Earthquakes in the United States, July-September 1977

Geological Survey

Introduction.................................................................... Cl Discussion of tables............................................................ 1 Modified Mercalli Intensity Scale of 1931....................................... 5 Acknowledgments................................................................. 24 References cited................................................................ 26

FIGURE 1. "Earthquake Report" form.............................................. C2

TABLE 1. Summary of U.S. earthquakes for July-September 1977:

2. Map showing standard time zones of the conterminous United States..... 4
3. Map showing standard time zones of Alaska and Hawaii.................. 5
4. Map of the earthquake epicenters in the conterminous United States for July-September 1977................................................... 6
5. Map of earthquake epicenters in Alaska for July-September 1977........ 7
6. Map of earthquake epicenters in Hawaii for July-September 1977........ 9
7. Intensity map for the southern California earthquake of 12 August 1977 19
8. Intensity map for the northeastern Utah earthquake of 30 September 1977.................................................................. 25

Alaska........................................................... CIO California....................................................... 12 California Off the coast........................................ 13 Colorado......................................................... 13 Hawaii........................................................... 13 Idaho............................................................ 14 Montana.......................................................... 14 Nevada........................................................... 14 New York......................................................... 15 Oregon Of f the coast............................................ 15 South Carolina................................................... 15 Tennessee........................................................ 15 Utah............................................................. 15

INTRODUCTION

The earthquake information in this publication supplements that published in the NEIS (National Earthquake Information Service) publications, PDE ("Preliminary Determination of Epicenters") and "Preliminary Determination of Epicenters, Monthly Listing," to the extent of providing detailed felt and intensity data, as well as isoseismal maps for U.S. earthquakes. The purpose is to provide a complete listing of macroseismic effects of earthquakes, which can be used in risk studies, nuclear power plant site evaluations, seismicity studies, and answering inquiries by the public.

This publication contains two major sections. The first (table 1) 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 computational source of the hypocenter. The second section consists of two maps and table 2, which lists detailed intensity information. The list of earthquakes in table 1 was compiled from those located in the United States or off the coasts that were published in the PDE; from hypocenters in California above magnitude 3.0, supplied by California Institute of Technology, Pasadena, the University of California, Berkeley, and other offices of the U.S. Geological Survey; from hypocenters in Hawaii supplied by the Hawaiian Volcano Observatory; and from any others that were felt or that caused damage, regardless of magnitude or availability of a hypocenter. Known or suspected explosions are also listed.

The intensities and macroseismic data were compiled from information obtained through mestionnaires, from newspaper articles, and with *:he cooperation of other Government agencies, State institutions, local organizations, and individuals. (See "Acknowledgments" for a list of collaborators.) Figure 1 is the questionnaire in current use by the NEIS. Other versions of this questionnaire are used by State agencies, engineering firms, and other Government agencies "o collect intensity data. Anyone wishing to ->ubmit felt or damage information on earthquakes "or inclusion in future reports should send it

Cl to the National Earthquake Information Service, Stop 967, Box 25046, Denver Federal Center, Denver, CO 80225. Copies of the current "Earthquake Report" questionnaire can be obtained at this address.

collect macroseismic information is a questionnaire canvass using the "Earthquake Report" forms, which are mailed to postmasters in the area affected by the earthquake. The postmasters complete the forms and return them to the NEIS, where they are evaluated and an intensity value is assigned. The intensity observations are mapped and contoured by isoseismals. Isoseismal contours present a generalization of intensity data and an extrapolation of these data to regions from which there are no observations; they do not necessarily account for every individual observation.

"Earthquake Description" section of "United States Earthquakes," an annual publication, to which later data from other sources may be added for the purpose of updating and completeness. "United States Earthquakes" is published jointly by the U.S. Geological Survey, Department of the Interior, and the Environmental Data Service, NOAA, Department of Commerce.

and table 2 include the date, origin time, hypocenter (epicenter and focal depth), magnitude, intensity, and hypocenter source. The origin time and date are listed in Universal Coordinated Time (UTC) and local standard time based on the time-zone maps in figures 2 and 3. The epicenters, which were taken from those published in the PDE, or from other sources as noted, are listed here to two decimals. The accuracy of the epicenters is that claimed by the institution supplying the hypocenter and is not necessarily the accuracy indicated by the number of decimals listed. The epicenters located by the NEIS have a varying degree of accuracy, usually two-tenths of a degree or less, depending on their continental or oceanic location. The oceanic hypocenters are The primary method used by the NEIS to

The data in table 2 will be included in the

DISCUSSION OF TABLES

The parameters for the earthquakes in table 1 form used for evaluating the intensities of FIGURE 1. Example of the "Earthquake Report" earthquakes. _A, front side.

C2 FIGURE 1. Example of the "Earthquake Report" form used for evaluating the intensities of earthquakes. ]}, reverse side.

C3 FIGURE 3. Standard time zones of Alaska and Hawaii. The number in each zone shows the number

by conversion of recorded ground motion to expected response of the torsion seismometer.

mbLg=3.30+1.66(logD)+log(A/T)

as proposed by Nuttli (1973), where A/T is expressed in micrometers per second, calculated from the vertical-component 1-second Lg waves, and D is the distance in geocentric degrees.

All of the intensity values (indicated by Roman numerals) listed in this summary were derived, using the Modified Mercalli Intensity Scale of 1931 (Wood and Neumann, 1931) shown below, from the evaluation of "Earthquake Report" forms; from field reports by U.S. Geological Survey personnel, engineering firms, or universities; and from detailed macroseismic data communicated to the NEIS by people in the area affected by the earthquake. All earthquake 18OC 165° 150C 135

of hours to be subtracted from Universal Coordinated Time to convert to local standard time. (Subtract 1 hour less for local daylight-saving time.)

MODIFIED MERCALLI INTENSITY SCALE OF 1931

II. Felt indoors by few, especially on upper floors, or by sensitive, or nervous persons. Also, as in grade I, but often more noticeably: sometimes hanging objects may swing, especially when delicately suspended; sometimes trees, structures, liquids, bodies of water, may sway, doors may swing, very slowly; sometimes birds, animals, reported uneasy or disturbed; sometimes dizziness or nausea experienced.

III. Felt indoors by several, motion usually rapid vibration. Sometimes not recognized to be an earthquake at first. Duration estimated in some cases. Vibration like that due to passing of light, or lightly loaded trucks, or heavy trucks some distance away. Hanging objects may swing slightly. Movements may be appreciable on upper levels of tall structures. Rocked standing motor cars slightly.

IV. Felt indoors by many, outdoors by few.

Awakened few, especially light sleepers.

Frightened no one, unless apprehensive from previous experience. Vibration like that due to passing of heavy or heavily loaded trucks. Sensation like heavy body striking building or falling of heavy objects inside. Rattling of dishes, windows, doors; glassware and crockery clink and clash. Creaking of walls, frame, especially in the upper range of this grade. Hanging objects swung, in numerous instances. Disturbed liquids in open vessels slightly. Rocked standing motor cars noticeably.

V. Felt indoors by practically all, outdoors by many or most: outdoors direction estimated. Awakened many, or most. Frightened few slight excitement, a few ran outdoors. Buildings trembled throughout. Broke dishes, glassware, to some extent. Cracked windows in some cases, but not generally. Overturned vases, small or unstable objects, in many instances, with occasional fall. Hanging objects, doors, swing generally or considerably. Knocked pictures against walls, or swung them out of place. Opened, or closed, doors, shutters, abruptly. Pendulum clocks stopped, started or ran fast, or slow. Moved small objects, furnishings, the latter to slight extent. Spilled liquids in small amounts from well-filled open containers. Trees, bushes, shaken slightly.

VI. Felt by all, indoors and outdoors.

Frightened many, excitement general, some alarm, many ran outdoors. Awakened all. Persons made to move unsteadily. Trees, bushes, shaken slightly to moderately. Liquid set in strong motion. Small bells rang church, chapel, school, etc. Damage VII. Frightened all general alarm, all ran

VIII. Fright general alarm approaches panic.

IX. Panic general. Cracked ground

C8 slight in poorly built buildings. Fall of plaster in small amount. Cracked plaster somewhat, especially fine cracks chimneys in some instances. Broke dishes, glassware, in considerable quantity, also some windows. Fall of knick-knacks, books, pictures. Overturned furniture in many instances. Moved furnishings of moderately heavy kind.

outdoors. Some, or many, found it difficult to stand. Noticed by persons driving motor cars. Trees and bushes shaken moderately to strongly. Waves on ponds, lakes, and running water. Water turbid from mud stirred up. Incaving to some extent of sand or gravel stream banks. Rang large church bells, etc. Suspended objects made to quiver. Damage negligible in buildings of good design and construction, slight to moderate in well-built ordinary buildings, considerable in poorly built or badly designed buildings, adobe houses, old walls (especially where laid up without mortar), spires, etc. Cracked chimneys to considerable extent, walls to some extent. Fall of plaster in considerable to large amount, also some stucco. Broke numerous windows, furniture to some extent. Shook down loosened brickwork and tiles. Broke weak chimneys at the roof-line (sometimes damaging roofs). Fall of cornices from towers and high buildings. Dislodged bricks and stones. Overturned heavy furniture, with damage from breaking. Damage considerable to concrete irrigation ditches.

Disturbed persons driving motor cars.

Trees shaken strongly branches, trunks, broken off, especially palm trees. Ejected sand and mud in small amounts. Changes: temporary, permanent; in flow of springs and wells; dry wells renewed flow; in temperature of spring and well waters. Damage slight in structures (brick) built especially to withstand earthquakes. Considerable in ordinary substantial buildings, partial collapse: racked, tumbled down, wooden houses in some cases; threw out panel walls in frame structures, broke off decayed piling. Fall of walls. Cracked, broke, solid stone walls seriously. Wet ground to some extent, also ground on steep slopes. Twisting, fall, of chimneys, columns, monuments, also factory stacks, towers. Moved conspicuously, overturned, very heavy furniture.

conspicuously. Damage considerable in (masonry) structures built especially to withstand earthquakes: Threw out of plumb some wood-frame houses built especially to withstand earthquakes; great in substantial (masonry) buildings, some collapse in large part; or wholly shifted frame buildings off foundations, racked frames; serious to reservoirs; underground pipes sometimes broken.

Cracked ground, especially when loose and wet, up to widths of several inches; fissures up to a yard in width ran parallel to canal and stream banks. Landslides considerable from river banks and steep coasts. Shifted sand and mud horizontally on beaches and flat land. Changed level of water in wells. Threw water on banks of canals, lakes, rivers, etc. Damage serious to dams, dikes, embankments. Severe to well-built wooden structures and bridges, some destroyed. Developed dangerous cracks in excellent brick walls. Destroyed most masonry and frame structures, also their foundations. Bent railroad rails slightly. Tore apart, or crushed endwise, pipe lines buried in earth. Open cracks and broad wavy folds in cement pavements and asphalt road surfaces.

Disturbances in ground many and widespread, varying with ground material. Broad fissures, earth slumps, and land slips in soft, wet ground. Ejected water in large amounts charged with sand and mud. Caused sea-waves ("tidal" waves) of significant magnitude. Damage severe to wood-frame structures, especially near shock centers. Great to dams, dikes, embankments often for long distances. Few, if any (masonry) structures remained standing. Destroyed large well-built bridges by the wrecking of supporting piers, or pillars. Affected yielding wooden bridges less. Bent railroad rails greatly, and thrust them XII,

FIGURE 6. Earthquake epicenters in Hawaii for July-September 1977, plotted from table 1.

C9 endwise. Put pipe lines buried in earth completely out of service.

Damage total practically all works of construction damaged greatly or destroyed. Disturbances in ground great and varied, numerous shearing cracks. Landslides, falls of rock of significant character, slumping of river banks, etc., numerous and extensive. Wrenched loose, tore off, large rock masses. Fault slips in firm rock, with notable horizontal and vertical offset displacements. Water channels, surface and underground, disturbed and modified greatly. Dammed lakes, produced waterfalls, deflected rivers, etc. Waves seen on ground surfaces (actually seen, probably, in some cases). Distorted lines of sight and level. Threw objects upward into the air.

n

10 00 [Sources of the hypocenter and magnitudes: (A) U.S. Energy Research and Development Administration; (B) University of California, Berkeley; (F) USGS Open-File Report 78-672 (Fuis and others, 1978). (G) U.S. Geological Survey, National Earthquake Information Service; (H) U.S. Geological Survey, Hawaiian Volcano Observatory; (L) Lamont-Doherty Geological Observatory, Palisades; (M) NOAA, Alaska Tsunami Warning Center, Palmer; (P) California Institute of Technology, Pasadena; (V) Virginia Polytechnic Institute and State University, Blacksburg; (W) University of Washington, Seattle. N, Normal depth; UTC, Universal Coordinated Time. For names of local time zones, see figures 2 and 3. Leaders (...) indicate no information available]

26.7 41.4 49.3 11.6 36.1 24.8 27.6 39.9 46.7 32.8 41.7 32.4 17.2 04.4 13.5 14.5 17.2 56.1 18.7 11.6 05.8 25.9 53.9 05.3 41.5 03.5 00.5 54.6 23.3 50.7 20.9 21.7 07.1 02.4 51.7 24.6 07.4 15.8 27.7 58.1 52.5 53.5 59.1 12.8 46.9 58.7 11.9 19.7 29.5 14.2 24.2 Table 1.-Summary of U.S. earthquakes for July-September 1977

52.68 N. 52.52 N. 52.62 N. 62.28 N. 60.07 N. 52.30 N. 52.13 N. 61.17 N. 62.33 N. 53.53 N. 58.92 N. 51.41 N. 64.56 N. 59.94 N. 55.54 N. 61.64 N. 51.26 N. 59.99 N. 59.91 N. 61.02 N. 51.59 N. 54.61 N. 60.13 N. 56.43 N. 60.00 N. 63.20 N. 61.03 N. 54.32 N. 52.80 N. 52.67 N. 68.14 N. 62.53 N. 61.56 N. . 146.20 W. 51.22 N. 61.33 N. 59.53 N. 58.88 N. 61.49 N. 60.91 N. 59.91 N. 61.11 N. 52.35 N. 60.89 N. 60.25 N. 57.72 N. 56.64 N. 65.65 N. 57.23 N. 63.88 N. 61.51 N. 61.30 N. 167.42 W.. 167.48 W. 167.48 W. 150.89 W. 152.89 W. 170.89 W. 171.32 W. 150.85 W. 150.10 W. 164.08 W. 151.64 W. 176.31 E. 147.27 W. 147.76 W. 155.60 W. 150.85 W. 175.95 E. 152.68 W. 152.95 W. 152.45 W. 179.45 W. 161.60 W. 152.47 W. 157.18 W. 153.32 W. 150.43 W. 150.40 W. 162.41 W. 169.21 W. 169.16 W. 158.20 W. 149.04 W. 175.34 W. 147.23 W. 152.89 W. 151.80 W. 150.11 W. 150.53 W. 152.12 W. 151.21 W. 176.32 W. 146.97 W. 153.07 W. 153.53 W. 152.73 W. 149.38 W. 152.52 W. 148.81 W. 151.22 W. 145.72 W.

5.0 33N 4.7 33N

5.0 4.7 4.7 33N 4.0 5.1 4.5 4*7 33N

4.6 33N

4.7 33N 5.3 4.1 4.4 4.3

3.8 5.1 4.2 4.0 33N ... 4.4

4.3 4.4 5.0 33N

n

CIO 01 A.M. BST 06 A.M. BST 07 P.M. AST 11 A.M. AST 04 A.M. BST 00 A.M. BST 09 A.M. AST 10 A.M. AST 00 A.M. BST

04 P.M. AST 07 P.M. BST 12 P.M. AST 10 A.M. AST 04 P.M. AST 12 12 11.4 00 24 33.2 17 45 16.1 06 30 18.5 15 59 23.9 16 48 31.3 12 56 51.9 13 14 31.6 19 02 49.0 04 28 58.3 09 08 05.0 15 34 37.8 20 55 22.6 13 42 40.1 07 15 48.2 03 51 50.4 07 16 50.5 20 59 59.2 22 03 37.8 22 08 53.6 02 07 58.7 06 50 39.9 15 12 27.6 20 07 59.4 20 45 01.7 08 58 27.1 21 38 48.3 15 40 57.3 15 53 40.8 15 59 04.4 16 09 48.0 16 32 40.9 16 44 25.2 16 48 44.7 17 10 30.6 17 16 15.5 17 24 42.8 17 38 24.8 18 00 11.9 18 25 49.8 18 38 23.6 19 23 00.5 21 27 08.3 22 18 38.8 23 20 44.9 23 41 01.9 23 54 27.2 00 58 10.9 09 13 22.8 12 52 12.4 22 31 04.6 14 20 36.4 15 58 56.4 22 00 17.0 12 42 50.4 14 38 36.9 09 20 58.4 16 39 07.2 15 42 42.2 16 28 54.2 18 26 29.9 21 25 21.4 01 05 33.0 64.70 N. 51.59 N. 57.60 N. 67.52 N. 56.63 N. 51.87 N. 50.91 N. 61.71 N. 51.83 N. 61.96 N. 61.96 N. 59.97 N. 52.05 N. 63.72 N. 51.49 N. 56.95 N. 63.33 N. 51.56 N. 51.67 N. 51.66 N. 51.72 N. 63.16 N. 51.38 N. 59.69 N. 56.63 N. 51.50 N. 64.64 N. 51.21 N. 51.02 N. 51.24 N. 51.17 N. 51.12 N. 50.85 N. 51.07 N. 51.10 N. 51.26 N. 51.14 N. 51.22 N. 51.12 N. 51.20 N. 51.16 N. 51.16 N. 55.82 N. 50.95 N. 51.18 N. 51.15 N. 51.47 N. 51.03 N. 51.12 N. 51.41 N. 51.51 N. 51.40 N. 62.19 N. 62.37 N. 51.89 N. 51.08 N. 53.91 N. 65.86 N. 60.86 N. 50.45 N. 61.03 N. 64.82 N. 60.37 N. 159.80 W. 176.38 W. 150.25 W. 160.65 W. 175.34 W. 174.67 E. 150.26 W. 175.18 W.

150.11 W. 153.03 W. 175.16 W. 149.38 W. 175.73 E. 151.72 W. 150.20 W. 173.97 W. 174.02 W. 173.94 W. 174.04 W. 151 . 11 W. 173.78 W.

152.53 W. 173.85 W. 160.11 W. 178.39 E. 178.56 E. 178.55 E. 178.54 E. 178.54 E. 178.43 E. 178.28 E. 178.26 E. 178.40 E. 177.95 E. 177.78 E. 178.25 E. 177.79 E. 178.25 E. 177.65 E. 178.33 E. 178.25 E. 178.33 E. 178.52 E. 177.81 E. 178.53 E. 178.52 E. 178.49 E. 178.60 E. 149.53 W. 149.61 W.

177.54 E. 165.98 W. 146.49 W. 150.84 W. 173.41 W. 152.92 W. 147.43 W. 152.07 W.

4.5 33N

5.4 5.3 4!2 33N 33N 33N 3.9 4.2 33N 4.1 4.9 4.7 33N 3.6 5.4 4.6 4.8 4.6 5.0 5.4

s!e5.0

33N 4.6 33N 4.3 33N 4.5 33N 5.3 33N 5.1 5.5 5.5 33N 5.8 5.3 4.9 5.3 5.0 5.0 4.1 33N 5.5 4.5 33N 4.6 5.0 4.3 33N 4.7 33N 4.6 33N 4.6 4.6 33N

4.7 4.3 ... 33N 4.8 33N 4.8

s!s

3.7M 6.4 ... II

... ... ... ... ... ... ... ... ... ... 6.4 ... II

e!e !!! "ii ... ... ... ...

3.3 ... ... ... ... ... II 3.6M

! 3.*8M !!!

3.7M .

C12

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C13

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16 06 22.1 14 07 00.2 16 40 00.1 01 10 35.5 04 51 41.5 19.37 N. 19.39 N. 19.40 N. 19.16 N. 19.35 N. 19.38 N. 19.35 N. 19.08 N. 19.39 N. 19.36 N. 19.35 N. 19.36 N. 19.36 N. 19.36 N. 19.42 N. 19.37 N. 19.36 N. 19.35 N. 19.33 N. 19.38 N. 19.37 N. 19.37 N. 19.36 N. 19.35 N. 19.36 N. 19.37 N. 19.46 N. 19.34 N. 19.37 N. 19.37 N. 19.32 N. 19.36 N. 19.36 N. 19.36 N. 19.36 N. 19.25 N. 19.36 N. 19.42 N. 19.28 N. 19.35 N. 19.38 N. 19.35 N. 19.36 N. 18.85 N.

44.65 N. 44.64 N. 44.66 N. 44.44 N.

46.00 N. 46.60 N.

37.23 N. 37.11 N. 37.09 N. 39.10 N. 37.58 N. 155.11 W. 155.07 W. 155.06 W. 155.05 W. 155.06 W. 155.10 W. 155.29 W. 153.99 W. 154.99 W. 155.06 W. 154.98 W. 155.02 W. 155.03 W. 155.12 W. 155.27 W. 155.25 W. 154.97 W. 155.28 W. 155.12 W. 155.33 W. 154.97 W. 154.99 W. 155.03 W. 155.07 W. 154.98 W. 155.07 W. 155.36 W. 155.07 W. 155.11 W. 155.11 W. 155.23 W. 155.26 W. 155.14 W. 155.13 W. 155.04 W. 155.50 W. 155.05 W. 155.26 W. 155.37 W. 155.06 W. 154.98 W. 155.06 W. 155.06 W. 155.39 W.

114.61 W. 114.60 W. 114.52 W. 111.88 W.

111.69 W. 112.14 W.

114.97 W. 116.08 W. 116.01 W. 115.62 W. 117.71 W.

5.7 5. OB 0 5.0

3. OH

3.7H 3.8H 3.5H 3.8H 4.1H 3.1H 3.2H

3. OH

3.4H

3. OH

3 . 6H 3.1H 3.5H 3.1H 3.3H 3.7H

3. OH

3.5H

3. OH

3.1H

4. OH

3.1H 3.3H 3 . 3H 3.3H 3.7H 3.1H 3.5H 3.5H 3.2H 4.1H

3. OH
4. OH
5. OH
6. OH

3.5H 3.2H

3. OH
4. OH

3.8H

3. OH

3 . 3A 3.1A 4.3G 3.0A

3.7G 3.2A

3 . 3G 3.7B 3.0G

4. OB II

... ... ... ... Ill ... ... Ill ...

... Ill ... ...

Ib 14 41 00.4 15 49 00.2 17 32 00.1 17 55 00.1 14 36 30.1 14 00 00.2

[Sources of the hypocenter and magnitudes: (A) U.S. Energy Research and Development Administration; (B) University of California, Berkeley; (D) University of Montana, Missoula; (G) U.S. Geological Survey, National Earthquake Information Service; (H) U.S. Geological Survey, Hawaiian Volcano Observatory; (M) NOAA, Alaska Tsunami Warning Center, Palmer; (P) California Institute of Technology, Pasadena; (V) Virginia Polytechnic Institute and State University, Blacksburg; (W) University of Washington, Seattle. Dates and origin times are listed in Universal Coordinated Time (UTC) giving the hour, minute, and second. Epicenters are shown in decimal degrees. Only earthquakes with intensity data and explosions are listed]

Alaska Con tinued Alaska Continued

3 July (G) Southern Alaska Origin time: Epicenter: Depth: Magnitude: Intensity III:

11 July (G) Central Alaska Origin time: 15 57 17.2 Epicenter: 64.56 N., 147.27 W. Depth: 14 km Magnitude: 4.5 mb, 4.2 MS, 4.6 ML(M) Intensity V; College, Eilson Air Force Base, Ester (many awakened, a few frightened).

4 August (G) Southern Alaska Origin time: Epicenter: Depth: Magnitude: Intensity II; 16 August (G) Northern Alaska 20 32 46.7 62.33 N., 150.10 W. 18 km 3.7 ML(M) Talkeetna.

Palmer, Wasilla. Anchorage.

15 10 24.6 59.53 N., 152.89 W, 102 km None computed. Origin time: Epicenter : Depth: Magnitude: Intensity IV: 06 30 18.5 67.52 N., 150.25 W. 39 km 3.5 ML(M) Wiseman .

Table 2.-Summary of macroseismic data for U.S. earthquakes, Table. 2.-Summary of macroseismic data for U.S. earthquakes, July-September /977-Continued July-September 7977-Continued 35' Maricopale] CALIFORNIA

FIGURE 7. Intensity map for the southern California earthquake of 12 August 1977, 02 19 26.1

Depth: 9 km Magnitude: 3.8 mb(G), 3.7 ML Intensity V; Geyserville. Intensity III; Healdsburg (B).

11 September (B) Northern California Origin time: 23 46 12.2 Epicenter: Depth: Magnitude: Intensity V; Geyserville Intensity IV;

12 September (P) Southern California Origin time: 06 17 42.6

Epicenter:

Depth:

Magnitude:

Intensity II;

EXPLANATION o San Pedro

UTC. Arabic numerals are used to represent Modified Mercalli intensities at specific sites.

California Continued California Continued 38.70 N., 122.80 W. 12 km 3.9 mb(G), 4.0 ML Calistoga, Cloverdale, Cobb, Stewarts Point. Finley, Healdsburg (G).

34.22 N., 116.98 W. 5 km 3.2 ML San Bernardino Mountain area.

C19 14 September (P) Southern California

19 September (P) Southern California

22 September (P) Southern California Barstowd)

Origin time: 21 35 23.3 Epicenter: Depth: Magnitude: Intensity III; Fullerton, Placentia, Yorba Linda.

Origin time: 10 34 54.6 Epicenter: Depth: Magnitude:

Intensity II; Diamond Bar (P).

Origin time: 09 41 10.5 Epicenter: 33.98 N., 116.58 W, Depth: 5 km Magnitude: 3.5 ML 33.88 N., 117.82 W. 2 km 2.7 ML

33.95 N., 117.78 W. 9 km 2.7 ML C20 Depth: 4 km Magnitude: 3.1 ML Intensity III; Volcano (H).

15 September (H) Island of Hawaii Origin time: Epicenter: Depth: Magnitude: Intensity III:

16 September (H) Island of Hawaii Origin time: Epicenter: Depth: Magnitude: Intensity II;

16 September (H) Island of Hawaii Origin time: Epicenter: Depth: Magnitude: Intensity III;

18 September (H) Island of Hawaii Origin time: Epicenter: Depth: Magnitude: Intensity III; Hilo (H).

19 September (H) Island of Hawaii Origin time: 19 01 45.2 Epicenter: 19.36N., 155.13 W. Depth: 9 km Magnitude: 4.1 ML Intensity III; Hilo (H), Kalalua, Nanawale

23 September (H) Island of Hawaii Origin time: Epicenter: Depth: Magnitude: Intensity IV;

Intensity III;

23 September (H) Island of Hawaii Origin time: Epicenter: Depth: Magnitude: Intensity III; Volcano (H).

27 September (H) Island of Hawaii Origin time: 04 05 39.8 Hawa ii Cont inued Hawaii Continued

Volcano (H).

Estates, Papaikou (H), Volcano (H).

Puako. 16 46 20 19.33 N. 8 km 3.7 ML Volcano

00 46 02.0 19.36 N., 155.03 W, 7 km 3.1 ML Hilo (H).

04 50 05.5 19.35 N., 155.07 W. 8 km 4.0 ML Black Sands subdivision (H),

01 19 23.7 19.37 N., 155.11 W, 9 km 3.7 ML

12 08 44.1 19.36 N., 155.05 W. 8 km 4.0 ML Glenwood (H), Hilo (H),

Mauna Kea Observatory (H),

12 59 56.9 19.42 N., 155.26 W. 5 km 3.0 ML .3 , 155.12 W

(H).

C22 28 September (H) Island of Hawaii

30 September (G) Northeastern Utah

4 September (G) Western Montana

4 August (A) Southern Nevada

19 August (A) Southern Nevada

15 September (A) Southern Nevada Epicenter: 19.35 N., 155.06 W, Depth: 7 km Magnitude: 3.2 ML Intensity III; Hilo (H).

Origin time:

Epicenter: Depth: Magnitude: Intensity III; Hilo (H)

Origin time: 10 19 21.0

See Utah listing.

Origin time: Epicenter: Depth: Magnitude: Intensity V; Intensity IV; East Helena.

Origin time: 16 40 00.074 Epicenter: Depth: Magnitude:

Nevada Test Site explosion "STRAKE" at 37°05'11.65" N., 116°00'24.73" W., surface elevation 1300 m, depth of burial 518 m.

Origin time: 17 55 00.075 Epicenter: 37.11 N., 116.06 W. Depth: 0 km Magnitude: 5.6 mb(G), 5.5 ML(B)

Nevada Test Site explosion "SCANTLING" at 37°06'36.12" N., 116°03'16.23" W., surface elevation 1272 m, depth of burial 701 m.

Origin time: 14 36 30.077 17 38 01.2 19.36 N., 155.06 W, 7 km 3.8 ML

20 54 20.2 46.60 N., 112.14 W. 5 km 3.2 ML(A), 2.8 ML(D) Canyon Ferry, Helena.

37.09 N., 116.01 W. 0 km 5.0 mb(G), 5.7 MS(G), 5.0 ML(B) Epicenter: Depth: Magnitude:

Nevada Test Site explosion "EBB TIDE" at

27 September (A) Southern Nevada Origin time: 14 00 00.161 Epicenter: 37.15 N., 116.07 W. Depth: 0 km Magnitude: 4.8mb(G), 4.8 ML(B)

Nevada Test Site explosion "COULMMIERS" at

25 August (G) Southeastern South Carolina Origin time: 04 20 07.0 Epicenter: 33.39 N., 80.69 W. Depth: 10 km Magnitude: 3.1 mbLg(V) Intensity V; Bowman (frightened a few Nevada Continued Tennessee Continued

37°01'58.05" N., 116°02'35.29" W., surface elevation 1221 m, depth of burial 381 m.

37°09'04.20" N., 116°04'03.20" W., surface elevation 1319 m, depth of burial 530 m.

people; buildings trembled; windows, doors and dishes rattled). 37.03 N., 116.04 W. 0 km 4.5 mb(G), 4.1 ML(B)

Tennessee Magnitude: 3.5 mbLg(V) Intensity V;

North Carolina Murphy (buildings trembled). Tennessee Athens (felt by many; some were frightened; moderate earth noise heard; windows, doors, and dishes rattled), Cokercreek, Ducktown (buildings trembled, pictures out of place, loud earth noise heard), Englewood, Etowah, Madisonville (a few frightened, buildings trembled, small objects shifted), Postelle, Reliance, Sweetwater, Tellico Plains. Intensity IV;

Georgia McCaysville.

Tennessee Farner, Riceville. Intensity III;

North Carolina Unaka. Intensity II;

Georgia Cisco. Utah Continued Washington

slump of a rock slab in Farnsworth Canal (dry) near Moon Lake were noted. Interviews in the area turned up a number of instances of persons awakened in advance of the quake by restless horses and barking and howling dogs. In two Instances horses 'raised a ruckus' in barns and corrals for half an hour before the quake. The two geologists also found road repairs in progress where the branch of the lineament on which the quake took place crosses the paved Forest Service Road leading to Moon Lake. The road obviously was not damaged by this quake, but the fault zone (lineament) does appear to coincide with a belt of very unstable ground about 100 feet wide. Where the road crosses this, repairs are required once or twice each year." Some of the intensity values listed below were from a questionnaire canvass by H. R. Ritzma, UGMS, Salt Lake City; they were evaluated by the U.S. Geological Survey. Figure 8 shows that this earthquake was felt over an area of approximately 20,000 sq km of Colorado and Utah, with isolated intensity values being reported in Idaho and Wyoming.

Intensity VI;

Colorado Fruita (plaster cracked unconfirmed), Grand Junction (stone fence and interior plaster cracked unconfirmed). Utah Mountain Home (septic-system drain reported broken, old mortar of log house cracked at corners, furniture shifted). Intensity V:

Colorado Mack, Maybell, Meeker, Palisade.

Idaho Downey, Preston.

Utah Altamont, Altona, Bluebell, Boneta (press report), Duchesne (pictures knocked from walls, windows cracked press report), Farnsworth Canal (possible slump of rock slab Survey Notes, 1977), Kamas, Lake Fork River (4.8 km southeast of Fisher Ranch), Rock Creek (cracked windows in Rock Creek Canyon press report, possible rock fall found by Utah geologists Survey Notes, 1977), Roosevelt, Salt Lake City, Sunnyside, Tabiona, Talmage, Wellington, White Rocks, Yellowstone River Canyon. Intensity IV;

Colorado Clifton, Gateway, Mesa, Rangely.

Utah Jensen, Robbins Ranch, Vernal. Intensity III;

C24 30 September (G) Northeastern Utah

furnished data to the National Earthquake Information Service for use in this Circular:

ALASKA:

CALIFORNIA:

HAWAII: Origin time: 10 19 21.0

See Utah listing.

ACKNOWLEDGMENTS

Listed below are the collaborators who Staff of NOAA, Alaska Tsunami Warning Center, Palmer. J. B. Townshend, College Observatory, College. Clarence R. Alien, Seismological Laboratory, California Institute of Technology, Pasadena. Bruce A. Bolt, Seismograph Station, University of California, Berkeley. Gary S. Fuis, U.S. Geological Survey, Pasadena. Robert Y. Koyanagi, U.S.

Geological Survey, Hawaiian Volcano Observatory, Hawaii National Park. WASHINGTON: Robert S. Crosson, Geophysics Gutenberg, B. and Richter, C. F., 1956, Magnitude

Acknowledgment is also given to B. B. Poppe for Nuttli, 0. W., 1973, Seismic wave attenuation and aid in editing the manuscript and drafting the magnitude relations for eastern North isoseismal maps, and to Paula Smith for preparing ^erica '' ^"^ °* Ge°Physical ^search, v. the computerized manuscript. 78 > no * 5 > P* «76-885.

REFERENCES CITED Francisco, Calif., W. H. Freeman and Co.,

Bath, Markus, 1966, Earthquake energy and *'

magnitude, in Physics and chemistry of the Utah Geological Survey, 1977, Earthquakes shake Earth, Volume 7: Oxford and New York, Northwestern Uinta Basin: Survey Notes, v. Pergamon Press, p. 115-165. 11, no. 4, p. 1-3. Fuis, G. S., Johnson, C. E., and Jenkins, D. J., Woodj H . 0>> and Neumanrij F ., 1931j Modified 1978, Preliminary catalog of earthquakes in Mercalli Intensity Scale of 1931: Bulletin southern California, October 1976-September of the Seismological Society of America, v. 1977: U.S. Geological Survey Open-File n no> 4 277-283. Report 78-672, 84 p. ' ' Program, University of and energy of earthquakes: Annali di Washington, Seattle. Geofisica, v. 9, no. 1, p. 1-15.

Richter, C. F., 1958, Elementary seismology: San

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