DISCLAIMER -- THIS IS NOT AN EARTHQUAKE PREDICTION OR WARNING! The commentary provided with these map(s) is for INFORMATIONAL USE ONLY, and SHOULD NOT be construed as an earthquake prediction, warning, or advisory. Responsibility for such warnings rests with the Office of Emergency Services of the State of California. PLEASE REMEMBER -- THESE ARE PRELIMINARY DATA Releasing these summaries on a timely basis requires that the data, analysis, and interpretations presented are PRELIMINARY. Of necessity they can only reflect the views of the seismologists who prepared them, and DO NOT carry the endorsement of the U.S.G.S. Thus while every effort is made to ensure that the information is accurate, nothing contained in this report is to be construed as and earthquake prediction, warning, advisory, or official policy statement of any kind, of the U.S. Geological Survey, or the U.S. Government. FOR QUESTIONS CONCERNING THIS REPORT Send e-mail to michael@andreas.wr.usgs.gov or reply to this message. Seismicity Report for Northern California, the Nation, and the World for the week of March 9 - 14, 1995 Data and text prepared by Steve Walter and Barry Hirshorn U.S. Geological Survey 345 Middlefield Rd. MS-977, Menlo Park, CA 94025 Graphics by Quentin Lindh NOTE: This report is being written one day early and covers the six-day period from March 9 through March 14 (actually through 1:00am on March 15 in order to include the M3.1 event on the Hayward). San Francisco Bay Area During the six-day period ending at midnight on Tuesday, March 14 1995 the U.S. Geological Survey office in Menlo Park recorded 19 earthquakes of magnitude one (M1) and greater within the San Francisco Bay area shown in Figure 1. Five of these were as large as M2.0 including a M3 on the Hayward fault that was felt in the North Bay. This total compares to 26 earthquakes during the previous seven-day period (March 2 - 8) four of which were as large as M2. The Hayward earthquake occurred just after midnight early Wednesday morning (#6 in figure 1). The preliminary epicenter of the quake was located in El Cerrito, just west of the Hayward fault. This section of the Hayward fault has produced over half a dozen M3+ earthquakes in the past 25 years. The most recent example was also the largest: a M4.1 on June 26, 1994. Other M2 earthquakes were all located in the South Bay, similar to last week. The central Calaveras experienced two M2.1 events Monday morning. The first of these occurred eleven miles north of Morgan Hill (#3/1); the second about six miles northeast of Gilroy (#4/1). The creeping segment of the San Andreas also experienced a M2.1 earthquake that was located about six miles northwest of San Juan Bautista (#5/1). The Quien Sabe fault also produced a M2.3 earthquake, the first M2 event since a pair of M2.4's occurred here in early November, 1994. Northern & Central California The rest of northern & central California was very quiet during the past six days. The Cape Mendocino fracture zone, site of numerous M2's, 3's, and 4's during the past several weeks, experienced only earthquake as large as M2 (#2/2). The northern Coast Range, in addition to four M2's at the Geysers, experienced just one M2 earthquake: a M2.2 on the Bartlett Springs fault about 20 miles northeast of Willits (#4/2). The northern Sierra saw two M2 events in the Markleeville area, aftershocks to a M6.0 last September (#5/2), and a M2.3 eleven miles northeast of Quincy (#1/2). Central California was equally quiet with just a couple M2's on the creeping San Andreas, a M2.3 in the Ciervo Hills 30 miles northwest of Coalinga (#6/2), and a M2.0 off the coast about 22 miles northwest of San Simeon (#3/2). Long Valley Caldera There were two M2 earthquakes last Thursday beneath the south rim of the caldera (#1/3), both aftershocks to a M4.4 on March 4. Neither was reported to have been felt. The only activity south of the caldera was a M2.7 last Thursday evening southeast of Mt. Morrison (#2/3). USA Seismicity (March 6 - 14) According to data provided by the National Earthquake Information Center, there were several domestic earthquakes of note outside of California. Eastern Kentucky of all places produced a pair of M3 earthquakes early last Saturday morning (#3/4). The largest had a magnitude of 3.8. Both occurred near Kentucky's historic city of Cumberland and were likely felt by local residents. Several of the western states were seismically active. A M3.1 occurred north of the Grand Canyon in northwestern Arizona (#1/4). Eastern Nevada saw a M3.3 south of Ely (#4/4). Western Oregon experienced a M2.7 that was felt in the small mountain town of Sweet Home (#5/4). Southern California was quiet during the week; the only event of note was a M3.0 last Wednesday that was felt in the northern San Fernando Valley (#2/4). Two domestic earthquakes of note occurred outside the conterminous U.S. Last Thursday a M3.9 occurred on the island of Hawaii that was felt at Glenwood. On Tuesday a M5.9 occurred offshore the Alaskan Peninsula about 50 miles southwest of Sand Point (#6/5). This earthquake was felt strongly at Sand Point, Cold Bay, King Cove, and Perryville but there were no initial reports of any damage. The Planet Earth (March 6 - 14) The largest earthquake on the planet was the Ms5.9 off southern Alaska, discussed above (#6/5). Only slightly smaller were a Ms5.8 in the Irian Jaya region of Indonesia (#5/5) and an Mb5.9 east of the Kuril Islands (#3/5). Smaller earthquakes worth noting include a Mb5.5 in the eastern Pacific plate (#2/5) and a Mb5.3 west of the Svalbard Islands in the Arctic Ocean (#1/5). Table 1. Northern & Central California Seismicity (M>1.0) --ORIGIN TIME (UT)-- -LAT N-- --LON W-- DEPTH N N RMS ERH ERZ DUR YR MON DA HRMN SEC DEG MIN DEG MIN KM RD S SEC KM KM REMKS MAG 95 MAR 9 1219 9.43 37 36.05 118 50.28 11.36 29 2 .13 .4 .5 SMO 2.0 95 MAR 9 1225 48.98 39 59.98 120 44.57 8.77 14 1 .19 1.313.4 WAK- 2.2 95 MAR 9 1235 1.73 37 35.97 118 50.19 11.44 29 1 .12 .4 .6 MOR 2.1 95 MAR 9 1305 41.76 40 17.19 124 17.67 9.26 8 1 .06 .4 1.0 MEN 2.1 95 MAR 9 1659 13.79 35 45.79 121 33.75 0.02 7 1 .13 3.0 1.4 SSM * 1.9 95 MAR 10 204 30.88 36 49.55 121 16.95 7.30 57 .13 .3 .5 QUI 2.4 95 MAR 10 221 33.07 37 57.39 122 3.40 15.23 15 .16 .9 1.2 CON 1.4 95 MAR 10 304 1.96 37 29.18 118 48.48 11.15 28 .10 .4 .9 MOR 2.8 95 MAR 10 357 24.82 37 29.15 118 59.86 2.01 14 .17 1.013.2 SIL - 1.5 95 MAR 10 418 14.16 38 47.14 122 46.15 2.68 15 .10 .3 1.4 GEY 1.9 95 MAR 10 550 45.51 36 36.97 121 13.37 6.38 37 .13 .3 .7 PIN 2.3 95 MAR 10 555 9.05 39 36.92 123 3.85 0.17 21 3 .13 .3 1.9 BAR 2.1 95 MAR 10 623 21.82 36 52.19 121 35.57 4.98 15 .07 .3 .5 SJB 1.4 95 MAR 10 740 14.10 38 56.18 122 37.78 4.46 12 .09 .4 .8 KON 1.7 95 MAR 10 751 43.50 37 26.72 118 42.65 8.33 9 .04 1.3 4.8 WCS 1.2 95 MAR 10 837 24.38 37 37.07 118 48.91 7.04 8 1 .11 2.3 1.6 HCF 1.1 95 MAR 10 903 39.44 37 54.50 121 58.56 13.49 13 .10 .5 1.0 CON 1.3 95 MAR 10 904 9.19 38 48.34 122 46.10 0.27 10 .03 .2 1.1 GEY 1.7 95 MAR 10 949 14.08 38 47.82 122 44.67 0.03 11 .08 .3 1.4 GEY * 1.9 95 MAR 10 1012 5.38 38 49.49 122 48.01 5.68 15 .10 .3 1.1 GEY 2.0 95 MAR 10 1200 41.13 37 37.73 118 58.10 9.73 15 .07 .5 1.1 SMO 1.3 95 MAR 10 1258 14.29 37 12.66 121 31.09 9.84 7 .16 3.0 2.3 HAM 1.1 95 MAR 10 1334 28.75 37 36.13 118 49.70 11.23 12 .10 .6 1.0 SMO 1.3 95 MAR 10 1409 41.41 37 34.92 118 47.15 14.70 9 1 .05 2.2 1.2 MOR 1.2 95 MAR 10 1637 44.19 37 38.72 118 54.57 0.87 9 .04 .3 .4 SMO 1.2 95 MAR 10 1643 45.23 38 47.59 122 44.32 2.85 18 .08 .2 .8 GEY 2.4 95 MAR 10 1651 56.27 38 47.78 122 44.40 1.30 11 .06 .3 .9 GEY 1.8 95 MAR 10 1653 21.04 38 47.78 122 43.73 3.13 9 .06 .5 1.3 GEY 1.5 95 MAR 10 1726 35.20 38 47.43 122 45.43 1.54 7 .03 .4 1.5 GEY 1.6 95 MAR 10 2206 30.87 37 35.94 118 50.21 12.07 14 .08 .6 .7 MOR 1.9 95 MAR 11 414 13.66 37 9.04 121 33.39 6.15 10 1 .08 .8 .9 CYN 1.2 95 MAR 11 438 26.54 38 50.20 122 49.12 0.89 8 .05 .3 1.3 GEY 1.4 95 MAR 11 522 52.24 37 34.23 118 50.92 7.72 10 1 .05 .5 .8 MOR 1.1 95 MAR 11 926 29.29 36 44.91 121 0.57 6.47 20 2 .10 .3 2.4 ORT 1.4 95 MAR 11 1012 48.72 37 22.23 121 43.63 9.08 16 2 .05 .3 .6 ALU 1.1 95 MAR 11 1112 22.25 37 36.18 118 27.73 7.00 14 1 .05 .3 .9 CHV 1.0 95 MAR 11 1503 30.04 37 38.63 118 55.77 7.37 13 2 .05 .5 .4 SMO 1.6 95 MAR 11 1543 28.04 35 48.85 120 22.08 8.73 23 1 .10 .3 .5 GOL 1.7 95 MAR 11 1550 24.58 37 35.17 119 0.59 4.67 11 .04 .5 1.2 SIL 1.1 95 MAR 11 1627 5.66 38 46.88 122 45.79 1.87 7 .03 .4 1.4 GEY 1.1 95 MAR 11 1633 25.09 38 50.00 122 49.50 0.11 8 .17 .6 4.3 GEY * 1.2 95 MAR 11 1720 26.68 38 48.44 122 45.81 5.17 15 .15 .4 1.1 GEY 2.1 95 MAR 12 150 19.17 36 37.21 121 13.33 4.78 29 1 .06 .2 .6 PIN 1.6 95 MAR 12 214 16.44 37 36.21 118 50.68 12.42 8 .09 .7 .9 SMO 1.0 95 MAR 12 241 27.66 38 48.62 122 48.89 3.55 7 .03 .4 2.3 GEY 1.2 --ORIGIN TIME (UT)-- -LAT N-- --LON W-- DEPTH N N RMS ERH ERZ DUR YR MON DA HRMN SEC DEG MIN DEG MIN KM RD S SEC KM KM REMKS MAG 95 MAR 12 432 26.47 36 45.33 121 15.79 9.73 19 .05 .3 .6 PAI 1.4 95 MAR 12 1231 35.46 36 34.07 121 3.86 9.26 48 1 .13 .3 .6 BVL 2.3 95 MAR 12 1257 6.55 36 49.05 121 32.37 5.67 29 .14 .3 .6 SJB 1.4 95 MAR 12 1339 38.11 38 49.41 122 48.01 1.58 9 .07 .3 1.4 GEY 1.4 95 MAR 12 1352 47.03 36 33.46 121 4.40 9.17 11 1 .05 .5 .9 BVL 1.2 95 MAR 12 1431 18.12 41 18.53 124 1.19 30.07 8 2 .08 1.9 1.7 DEL 1.9 95 MAR 12 1608 17.67 36 23.73 120 59.18 6.30 17 2 .11 .5 1.8 BIT- 1.4 95 MAR 12 1615 46.22 37 26.63 121 46.66 7.94 20 1 .05 .2 .4 ALU 1.3 95 MAR 12 1819 23.64 38 48.17 119 42.56 0.12 25 3 .09 .6 1.1 WAK 2.4 95 MAR 13 222 12.91 37 8.23 121 31.92 8.12 16 .04 .3 .7 CYN 1.4 95 MAR 13 347 52.65 38 41.64 122 8.78 18.40 7 1 .03 1.2 .6 SAC 1.7 95 MAR 13 404 9.62 37 54.52 121 59.74 10.06 21 3 .11 .4 .6 CON 1.7 95 MAR 13 612 23.76 38 47.21 122 45.26 3.13 18 1 .13 .3 1.1 GEY 1.9 95 MAR 13 930 47.74 38 47.71 122 48.13 1.92 7 .11 .4 2.1 GEY 1.2 95 MAR 13 1408 31.16 37 17.33 121 40.24 1.82 39 2 .05 .2 .5 SFL 2.1 95 MAR 13 1522 25.03 38 47.45 122 44.34 3.02 19 .09 .2 .7 GEY 2.2 95 MAR 13 1541 9.62 37 3.42 121 29.15 8.61 59 .10 .2 .4 CYS 2.1 95 MAR 13 1620 42.63 38 45.72 119 43.32 1.75 8 1 .05 1.3 7.2 WAK - 2.0 95 MAR 13 1720 38.98 36 34.13 121 4.01 8.50 36 .17 .4 .7 BVL 1.9 95 MAR 13 1749 41.17 36 33.68 121 4.48 8.28 13 1 .04 .6 .8 BVL 1.2 95 MAR 13 1750 23.47 36 33.95 121 4.10 9.53 12 3 .08 .5 .8 BVL 1.2 95 MAR 13 1858 36.14 38 48.44 122 46.43 1.13 7 .05 .3 1.9 GEY 1.1 95 MAR 13 1921 3.95 37 13.91 118 19.44 10.99 13 2 .08 1.5 .9 OWV 1.4 95 MAR 13 2038 1.06 37 36.53 119 25.07 6.82 12 .19 1.015.3 KAI - 1.2 95 MAR 13 2117 18.84 38 48.77 122 45.47 13.60 9 .21 1.2 1.5 GEY 1.3 95 MAR 13 2150 10.16 36 9.24 120 16.46 10.29 16 1 .15 .7 1.2 COA 1.5 95 MAR 13 2159 43.19 37 14.94 122 0.76 5.51 13 1 .09 .6 .7 BLM 1.1 95 MAR 13 2242 49.34 38 23.94 122 38.04 1.52 9 .17 .7 1.2 ROG 1.3 95 MAR 13 2347 51.93 36 33.98 121 8.87 8.18 12 3 .06 .4 .6 PIN 1.3 95 MAR 14 307 2.15 38 51.41 122 49.64 0.12 8 .11 .4 2.4 GEY * 1.2 95 MAR 14 309 5.62 38 51.21 122 49.44 0.02 11 .10 .3 1.4 GEY * 1.8 95 MAR 14 1106 41.47 36 34.06 121 7.43 8.38 16 .10 .4 .8 PIN 1.2 95 MAR 14 1119 28.85 38 46.32 122 54.41 6.60 19 3 .14 .4 .7 GEY 1.4 95 MAR 14 1120 25.91 38 47.19 122 46.61 3.16 7 .02 .4 2.3 GEY 1.1 95 MAR 14 1417 12.09 37 27.83 121 48.51 6.57 29 1 .09 .2 .4 ALU 1.6 95 MAR 14 1743 12.13 35 55.74 120 28.44 4.99 9 .02 .7 .6 MID 1.4 95 MAR 14 2112 28.99 38 49.51 122 47.69 4.08 15 .05 .3 1.1 GEY 1.9 95 MAR 14 2139 2.71 36 53.95 121 37.22 0.12 8 .05 .3 .9 SJB * 2.1 95 MAR 14 2156 40.48 38 34.89 122 40.14 1.29 8 .06 .3 1.4 NAP 1.7 95 MAR 14 2252 0.41 36 34.33 121 9.75 2.66 17 .09 .4 .5 PIN 1.8 95 MAR 14 2331 53.13 36 58.73 121 37.16 1.68 25 .18 .4 1.9 SAR 1.5 95 MAR 15 403 32.81 36 33.06 120 33.24 2.30 52 .26 .4 2.0 PIN 2.6 95 MAR 15 612 28.70 38 47.00 122 45.28 1.49 14 .05 .2 .7 GEY 1.9 95 MAR 15 634 2.04 38 32.84 122 38.97 5.46 13 .08 .3 .7 NAP 1.6 95 MAR 15 822 58.83 37 55.46 122 17.70 5.03 44 .13 .2 .5 HAY 3.1 TABLE 2. Data from National Earthquake Information Center (NEIC) UTC TIME LAT LONG DEP GS MAGS SD STA REGION AND COMMENTS HRMNSEC MB Msz USED ------------------------------------------------------------------------------ MAR 06 020209.1? 45.00 N 138.66 E 33N 4.3 1.3 7 EASTERN SEA OF JAPAN 033914.4% 11.173N 61.873W 33N 1.0 6 WINDWARD ISLANDS. MD 3.5 041810.2& 60.060N 152.780W 111 60 SOUTHERN ALASKA. 073854.1% 32.669S 70.129W 120G 0.3 11 CHILE-ARGENTINA BORDER. MD 2.6 090117.8? 53.80 N 160.12 E 150G 4.4 0.6 19 NEAR EAST COAST OF KAMCHATKA 100214.1% 32.620S 71.558W 10G 0.4 9 NEAR COAST-CENTRAL CHILE. MD 3.3 104858.8* 51.533N 176.712E 33N 4.0 0.9 12 RAT ISLANDS, ALEUTIAN ISLANDS 203221.4* 31.991S 69.998W 100? 0.9 13 SAN JUAN PROVINCE, ARGENTINA 220917.1* 33.446S 69.136W 5G 1.0 11 CHILE-ARGENTINA BORDER. MD 3.3 MAR 07 064741.4& 62.730N 149.660W 83 82 CENTRAL ALASKA. . Felt (III) at Sheep Creek. 065355.4? 31.85 S 70.13 W 120G 0.8 10 CHILE-ARGENTINA BORDER. MD 2.9 183813.6 43.170N 140.699E 174* 4.6 0.7 45 HOKKAIDO, JAPAN REGION 223319.3 36.616N 113.467W 5G 1.1 13 WESTERN ARIZONA. ML 3.1 (GS). MAR 08 015214.6 51.070N 179.601E 33N 4.7 0.9 51 RAT ISLANDS, ALEUTIAN ISLANDS. ML 4.9 (PMR). 015913.1* 50.876N 179.717E 33N 4.7 1.1 15 RAT ISLANDS, ALEUTIAN ISLANDS. ML 4.7 (PMR). 052645.8? 34.56 S 70.53 W 120G 0.1 11 CHILE-ARGENTINA BORDER. MD 3.4 071035.5* 22.190S 68.409W 114D 4.9 1.0 31 NORTHERN CHILE 111148.6* 51.526N 16.085E 10G 0.4 6 POLAND. ML 3.9 (GRF), 3.9 (VIE). 140704.1* 82.349N 71.784W 10G 4.7 0.9 37 QUEEN ELIZABETH ISLANDS, CANADA 144910.2 34.371N 118.662W 5G 0.8 36 SOUTHERN CALIFORNIA. ML 3.0 Felt in the northern part of the San Fernando Valley. 163001.0 50.753N 129.548W 10G 4.2 0.9 39 VANCOUVER ISLAND REGION 172225.4* 51.770N 176.705E 33N 4.3 1.1 10 RAT ISLANDS, ALEUTIAN ISLANDS. ML 4.6 (PMR). MAR 09 070422.6 78.122N 1.101E 10G 5.3 0.8 51 GREENLAND SEA 081216.2& 19.340N 155.126W 5 3.9 36 HAWAII. . MD 4.0 (HVO). Felt at Glenwood. MAR 10 052223.3 46.052N 143.491E 363D 5.5 0.9 97 SAKHALIN ISLAND 070653.6 15.017N 92.750W 69D 4.6 0.9 34 MEXICO-GUATEMALA BORDER 072123.7 18.328S 69.035W 70G 4.9 0.8 49 NORTHERN CHILE 082237.7 11.565S 130.793W 10G 5.5 4.9 0.8 71 SOUTH PACIFIC OCEAN. MAR 11 044956.9* 39.357N 142.182E 48D 4.8 0.9 19 NEAR EAST COAST OF HONSHU, JAPAN. Felt (III JMA) at Ofunato. 053916.5 31.251S 67.804W 33N 4.7 0.6 16 SAN JUAN PROVINCE, ARGENTINA 081552.4 36.981N 83.165W 5G 3.6 0.8 20 TENNESSEE. mbLg 3.8 (GS). 093643.6 38.867N 115.010W 5G 1.3 12 NEVADA. ML 3.3 (GS). 095004.7 36.996N 83.196W 5G 0.5 9 TENNESSEE. mbLg 3.3 (GS). 152110.2 43.929N 148.121E 33N 5.9 5.6 0.6 153 EAST OF KURIL ISLANDS. Mw 6.1 MAR 12 044046.0* 40.234N 143.493E 33N 4.7 0.8 16 OFF EAST COAST OF HONSHU, JAPAN 120943.7 5.305S 146.683E 231D 5.6 0.8 42 EASTERN NEW GUINEA REG., P.N.G. 143922.5 35.443N 140.780E 33N 4.9 1.0 22 NEAR EAST COAST OF HONSHU, JAPAN MAR 13 035431.4* 3.383S 80.533W 33N 4.6 0.7 18 PERU-ECUADOR BORDER 045134.7 44.634N 122.811W 10G 0.6 28 OREGON. MD 2.7 (SEA). Felt at Sweet Home. 103149.4* 2.835S 134.319E 33N 5.3 5.8 1.0 16 IRIAN JAYA REGION, INDONESIA. Mw 135032.1* 16.229S 173.460W 94D 5.0 0.8 24 TONGA ISLANDS MAR 14 173350 Q 54.8 N 161.4 W 33N 5.9 1.2 81 ALASKA PENINSULA Note: Computer users can get faster acces to the Weekly Seismicity Reports in any of three ways: 1. World-Wide-Web (WWW) access: http://quake.wr.usgs.gov 2. Anonymous FTP access: quake.wr.usgs.gov (in pub/www/QUAKES/WEEKREPS) 3. Email Access: (send email to michael@andreas.wr.usgs.gov) Notes for Table 1: Origin time in the list is in GMT, in the text and on maps it is in local time. N RD: is the number of readings used to locate the event. N S: is the number of S waves in N RD. RMS SEC: is the root mean squared residual misfit for the location is seconds, the lower the better, over 0.3 to 0.5 seconds is getting bad, but this is machine, not hand timed, data. ERH: is the estimated horizontal error in kilometers. ERZ: is the estimated vertical error in kilometers. N FM: is the number of readings used to compute the magnitude. REMKS: obtuse region codes that denote the velocity model used to locate the event. DUR MAG: is the magnitude as determined from the duration of the seismograms, not the amplitude. Sort of like going to echo canyon and measuring how loud your yell is by counting echos. FIG: denotes the figure/event number in the maps posted separately.