National 

Geophysical and Solar-Terrestrial Data Center

As part of the 1973 agreement under which 

most of the seismological activities of NOAA 

were transferred to USGS, many of the seismological data services were retained in NOAA's EDS 

(Environmental Data Service), more specifically 

NGSDC (National Geophysical and Solar-Terrestrial 

Data Center). In addition to their traditional 

responsibility for collecting, microfilming, 

archiving, and disseminating copies of the seismograms from the WWSSN, NOAA (via NGSDC) retained 

responsibility for maintenance of the historical 

earthquake data files and the dependent data 

services. Furthermore, operation of World Data 

Center A for Solid Earth Geophysics was implemented, with the present chief task being collection of worldwide seismograms for selected 

major earthquake events.

The efforts to date have resulted in two 

important magnetic tape files, one containing 

the hypocenter locations, magnitudes, and other 

coded information on 130,000 earthquakes of historical record derived from NEIS, ISC (International Seismological Centre), and many local 

sources; and the other, a catalog of all intensity reports for U.S. earthquakes that have been 

collected for the years from 1928 to 1974. Both

files are continuously updated and expanded by 

the addition of earlier information gathered 

from older sources. The tapes are in a multiaccess format, by which investigators may acquire information based on 15-20 single parameters such as area, time interval, magnitude, 

and maximum intensity, or on multiple combinations of these factors. A microfilm file of all 

strong-motion seismograms written by instruments 

of the Seismological Field Survey of Menlo Park, 

Calif., and a file of tsunami mareograms are 

also available. Digitized tapes of the more 

significant of the strong-motion seismograms 

(currently about 350) are also on file. They 

were produced, for the most part, by the Earthquake Engineering Research Laboratory of the 

California Institute of Technology, with some 

additions digitized by NGSDC in Boulder. Investigative work during the period has been confined to search out and editing source materials 

and a detailed analysis of the Modified Mercalli 

Scale.

The newest activity of NGSDC is collecting 

very long period digital seismic recordings from 

the IDA (International Deployment of Accelerometers) program and making them available to users. 

The IDA is a worldwide network of digitally recording La Coste-Romberg gravimeters, operated 

by the University of California at San Diego in 

cooperation with many foreign institutions and 

with support from the Cecil and Ida Green Foundation and the National Science Foundation. Of 

the projected 20 stations, seven are already in 

operation, including the Western Hemisphere 

stations of Halifax, Nova Scotia; Pinon Flat, 

Calif.; and Nana, Peru. These data are unique 

in providing very long-period digital recordings 

of Earth tides and of free oscillations of the 

Earth. They have applications in the analysis 

of the Q of the free oscillations, elasticity, 

and density of Earth; earthquake source mechaism; and Earth and regional structure models.

For further information refer to NGSDC's 

"Earthquake Data Services and Publications" and 

"Earthquake Data File Summary, Key to Geophysical 

Records Documentation No. 5."

Engineering applications 

Induced seismicity

Seismicity studies in the United States 

are under way at Auburn dam, California; New 

Melones dam, California; and Teton dam, Idaho. 

The Auburn dam network comprises 19 seismograph 

stations covering an area from Oroville on 

the north to New Melones on the south. These 

stations monitor the Foothills fault zone. 

Eight seismograph stations are located in the 

vicinity of the New Melones damsite. A threestation seismograph unit is operating at Teton 

dam.

Post-impoundment studies are continuing 

at Lake Oroville, Calif., where a 24-station 

seismograph array is operating. A cause-andeffect relationship between the seismicity 

observed at Lake Oroville and the lake impoundment 

is not clearly defined. No earthquakes were 

observed for the first 6 years after the lake 

was filled in 1969. The seismicity, which 

began in 1975 and included a magnitude 5.9
U.S. DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY

EARTHQUAKE REPORT

Form Approved 

OMB No. 42-R1700

Please answer this questionnaire carefully and return as soon as possible. 

1. Was an earthquake felt by anyone in your town or zip code area recently?

D Not felt: Please refold and tape for return mall.

D Felt: Date__________Time Q AM D Standard time

D PM D Daylight time

Name of person filling out form . 

Address_____________ 

City________________

State.

If you felt the earthquake, complete the following section. If others felt the earthquake 

but you did not, skip the personal report and complete the community report.

PERSONAL REPORT

2a. Did you personally feel the earthquake? 1D Yes D No 

b. Were you awakened by the earthquake? 2Q Yes D No 

c. Were you frightened by the earthquake? 3D Yes D No 

d. Were you at 4 Q Home 5 Q Work 6Q Other? 

e. Town and zip code of your location at time of earthquake 

f. Check your activity when the earthquake occurred:

7Q Walking SO Sleeping 9Q Lying down 10D Standing 

11D Driving (car in motion) 12D Sitting 13Q Other 

g. Were you 14Q Inside or 15D Outside? 

h. If inside, on what floor were you? 16DD 

Continue on to next section which should include personal as well as reported observations.

COMMUNITY REPORT

Check one box for each question that is applicable.

3a. The earthquake was felt by D No one 17Q Few 18Q Several 19Q Many 20Q All? 

b. This earthquake awakened D No one 21Q Few 22Q Several 23D Many 24Q All? 

c. This earthquake frightened D No one 25 Q Few 26Q Several 27 Q Many 28Q All?

4. What outdoor physical effects were noted in your community? 

Parapets or cornices fallen 29Q Yes D No 

Trees and bushes shaken 30Q Slightly 31Q Moderately 

Standing vehicles rocked 33Q Slightly 34Q Moderately 

Moving vehicles rocked 36Q Slightly 37Q Moderately 

Ground cracks 39Q Wet 40Q Steep slopes

Landslides

Underground pipes

Water splashed onto, sides of

lakes, ponds, swimming

pools

29 D Yes 

30Q Slightly 

33Q Slightly 

36Q Slightly 

39 Q Wet

ground 

42Q Small 

44Q Broken

43 D Large

45Q Out of service

32 D Strongly 

35 D Strongly 

38 D Strongly 

41Q Dry and le 

ground

Air coolers

Stone or brick fences

Tombstones

Chimneys

Highways or streets

Sidewalks

4/u Cracked «U Twisted

50Q Displaced 51 Q Rotated

53Q Slightly 54 Q Greatly 

55Q Cracked 56Q Fallen

58 D Displaced 59 D Cracked

61 D Fallen

62 D Cracked 63 Q Twisted

65 D Broken at roof line

67 D Cracked slightly 68 Q Large cracks

70 D Crecked slightly 71 D Large cracks

"LI Fallen 

(thrown down)

52 D Fallen

57 D Destroyed

60 D Rotated

64Q Fallen

66 D Bricks fallen

69 D Displaced

72 Q Displaced

Continued on the reverse side

5. What indoor physical effects were noted in y

Windows, doors, dishes rattled 73 Q 

Buildings creaked

Building tren

Hanging pict

Water in sma

Windows

ibled (shook)

ures

II containers

74 D 

75 D 

76 D 

79 D 

8lD Few crac

6a. Did hanging objects, doors swing? D No 

la. Were small objects (dishes, knick-knacks, p 

91 D Overturned 

b. Was light furniture D Unmoved 

95 D Overturned 

c. Were heavy furniture or appliances

B. Indicate effects of the following types to int

Plaster 101D Cracked 102

Dry wall 103 D Cracked 104 

Ceiling tiles 105D Cracked 106

9a. Check below any da 

Foundation 

Interior walls 

Exterior walls

ge to buildings or str

107 D Cracked 

109Q Split HOD Fa

112D Hairline cracks 

115Q Partial collapse 

117 D Moved on founBuilding 

b. What type of construction was the building 

119DWood 120D Stone 

I23D Brick 124D Cinderblock 

c. What was the type of ground under the buil

126D Don't know 127 D Sandy so

130 D Hard rock 131 D Clay soil 

133 D Level d. Was the ground:

e. Check the approximate age i

136 O Built before 1935

the building: 

137 D Built 

10a. What percentage of buildings were damaged

Within 2 city blocks of your location 

140 

b. In area covered by your zip code 

143 

11a. Were springs or well water disturbed? 

b. Were rivers or lakes changed?

12a. Was there earth noise? DNO 

b. Direction of noise 152 D North 

c. Estimated duration of shaking 156 D S

(le

158 D S

13. What is the approximate population of you

160D Less than 1,000 161 D 10,00

162 D 1,000 to 10.000 163 Q Over 

This community report is associated wi
(in, ) event in the same year, has shown no 

correlation with lake level and occurred as 

much as 18 km south of the lake. Study of 

the lake-induced stresses indicates that it 

is unlikely that they triggered the main shock; 

however, a pore-pressure increase along the 

fault zone has not been eliminated as the cause 

of the seismicity.

Post-impoundment studies are also under 

way at Lake Jocassee, S.C., where about five 

portable seismograph stations are operating. 

This area was one of low natural seismicity, 

but seismic events have increased since impoundment and seem correlated with the lake level 

in a complicated way.

A recently completed 1%-year study at 

Lake Mead, Nevada-Arizona, found lower levels 

of seismicity than in the past; strike-slip 

orientation and tension axes were in agreement 

with those for tectonic earthquakes in other 

parts of the Basin and Range province. No 

correlation was noted between lake level and 

seismic rates.

An induced seismicity study has been initiated in the last year in the vicinity of 

the Central Basin Platform in west Texas. 

This area overlies several major oil and gas 

fields that have been operated under secondaryrecovery water-injection programs for many

years. A low level of seismicity has been 

recorded in the area; however, since the array 

was installed, three felt earthquakes have 

occurred. No relation has been established 

between the water injection and the seismicity.

Figure 3 shows U.S. Army Corps of Engineers 

facilities, some of which are currently being 

studied for induced seismic effects (Johnson 

and others, 1977). The U.S. Bureau of Reclamation 

and various State agencies are also concerned 

with the problem and have active programs.

Seismological and geological review 

of nuclear reactor sites

The seismic review of about 27 nuclear 

reactor sites has been undertaken by USGS since 

the beginning of 1974. Of these reviews, about 

20 have been completed. Current status is shown 

in figure 4.

The procedures that a power company must 

follow in order to obtain a license to build 

and eventually operate a nuclear powerplant are 

complicated and comprehensive; they involve aspects of demography and environmental impact, in 

addition to seismology and geology. The power 

company compiles a large summary report of its 

investigations a PSAR (Preliminary Safety Analysis Report) to suport its conclusions. The

128° 124° 120° 116° 112° 108° 104° 100° 96° 92° 88° 84° 80° 76° 72° 68° 64°

^ i 1 ' 1 J 1 Jif 1 1 I T ? I I I P I I I I t T J 1 1 \J ^ ^ T V \ -^

46'

42'

38'

34'

30°

26° -

22° -

3«TSr---S*S*9A

B.ear Creek j___ _ _

\ /"lurrftd

/ pa 

Bull Shoals x '- ^yiotf-s'*

"' n^-U^'-Voar^

Beaver AQree'rs Ferry ^center J^HJ

EXPLANATION 

Major CE dam

CE microseismic monitoring 

of reservoir area

I,^Broken Bow |* 

^"'"Va"x- " -i-. Degrayi

^^__ i x^iits__i r « j

MeX/CO N Stiflhouse Hollow. \ i \

A } »-- 7 I

.Canyon

FIGURE 3. Location of major Corps of Engineers projects and of reservoirs instrumented for 

microearthquake monitoring (modified from Johnson and others, 1977).
128° 124° 120° 116° 112° 108° 104° 100° 96? 92° 88° 84° 80° 76° 72° 68° 64°

46

42°

38'

34'

30'

26°

 -_ CANADA UNITED ~~~~~r~~

' STATES

L ~~~-- Braidwood

, _ 

* " 6Dr._c^.._. Commanche

-' Aliens Creek A

/___/___i___i i___i___i___i___i___i___i___i___i___i___i___i_____\

NUCLEAR GENERATING UNIT CAPACITY ,.. _^ kilowatts

 Operable

58 licensed by NRC to operate 40,317,400 

2 others authorized to operate (ERDA-owned) 940,000 

A Being Built

74 construction permits 76,931,200 

19 site work authorized 20,490,000

 Planned

61 reactora ordered 69,394,000

24 reactors not ordered* 28,900,000

238 236,972,600

* 

There are no symbols for units planned but not sited.

FIGURE 4. Nuclear power reactors in the United States. Reactor reviews completed, with

involvement of the U.S. Geological Survey: River Bend, La.; Aliens Creek, Tex.; Commanche 

Peak, Tex.; Bellefonte, Ala.; Summit, Del.; Douglas Point, Md.; Seabrook, N.H.; Perry, 

Ohio; Greenwood, Mich.; Byron, 111.; Braidwood, 111.; Fort Calhoun, Nebr.; Palo Verde, 

Ariz.; WPPSS 1, 2, 4, Wash. (USGS not involved in 3,5); San Onofre, Calif.; Diablo 

Canyon, Calif.; Marble Hill, Ind. (USGS involved in early work but not in final at NRC request); Surry 3, 4, Va.; Vogtle, Ga.; No. Anna, Va. Reactor reviews in progress: Diablo 

Canyon, Calif, (review recently reactivated); Pilgrim, Mass.; Skagit, Wash.; Pebble Springs, 

Oreg.; San Joaquin, Calif.; NORCO, P.R.; Humboldt Bay, Calif.; Sundesert, Calif. Reactor 

review to be undertaken soon (1978?): Stanislaus, Calif. From ERDA press release (June 

30, 1976).
seismic and geologic sections of the PSAR are 

written in compliance with the criteria in the 

Congressional Federal Register, v. 38, no. 218, 

p. 31279-31285, "Seismic and Geologic Siting 

Criteria," which sets forth the definitions and 

required investigations.

USGS, as a consultant to the Nuclear Regulatory Commission, reviews the geologic and 

seismic data and conclusions presented in the 

seismology and geology sections of the PSAR for 

technical content and validity. USGS personnel 

having expertise in given areas that are appropriate to the site being considered are normally consulted.

Much of the investigative work performed by 

the power companies and USGS is state-of-the-art 

in nature and has contributed to the knowledge 

of seismology. For example, errors in earthquake 

catalogs have been corrected, maximum intensities have been reevaluated, and epicentral locations have been redefined.

Strong-motion program

The U.S. accelerograph network has grown rapidly in the last few years. As of September 1976, 

a total of 1,739 accelerographs were installed and 

in operating order throughout the United States.

Figure 5 indicates the number of accelerographs in 

each of the 50 States plus Puerto Rico. More than 

80 different organizations have purchased or required the purchase and installation of these accelerographs. Table 2 lists 18 instrument owners 

who have made an initial purchase of more than 10 

accelerographs. Only 10 States are now without 

strong-motion instruments. These 10 States are in 

seismic risk zones 0 or 1, and there is little possibility that these States will be instrumented in 

the future.

Figure 6 is a map of Central America; it includes a table indicating the number of accelerographs and seismoscopes that were in place during 1976. Figure 7 is a map of the Latin American and Caribbean countries, showing the number 

of accelerographs installed in each country.

Digitization and analysis of the five 

significant 1971 records subsequent to the 

February 9, 1971, San Fernando earthquake have 

been published (U.S. Geological Survey, 1976). 

Table 3 lists those accelerograph records for 

the period 1973-76 that are considered significant (arecord with a peak amplitude of 10 

percent g or more). Digitization and analysis 

of these significant records are being carried 

out by the USGS Office of Earthquake Studies.

128° 124° 120° 116° 112° 108° 104° 100 92° 88° 84° 80° 76° 72° 68° 64°

FIGURE 5. U.S. accelerograph network, September 1976. (Number indicates total number of 

accelerographs in State.) Total accelerographs 1,739 (modified from Mathiesen, 1974).
Table 2. Agencies in the United States with 10 or More 

Strong-Motion Instruments

Instrument owners Accelerographs

Los Angeles City Ordinance 

California Division of Mines and Geology 

Corps of Engineers, U.S. Army 

Seismic Engineering, USGS 

California Institute of Technology 

California Dept. of Water Resources COOP ProjectU.S. Veterans Administration 

Beverly Hills City Ordinance 

Coronado City Ordinance - 

Metropolitan Water District 

Newport Beach City Ordinance 

U.S. Bureau of Reclamation 

Santa Ana City Ordinance . - 

El Segundo City Ordinance 

Santa Rosa City Ordinance 

Inglewood City Ordinance 

Pacific Telephone & Telegraph Co.- 

Palo Alto City Ordinance 

469

263

222

163

73

65

61

48

24

23

21

20

18

15

12

12

11

11

INSTRUMENTS

FIGURE 6. Central America strong-motion stations. Modified from Knudson (1975)

10
^5

* £>.£PUEFTO RICO(6)

6UATEMALA(2 

EL SALVADOR(4 

NICARAGUA <2I) 

COSTA RICA 8) 

PANAMMI)

Is GUADELOUPE-! 

Y-MART!NQUE->*llO) 

«*-BARBADOS(6) 

 TRINIDAD (6)

ECUADOR

(I) /L'~ ..i

CHILE 

(27)

FIGURE 7. Latin America and Caribbean strong-motion accelerographs. Number in parentheses, 

number of accelerographs in country. Modified from Knudson (1975).

Date of 

event

Table 3. Significant Accelerograph Records, 1973-1976 

Station location Maximum 

accel.

(g)

1973

Feb. 21 Port Hueneme, Calif.; U.S. Naval LaboratoryMar. 31 Managua, Nicaragua; National University 

Apr. 26 Kilauea, Hawaii; Namakani Paio campground 

Aug. 8 Ferndale, Calif.; Old City Hall - 

Sept. 16 Berryessa, Calif.; CDF Fire Station 

0.13 

.60 

.17 

.14 

.18

11
Table 3. Significant Accelerograph Records, 1973-1976 Continued

Date of 

event

Station location Maximum 

accel.

(g)

1974

Jan. 5

Jan. 31 

Feb. 11

Aug. 14 

Oct. 3

Nov. 9 

Nov. 28

Dec. 6

Los Angeles, Calif.; 700 W. 7th2 

Los Angeles, Calif.; 420 S. Grand2 -- - 

Hollister, Calif.; City Hall 

Imperial, Calif.; Imperial Valley College Adm. Building0.16 

.11 

.16 

.10 

.13 

.18 

.25 

.10 

.12 

.10 

.18 

.21 

.14 

.17 

.12 

.14 

.11

1975

Jan. 11

Jan. 23 

Mar. 6 

May 6 

June 7

June 19 

June 20

Aug. 1 

Aug. 2 

Sept. 13 

Nov. 14

Nov. 29 

0335 

(local 

time) 

Nov. 29 

0447 

(local 

time)

Imperial, Calif.; Imperial Valley College Adm. BuildingFerndale, Calif.; Old City Hall 

Ferndale, Calif .,- Old City Hall 

Hilo, Hawaii; University of Hawaii Cloud Physics 

Laboratory .

0.10 

.19 

.11 

.18 

.18 

.19 

.22 

.19 

.10 

.10 

.13 

.15 

.13 

.11 

.08 

.13 

.14 

.18 

.18 

.13 

.10 

.15

.11

1976

Jan. 1

Feb. 18 

Apr. 14 

Nov. 4

Santa Ana, Calif.; Orange County Reservoir, abutment 

0.13 

.10 

.12 

.14 

.14 

.18 

.28 

.10 

.14 

.11

Maximum acceleration at ground level.

2 The records from the upper levels of these buildings are being

digitized.

12
Figure 8 shows important earthquakes (large 

magnitude or destructive) that have occurred in 

Central America and parts of northern South America since 1898. Preliminary efforts are under 

way to increase the number of strong-motion instruments in the region. The operation of these 

instruments should be useful for all concerned 

with earthquake risk studies.

Earthquake hazards

Earthquake-hazards research in the USGS 

has the long-range objective of quantifying earthquake hazards throughout the United States. The 

principal research efforts are focused on (1) locating the zones where potentially damaging earthquakes might occur; (2) identifying the areas that 

have a high potential for rupture of the ground 

surface by faulting; (3) identifying the potential 

for damaging levels of ground shaking on different geologic units at various distances from, 

the earthquake source; (4) specifying the areas 

that are susceptible to ground shaking, causing 

induced ground failures such as landslides and 

liquefaction; and (5) delineating the areas that 

are susceptible to flooding from dam failures, 

tsunamis, seiches, and tectonic changes of sea 

level.

A seismic-risk map (fig. 9) was a major 

product of the earthquake-hazards research program during 1976 (Algermissen and Perkins, 1976). 

It depicts the peak ground acceleration expected 

at a rock site in the contiguous United States in 

a 50-year period, at the 90-percent probability 

level. This map, unlike past seismic-risk maps, 

provides quantitative data needed for many engineering applications.

A team of scientists went to Guatemala following the February 4, 1976, earthquake to examine 

the geologic and hydrologic effects, to inspect 

areas of damage and nondamage to buildings and 

city lifeline systems, and to record aftershocks of 

the earthquake. Working cooperatively with Guatemalan scientists, engineers, and government officials, the scientists were able tolearn a great 

deal about earthquake effects, and the research 

findings have been published (Espinosa, 1976).

The present near-term objectives of earthquake-hazards research in the United States are 

twofold: (1) to obtain information needed for 

improved national seismic-risk assessment, and 

(2) to establish a framework for undertaking 

regional and local hazards assessment to aid 

regional, State, and local governments.

Examples of research projects that are designed to meet these objectives include (1) 

ground response, Los Angeles, Calif., region; 

(2) ground respon, Salt Lake City, Utah, 

region; (3) relation of seismicity to regional 

geology; (4) active faults and recent tectonic 

deformation, southern California; (5) assessment 

of seismic hazards, northern Mississippi embayment; (6) seismic attenuation, United States; and 

(7) U.S. seismogenic zones.

Prediction of seismic and volcanic activity

The following description is excerpted from 

the Federal Register, v. 42, no. 70, April 12, 

1977:

"Geologic processes and conditions that could 

result in harm to people and property include 

earthquakes, volcanic eruptions, landslides, mudflows, subsidence, faulting and fissuring of the-

 Moqnitud* 7.5 a Abov« 1898 to 1974 

Dwtructiw EorthquokM I965tol976

FIGURE 8. Large-magnitude and destructive earthquakes in Middle America.

13
46'

42'

38'

34<

30'

26°

128° 124° 120° 116° 112° 108" 104° 100° 96° 92" 88° 84° 80° 76" 72" 68° 64C

UN/TED STATES]---- T '\

f f -^""t.

FIGURE 9. Horizontal acceleration (percent of gravity) in rock with 90 percent probability of 

not being exceeded in 50 years. Maximum acceleration within the 60 percent contour along 

the San Andreas and Garlock faults in California is 80 percent of g (using the attenuation 

curves of Schnabel and Seed, 1973). From Algermissen and Perkins (1976).

ground surface, and glacier-related phenomena 

such as release of glacier-dammed lakes and 

rapid ice surges or retreats. Under certain 

conditions, these events may occur suddenly 

and affect large numbers of people and property 

over a wide area; in other instances, however, 

the processes involved occur slowly or affect 

very limited areas so that few if any people 

are endangered. The present capability of scientists to predict hazardous events varies greatly 

as to the type of event and knowledge of its time, 

place, and magnitude of effects."

Earthquakes

Much of the United States is subject to some 

degree of earthquake hazard. The western States 

of Alaska, California, Hawaii, Idaho, Montana, 

Nevada, New Mexico, Utah, Washington, and Wyoming 

are particularly susceptible, but major earthquakes 

have also struck the eastern and central parts of 

the United States (Hadley and Devine, 1974), particularly Arkansas, Georgia, Kentucky, Indiana, Illinois, Massachusetts, Mississippi, Missouri, New 

York, North Carolina, South Carolina, and Tennessee.

In many instances, earthquake-generated ground 

shaking causes the most widespread earthquake damage, principally through failure of buildings.

Earthquakes also give rise to various geologic 

processes that may cause injuries and property 

damage, including surface faulting, landsliding 

and associated ground failures, generation' of 

large waves in water bodies, and regional vertical movements (downwarping and upwarping).

The surface effects of earthquakes have been 

evaluated on the basis of geologic and seismologic studies in parts of Alaska (Page and others, 

1972), California (Borcherdt, 1975), Idaho (Witkind, 1972), Nevada (Bingler, 1974), Utah (U.S. 

Geological Survey, 1976), Washington (Pitt, 1972; 

U.S. Geological Survey, 1975), and the Eastern 

United States (Button, 1389). The results of 

regional studies under way in these and other 

States will be published as they are completed.

Predictions of the precise location, time, 

and magnitude of specific earthquakes cannot generally be made now. Certain precursors, such as 

ground tilting and changes in water levels in 

wells, the magnetic field, and seismic-wavevelocity characteristics in rock, may be useful 

in predicting earthquakes. Experimental instrumental arrays have been installed in a few research areas, such as near Hollister, Calif., to 

evaluate these precursors and to help develop an 

earthquake-prediction capability.

14
Locations of faults that may be the sources 

of future damaging earthquakes have been determined in some regions of the country, particularly 

in parts of Alaska, California, Nevada, Idaho, 

Montana, and Utah» Geologic and seismologic studies in these regions, however, are not adequate to 

assure that all such faults have been delineated. 

Geologic studies of recurrence intervals of earthquakes have been made on only a few faults, principally in California. Some of these studies provide a basis for estimating the magnitudes of 

earthquakes that are likely to be generated by 

movement along a particular fault. Broad-scale 

estimates of the susceptibility of the various 

regions of the United States to earthquake hazards have been made and are published in earthquake-hazard maps and reports (Algermissen and 

Perkins, 1976), which will be updated as new information is acquired. These maps, and the more 

detailed studies on which they are based, identify those regions known to be highly susceptible 

to earthquakes, even though they may not identify 

all faults along which movement may take place.'

Regional earthquake-hazard assessments are 

also under way in parts of New Mexico, New York, 

South Carolina, and Washington, and in the lower 

Mississippi Valley.

Volcanic eruptions

At the present time, volcanoes are active in 

Alaska and Hawaii; volcanoes in California, Oregon, and Washington are dormant, but have erupted 

within the last 150 years. The likelihood of 

future eruptions that will be damaging to man is 

greatest in the vicinity of volcanoes in these 

States. Geologic evidence indicates that volcanic activity could occur in other areas, such 

as Arizona, Nevada, New Mexico, Wyoming, and 

Idaho (Mullineaux, 1976), where eruptions have 

occurred as recently as 350 years ago; no current evidence, however, suggests that volcanic 

activity may occur in these areas in the near 

future. Broad estimates have been made of 

regional susceptibility and types of volcanic 

hazards in the conterminous United States and 

Hawaii (Crandell, 1976; Crandell and Mullineaux, 

1975; Mullineaux, 1976; and Powers, 1948); these 

will be updated as new information is acquired.

Volcanic eruptions produce a wide variety 

of primary and secondary hazards to life and 

property, stemming mainly from hot avalanches, 

mud flows, ash falls, lava flows, volcanic gases, 

hot-particle and gas clouds, and floods.

Studies of the products of past volcanic 

activity in the Cascade Range, including lava 

flows, ash falls, mud flows, and hot avalanches, 

have been completed on the volcanoes of Mt. 

Baker (Hyde and Crandell, 1975), Lassen Peak 

(Crandell and others, 1974), Mt. Rainier 

(Crandell, 1973), and Mount St. Helens (Crandell 

and Mullineaux, 1976; Crandell and others, 1975); 

similar studies are planned or in progress for 

other major volcanoes in the Cascade Range, such 

as Mt. Hood and Mt. Shasta, and for Augustine 

Volcano in Alaska.

Detailed studies at Kilauea and Mauna Loa 

Volcanoes in Hawaii show that the products of 

most historic and prehistoric eruptions are lava 

flows; subordinate products include ash falls

and hot-particle and gas clouds. Eruptions issue 

from fissures and vents both in the summit areas 

and along rift zones on the flanks of the volcanoes. Assessments of hazard-susceptible areas 

have been made for the islands of Hawaii (Mullineaux and Peterson, 1974) and Oahu (Crandell, 

1975).

Kilauea and Mauna Loa Volcanoes are monitored by an array of instruments and by systematic measurements that permit assessment of the 

likelihood of impending activity (Waesche and 

Peck, 1966; Kinoshita and others, 1974). Physical precursors often permit predictions to be 

made within time frames of weeks or days, and 

sometimes highly specific signals precede eruptions by one to several hours (Swanson and 

others, 1971; Fiske and Kinoshita, 1969).

A study of the historic cycles of activity 

on Mauna Loa indicates the possibility of longterm prediction of the general locality and the 

general time frame (months or years) of the next 

eruptive event (Lockwood and others, 1976).

Predictive capability has not been achieved 

for volcanoes in the Cascade Range or in Alaska, 

although it is possible that the methods developed in Hawaii can be modified and adapted to be 

useful in these regions. Detailed estimates of 

hazard-susceptible areas surrounding some of 

these and other volcanoes have been made, as indicated earlier. Other studies are under way 

and will be published as completed.

Geophysical exploration

Exploration geophysics is the application 

of the principles of physics to the search for 

minerals, including metals, coal, oil, gas, and 

water, that occur in Earth's subsurface. Most 

geophysical work is done using sophisticated 

electronic equipment ,that has been calibrated to 

detect contrasts in such physical properties as 

density, electrical conductivity, heat conductivity, seismic velocity, and magnetic susceptibility. The common techniques used are the 

gravity, magnetic, electrical, electromagnetic, 

seismic, and radioactivity methods. Measurements may be made from aircraft, at Earth's surface, or in boreholes. The discussions here 

will be limited to geophysics as applied to 

evaluations of metallic mineral resources.

USGS is active in several aspects of geophysical research that have applications in mineral resource evaluations. A combination of 

geophysical techniques, including both direct 

and indirect, is often applied to a particular 

problem in order to obtain a more diagnostic 

evaluation of an area. The objectives of USGS 

programs have been to define areas that seem 

likely to contain mineral deposits and not specifically to explore for discrete ore bodies. 

It has been left for the private sector to discover, develop, and mine ore deposits.

The aeromagnetic and gravity methods are 

used singly or in combination and have proven 

to be among the most useful methods for analyzing regional geologic framework and for identifying intrusives or other major rock types that 

may be useful in mineral resource evaluation. 

The truck-borne magnetometer has been effective 

as a rapid and economical means of examining the

15
magnetic signature of an area. This information 

may be used in planning aeromagnetic work; or, 

in a more detailed evaluation of specific anomalies, it may denote unmapped or blind intrusives 

that have associated mineralization, such as the 

porphyry copper deposits at Ruth, Nev. Conversely, it may directly reflect iron ore deposits as at Marmora, Ontario. Negative anomalies 

aj_so may be significant for cases in which the 

magnetite content of the host rock has been 

greatly reduced by hydrothermal alteration associated with ore emplacement, as at Cripple Creek, 

Colo.

Electrical-resistivity and electromagnetic 

surveys are well suited for follow-up to provide 

additional information about target areas delineated using gravity and magnetic surveys; 

they are particularly useful in the identification of buried conductors indicative of massive 

sulfide deposits. In studies of lateral variations in stratigraphy in sedimentary and highly 

foliated crystalline rocks, these methods can 

be used in investigating stratabound ore deposits and locating buried channels that may con- ' 

trol uranium deposits.

In uranium and thorium studies, radioactivity surveys will be used by USGS directly to detect radioactive minerals and to correlate rock 

units in geologic mapping. Gamma-ray spectrometers are used to discriminate radiation from 

uranium, thorium, and potassium sources on the 

basis of the identification of energy levels in 

the total-count radiation spectrum. In other 

exploration research, gamma-ray spectrometers are 

used to study radioactive potassium associated 

with hydrothermal alteration that may have occurred during mineralization.

In geothermal exploration, a number of mineral prospecting techniques have been adapted, 

and developments offer promise for improved mineral exploration techniques for the future. 

Large self-potential anomalies have been observed over geothermal systems. In measurements 

of natural earth currents, telluric current, 

audio-magnetotelluric and conventional magnetotelluric methods have proven useful as economical reconnaissance techniques in exploring for 

conductive anomalies that may be associated with 

geothermal systems. As a follow-up, resistivity 

and transient electromagnetic measurements are 

used for detailed studies of suspected geothermal anomalies.

In remote sensing, USGS is conducting experiments in flying a multi-spectral four-band 

camera and thermal IR (infrared) scanner over 

areas of known base-metal and uranium mineralization to study resolution of subtle surfacealteration patterns. In studies of the Virginia 

City, Nev., area, a combination of digital computer processing and color compositing of ERTS 

(Earth Resources Technology Satellite; now called Landsat) MSS (Multi-Spectral Scanner) images 

was used to enhance spectral-reflectance differences; the result was detection and mapping of 

hydrothermally altered areas associated with the 

mineral deposits.

The anticipated increased demand for metal 

in the near future portends an urgent need to 

accelerate research and development of improved 

field measurements, streamlined data handling,

and computer modeling of results to achieve more 

accurate interpretations of geophysical data in 

terms of identifying blind mineral deposits.

A number of developments are under way by 

USGS in electrical methods as applied to mining 

geophysics. The techniques of total-field resistivity mapping promise to be a rapid, yet 

good-resolution reconnaissance approach for deep 

resistivity studies. The method consists of 

grounding a long current bipole and calculating 

the total electrical field at various field stations. An improved electromagnetic technique, 

designated as ELF (extra low frequency), is 

being developed, which uses a ground transmitter 

as a multiple-frequency source and an aircraft 

to carry the receiver. The system has the advantages of providing a reliable signal along 

with rapid, systematic coverage possible only by 

using aircraft. The depth of penetration for 

large targets is about 500 m in areas of resistive country rock.

Progress is being made in interpretation of 

geophysical data using electronic computers. 

Highly effective computer programs for automatic 

interpretation of two- and three-dimensional 

models based on both d.c.-resistivity and electromagnetic data are being developed. Of most 

interest using the magnetic method are new computer techniques for making automatic depth determinations and for calculating the pseudogravity field from magnetic data. More rigorous 

mathematical treatment of filtering, such as 

recursive filtering, is being applied to magnetic data in attempts to effectively separate 

superimposed magnetic anomalies whose sources 

are at different depths in the subsurface. This 

treatment is particularly significant in detecting buried stocks that may be mineralizers in 

areas of surface volcanics and offers promise 

for a more rapid and economical evaluation of 

mineral resource potential using magnetic data. 

USGS has developed computer techniques for removing the terrain effects from magnetic data 

gathered in high-relief mountainous areas.

For a broader in-depth discussion of stateof-the-art geophysics, see Campbell (1977) and 

Espey (1977).

USGS conducts research in coordinated programs with other countries. High priority is 

given to training, generally on a one-to-one 

basis, of a USGS scientist working with a counterpart scientist both in the field and in interpretation of the data. In northern Mexico, 

for example, in cooperation with the CRM (Consejo 

de Recursos Minerales), USGS is engaged in an 

experimental studies program to develop new geochemical, geophysical, and geological exploration 

techniques useful in the search for mineral deposits, especially porphyry systems, in the 

Sonoran environment.

This program is an international, multiphase, and interdisciplinary evaluation of mineral exploration methods. Phase one, about 75 

percent completed, is a regional evaluation of 

a belt having high mineral potentials; it is a 

belt of about 15,000 km in the State of Sonora, 

extending from west of Nogales, through Cananea, 

Nacozari, and Oputo. The ongoing regional 

stream-sediment, gravity, and aeromagnetic surveys; structural and alteration studies; and the

16
revision of geologic maps provide the framework 

for phase-two investigations. In phase two, regional studies will continue for the purpose of 

comparing the effectiveness of additional techniques at this scale; however, emphasis will be 

on interdisciplinary investigations of selected 

smaller areas of highest priority, as established 

by evaluation of phase-one data.

A variety of geological, geochemical, geophysical, and remote-sensing field and interpretive techniques are to be tested in the different physiographic, geologic, and climatic zones 

of the study areas. In the large areas of pediment gravels, which probably cover existing mineral deposits, combined geophysical techniques 

such as gravity, geoelectrical, and (or) seismic 

methods; geochemical techniques using elementand compound-concentration variation in soil 

gases, vegetation, and ground water; and remotesensing techniques using luminescence and reflectance measurements will be evaluated. In areas 

of thin soil cover and outcrop, geologic studies 

of rock-unit relationships, structure, and alteration furnish guides to the type of geochemical 

and geophysical techniques to be applied.

Geomagnetism 

Operations

The Project MAGNET RP-3D aircraft of the 

U.S. Naval Oceanographic Office has surveyed 

1,337,000 line-kilometers of geomagnetic data in 

this quadrennium. Area coverage was worldwide, 

and both high-level (7,600-m) vector survey missions and low-level (150-m) scalar survey missions were flown.

Survey coverage in the PAIGH area included 

approximately 322,000 line-kilometers of vector 

data collected at the 7,600-m flight level. 

Survey lines are shown on the accompanying chart 

(fig. 10). The survey data will be used to improve the mathematical model of Earth's main geomagnetic field. Vector magnetic data points at 

various intervals (usually at 37 nautical-kilometer intervals) are available at the Geomagnetic 

Data Library, Magnetics Division, U.S. Naval 

Oceanographic Office, Bay St. Louis, Miss. 39522.

GASS (Geomagnetic Airborne Survey System) 

has been improved and expanded to provide a greater computer capacity and to upgrade positional accuracy. Both 16K capacity computers now have an 

auxiliary 16K memory unit. This allows the survey 

team to increase the sampling rate for a particular parameter. An electrostatic suspended gyro 

inertial system was added to GASS to provide more 

accurate references for the vector magnetometer 

and more accurate dead-reckoning information between navigational satellite fixes. More reliable 

synchro-to-digital converters were procured and 

integrated into GASS.

GASS accuracies that were realized are as 

follows: variation of compass, +0.1 degree; inclination, +0.1 degree; vertical intensity, +5 

nanoteslas; horizontal intensity, +7 nanoteslas; 

total magnetic intensity, +1 nanotesla; and position, +0.5 kilometer.

In 1973, most of the magnetic observatories 

that had been operated by NOAA were transferred 

to USGS. These observatories were located at 

Barrow, College, and Sitka, Alaska; Fredericksburg, Va.; Boulder, Colo.; Dallas, Tex.; Newport,

Wash.; Tucson, Ariz.; Castle Rock, Calif.; San 

Juan, P.R.; Guam, Mariana Is.; and the South 

Pole. The NOAA National Weather Service continued operation of the Honolulu Observatory in 

Honolulu, Hawaii. The South Pole station was 

closed at the end of 1974. Dallas Observatory 

terminated operations in April 1975, Castle 

Rock Observatory in May 1976. 'Digital magnetometer systems recording declination and horizontal and vertical intensities using fluxgate magnetometers, and total intensity using a proton 

magnetometer were installed at College, Sitka, 

Barrow, Newport, Tucson, and Boulder. Similar 

systems are planned for eventual installation 

at all USGS observatories.

In 1974 a USGS geophysicist visited magnetic 

observatories in Mexico, Colombia, Peru, Bolivia, 

and Brazil to make comparative measurements between the absolute instruments used in these countries and the instruments used in the United States, 

These measurements permit establishment of a common baseline or international standard of magnetic 

measurements. This cooperative work was funded 

primarily by PAIGH. In 1976 PAIGH approved funding for USGS geophysicists (1) to visit Brazil 

and Argentina (in 1977) to continue these comparative measurements, and (2) to visit the University 

of Costa Rica to advise and assist in the establishment of a magnetic observatory in Costa Rica, 

for which USGS will provide most of the instrumentation. (For more information on these PAIGH 

projects, see the section entitled "Special 

Projects of the PAIGH involving the U.S. Commission on Geophysics.")

USGS conducted a magnetic measurements program at more than 100 repeat-survey field sites 

to provide data for the 1975 magnetic charts. 

The measurements were made at these sites utilizing a fluxgate magnetometer mounted on a theodolite for measuring declination and inclination. 

Total field measurments were made with a proton 

magnetometer, permiting calculation of the horzontal and vertical components. A three-component 

fluxgate recording system was operated at these 

sites to provide information for removing tranient and diurnal variations from the observations.

Data services

In cooperation with the U.S. Naval Oceanographic Office, USGS produced a new world model 

of Earth's magnetic field for epoch 1975.0, which 

was used to create the world magnetic charts subsequently published by the Defense Mapping Agency. 

The model, consisting of 168 coefficients derived 

using a spherical harmonic analysis, utilized an 

initial set of 600,000 worldwide measurements of 

the geomagnetic field made from 1939 to 1974. 

The models of secular variation, also derived 

by spherical harmonic analysis, used the annual 

means from 140 worldwide magnetic observatories 

to produce a series of 80 coefficients. World 

maps were published for declination, inclination, 

horizontal intensity, vertical intensity, and 

total intensity. USGS also published a series of 

five magnetic charts of the United States for 

epoch 1975.0 in cooperation with NOAA. The new 

U.S. charts, for all five components, were derived by polynomial analyses using more than 

60,000 regional observations collected since 1900. 

The declination chart for the conterminous 48

17
90° 60°

MEXICO

Caribbean Sea

CENTRAL 

AMERICA

> <

PA CIFIC

Tropic of Capricorn .-J

OCEAN

30°

FIGURE 10. Project MAGNET surveys, southern PAIGH area, 1973-76. Lines, flight lines; circles, 

base stations. Data from: Geomagnetic Data Library, Magnetics Division, Bay St. Louis, 

Miss. 39522.

18
States was derived by partitioning the region into 

five 12 X 12 longitudinal bands having 2 overlap and performing a degree-7 analysis, yielding 

36 coefficients for each partition. The other 

components are represented by single degree-7 

models. For the lines of equal annual change, 

data from regional magnetic observatories and 

more than 100 U.S. repeat stations were analyzed 

to produce models of annual change, each consisting of 28 coefficients. All models, both of 

the main field and its annual change, were used 

directly on the CDC6400 computer to contour the 

required isolines.

NOAA's EDS in Boulder, Colo., continued its 

WDC (World Data Center) operations in geomagnetism via WDC-A for Solar-Terrestrial Physics and 

WDC-A for Solid Earth Geophysics. The normal 

flow of data input was enhanced by the visit of a 

WDC-A representative to the Latin American institutions that operate magnetic observatories. Using a portable microfilming camera, this representative filmed all available magnetograms and 

tables of hourly values that were not already in 

the WDC collection. Requests for copies of data 

from WDC-A, mostly from geophysical researchers, 

have continued to increase, and it is expected 

that the present augmented collection will result 

in an even greater number of data requests. WDC-A 

has continued to collect all forms of worldwide 

geomagnetic data, maintaining the data bases that 

are used by the other U.S. Government agencies in 

their analyses. In addition, WDC-A has digitized 

magnetograms from 11 polar observatories for the 

years 1966-75, obtaining values for every 2.5 

minutes, for the purpose of computing indices of 

AE (auroral electrojet) activity. Most of this 

work has been accomplished using semiautomatic 

digitizers, but a new automatic digitizer was acquired in 1974 and some of the magnetically quiet 

intervals were processed using this new machine. 

Other new hardware provided for a system for the 

review of results and correction of errors by 

interactive graphics.

Heat flow

WDC-A for Solid Earth Geophysics published a 

unique heat-flow map of the world. The first of 

its kind, the map shows the amount of heat flowing 

outward from the interior of Earth and indicates 

where heat-flow measurements have been made and 

the approximate value of heat flow at each site. 

Heat-flow measurements are shown by one of five 

different colors, each indicating a different 

range of heat-flow values. Measurements number 

about 5,500 for the entire globe. The map also 

shows the locations of all known active volcanoes, 

along with earthquake epicenters for the years 

from 1961-73. These areas of volcanic and seismic 

activity delineate regions of Earth where the 

litospheric plates are interacting. The data for 

this map were compiled under the auspices of the 

International Heat Flow Commission IASPEI/IUGG 

(International Association of Seismology and 

Physics of the Earth's Interior/International 

Union of Geodesy and Geophysics) by A. Jessop, 

M. Hobart, and J. Sclater. The map was prepared 

by P. Grim of WDC-A for Solid Earth Geophysics.

Volcanology

Since 1973 the National Museum of Natural 

History, Smithsonian Institution, has been engaged in a collaborative program with the Escuela 

Politecnica Nacional in Quito, Ecuador, to study 

Volcan Reventador in Ecuador. This study was accelerated following the January 1976 eruption of 

Reventador. Principal investigators are Minard 

Hall of the Escuela Politecnica Nacional and Tom 

Simkin of the National Museum.

A larger project has been the study of three 

volcanoes, Fernandina, Marchena, and Cape Berkeley, 

in the Galapagos Islands. This study began in mid1968 after the major eruption and caldera collapse 

of Fernandina, and several investigators are continuing to collaborate. Principal investigator is 

Tom Simkin of the National Museum (Simkin and 

others, 1972; Case and others, 1973; Simkin, 1972; 

Filson and others, 1973; and Simkin and Howard, 

1970).

The National Museum has also compiled a computerized volcano data file and is preparing a publication to summarize much of the physical and 

chronological information that has been compiled 

on the volcanism of the last few thousand years 

(Simkin, 1976).

Marine geophysics

International Decade of Ocean Exploration and 

International Phase of Ocean Drilling

Marine geophysical activities in the United 

States flourished during the 1973-76 quadrennium. 

The IDOE (International Decade of Ocean Exploration), begun in 1971, gained further momentum. 

Detailed geophysical surveys under the IDOE-funded 

Seabed Assessment Program were conducted along the 

Atlantic Continental Margins of both Africa and 

South America. In the Pacific, the IDOE marine 

geophysical programs concentrated on the Nazca 

Plate in the first half of the quadrennium; since 

that time a program has been initiated to explore 

the geophysical characteristics of East and Southeast Asia in conjunction with the IOC (Intergovernmental Oceanographic Commission). Additional 

details follow on the Nazca Plate study. (See 

section entitled "IDOE" for a summary of the IDOECUEA program.)

Cooperative Investigation of the 

Caribbean and Adjacent Regions

and Intergovernmental Oceanographic Commission Association for the Caribbean and Adjacent Regions

NOAA's Atlantic Oceanographic and Meteorological Laboratory in Miami, Fla., participated in the 

CIGAR II (Cooperative Investigation of the Caribbean and Adjacent Regions) Symposium held at 

Caracas, Venezuela, July 12-16, 1976. The group 

agreed to continue the marine studies in the 

Caribbean area and welcomes any other group or 

individual to join in the study. Objectives of 

the study are described in the following 

recommendation (Intragovernmental Oceanographic 

Commission/IOCARIBE-I/3, 1976):

19
"Environmental Geology of the Caribbean Coastal 

Area

The IOC Association for the Caribbean and adjacent 

regions,

Recognizing that the coastal area of islands and 

mainlands is most strongly affected by man's 

activities and is therefore the immediate concern 

of coastal zone management,

Proposes a systematic and time-progressive geological programme of investigation collectively 

referred to as Environmental Geology of the 

Coastal Area within the IOCARIBE area - the term 

"coastal area" being 'defined as those contiguous 

marine and land areas characterized by direct interaction (typically the coastal plains and submerged continental and insular shelves) - and 

being guided in the formulation of this programme 

by information contained in Programme 10 of the 

ad hoc Group of Experts (Puerto Rico, March 

1976) and the draft programme "Morpho- and Lithogenesis of the Mexico-Caribbean Coastal Shelf 

Zones," presented by the delegation of the Soviet 

Union;

Recommends that one of the products of this investigation will be a series of folios (quadrangular maps) of these coastal areas. 

Recognizing further that various countries do not 

have the capability to produce such folios, 

Decides that two pilot programmes should be developed,

Suggests that areas which might be considered 

for these pilot studies include all the coastal 

areas of the region but in particular the Lesser 

Antilles, Central America, and portions of the 

Greater Antilles, 

Recommends that a workshop be convened to:

i) define the content of the above folios

ii) identify investigative procedures and 

methods

iii) develop a co-ordinative scheme for existing national programmes which could produce 

such folios

iv) identify areas for the two IOCARIBE pilot 

studies mentioned above

v) select Project Managers and Assistant 

Project Managers as needed;

Appoints Dr. John P. Scott of Trinidad and Tobago 

as Chairman of a Steering Committee to convene 

this Workshop and empowers him, in consultation 

with the Chairman of IOCARIBE, to select the remaining members of the Steering Committee."

Nazca Plate

The Nazca Plate project was initiated in 

1971 as a joint research effort by HIG (Hawaii 

Institute of Geophysics) of the University of 

Hawaii and the School of Oceanography of OSU 

(Oregon State University), with supporting collaboration from both individual scientists and 

various agencies in Colombia, Ecuador, Peru, and 

Chile. NOAA's POL (Pacific Oceanographic Laboratory) was involved in the program in its 

initial phases. The investigation employed a 

wide range of marine geophysical, geological, 

and geochemical experimental techniques directed 

at determining the interrelationship of an 

oceanic crustal-plate tectonic cycle to metallogenesis and eventual ore emplacement. This tectonic cycle has been considered in terms of (1) 

the primary locus of metallogenesis at a divergent crustal-plate boundary, where new oceanic 

crust is being generated (the East Pacific Rise); 

(2) the transport, and accumulation of sediment 

on the moving plate and interaction of the crust 

with seawater; and (3) the zone of continental 

plate collision (Peru-Chile Trench) where the 

oceanic plate is subducted, loses its identity 

and is assimilated beneath the continent, witu 

consequent mountain building, seismicity, volcanism, and intrusion into the overlying crust 

to create zones of mineralization.

During 1972-74, the participating institutions 

conducted extensive and comprehensive research 

cruises on the Nazca Plate, with emphasis on the 

divergent and convergent boundaries. OSU was involved in the data collection in 1972 and 1974 with 

the R/V YAQUINA and participated in one leg of the 

POL (NOAA) cruise in 1973, ' During April-May 1975, 

OSU also obtained dredge samples on the R/V MELVILLE from the basaltic crust of the Peru-Chile 

Trench.

Since the termination of field work in 1975, 

Nazca Plate scientists have been analyzing data 

and collected samples. During 1977 and early 1978, 

these analyses and interpretations will be completed. Publication of this work will occur in 

standard scientific journals. A special synthesis 

volume of papers will also be prepared to relate 

the various scientific tasks of the program to 

their metallogenesis theme. A series of maps 

accompanying this volume will depict various geological, geochemical, and geophysical data across 

the plate. Principal investigator for this 

project is LaVerne D. Kulm of OSU.

Other activities

The 1973-76 period saw the development and 

growth of a national marine geophysical data 

center at NOAA's EDS. This center, NGSDC (National Geophysical and Solar-Terrestrial Data 

Center), located^in Boulder, Colo., presently 

serves major U.S. marine-oriented universities, 

Federal and State agencies, and many international organizations as a secure data archive 

and a source for all types of marine geophysical 

data in variable format. Its data collections 

already number some millions of track-kilometers 

of bathymetric, seismic, magnetic, and gravity 

data.

The U.S. Naval Oceanographic Office conducts 

multi-purpose surveys to obtain information in 

oceanic areas to support U.S. Navy requirements 

for Oceanographic information, and in addition, 

where feasible, to contribute information to the 

scientific and economic community. This information is made available to the user through NGSDC. 

Oceanographic and geophysical data are collected 

from three civilian-manned Oceanographic ships 

under the operational control of the Oceanographer 

of the Navy. During the past quadrennium (1973- 

76), USNS SILAS BENT (T-AGS 26) operated in the 

North Pacific Ocean, while USNS KANE (T-AGS 27) 

and USNS WILKES (T-AGS 33) were operating in the 

North Atlantic Ocean. These ships are equipped 

to collect Oceanographic information on station 

and geophysical information while under way. 

Geophysical data are collected from a variety of 

sensors including magnetometer, seismic subbottom 

profiler, 3.5-kHz shallow profiler, and narrow20
beam 12-kHz echo sounder. These systems are 

briefly described below:

1. Magnetic System A proton precession-type

magnetometer having a+0.1 nanotesla sensitivity is towed 180-240 m astern of the ship 

to measure Earth's total magnetic intensity. 

Data are recorded in both digital and analog 

form.

2. Bathymetry System A Harris Model 853D, NBES 

(Narrow Beam Echo Sounder), operating at a 

12-kHz frequency, is the system primarily 

used for bathymetry data acquisition; data 

are recorded digitally and in analog form. 

Selection of separate elements, within independent hull-mounted receiver and transmitter 

arrays, is gyro-controlled to always "look" 

vertically. Combined transmitter and receiver beams cross in a pattern that effectively produces a nominal 3 beam width. 

Data are recorded in sonic meters with a 

+2-m accuracy at a depth of 8,000 m (system 

specifications).

3. 3.5-kHz Shallow Subbottom Profile System Continuous profiles showing shallow subbottom 

reflectors are collected using an Edo 240 

system employing a hull-mounted transducon 

array operated at a 3.5-kHz frequency. 

Output power is variable up to 5,000 watts. 

Data are collected in graphic analog form 

only, generally using a 1- or 2- ms pulse 

width at a 1-second recorder sweep rate.

4. Seismic System A Teledyne SSP sparker seismic 

system, capable of energy outputs to as much 

as 90,000 joules, is used to produce continuous reflection profiles of the ocean-bottom 

sediment section. Arcer cables and a multielement dual-channel hydrophone streamer are 

towed behind the ship. Received signals are 

processed through an amplifier system that provides the filter control required to optimize 

the quality of data recorded on graphic-chart 

recorders. Records are generally collected 

using a 10-second recorder sweep rate and a 

slave recorder at a delayed 4-second sweep 

rate.

Navigation is provided by Satellite, LORAN-C, 

and LORAN-A systems. Magnetometer and echo-sounder 

data are acquired and processed on Digital Equipment Corporation PDP-9 computers onboard ship; navigation data are processed on the computer, while 

subbottom profiling data are acquired on analog recorders.

Automated data are returned to the U.S. Naval 

Oceanographic Office where they are stored in digital form in a UNIVAC 1108 computer data bank; analog data are microfilmed and original records are 

preserved. These data are analyzed and reported 

to various U.S. Navy users.

During the period from 1973-76, the following 

geophysical data were collected in the Geophysical 

Surveying Project in the Northern Hemisphere: mag-i 

netic, 178,503 km; narrow beam ES, 282,115 km; 

seismic, 221,867 km; and 3.5-kHz SSP, 429,808 km. 

Differences in distance arise because not all 

parameters are necessarily collected on every 

track. When processing is completed, copies of 

3.5-kHz and seismic subbottom profiling data are 

forwarded to NGSDC; NBES data are sent to the Defense Mapping Agency Hydrographic Center, and 

magnetic data are deposited in the Magnetics

Library of the U.S. Naval Oceanographic Office. 

Cruises made by the USNS SILAS BENT (in conjunction with USNS DESTEIGUER, T-AGOR 12) off the 

Pacific coast of Latin America, and cruises by 

USNS KANE and WILKES in the Caribbean Sea may be 

of interest. The data from the Caribbean Sea 

have been combined with other data in a publication entitled "Regional Geological/Geophysical 

Study of the Caribbean Sea" (Matthews and Hoicombe, 1976). The study consists of seven geophysical maps and three track-control maps that 

have been compiled for the eastern Caribbean 

Sea. These maps are based upon bathymetric, magnetic, and seismic data from all available 

sources; they are estimated to contain between 

90 and 95 percent of all data in existence for 

the Venezuela Basin. A comparison of the seismic maps with the bathymetric map indicates that 

eastern Caribbean bathymetry is primarily controlled by structure. Sedimentary processes 

have tended to subdue the structural expression 

by partially filling depressions. The geomagnetic map shows generally low relief resulting 

from the low magnetic latitude of the mapped 

area» High-amplitude, short-wavelength anomalies are associated with igneous activity along 

the island chains and the Aves Ridge. Interpretations are limited, with emphasis placed on 

criteria used for compilation of the maps.

Brief descriptions of the surveys conducted 

by USNS SILAS BENT and USNS DESTEIGUER off the 

west coast of Latin America are contained in U.S. 

Naval Oceanographic Office, 1973a and 1973b. The 

point of contact for this project is James L. 

Carroll, Code 3430, U.S. Naval Oceanographic Office, Washington, D.C. 20373.

Scientific Event Alert 

Network (SEAN)

In 1975, the Smithsonian Institution reassessed the performance of the SCSLP (Smithsonian 

Center for Short-Lived Phenomena) and concluded 

that the scientific community, as well as other 

interested correspondents, needed more timely 

and thorough reporting of natural scientific 

events. Accordingly, in October 1975 the Institution transferred three SCSLP employees from 

Massachusetts to the National Museum of Natural 

History in Washington, D.C., and formed SEAN 

(Scientific Event Alert Network). The objectives 

of SEAN are (1) to act as a communications hub 

for transient natural events gathering information on events and passing it rapidly (via 

telephone or telex) to scientists immediately 

concerned with such events; (2) to distribute 

this information at no cost to a broader group of 

interested scientists and correspondents via a 

monthly bulletin; (3) to prepare follow-up reports 

in subsequent monthly bulletins on events of 

longer duration; (4) to concentrate on natural 

scientific events (man-made pollution events are 

normally not reported); and (5) to guarantee the 

close involvement of Smithsonian scientists with 

SEAN's communications activities.

Also in October 1975, the remaining members 

of SCSLP (Director Robert Citron and one parttime employee) formed a private corporation. 

This corporation, known as CSLP (Center for 

Short-Lived Phenomena), is no longer affiliated

21
with the Smithsonian Institution. CSLP continues to serve its paid subscribers via postcard 

reports.

There are many correspondents in Latin 

America; in the last year they have reported 

nine volcanic eruptions and one fireball event. It 

is hoped that an even wider network of correspondents in Latin America will give better coverage 

and, in turn, stimulate more work on the transient 

geophysical events of that part of the world.

.Earth-structure studies by the 

Department of Terrestrial Magnetism of the

Carnegie Institution of Washington 

and various groups in Latin America

During the period 1973-76, the DTM/CIW 

(Department of Terrestrial Magnetism of the 

Carnegie Institution of Washington) has been 

involved in a variety of cooperative geophysical 

studies in Latin America. Several of these are 

continuing in nature; others represent efforts 

in new localities or with new groups. In 

summary, these studies are concerned with the 

region of the west coast of South America where 

it interacts with the Nazca Plate. The attempt 

has been made to delineate the nature of this 

interaction through studies of seismic structure 

from seismicity, studies of attenuation of seismic energy, surface-wave and refraction studies 

using earthquake and artificial sources, and 

studies of electrical-conductivity structure 

using magnetic storms as probes. The emphasis 

of DTM/CIW has been on the collaborative aspects 

of geophysical observations, continuing a long 

history of helping graduate students undertake 

their studies in North America. In this report 

period, for example, two students were Carnegie 

predoctoral fellows at Canadian universities. 

Several investigations will be briefly discussed, 

and resulting publications listed. Added support 

needed for this work has come primarily from the 

National Science Foundation, the A. L. Day Fund, 

and the H. 0. Wood Fund. Important contributions 

in transporting equipment to and from the United 

States and South America and between various 

countries in South America have been helpfully 

provided by the Interamerican Geodetic Survey, 

Fort Clayton, Canal Zone. The Center for Research in Seismology in Lima, A. A. Geisecke, 

Director, has also provided invaluable contributions in support of these studies.

Anelasticity

This study was undertaken in Chile from 

1966 to 1970 and in Peru from 1966 to the present. Broad frequency range (0.01-Hz), large dynamic range (2 cm-ground noise) tape recording 

seismographs were installed at three sites: 

Toconce in northern Chile, Cuzco in central Peru, 

and Trujillo in northwest Peru (Sacks, 1966). 

Using a technique equivalent to reversed refraction in explosion seismology, spectral ratio 

data derived from earthquakes at different depths 

are analyzed to determine Q structure (Sacks, 

1969; Sacks and Okada, 1974). The broadband 

seismographs also have been used for source spectral studies of South American earthquakes (Linde 

and Sacks, 1972; Linde, 1974).

The lithosphere beneath South America has 

been shown to be very much thicker than was expected from the earlier, simple plate-tectonic 

models. A technique using shear-to-compressional 

wave conversion has been developed, which allows 

a fairly precise determination of the base of 

the lithosphere (James, 197la; Sacks and Okada, 

1974; Sacks and Snoke, 1977).

Evidence based on converted phases shows 

that the angle of subduction of the Nazca Plate 

under central Peru is about 30 instead of about 

10 as proposed by others on the basis of seismicity (Okada, 1974; Snoke and others, 1977).

Seismicity

A number of high-sensitivity short-period 

seismographs were sited and operated to give 

good control of hypocenter determinations, in 

collaboration with A. Rodriguez B., Universidad 

Nacional de San Agustin, Arequipa, Peru; F. Volponi, Cuyo Universidad, San Juan, Argentina; 

Ramon Cabre, S.J., San Calixto Universidad, La 

Paz, Bolivia; German Saa, S.J., deceased, Universidad del Norte, Arica, Chile; and L. Ocola, 

IGP (Institute de Geofisica del Peru, Lima, Peru) 

(James and others, 1969; Sacks and others, 1976). 

I. Selwyn Sacks was the principal investigator.

A discovery has been made of the interrelationship between the anelasticity structure 

(Q), the seismicity, and the volcanoes (Sacks, 

1977).

Explosion seismology

This study was made in collaboration with 

L. Ocola, Lima, Peru; Ramon Cabre, S.J., 

La Paz, Bolivia; E. Ramirez, S.J., Bogota, Colombia; and A. Rodriguez B., Arequipa, Peru. 

The experience in southern Peru and northern 

Chile during the IGY, in which the Carnegie 

group led by H. Tatel and M. Tuve found large 

attenuation of seismic energy normal to the Andean Chain and little evidence for a refracted 

wave from the upper mantle, has led to continued 

efforts to learn the structure in southern Peru 

and central Bolivia. The latest of these observations was completed in July 1976, at which time 

colleagues from the University of Washington, 

Seattle (B. Lewis); University of Wisconsin (R. 

Meyer); and the University of Texas at Dallas 

(C. Helsley) joined in an offshore-onshore study 

with Carnegie and South American collaborators. 

Explosion studies, which were also a major 

effort in 1973, include a study in southern Colombia and northern Ecuador that was carried out 

in collaboration with J. E. Ramirez of the Institute Geofisico de los Andes Colombianos and J. 

Egred of the Universidad Politecnica, Quito, 

Ecuador. In addition to three papers already 

published (Ocola and others, 1971; Ramirez and 

Aldrich, 1973; and Ocola and others, 1975), a 

monograph is currently in preparation summarizing the entire experiment and giving a number of 

results obtained. In addition to the university 

collaboration mentioned above, the University of 

Hawaii and its ship, the KANA KEOKI, made important contributions (E. Berg and D. Hussong). 

The principal investigator was L. T. Aldrich.

Electrical conductivity structure 

in the Andes

Several areas have been studied from 1962 

to the present. The bulk of the data has been

22
obtained in central and southern Peru and in 

western Bolivia. Reconnaissance studies have 

also been made in northern Chile and central Colombia. A concentrated study using 15 temporary 

variograph stations included observations across 

the Andes in the region from lat 30° to 33° S. The 

Latin American collaborators include M. Casaverde R., IGP, Lima; A. Rodriguez B. .and L. 

Tamayo, Universidad Nacional de San Agustin; R. 

Salgueiro P. and S. del Pozo in Bolivia; J. Bannister P., Universidad de Chile, Santiago; E. 

Triep, Cuyo Universidad, San Juan, Argentina; C. 

Garavito, Planetario Bogota; and J. S. Ramirez, 

S.J., Colombia. L. T. Aldrich is the principal 

investigator.

An early reconnaissance study of about 15 

sites by Schmucker (1969) showed the existence 

of an anomalously high conductivity region paralleling the eastern Cordillera in Peru and central 

Bolivia. The data of Schmucker have been augmented by another set of over 75 stations in this 

region that extends into northern Chile and 

northern Peru. The structure appears to be complex, and analysis of the data is currently in 

progress.

The Defense Mapping Agency 

Inter-American Geodetic Survey

geophysical activities in Latin America

The DMA/IAGS (Defense Mapping Agency InterAmerican Geodetic Survey) contribution to geophysical activities in Latin America included 

support of regional reconnaissance gravity mapping and collection of geomagnetic data for revision of magnetic charts. Occasional coordination 

and reimbursable logistic support were provided 

for a variety of geophysical projects of significant international interest. Support for gravity mapping was provided in the form of instrument and equipment loans, occasional direct financial support, and regional coordination of 

planning and field activities. Through the international cooperation of cartographic and geophysical agencies in all Latin American countries, 

good progress was made toward reduction of existing gravity data to world standards and the preparation of national gravity anomaly maps at a 

scale of 1:500,000 and 1:1,000,000.

DMA/IAGS contributed to a Latin American geomagnetic program consisting of vector-component 

field observations used in compilation of magnetic 

charts and sufficient reoccupations for periodic 

revision of these charts. Instruments, planning 

coordination, and limited logistic support were 

provided. Permanent magnetic observatories were 

upgraded instrumentally, and minor items and expendable supplies were provided. Coordination of 

data collections from the observatories to WDC-A 

was improved.

DMA/IAGS, through its logistical, communications, and administrative systems, furthered 

the extent and feasibility of international geophysical projects to minimize effects of earthquakes and other natural disasters and to promote 

development of Earth resources.

Other related geophysical activities of DMA/ 

IAGS are described in the U.S. report to the 

Commission on Cartography.

National Aeronautics and Space Administration 

geophysical projects in Latin America

One NASA (National Aeronautics and Space 

Administration) project is under way and another 

is in the planning stage. The former is the 

Cotopaxi Volcano Monitoring System; its purpose 

is to look for unusual tilts or seismic activity 

that might precede possible eruption. Hardware 

has been installed. The system is based on USGS 

designs and consists of two vertical borehole 

tiltmeters and one single-axis, vertical, shortperiod (1-Hz) seismometer. It is now installed 

on the side of Cotopaxi, and the data are radiorelayed to the NASA STDN (Spaceflight Tracking 

and Data Network) Tracking Station about 20 km 

away. Data are recorded in analog form and made 

available immediately to interested Ecuadorian 

geophysicists. Planned duration of the project 

is 5 to 10 years. Local contacts are C. 

Shaddeau, NASA STDN station director, Quito; and 

M. Hall, Escuela Politecnica Nacional, Quito.

The other project being planned is the 

South American Seismic Data Relay System. This 

would be a cooperative experiment between NASA 

and CERESIS (Centro Regional de Sismologia para 

la America del Sur) to establish a system of 10 

to 20 seismic stations in South America that 

would utilize data-collection platforms and a 

synchronous satellite to relay, in near real 

time, seismic data to a central receiving station, 

probably located in Peru. Implementation would 

begin in the 1979-80 period. Local contact is 

A. Giesecke, Director of CERESIS, Institute Geofisico del Peru, Lima.

Oceans and atmospheres

International Decade of Ocean Exploration (IDOE) 

Living resources program

The long-term goal of the CUEA (Coastal Upwelling Ecosystems Analysis) program is to understand coastal upwelling ecosystems sufficiently 

to predict their response far enough in advance 

to be useful to mankind. This goal, when 

achieved, provides the basis for protecting the 

long-term productivity of fisheries in these 

ecosystems. There are 20 multi-disciplinary projects. To achieve its goal, CUEA has four objectives:

1. To describe and understand the mesoscale distributions that define coastal upwelling 

ecosystems in space and time, including such 

variables as radiation, winds, currents, 

density, nutrients, phytoplankton, zooplankton, nekton, and benthos, as well as 

analyses of the spectral characteristics 

of each.

2. To understand the dynamic processes that affect the total behavior of these ecosystems 

and to derive quantitative values of windinduced upper oceanic circulation, mesoscale 

flow fields, uptake of nutrients by phytoplankton, and other processes that can limit 

grazing, predation, excretion, respiration, 

and remineralization.

3. To learn more about the physical, chemical, 

and biological interactions that increase

23
the production of coastal upwelling ecosystems by an order of magnitude over that of 

open-ocean areas.

4. To develop models that will simulate the northwest African and Peruvian upwelling ecosystems and that will provide the basis for predicting the response of these ecosystems to 

variabilities in scales and rates of processes, 

or to different fishery management strategies.

Five field programs are complete: MESCAL-I 

and -II, CUE-I and -II, and JOINT-I. 1 The 

sixth, JOINT-II, began in March 1976. The 

methods developed and experience gained in the 

first four field programs were brought together 

in JOINT-I, the first major CUEA interdisciplinary expedition. Cooperation with scientists 

in the CINECA (Cooperative Investigations of 

the Northern Part of the Eastern Central Atlantic) 

program made possible an international experiment involving ships, aircraft, equipment, and 

personnel from 11 countries. The field programs

have provided comprehensive and detailed descriptions of the physical, chemical, and biological processes that influence the productivity or 

potential economic yield of each upwelling 

ecosystem. The usefulness of the data and findings obtained through the observational phases 

and theoretical research in the field was confirmed at the meeting of the UNESCO SCOR (Scientific Committee on Ocean Research) Working Group 

36 in June 1974, at Which meeting results from 

other laboratories and from cruises to the northwest African and Peruvian upwelling regions were 

compared.

CUEA tested newly gained knowledge of upwelling processes in JOINT-II, an intensive collaborative study of the Peruvian upwelling region ecosystem from March 1976 to May 1977. Most 

JOINT-II investigations were in an area about 

100 by 100 km, centered at lat 15° S. between 

Pisco and San Juan, Peru (fig. 11), during three 

intensive phases: March-May 1976 (MAM 76), July-

^ESCAL-I and -II were primarily biological 

studies off the coast of Baja California during March 

1972 and March and April 1973. CUE-I and -II were 

physical oceanographic studies off the Oregon coast 

from April-October 1972 and the summer of 1973. JOINT-I 

was the first integrated biological and physical field 

study; it was located off the northwest coast of Africa 

during February-May 1974.

77 76° 75° 74

14c

15 C

16°

FIGURE 11.--JOINT-II area and hydrography lines 

A-D, which form the JOINT-II research grid. 

Modified from Holt (1976).

24
November 1976 (JASON 76), and March-May 1977 

(MAM 77). Observations were made from seven 

U.S. research vessels, Peruvian research vessels, aircraft, moored current meters, coastal 

meteorological stations, and satellites. The 

conceptual framework includes four areas of investigation: (1) physical mesoscale studies, 

(2) frontal studies, (3) biological mesoscale 

studies of the circulation, and (4) phytoplankton 

processes.

At the beginning of the CUBA program in 1972, 

the Peruvian upwelling region was selected as the 

site for JOINT-II. This selection now appears appropriate for the following reasons:

1. Concepts have been developed concerning processes that enhance the biological productivity off Peru as opposed to the other major 

upwelling regions of the world. These now 

can be tested.

2. The Peruvian research institutions IMARPE 

(Institute del Mar del Peru), SENAMHI (National Meteorological and Hydrological Service), DHNM (Naval Hydrographic and Navigational Directorate), IGP (Peruvian Geophysical Institution) have initiated a program 

titled "A Study of the Coastal Upwelling System off Peru." The Peruvian program includes 

coast and detailed studies in four important 

achoveta fishery regions. These studies will 

complement the intensive mesoscale studies of 

CUEA in JOINT-II.

3. IMARPE is participating in the scientific program of JOINT-II through collaboration of 

IMARPE scientists with various CUEA components; 

by contributing one complete scientific component (Component 19, Zooplankton Fields); and 

by contributing the use of IMARPE space, facilities, and services for the JOINT-II investigation. This collaboration has made it possible to compare the complex IMARPE fish stock 

models with CUEA ecosystem models. IMARPE and 

the Food and Agriculture Organization of the 

United Nations have developed an assessment 

and prediction system using five independent 

determinations of abundance and catch. This 

program provides monthly predictions of anchoveta stocks. The opportunity exists to 

combine both IMARPE and CUEA capabilities 

into a tool for understanding and managing 

the protein resources of upwelling regions. 

In June 1975, a formal agreement was reached 

between CUEA and IMARPE on the areas of participation and collaboration.

4. The Latin American countries along the Pacific 

coast have initiated a study entitled ERFEN 

(Estudio Regional del Fenomeno El Nino). 

This program will monitor the oceanic and 

atmospheric environment from about lat 

10° N. to lat 35°S. and from the Pacific 

coast of South America to 500 km west. It 

will document the large-scale climatic and 

oceanographic features within the JOINT-II 

study area. JOINT-II results will increase 

understanding of the El Nino phenomenon by 

identifying mesoscale processes that are 

driven by the large-scale disturbance and 

that cause the productivity of the region 

to collapse.

Seabed Assessment Program

Activities are described in the section 

"Nazca Plate."

Tsunami Warning System

The Tsunami Warning System is operated by 

NOAA's National Weather Service in cooperation 

with other U.S. and foreign informational groups; 

it functions in concert with the Intergovernmental 

Oceanographic Commission and member states.

An agreement of major importance was reached 

during December 2-7, 1974, when U.S. and USSR tsunami experts met in Silver Spring, Md., and signed 

a Bilateral Agreement on the Integration of the 

Tsunami Warning Systems of the two countries. In 

1975 the United States and the Union of Soviet 

Socialist Republics participated in a 2-month 

Kuril Tsunami Experiment; they met again in September 1976 in Novosibirsk for a second meeting of 

tsunami experts.

The Tsunami Warning System in the Pacific has 

continued to expand and improve its services; it 

now distributes watch and warning information to 

15 countries and territories throughout the Pacific 

and receives reports from 31 seismic and 54 tide 

stations. Seismograph stations at Yuzhno-Sakhalinsk 

and Petropavlovsk, USSR; Albuquerque, N.M.; 

Dugway, Utah; Glamis, Calif.; Blacksburg, 

Va.; and Fort Yukon and Yakutat, Alaska, 

now report data to the system. New tide 

stations participating in the warning system 

are located at Kushiro, Japan; Langara Island, 

Canada; Socorro Island, Colima, Mexico; Sand 

Point, Alaska; and San Francisco and San 

Diego, Calif.

A major improvement in the warning 

system occurred when facilities for automated 

imessage preparation and data-handling were 

provided to the warning unit at Honolulu 

Observatory. The time involved in composing, 

verifying, and transmitting a watch or warning 

message has been cut from approximately 

45 minutes to less than 5 minutes.

Work continues on the development of 

automated tide and seismic platforms that 

can be interrogated through a GEOS (geostationary satellite). Prototype platforms 

have been undergoing testing for a year, 

and second-generation platforms will begin 

operational testing in 1977.

One of the main tsunami research activities within the United States is focused 

on instrumentation systems and the development of a real-time mid-ocean tsunami reporting system. The research objectives are to 

obtain data on the untransformed wave in 

deep ocean and to measure and study the 

changes that occur as the wave interacts 

with the shoreline. The mid-ocean tsunami 

reporting systems, when operational, will 

make possible a quantitative warning. A 

numerical hydro-dynamic study of tsunami 

runup serves to outline areas of potential 

inundation and to limit the type of structures 

that may be put in any particular place. 

Nonlinear studies of runup have continued,

25
but almost without exception are in the 

realm of nonoperational and nonapplied 

research.

The WDC-A for Tsunamis was relocated 

from Honolulu to Boulder, Colo., in December 

1974 to take advantage of the data-processing 

capability and staff available in WDC-A for 

Solid Earth Geophysics. WDC-A is in the 

process of microfilming the large file of 

mareographic data in NOS.(National Ocean 

Survey). When completed, WDC-A will have on 

35-mm microfilm approximately 1,000 tide 

records from more than 100 tsunami events 

worldwide. WDC-A will then proceed to 

complete its holdings, as called for in the ICSU 

(International Council of Scientific Unions) 

Guide to International Data Exchange, by requesting records through the International Tsunami Information Service from the participating stations.

Table 4 gives a summary of tsunami activity, 

1973-76. Reporting stations are shown in figure 

12.

Solar-terrestrial physics

Data bases

One of the requirements necessary for 

the study of the phenomena of solar-terrestrial physics is the availability of an adequate data base. To accumulate such a base, 

contributions must be made from a worldwide 

network of ground-based observatories and 

from observations monitored from satellites 

in the magnetosphere and the interplanetary 

medium. In many cases these observations 

need to extend through several solar cycles 

in order to delineate and to make comprehensible the complex time variation.

Table 4. Tsunami Activity, 1973-2976

Earthquake epicenter Maximum tsunami Remarks

Mo D Hr Min Lat Long Ht(m) Mag(ms) Location

1973

01 30 21 01 18.5 N. 103.0 W. 1.16 7.3 Manzanillo, Mexico02 28 06 38 50.5 N. 156.6 E. 1.50 7.1 Shumshu Island 

06 17 03 55 43.2 N. 145.8 E. 3.04 7.7 Nemuro, Japan 

06 24 02 43 43.3 N. 146.4 E. 1.22 7.1 Hokkaido, Japan - 

10 05 05 45 33.0 S. 071.9 W. .40 6.3 Valparaiso, ChileMinor tsunami.

Several fishing boats sunk.

1974

01 31 23 30 

02 01 03 12

09 27 05 47 

10 03 14 22

07.5 S. 

07.4 S.

43.2 N. 

12.3 S.

155.9 E. 

155.6 E.

146.7 E. 

077.8 W.

1.52 

4.60

.38 

1.83

6.9 

6.8

6.7 

7.5

Choiseul Island, Minor damage on Choiseul Island. 

Shortland Island.

1975

05 26 09 12 36.0 N. 017.7 W. 2.13 8.0

06 10 13 47 43.0 N. 147.7 E. 3-5 7.1

07 20 14 38 06.6 S. 155.1 E. ^2 7.8

10 31 08 28 12.5 N. 126.0 E. .50 7.2

11 29 14 48 19.3 N. 155.0 W. 7.91

12 26 15 57 16.3 S. 172.5 W. .75 7.!

Ponta Delgada, Azores

Islands.

Kanashir, Kuril IslandsNear Bougainville----- 

Chosi, Japan------ 

7.2 Halape, Hawaii Island 

Pago Pago, 

Samoa.

American

Minor damage at Torokina.

One death; 30 houses lost on 

east coast of Samar Island.

One death; one missing; $1.5 

million damage on Hawaii 

Island; $2 thousand damage 

on Santa Catalina Island, 

Calif.

1976

01 14 16 48 28.4 S. 177.7 W. .90 8.0

01 21 10 05 44.9 N. 149.2 E. .13 7.0

02 04 09 02 15.3 N. 089.1 W. .24 7.5

08 16 16 11 06.3 N. 124.0 E. 4.57 7.9

Suva, Fiji 

Burevestnik, USSR 

Puerto Cortez, HondurasMoro Gulf Five to eight thousand killed 

or missing due to tsunami and 

earthquake; extensive damage 

on Moro Gulf.

Information was extracted from U.S. Earthquakes and ITIC Newsletters. Leaders (- I indicate small, 

local events causing no deaths and little, if any, damage.

26
NOVEMBER, 1911

FIGURE 12. Reporting stations of the Tsunami Warning System.

NSSDC (National Space Science Data 

Center) and NGSDC (National Geophysical 

and Solar-Terrestrial Data Center) were 

established to acquire, archive, and disseminate data throughout the scientific community. 

Consequently, these centers have developed 

an enormous data information system that can 

be utilized by anyone in the world.

NSSDC is located at the Goddard Space 

Flight Center of NASA, Greenbelt, Md., and 

is collocated with WDC-A for Rockets and 

Satellites,, Because it is not practical to archive 

the large amount of satellite data acquired 

from every scientific experiment on every 

satellite, NSSDC does not normally maintain 

complete files of raw or calibrated data, 

but does assist scientists in obtaining 

copies of data either held by experimenters or 

available through national archives. This 

data center is also responsible for maintaining records on sounding rockets, satellites, 

and space-probe launchings. During the 

past four years, NSSDC has responded to many 

data requests received from Latin American

scientists. For example, during 1974 the 

data center processed 163 individual requests 

from scientists in Argentina, Bolivia, Brazil, 

Chile, Mexico, and Venezuela.

NGSDC is located at EDS, NOAA, Boulder, 

Colo. This center, collocated with WDC-A 

for Solar-Terrestrial Physics, acquires, 

archives, and provides data in the following 

areas of solar-terrestrial physics: ionosphere, solar and interplanetary phenomena, 

geomagnetic variations, aurora, cosmic rays, 

and airglow. Atmospheric-ozone data are not 

the primary responsibility of this data center; 

they are available through the National 

Climatic Center, Asheville, N.C.

WDC-A for Solar-Terrestrial Physics (or 

NGSDC) maintains a record of all locations 

where solar-terrestrial physics observations 

are being conducted throughout the world. 

See Buhmann and others (1974) for a list of 

stations currently in operation; the geographic 

coordinates of each station; the type of observation identified by discipline; and,

27
for those stations where observations have 

terminated, a record of the time period 

during which the experiment was operating. 

Figure 13 illustrates the locations where 

solar-terrestrial physics observations are 

presently being conducted in the Western 

Hemisphere.

Many requests for solar-terrestrial physics 

data acquired at Latin American stations are 

received by WDC-A for Solar-Terrestrial 

Physics each year. For example, in the 

period from July 1975 to July 1976, the data 

center received 34 individual requests for 

ionospheric vertical sounding data acquired

in South America,, These requests represented 

899 station-months of data.

Catalog of possible collaborators

A catalog containing the names of scientists 

in the United States and Canada who are engaged 

in various experimental and theoretical investigations in solar-terrestrial physics and who also 

are willing to collaborate with Latin American 

scientists is currently being prepared by 

M. A. Shea of the Air Force Geophysics Laboratory. 

With the cooperation of WDC-A for SolarTerrestrial Physics and AGU (American Geophysical 

Union), a list of approximately 1,500 people

FIGURE 13. Solar-terrestrial physics stations (triangles) in the Western Hemisphere,

Data from NOAA/EDS.

28
interested in solar-terrestrial physics was 

compiled. A letter with questionnaire was sent 

to each of these people asking whether he 

was willing to collaborate with Latin American 

scientists in various projects.

Approximately 150 people responded to this 

questionnaire. These replies are being compiled 

into a format that will list the name and address 

of each scientist; the area of interest; the 

type and location of experimental equipment in 

operation (if applicable); and whether the 

respondent's group or institution can accept 

a scientist, technician, or student for a specified 

period of time in a cooperative and (or) 

training endeavor. Respondents indicating that 

some financial support might be available for 

various projects are also identified.

The text of this report will be prepared 

in English and Spanish, and copies will be 

sent to each scientist and principal investigator listed in the report. Additional copies 

will be sent to the PAIGH executive office. 

This publication will also include names and 

addresses of the people listed in the STP 

catalog (Comision de Geofisica del IPGH, 1975).

Other activities

Other formal and informal programs of a 

cooperative nature between scientists in the 

United States and Latin America have been undertaken.

Since 1973 studies of transionospheric 

radio propagation have been made, in collaboration with the Air Force Geophysics Laboratory, 

through observations of ionospheric scintillation and total electronic content at Huancayo, 

Peru, and Natal, Brazil. These observations 

are made by monitoring radio signals transmitted by satellites equipped with radio 

beacons. The measurements are being used to 

develop global models of ionospheric scintillation and total electron content. In order to 

gain information on the formation of scintillation-causing mechanisms the scintillation 

measurements at Huancayo recently have been 

supplemented with measurements made by the incoherent scatter radar located at Jicamarca, 

Peru. (See Mullen and others, 1976.) Principal 

investigator is Jules Aarons of the Air Force 

Geophysics Laboratory (PHP).

Also in collaboration with the Air Force 

Geophysics Laboratory, observations of the total 

intensity and circular polarization of quiet-sun 

and burst emission have been carried out since 1972 

at 9.4 GHz at the Huancayo Observatory of the 

Institute Geofisico del Peru and at 7 GHz 

at the Itapetinga Observatory of Mackenzie 

University, Sao Paulo, Brazil. Data from 

these observations, and similar ones at 5 GHz at the 

Air Force Geophysics Laboratory's Sagamore Hill 

Radio Observatory, Hamilton, Mass., have been 

used to obtain centimeter wavelength circularpolarization spectra of a number of radio bursts. 

These spectra are used to investigate burstregion properties (magnetic field, electron 

density, and energy distribution) and solar 

emission-mechanism theories. Principal investigator is D. Guidice, Air Force Geophysics Laboratory (PHP).

Studies of ionospheric irregularities 

using VHF radars were made in Peru and Brazil. 

Approximately 12 trips to take experimental 

measurements at various locations in South 

America were made, with each trip taking 3-4 

weeks. The locations include Jicamarca Radar 

Observatory near Lima, Peru; Geophysical 

Observatory at Huancayo, Peru; and Brazilian 

Rocket Launch Facility near Natal, Brazil. 

The following scientists participated in one 

or more of these trips: B. B. Balsley, 

W. L. Ecklund, D. A. Carter, and P. E. Johnston, 

all of NOAA. The purpose of these trips 

varied considerably. Data on equatorial 

spread F in conjunction with a chemical 

release of barium by an instrumented rocket 

were acquired in Brazil; neutral wind measurements at E-region heights were made in a 

recent experiment between Huancayo and Jicamarea; 

and a series of experiments designed to measure 

various aspects of equatorial sporadic E, 

equatorial spread F, neutral winds in the 

E-region, as well as specific parameters of 

mesospheric, stratospheric, and tropospheric 

wind fields was conducted at Jicamarca. 

Pertinent publications include the following: 

Balsley and Parley (1973); Balsley, Carter, 

and Woodman (1976); Balsley and Farley (1975); 

Balsley, Fejer, and Farley (1976); Balsley, 

Rey, and Woodman (1976); Farley and Balsley 

(1973); Fejer, Farley, Balsley, and Woodman 

(1975a; 1975b, 1976a, 1976b); Kelley and others 

(1976). Principal investigator is Ben B. 

Balsley, Aeronomy Laboratory of NOAA, Boulder, 

Colo.

Another cooperative program between NOAA 

and Huancayo is the Dobson Spectrophotometer 

Observations of Atmospheric Total Ozone at 

Huancayo. Measurements of total ozone have 

been made three times per day since 1964. 

Processing of the data by computer is accomplished 

at the NOAA/ERL Air Resources Laboratory, Boulder, 

Colo. Final results are archived routinely 

at the World Ozone Data Center by the Canadian 

Atmospheric Environment Service, Department 

of the Environment, in cooperation with the 

World Meteorological Organization. One important 

finding has emerged from these measurements: 

In a study of global trends in total ozone 

during the 1960's, it was found that the rate 

of increase in total ozone for Huancayo is 

6.0+0.4 percent per decade (Komhyr and others, 

1971). Principal investigator is W. D. Komhyr of the 

NOAA/ERL Air Resources Laboratory.

Cooperative projects concerning equatorial 

ionospheric irregularities and upper-lower 

atmospheric coupling have been conducted 

between scientists at the Jicamarca Radar 

Observatory in Peru and the Aerospace Corporation 

in California. One of the projects was the building of the Chilca rocket range to launch the 

EOUION rocket probe. Additional rocket and radar 

projects, and possibly a balloon and radar 

project, are being planned. Principal investigators are F. A. Morse and C. J. Rice of the 

Space Sciences Laboratory, Aerospace Corporation, 

Calif.

A cooperative program to study equatorial 

airglow and dayglow emissions is being conducted 

between scientists at the University of Texas

29
at Dallas and Huancayo, Peru. The equatorial 

emissions are made using a 1-m grille spectrometer and filter photometers. Principal investigator is A. Ba Christensen of the Center for 

Space Science at the University of Texas at Dallas.

Observations of radiowave scintillation 

produced by electron-density irregularities in 

the ionosphere are being studied. Radio signals 

from a coherent beacon aboard a polar orbiting 

satellite are being received at Ancon, Peru, 

Stanford, Calif., and Poker Flat, Alaska. 

Analyses of these data are then made in comparison 

with other ionospheric and geomagnetic phenomena. 

Principal investigator is E. J. Fremouw of the 

Radio Physics Laboratory of Stanford Research 

Institute.

The phase and amplitude of VLF signals are 

being measured in a joint project between 

scientists at the USAECOM (U.S. Army Electronics 

Command), Fort Monmouth, N. J., and the Centre 

de Radio-Astronomia e Astrofisica, Sao Paulo, 

Brazil. The purpose of this experiment is to 

observe solar-induced changes in the lower 

ionosphere by monitoring the VLF signals 

emitted by Omega transmitters. The groundbased equipment is located at Fort Monmouth 

and Sao Paulo. Principal investigator is 

F. M. Reder of USAECOM in Fort Monmouth.

Since 1974 there has been an informal 

cooperative program between scientists at the 

Air Force Geophysics Laboratory and the Institute 

de Pesquisas Espaciais, Sao Jose dos Campos, 

Brazil, involving the calculation of cosmicray geomagnetic cutoff rigidities and the 

utilization of these values for the analyses 

of cosmic-radiation data acquired from 

balloon measurements over Brazil. Initial 

results of this study are given in 

Shea, Smart, and Palmeira (1976). 

Principal investigators are M. A. Shea and 

D 0 F. Smart of the Air Force Geophysics Laboratory 

(PHG), Hanscom Field, Mass.

Other cooperative projects also exist: 

Magnetic field measurements are being conducted 

at Eusebiom, Brazil, with principal investigator 

Paul J. Coleman, Jr., of the Department of Geophysics and Space Physics of the University of 

California at Los Angeles; electric field measurements are being conducted at Jicamarca, 

Peru, using the Jicamarca radar with principal 

investigator Michael C. Kelley of the School of 

Electrical Engineering, Cornell University; and 

an electric field mill is in operation at Cerro 

Tololo, Chile, with principal investigator Chung 

G. Park of the Radioscience Laboratory of 

Stanford University.

Progress in the science

Although past emphasis in solar-terrestrial 

physics has been largely on research leading to 

an understanding of the processes in the upper 

atmosphere and on the physical mechanisms of the 

effect of solar-interplanetary phenomena on 

this atmosphere, some phases of the work have 

been directed toward more practical applications. 

For example, ionospheric measurements have 

been and continue to be used to improve the 

planning and operation of radio telecommunications

using the high-frequency band on which longdistance, point-to-point communication is made 

possible by radio-wave reflections from the ionosphere. Interruptions caused by ionospheric 

disturbances to such telecommunications circuits 

can often be traced to specific solar phenomena 

such as the emission of solar X-rays. Other 

types of ionospheric disturbances associated with 

geomagnetic storms can be forecast in some 

cases; prompt warnings of the onset of these 

storms enable telecommunication services to 

take action to minimize the effect of the disruptions.

As our measurement techniques became more 

sophisticated and our technology more advanced, 

additional areas of solar-terrestrial physics 

were found to have direct application to ordinary 

daily activities. When it became known that 

the occurrence of a major solar flare on the sun 

had both immediate and delayed effects on 

communication systems, scientists found it 

necessary to acquire enough data of these 

phenomena to describe, model, and predict 

the disturbances of our environment that could 

be expected after a solar flare was visually 

observed. In the past few years, although 

neither direct nor indirect relationships are 

clearly evident from the data, increasing evidence 

has accumulated that many of the climatic 

changes over the decades may be related to solar 

activity. Certainly, economic benefits would be 

associated with the ability to predict from the 

observations of solar activity, long-term changes 

in the weather patterns in specific areas of 

the world.

During the next four years, research in 

solar-terrestrial physics is expected to increase, 

particularly in magnetospheric and geomagnetic 

studies. Scientists will be participating in 

the International Magnetospheric Study project 

in an attempt to gain a better understanding of 

Earth's magnetosphere, the interplanetary medium, 

and the interaction between the two. A large and 

comprehensive Middle Atmosphere Program on 

atmospheric studies, including the possibility 

of solar effects on the weather, is tentatively 

planned for the period 1978-85. The exchange 

of scientific information and data, plus the 

cooperative efforts of various scientists 

participating in projects such as the International Magnetospheric Study and the Middle 

Atmosphere Program, should prove most fruitful, 

not only for the scientists participating in 

these programs, but also for those who gain increased understanding of the environment in 

which we live and the subsequent benefit for 

mankind.

Special projects of the PAIGH involving 

The U.S. Member of the Commission on Geophysics

Geomagnetism projects

Latin American-United States cooperative 

work in geomagnetism

This refers to PAIGH Special Project 

No. 3.4.1.14. COMGEOFIS (Commission on Geophysics) resolution no. 4 of the X General 

Assembly of PAIGH recommended that the United

30
States send a geophysicist to Central and South 

American magnetic observatories for the purpose 

of standardizing and comparing magnetic instruments used in the network of observatories. 

There were three primary objectives: (1) to use 

instruments calibrated against the magnetic 

standards of Fredericksburg Observatory for making comparative observations about observatory 

standards in each country; (2) to establish 

mutual consultation on problems with magnetographs, magnetometers, data processing, and 

so forth; (3) to exchange information on the 

development of new instrumentation and recording 

techniques being utilized in geomagnetic data 

collection.

Travel funds and living expenses were provided 

by PAIGH, and in 1974 A. H. Travis, a geophysicist 

of the U.S. Geological Survey who is Chief of the 

Fredericksburg Geomagnetic Center in Fredericksburg, 

Va., went to Latin America to accomplish this 

mission. Offices and observatories visted were:

Institute de Geofisica 

Ciudad Universitaria 

Mexico, D. F.

Teoloyucan Observatory 

Teoloyucan, Mexico

Institute Geografico 

Bogota, Colombia

Fuquene Observatory 

Fuquene, Colombia

Institute Geofisico del Peru 

Lima, Peru

Huancayo Observatory 

Huancayo, Peru

Institute Geofisico 

Univ. Nac. de San Agustin 

Arequipa, Peru

Arequipa Observatory 

Arequipa, Peru

Institute Investigaciones Fisicas 

Universidad Mayor San Andres 

La Paz, Bolivia

La Paz Observatory 

La Paz, Bolivia

Oficina Meteorologica de Chile 

Santiago, Chile

Isla de Pascua Observatory 

Easter Island

Observatorio Nacional 

Rio de Janeiro, Brazil

Vassouras Observatory 

Vassouras, Brazil

Tatuoca Observatory 

Tatuoca, Brazil

Mr. Travis also intended to visit Argentine 

observatories, but he was able to visit only the 

Buenos Aires office of the Servicio Meteorologico 

Nacional.

At each station the instruments were inspected, technical discussions were held, and, 

where possible, preliminary comparative results 

were determined and furnished to the staff 

during the visit. Final results were sent from 

Fredericksburg following completion of computations. Details of Mr. Travis's findings are 

given in his trip report.

As part of this cooperative project, William 

Paulishak of WDC-A visited the same offices 

(except for Santiago) in January-March 1976, 

using a portable microfilming camera to film 

magnetograms and tables of hourly values that 

were not already in the data center collection. 

About 100 observatory-years of records and data 

were copied. Salary and travel expenses were 

borne by WDC-A (NOAA). Considerable logistical 

assistance was provided by IAGS, ,and coordinated 

by Roman Geller. A letter signed by Jose Saenz 

explaining the informational and scientific 

nature of the project expedited customs formalitie 

in the various countries. The excellent cooperation by the institutions visited was invaluable in making this project a success.

Site planning for geomagnetic 

facility in Costa Rica

This refers to PAIGH Special Project No. 

76-058-22. At the request of the University of 

Costa Rica, J. D. Wood, a geophysicist of the 

U.S. Geological Survey in Denver, Colo., traveled 

to Costa Rica in February 1977 for the purpose 

of assisting and advising in the selection of a 

site for the future magnetic observatory to 

be operated by the University. Mr. Wood 

carried a proton magnetometer for the purpose 

of making magnetic observations at the various 

sites. Sites considered were Turrialba, 

Ochomogo, Jardin Lancaster, Finca Baudrit, 

and San Ramon. On the basis of the observations 

and other considerations, San Ramon was determined to be the best site. Details of Mr. 

Wood's findings are contained in his report 

to the Director of the Department of Physics 

at the University (Wood, 1977). When the 

University completes the buildings and facilities 

required for the proposed observatory, Mr. Wood 

plans to return to Costa Rica to assist and 

advise on the installation of the observatory 

instrumentation. The Institute Geografico 

Nacional, also interested in establishment of 

this observatory offered considerable assistance 

to Mr. Wood during his visit.

Latin American-United States cooperative 

work in phase two geomagnetism

In a continuation of the project entitled 

Latin American-United States Cooperative Work 

in Geomagnetism, A. H. Travis returned to 

Brazil and Argentina early in 1977. He visited 

the following offices and observatories:

Observatorio Nacional 

Rio de Janeiro, Brazil

31
Vassouras Observatory 

Vassouras, Brazil

Institute de Geofisica 

Servicio Meteorologico Nacional 

Buenos Aires, Argentina

Pilar Observatory 

Filar, Argentina

Observatorio Astronomico 

La Plata, Argentina

Las Acacias Observatory 

La Plata, Argentina

In Brazil he assisted in checking orientation 

of magnetograph magnets, installation of a 

new magnetometer, and other instrumental 

matters; in Argentina he accomplished the 

instrumental comparisons scheduled earlier.

This mission was a complete success. Corrections to International Magnetic Standard are 

now known with certainty for all Latin American 

observatories visited, and this standard may be 

carried by the institutions to the observatories 

not visited directly by Mr. Travis.

Preparation of a catalog of principal

facts for gravity stations and gravity

anomaly maps on a common scale for

Latin America.

This refers to PAIGH Special Project No. 

74-033-11. The proposal submitted under this 

project had as its ultimate aim, as expressed 

in its title, the preparation of catalogs of 

principal facts on gravity observations and 

gravity anomaly maps on a country-by-country 

basis for each of the Latin American countries. 

These were to be based on a common scale and 

the IGSN 1970 gravity standard adopted at the 

Moscow meetings of the International Union of 

Geodesy and Geophysics. A critical step in 

meeting the objectives was to obtain releases 

in each country of the data"available, as well 

as to determine whether the data had been reduced and put on the national datum for each 

country, and whether auxiliary information (position and elevation values) was available for 

anomaly reductions. Because this, as well as a 

commitment for cooperation on the project by all 

of the principals working in gravity, could be 

determined only at a joint meeting of the principals, the proposal submitted to PAIGH was only 

for funds to cover the cost of such a meeting. 

It was this proposal that was approved by PAIGH, 

and the meeting was held in Panama City, Panama, 

in November 1975. Twenty-five attendees came 

from 14 countries, and the meeting was declared 

"one of the most successful working group meetings that has ever been held." All attendees 

were active in gravity investigations, all had 

full appreciation of the problems involved, and 

all came fully prepared with information on the 

status of gravity investigations in their countries. They were enthusiastic about the objectives and were prepared to work to achieve 

success.

The formal accomplishments of the Panama meeting are summarized in the following: 

"Considering:

1. That (this) meeting constituted a technical 

working group in gravimetry of the Latin 

American countries.

2. That the presentations and technical discussions have evidenced the notable quality and 

quantity of gravimetric information existing 

at this time.

3. That in the light of the problems of scientific and practical kinds, the necessity of 

establishing a uniform reference system of 

gravimetry was appraised.

4. That the assembly recognized the socioeconomic importance that gravimetric studies 

have in the problems of the community. 

The working group on gravimetry adopted the following recommendations:

No. 1: That the group here constituted acquire a 

permanent character and officialize the representation of its members before the respective 

national sections of PAIGH in the corresponding 

countries.

No. 2: That the PAIGH sponsor a special training 

course of observation, maintenance and primary 

reduction of gravimetric data; at the same time, 

as a product of the development of the said 

course, the publication of a manual of gravimetric 

observations is recommended.

No. 3 That the Latin American countries continue lending their support and collaboration 

with SILAG (Sistema Latin Americana de 

Gravimetria). That each country effect a critcal evaluation of existing gravimetric information in accordance with SILAG standards. This 

evaluation should be communicated to SILAG before 

the first of June 1976.

No. 4: To solicit to the COMGEOFIS of PAIGH and 

to the chairman of the SILAG working group that 

they study alternatives concerning the future location of SILAG in a Latin American country. 

No. 5: To establish by the first of June 1976 the 

necessary gravimetric ties between the countries 

contained in Annex 3, in order to improve the 

Latin American Net (Annex 2). At the same time it 

is recommended to establish gravimetric stations 

in the areas presently lacking observations, such 

as the Amazonian Basin, the Strait of Magellan, 

and forested regions of Central America and southern 

Mexico, observing simultaneously with the Geoceiver 

system.

No. 6: It is recommended to incorporate the marine 

gravity survey into the Latin American Net. 

No. 7: It is recommended to maintain a permanent 

relationship with the working groups of the Committee on Geodesy of PAIGH.

No. 8: It is recommended to exhort IAGS that it 

continue lending its valuable collaborations 

through its technical support and infra-structure 

of communications, to this working group and to 

SILAG.

No. 9: To support all the expanding efforts: a) 

Prompt publication of national gravimetric maps 

and catalogs; b) Reobservation of ancient gravimetric stations; c) Integration of gravimetric 

data at a regional level by the publication of a 

gravimetric map of Latin America. 

No. 10: To utilize the Boletin Aereo of PAIGH to

32
regularly inform the scientific community of the 

advances and needs of the gravimetric work. 

No. 11: To hold the second meeting of this technical group in Ottawa in September 1976, in conjunction with the meeting of COMGEOFIS of PAIGH, 

organized by the National Section of Canada."

Since the Panama meeting, the following has 

been accomplished:

1. Using two La Coste gravimeters, J. Monges C. 

(Mexico) has interconnected most of the primary national gravity bases, as well as other 

key gravity sites in South America, Central 

America, and Mexico, to the primary Western 

South American standard sites.

2. J. Tanner (Canada) agreed to have IGSN 1970 

values determined for some 1,500 gravity 

bases distributed throughout Latin America, 

and these values are now essentially ready.

3. R. Geller (IAGS) completed the three secular 

change traverses in Chile, as well as made 

the Santiago-Buenos Aires connection that 

J. Monges could not do earlier because of 

political considerations.

4. G. Woollard (USA) submitted a proposal to the 

U.S. National Science Foundation (now funded) 

for support in adjusting and compiling all 

existing data in Latin America on the IGSN 

1970 standard; he has been assured of computer 

support by the DMA-AC (Aerospace Center) Gravity 

Library (formerly Aeronautical Charts Information Center) on a no-cost basis for computing 

anomaly values as a first step in preparing 

catalogs of principal facts on each country 

and preparing gravity anomaly maps.

5. There were unexpended funds from the Panama

meeting in the amount of about $6,500, owing 

in large part to saving on hotel accommodations. These funds were used to support 

travel expenses of Latin American participants to the meeting in Ottawa in September 

1976.

6. Since 1972 and since initiation of coordination in the gravity program, catalogs of 

gravity values on a nationwide basis have 

been published for Uruguay, Colombia, Chile, 

northern Venezuela, Bolivia, Ecuador, El 

Salvador, areal segments of Brazil, and 

regional base values for Argentina. New 

free-air and Bouguer gravity anomaly maps 

based on observed and predicted values have 

been published by DMA-AC (St. Louis). Over 

4,000 observations have been compiled and 

adjusted for Peru and should be ready for 

publication, along with regional coverage 

for Argentina, in late 1977. Several 

thousand observations are now being adjusted 

for Mexico, and field work is in progress to 

complete the regional coverage of gravity 

values in Mexico. Over 10,000 observations 

are now in various stages of reduction and 

adjustment for the various countries in 

Central America. A considerable body of 

oil-company gravity exploration data has 

been obtained, as well as anomaly maps; and, 

with the exception of Paraguay and major 

segments of Brazil, significant progress in 

turning out complete catalogs of. principal 

facts for gravity sites as well as anomaly 

maps for each country can be expected over 

the next 2-year period.

The support supplied through PAIGH for the 

Panama meeting was the key action necessary to 

bring into being the coordination of effort and 

focus on problems and standards required to put 

all gravity in Latin America on a uniform highquality basis. It further resulted in the 

establishment of a program that will allow the 

objectives of the proposal to be met in a reasonable time frame, and the organization of what 

is now a team effort of all principals in each 

country working together to produce what promises to be an exceptionally well coordinated 

international effort in the geophysical study of 

any continent.

Seminar on seismic and 

volcanological risk

This refers to a joint undertaking of PAIGH 

(Special Project No. 74-031, Seminar and Workshop on Seismic Risk and Other Natural Hazards 

in Central America and Adjacent Regions) and the 

OAS (Organization of American States).

This seminar was held at the EGG (Escuela 

Centroamericano de Geologia) of the University 

of Costa Rica in San Jose, July 13-18, 1975. 

Chairman of the local committee was Cesar 

Dondoli. Organizers of the technical program 

were S. T. Algermissen (USA), Gabriel Dengo 

(Guatemala), and J. E. Ramirez, S. J. (Colombia). 

Coordinators were James N. Jordan for the 

PAIGH and Antonio Quesada for the OAS. There 

were 103 attendees from 22 countries. Travel 

expenses were paid for 31 and per diem expenses 

for 36. Forty-nine formal papers were presented, 

the majority of which were published in Revista 

Geofi-sica.3 no. 5.

The purpose of the seminar was to summarize 

progress in the investigation of earthquake and 

volcanic risks in Central America. It also included reviews of current programs in the United 

States, the Caribbean area, and other parts of 

Latin America, together with discussions of 

recent earthquake and volcanic studies. A forum 

was provided, both formally and informally, for 

the discussion of programs funded and likely to 

be funded by the OAS, UNESCO, PAIGH, and others.

Most of the investigators felt that the 

assessment of seismic and volcanic risk is in 

the infancy stage. Relating these studies to 

the socio-economic conditions within a viable 

framework is a challenge for all concerned. The 

seminar afforded the chance to discuss data systems, analysis methodologies, and some of the 

possible products. Engineers, geologists, seismologists, planners, and others related to the 

seminar theme. The assessment of seismic and 

volcanic risk is multi-disciplinary, and most 

realized the importance of understanding the 

requirements and work of the others. It is felt 

that the seminar helped to create this dialogue 

and understanding.

lonogram scaling course

This refers to PAIGH Special Project No. 

76-039-12. The United States actively participated in an effort to unify the ionogram 

data-interpretation and data-reduction work 

throughout the Americas. R. 0. Conkright, from

33
NOAA's WDC-A for Solar-Terrestrial Physics and 

an expert in ionospheric data interpretation and 

reduction, conducted a 2-week ionogram scaling 

course in Buenos Aires, Argentina, in November 

1976.

This course, held at the Ionospheric Laboratory of the Navy of the Republic of Argentina, 

was attended by 24 scientists and technicians 

from Argentina, Bolivia, Chile, and Peru. The 

first week was devoted to ionospheric physics, 

the formation and variation of the undisturbed 

ionosphere, and data-reduction techniques. 

Because the group represented a vast range in 

geographic latitude, and because the problems 

encountered in equatorial, mid-latitude, and 

polar-region ionograms are quite different, 

most of the second week was devoted to questions on specific ionograms that had been 

difficult for the sealers to interpret confidently. At the end of the course, the 

participants decided to formulate a simple 

set of local rules for the scaling procedures that gave them the most difficulty. 

Mr. Conkright was asked to guide them in 

preparing this document, so that their local 

rules would conform with the international 

rules as much as possible. This set of rules 

will be sent to the Ionospheric Network Advisory Group when finalized. The techniques 

learned during this course will provide the 

scientific community with more uniform and 

accurately reduced data from the .Latin American chain of vertical ionospheric sounding 

stations.

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Ml*. GOVBWHENT HtlHTINS OWICti 1W7.J77-004/5S

37