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 -- THIS IS 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 andy@pangea.stanford.edu Seismicity Report for Northern California, the Nation, and the World for the week of May 13 - 19, 1993 Data and text prepared by Steve Walter, Barry Hirshorn, and Allan Lindh U.S. Geological Survey 345 Middlefield Rd. MS-977, Menlo Park, CA 94025 Graphics by Quentin Lindh San Francisco Bay Area For the 7-day period ending at midnight on Wednesday, May 19, 1993 the U.S. Geological Survey office in Menlo Park recorded 27 earthquakes of magnitude one (M1) and greater within the San Francisco Bay area shown in Figure 1. Seven of these events were as large as M2.0, including one M3.0 earthquake on the southern Calaveras fault . This compares to 28 earthquakes during the previous week, ten of which were as large as M2.0. The week would have been very quiet except for activity on the southern Calaveras, a tight cluster of events located about 6 miles northwest of Hollister. As it was, this cluster of 14 earthquakes accounted for over half the activity observed in the Bay Area during the week. These earthquakes began Monday afternoon with a M3.0 felt event, followed by four M2's within the next 90 minutes, the largest a M2.9 (#3 in Fig. 1). The most recent M3 in this epicentral area occurred in mid- April of 1992. Incidentally, the M5.0 in mid-January of this year that was widely felt throughout the Bay Area occurred just 5 miles farther north along the Calaveras. The only other events as large as M2 were two M2.0 events last Thursday, one on the San Andreas about 2 miles south of San Juan Bautista (#2/1), the other on the central Calaveras about 10 miles east of San Jose (#1/2). Finally, a M1.9 occurred on the northern Hayward fault last Friday afternoon beneath the Berkeley Hills. Northern & Central California The main news this week is a M6.0 earthquake and active aftershock sequence in the Eureka Valley area of east-central California. The mainshock was widely felt throughout much of central and southern California and western Nevada. Because of the remoteness of the epicentral area, damage from the earthquake was minimal and no injuries were reported. A fuller description of the Eureka Valley sequence follows the Long Valley caldera section below. Seismicity throughout most of the rest of northern and central California was pretty low level. The only area that saw any noticeable increase was the Coalinga/Parkfield. There were five M2 events in the Coalinga area during the week, the largest a M2.8 last Thursday afternoon (#1/2). It was followed later that evening by a M2.0 on the Parkfield segment of the San Andreas, approximately one mile northwest of the town of Parkfield (#2/2). Early the next morning, a M2.4 occurred northwest of the Parkfield segment, about 15 miles northeast of San Ardo (#3/2). Activity north of the Bay Area was also pretty limited. The Coast Ranges saw a pair of M2 events, the first a M2.9 fourteen miles south of Ukiah (#8/2), the second a M2.1 about 18 miles northeast of Lakeport (#9/2). Cape Mendocino experienced just three M2 earthquakes during the week, none larger than a M2.6 last Sunday morning (#4/2). A somewhat larger M2.9 occurred in the Gorda plate about 110 miles offshore of Crescent City (#6/2). Finally, a couple small 2's occurred in the northern Sierra Nevada last Friday afternoon. The first occurred about 18 miles northwest of Quincy (#5/2), the second about 11 miles southeast of Susanville (#7/2). Long Valley Caldera Seismicity within the caldera was up slightly during the past week with a dozen or so earthquakes distributed throughout the south moat area. Among these was a M3.4 event early Saturday morning that was felt in the town of Mammoth Lakes (#2/3). This was the largest earthquake in the western end of the south moat since a M3.0 in early March. South of the caldera, a M2.9 occurred last Thursday southeast of Mt. Morrison and a M2.0 occurred about 4 miles southwest of Silver Peak (#3/3). Eureka Valley Swarm A M6.0 earthquake occurred at 4:20 pm (PDT) Monday afternoon, May 17. It was widely felt in California and Nevada with reports coming from the San Francisco Bay Area, Sacramento, and Los Angeles in California and from Carson City, Ely, and Las Vegas in Nevada. A fairly energetic aftershock sequence followed, producing two M5's, six M4's, and at least forty M3's as of midnight on Wednesday. The number of aftershocks is typical for a California earthquake sequence; their rate of occurrence continues to decrease with time. The epicenter of this earthquake (see Table 3) locates in the southwest side of the Eureka Valley, about 33 miles southeast of Bishop (Fig. 3a). Part of the Basin and Range Province, Eureka Valley is about 15 miles east of the Owens Valley (generally taken as the boundary between the Basin and Range and the Sierra Nevada provinces) and about 10 miles west of the Northern Death Valley/Furnace Creek fault zone. Because of the remoteness of the area, earthquake damage was minimal (mostly products knocked off shelves) and no injuries were reported. The locations of earthquakes shown in Figure 3a are preliminary and as a result show a fair amount of scatter. Subsequent analysis will improve the locations and refine the structure of the fault that ruptured in the mainshock. Even so, the aftershocks appear to form a trend oriented north to northeast. This orientation of aftershocks is consistent with the focal mechanism for the mainshock which showed vertical movement along a fault striking in a north-northeasterly direction. Figure 3a shows that most faults in the Eureka Valley are also oriented in this direction. The Eureka Valley earthquake is the largest earthquake to occur in California since the M7.5 Landers earthquake in June of last year. USA Seismicity There were a number of earthquakes in the lower 48 states outside of California according to data provided by the National Earthquake Information Center (NEIC). Several occurred in the Basin and Range province, as did the Eureka Valley sequence described above. Among these were a M2.9 in southern Nevada (#1/4), a M3.8 in north-central Nevada (#6/4), and a M3.1 in southwestern Utah (#4/4). A second Utah quake occurred in the northern Colorado plateau (#3/4). Several interesting earthquakes occurred in the central and eastern U.S. A M3.0 occurred in southern Texas that was felt in the Jourdanton area (#5/4). The careful reader may remember that a M4.2 occurred in this same area in early April. Finally, a pair of small but reportedly felt earthquakes occurred in the area of Reading, Pennsylvania, the second week in a row that earthquakes were recorded in this area. The Planet Earth (May 12 - May 19) The Pacific margin was quite active during the past week, producing seven earthquakes as large as M6. Two of the largest were in the northern Pacific along the Aleutian archipelago. The first and largest of these was a Ms6.9 last Thursday on the Alaskan Peninsula about 15 miles southeast of Sand Point (#1/5). On Saturday a slightly smaller Ms6.7 occurred in the Andreanof Islands that was felt on Adak and Amchitka (#5/5). The southern Pacific also experienced M6 earthquakes with a Ms6.7 in the Tonga Islands (#6/5), a Ms6.5 in the New Britain region of Papua New Guinea, and a Mb63 in the Philippines region. Along the eastern Pacific margin, in addition the M6.0 in eastern California, there was a Mb6.0 along the Mexican coast that was strongly felt in Mexico City (#3/5) and a Ms5.5 on the Pacific-Antarctic Ridge (#4/5). Table 1. 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 93 MAY 13 1106 56.28 38 47.70 122 44.43 2.18 22 1 .11 .2 .5 GEY 1.8 93 MAY 13 1109 38.49 37 11.28 121 34.89 4.56 17 .08 .3 2.0 SFL 1.1 93 MAY 13 1146 8.04 37 21.40 121 43.09 7.59 47 1 .09 .2 .5 ALU 2.0 93 MAY 13 1244 19.77 38 34.05 122 38.88 6.00 11 2 .08 .4 1.1 NAP 1.1 93 MAY 13 1257 39.82 38 47.73 122 46.82 4.15 9 .02 .3 .7 GEY 1.2 93 MAY 13 1405 53.25 38 49.67 122 47.95 3.99 8 .02 .4 .9 GEY 1.2 93 MAY 13 1426 14.94 38 47.78 122 44.52 0.61 7 .06 .3 1.3 GEY 1.0 93 MAY 13 1528 52.03 36 16.83 120 24.11 10.29 33 2 .13 .3 .5 COA 2.3 93 MAY 13 1548 49.55 37 30.38 118 47.96 11.96 35 2 .12 .3 .7 MOR 3.0 93 MAY 13 1550 9.82 36 49.31 121 32.84 6.27 35 .19 .3 .6 SJB 2.0 93 MAY 13 1757 16.54 36 24.01 120 58.20 1.45 25 1 .12 .4 .8 BIT 1.7 93 MAY 13 2027 25.92 36 12.82 120 13.91 8.16 50 .21 .6 2.2 COA 3.0 93 MAY 13 2038 16.10 38 49.31 122 48.34 4.20 8 .01 .4 .7 GEY 1.1 93 MAY 13 2124 57.47 38 47.20 122 45.20 3.14 12 .11 .4 .9 GEY 1.6 93 MAY 13 2208 22.82 38 48.20 122 48.98 1.34 9 .04 .3 .6 GEY 1.4 93 MAY 13 2246 30.91 37 39.36 118 57.18 8.98 13 2 .09 .9 .6 SMO 1.6 93 MAY 14 41 17.20 36 31.83 121 4.69 8.92 23 2 .06 .3 .6 BVL 1.2 93 MAY 14 255 57.15 35 54.43 120 27.21 6.45 37 6 .10 .3 .3 GOL 2.1 93 MAY 14 326 27.04 40 47.12 121 58.16 16.88 12 1 .10 .5 .8 SHA 1.8 93 MAY 14 414 43.07 36 59.83 121 45.46 13.48 20 .10 .4 .7 LOM 1.1 93 MAY 14 450 53.81 37 0.94 121 44.07 8.00 25 .08 .3 .6 LOM 1.1 93 MAY 14 843 7.54 36 32.19 121 7.20 3.24 21 1 .06 .2 .6 PIN 1.2 93 MAY 14 1016 50.95 39 21.75 123 6.58 6.43 10 .05 .4 3.0 BAR 1.4 93 MAY 14 1059 4.60 38 48.11 122 47.94 2.84 34 .12 .2 .5 GEY 2.4 93 MAY 14 1247 58.28 36 7.97 120 40.90 6.11 27 2 .08 .3 .4 SLA 2.7 93 MAY 14 1248 2.64 36 7.51 120 40.79 6.35 38 2 .19 .4 1.0 SLA 2.5 93 MAY 14 1415 3.07 38 46.86 122 42.98 3.79 34 1 .12 .2 .5 GEY 2.4 93 MAY 14 1416 53.71 38 45.49 122 42.16 2.32 15 .17 .4 .8 GEY 1.7 93 MAY 14 1557 40.75 40 17.95 124 30.98 21.19 10 .09 1.6 .7 MEN 2.5 93 MAY 14 1605 11.76 37 38.60 118 52.60 7.88 11 .05 .6 .7 SMO 1.5 93 MAY 14 1606 15.72 37 39.00 118 52.68 7.42 11 .05 .6 .8 SMO 1.8 93 MAY 14 1607 38.71 37 38.66 118 52.57 9.38 17 1 .11 .5 .8 SMO 1.4 93 MAY 14 1621 14.10 37 38.96 118 52.18 8.93 11 .05 .6 1.0 SMO 1.3 93 MAY 14 1624 28.85 37 35.91 118 50.11 12.24 24 .14 .5 .9 MOR 1.7 93 MAY 14 1706 22.01 37 30.31 118 39.99 12.44 15 .08 .5 1.3 WCS 1.1 93 MAY 14 1746 52.09 36 45.60 121 3.32 1.29 33 .23 .4 6.7 ORT 1.9 93 MAY 14 1955 23.65 38 49.48 122 49.69 2.19 11 .04 .3 .6 GEY 1.3 93 MAY 14 2036 47.68 40 1.73 121 15.04 6.64 11 1 .11 .8 4.2 ALM 2.1 93 MAY 14 2043 52.96 36 45.65 121 28.24 9.82 29 .17 .4 .7 SJB 1.4 93 MAY 14 2045 36.57 37 38.42 118 52.39 8.53 14 .07 .4 .8 SMO 1.6 93 MAY 14 2058 21.08 41 26.93 126 19.86 18.99 25 .18 5.617.4 PON - 2.8 93 MAY 14 2211 4.00 37 25.88 118 20.51 4.67 8 .10 .5 1.9 CHV 1.0 93 MAY 14 2254 31.79 37 52.30 122 14.70 10.32 55 2 .18 .2 .5 HAY 2.0 93 MAY 14 2345 25.67 36 56.38 121 26.12 8.14102 4 .19 .2 .4 HOL 3.1 93 MAY 14 2353 50.78 35 44.60 118 14.89 12.05 8 .02 .5 1.0 WWF 1.4 --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 93 MAY 15 3 54.40 40 16.45 120 34.18 3.44 14 .24 5.615.6 MOD - 2.1 93 MAY 15 31 49.43 36 56.56 121 26.18 7.62 84 4 .18 .2 .5 HOL 3.0 93 MAY 15 39 46.58 36 56.34 121 25.96 4.39 14 .09 .3 .9 HOL 1.1 93 MAY 15 43 21.61 36 56.48 121 26.03 6.91 53 1 .13 .2 .7 HOL 2.1 93 MAY 15 52 39.86 36 56.52 121 26.11 5.16 25 .08 .3 .9 HOL 1.5 93 MAY 15 101 38.10 36 56.46 121 25.97 5.10 21 .08 .3 .8 HOL 1.2 93 MAY 15 101 56.85 36 56.45 121 25.98 5.72 43 1 .10 .2 .7 HOL 2.0 93 MAY 15 114 48.60 36 56.42 121 26.02 5.10 12 .07 .3 1.2 HOL 1.3 93 MAY 15 115 39.64 36 56.41 121 25.94 5.97 58 .12 .2 .7 HOL 2.3 93 MAY 15 228 37.21 38 47.10 122 27.44 7.26 7 .10 .4 .8 GVL 1.2 93 MAY 15 447 54.56 36 56.25 121 25.96 5.15 28 .08 .2 .7 HOL 1.1 93 MAY 15 528 57.63 38 50.42 122 29.70 6.98 12 .21 .7 1.2 GVL 1.3 93 MAY 15 554 0.31 36 56.18 121 25.84 5.42 30 .09 .2 .7 HOL 1.2 93 MAY 15 615 59.69 38 48.52 122 45.38 2.02 10 .04 .3 .7 GEY- 1.2 93 MAY 15 650 41.08 37 39.49 118 54.35 8.09 11 .05 .7 1.0 DOM 1.0 93 MAY 15 727 18.39 36 0.84 120 33.82 4.91 12 1 .08 .4 .9 SLA 1.1 93 MAY 15 807 8.56 38 27.83 122 41.60 7.97 17 .07 .3 .8 ROG 1.3 93 MAY 15 808 20.26 37 38.63 118 56.76 6.97 15 .10 .5 .8 SMO 1.5 93 MAY 15 818 34.09 37 38.54 118 57.51 7.90 34 .16 .4 .5 SMO 3.3 93 MAY 15 821 46.93 37 38.72 118 57.01 7.21 15 .12 .5 .9 SMO 1.5 93 MAY 15 826 18.87 37 38.87 118 56.35 8.48 14 .09 .5 1.1 SMO 1.5 93 MAY 15 830 53.66 38 47.35 122 44.72 1.00 12 1 .04 .2 .6 GEY 1.4 93 MAY 15 905 5.59 37 39.06 118 56.55 8.75 7 .09 1.0 1.7 SMO 1.0 93 MAY 15 1037 5.27 37 33.29 118 26.13 7.24 15 .07 .3 .7 CHV 1.1 93 MAY 15 1103 49.47 40 23.69 124 15.59 10.34 17 1 .10 .3 .4 MEN 1.7 93 MAY 15 1107 39.74 37 39.14 118 56.66 8.26 9 .11 1.1 1.4 SMO 1.0 93 MAY 15 1243 43.98 37 30.53 118 48.07 12.62 27 .11 .4 1.1 MOR 1.6 93 MAY 15 1324 25.19 40 18.42 124 24.59 18.07 12 1 .10 .8 .4 MEN 1.9 93 MAY 15 1343 35.06 37 38.57 118 52.35 9.59 8 .06 1.0 2.0 SMO 1.0 93 MAY 15 1343 50.08 37 38.20 118 52.68 8.48 9 .05 .6 1.1 SMO 1.1 93 MAY 15 1503 54.94 40 25.75 124 25.46 10.64 13 1 .08 1.0 .4 MEN 1.7 93 MAY 15 1533 0.72 38 48.60 122 45.21 1.74 10 .04 .3 .6 GEY 1.0 93 MAY 15 1613 10.99 38 49.51 122 47.77 0.59 9 .08 .3 .9 GEY 1.0 93 MAY 15 1646 46.02 38 55.00 122 37.37 4.05 8 .11 .6 1.5 KON 1.5 93 MAY 15 1737 33.19 36 1.43 120 34.16 5.44 22 2 .07 .3 .3 SLA 1.3 93 MAY 15 1833 41.04 38 48.83 122 48.57 3.64 12 1 .06 .5 .6 GEY 1.2 93 MAY 15 1849 55.42 36 56.33 121 26.02 4.62 29 1 .09 .2 .7 HOL 1.5 93 MAY 15 2128 4.46 38 48.77 122 48.38 4.01 8 .02 .3 .8 GEY 1.1 93 MAY 15 2132 11.15 37 38.51 118 56.68 8.17 16 .12 .6 .7 SMO 1.6 93 MAY 15 2135 30.85 37 36.42 118 56.15 8.85 9 .19 2.0 2.6 SHE 1.0 93 MAY 15 2139 21.82 37 11.81 122 3.08 8.21 24 2 .11 .3 .6 BLM 1.2 93 MAY 15 2249 31.34 37 38.51 118 56.60 8.48 19 .11 .4 .6 SMO 1.7 93 MAY 16 101 17.04 37 38.68 118 56.58 7.84 10 .07 .6 1.1 SMO 1.2 93 MAY 16 127 53.25 38 48.86 122 48.60 3.93 14 .06 .3 .7 GEY 1.2 93 MAY 16 300 14.13 38 47.03 122 44.40 2.15 17 .12 .3 .7 GEY 1.6 --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 93 MAY 16 314 0.70 35 58.41 120 31.35 7.32 16 1 .04 .3 .4 MID 1.0 93 MAY 16 326 35.93 37 29.91 118 52.14 11.03 31 2 .13 .4 1.1 MOR 1.8 93 MAY 16 504 8.10 38 48.20 122 47.01 1.57 19 .08 .2 .4 GEY 1.7 93 MAY 16 546 33.72 37 12.57 118 14.34 8.01 7 2 .06 .9 1.2 DEV 1.0 93 MAY 16 720 2.07 37 38.56 118 51.88 4.89 30 .13 .3 .4 SMO 2.3 93 MAY 16 749 5.71 38 45.27 122 42.23 2.42 17 .11 .3 .6 NAP 1.6 93 MAY 16 749 38.73 38 44.97 122 41.65 1.79 14 .13 .4 .9 NAP 1.4 93 MAY 16 749 54.40 38 47.62 122 46.87 6.26 7 3 .14 .9 1.6 GEY 1.5 93 MAY 16 913 38.29 38 47.16 122 46.79 4.73 23 .08 .2 .6 GEY 2.1 93 MAY 16 1112 16.44 37 29.79 118 56.45 9.92 11 .09 1.0 2.9 SIL 1.6 93 MAY 16 1206 22.95 36 12.94 120 45.14 8.26 10 1 .08 .4 .7 BIT 1.0 93 MAY 16 1231 44.08 37 38.69 118 56.68 7.16 15 .11 .5 .9 SMO 1.5 93 MAY 16 1408 47.34 38 47.81 122 47.46 0.10 7 .07 .3 .8 GEY 1.2 93 MAY 16 1410 5.32 37 38.48 118 57.11 8.00 22 .15 .5 .7 SMO 2.1 93 MAY 16 1414 52.68 37 38.69 118 56.77 6.83 7 .01 .6 1.1 SMO 1.0 93 MAY 16 1434 15.12 38 47.08 122 45.51 1.34 16 .05 .2 .6 GEY 1.8 93 MAY 16 1437 25.17 40 19.67 124 37.14 19.60 18 1 .16 1.6 .4 MEN 2.6 93 MAY 16 1931 49.60 40 3.46 122 54.25 0.25 25 .35 .6 4.8 KLA 2.0 93 MAY 16 2000 47.29 37 1.35 121 28.46 7.83 65 1 .12 .2 .5 CYS 1.5 93 MAY 16 2104 34.74 38 48.87 122 50.52 1.73 9 .06 .4 .8 GEY 1.3 93 MAY 16 2109 56.22 37 28.66 118 51.07 10.24 28 1 .10 .3 1.0 MOR 1.6 93 MAY 16 2139 3.71 38 47.85 122 44.92 2.30 27 .15 .3 .7 GEY 1.8 93 MAY 16 2203 58.43 36 48.20 121 30.73 8.97 18 1 .15 .5 .8 SJB .9 93 MAY 16 2228 25.18 37 38.17 118 52.83 8.52 27 2 .12 .4 .5 SMO 1.8 93 MAY 17 246 50.64 37 38.54 118 56.68 8.00 16 1 .14 .6 .6 SMO 1.2 93 MAY 17 329 37.09 35 34.78 120 46.56 9.10 7 .11 1.1 8.8 ROB - 1.2 93 MAY 17 422 30.55 36 56.58 121 26.10 5.83 40 2 .09 .2 .6 HOL 1.3 93 MAY 17 630 46.86 37 25.14 119 3.60 9.31 33 2 .12 .3 1.5 SIL 2.2 93 MAY 17 631 51.65 38 47.85 122 44.95 0.53 8 .07 .3 1.2 GEY 1.4 93 MAY 17 809 34.79 38 46.71 122 44.63 1.07 15 .05 .2 .6 GEY 1.5 93 MAY 17 811 19.90 37 32.01 118 49.85 8.95 13 .07 .5 1.0 MOR 1.7 93 MAY 17 1047 58.71 37 25.32 119 3.62 9.24 25 .13 .4 1.8 SIL 1.7 93 MAY 17 1058 0.72 36 56.68 121 26.22 5.80 45 2 .10 .2 .6 HOL 1.6 93 MAY 17 1101 37.74 37 38.70 118 56.90 7.26 16 2 .08 .5 .7 SMO 1.1 93 MAY 17 1225 24.29 37 38.68 118 56.60 7.23 14 1 .07 .4 .7 SMO 1.1 93 MAY 17 1431 54.04 40 28.03 124 29.03 17.53 21 1 .11 .9 .2 MEN 2.3 93 MAY 17 1505 40.16 37 38.50 118 56.41 6.64 10 .03 .3 1.0 SMO 1.2 93 MAY 17 1815 46.39 36 40.45 121 17.64 3.85 22 .09 .3 .5 STN 1.9 93 MAY 17 1918 27.31 37 10.61 121 56.71 3.05 7 .06 .5 .6 LOM 1.1 93 MAY 17 2309 33.36 37 16.74 121 39.20 5.61 9 .02 .7 .4 SFL 1.1 --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 93 MAY 18 49 22.90 38 48.77 122 47.88 0.00 9 .09 .3 1.9 GEY * 1.4 93 MAY 18 102 15.23 37 38.21 118 53.10 6.47 7 .06 .9 .7 SMO 1.7 93 MAY 18 145 15.35 37 31.03 118 41.95 15.06 19 .09 .5 1.1 WCN 1.2 93 MAY 18 245 8.60 38 47.32 122 46.27 2.46 8 .05 .3 .8 GEY 1.3 93 MAY 18 250 37.24 38 49.01 122 48.53 4.41 11 .03 .3 .7 GEY 1.6 93 MAY 18 342 49.60 37 33.91 118 28.71 11.38 21 .08 .4 .8 CHV 1.8 93 MAY 18 540 11.29 38 48.15 122 48.32 0.00 22 .17 .3 1.3 GEY * 1.9 93 MAY 18 945 31.09 38 57.06 123 11.69 5.60 8 .06 .5 .7 PAR 1.4 93 MAY 18 958 32.63 38 57.11 123 12.17 6.01 47 .16 .3 .6 PAR 2.9 93 MAY 18 1650 23.15 36 9.44 120 8.23 7.48 12 .11 .5 1.0 COA * 2.0 93 MAY 18 1739 30.17 38 48.94 122 47.32 0.44 16 .09 .3 .5 GEY 1.6 93 MAY 18 2132 52.18 37 39.06 118 50.39 6.35 14 .12 .5 .7 HCF 1.5 93 MAY 18 2136 52.78 38 46.93 122 43.22 2.66 8 .03 .3 .5 GEY 1.4 93 MAY 18 2355 32.25 38 49.55 122 47.81 0.03 8 .06 .4 1.5 GEY * 1.1 93 MAY 19 3 52.19 38 49.77 122 47.92 0.98 13 .06 .2 .7 GEY 1.7 93 MAY 19 424 35.12 36 9.48 120 8.05 7.93 27 .21 .4 .9 COA 2.3 93 MAY 19 614 45.33 38 50.84 122 47.33 0.11 7 .07 .4 1.7 GEY * 1.1 93 MAY 19 653 38.57 38 49.68 122 47.03 3.06 15 .11 .3 .9 GEY 1.5 93 MAY 19 852 22.02 39 15.35 122 43.01 9.93 23 .22 .7 2.0 BAR 2.1 93 MAY 19 853 32.73 38 47.91 122 45.80 1.31 13 .07 .3 .7 GEY 1.6 93 MAY 19 855 36.80 38 47.76 122 45.85 0.02 7 .03 .3 1.9 GEY * 1.4 93 MAY 19 856 38.61 38 47.80 122 45.86 1.50 9 .03 .2 .7 GEY 1.4 93 MAY 19 956 6.75 38 48.67 122 49.62 0.95 14 .09 .3 .8 GEY 2.0 93 MAY 19 959 57.65 38 50.30 122 46.21 0.19 9 .09 .3 1.5 GEY 1.4 93 MAY 19 1435 28.51 36 15.85 120 24.77 8.20 12 .10 .8 .9 COA 2.0 93 MAY 19 1810 59.39 38 49.00 122 49.75 1.16 9 .10 .3 1.1 GEY 1.0 93 MAY 19 1811 10.95 38 49.33 122 49.89 0.00 40 .24 .3 1.2 GEY * 2.5 93 MAY 19 1812 48.02 38 49.21 122 50.16 0.14 9 .06 .3 1.2 GEY * 1.1 93 MAY 19 1942 50.15 37 35.09 118 47.04 4.06 12 .09 .4 1.0 MOR 1.4 93 MAY 19 2007 2.45 37 38.39 118 55.18 4.70 13 .12 .5 .7 SMO 1.5 93 MAY 19 2105 26.51 38 47.68 122 44.60 0.77 7 .06 .3 1.2 GEY 1.2 93 MAY 19 2137 39.03 38 49.49 122 47.85 0.98 16 .12 .3 .8 GEY 1.9 93 MAY 19 2138 51.35 38 49.67 122 47.96 1.39 25 .08 .2 .6 GEY 2.2 93 MAY 19 2221 57.07 37 32.98 118 47.63 9.24 9 .11 .9 2.0 MOR 1.0 93 MAY 20 110 26.60 37 33.69 118 48.72 8.31 11 .17 .9 2.4 MOR 1.0 93 MAY 20 237 7.70 37 38.71 118 56.95 6.51 12 .09 .5 1.0 SMO 1.4 93 MAY 20 406 12.79 38 49.04 122 49.69 0.19 8 .05 .3 .9 GEY 1.2 93 MAY 20 407 11.10 38 48.99 122 49.14 1.36 33 .16 .3 .7 GEY 2.4 93 MAY 20 408 8.89 38 49.48 122 49.62 0.06 7 .19 .8 3.0 GEY * 1.0 93 MAY 20 408 34.45 38 49.03 122 49.02 1.94 9 .03 .3 .6 GEY 1.2 93 MAY 20 409 38.25 38 49.37 122 48.96 1.61 21 .08 .2 .6 GEY 2.3 --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 93 MAY 20 410 27.49 38 49.68 122 49.27 0.09 7 .08 .4 2.2 GEY * 1.5 93 MAY 20 411 11.11 38 49.83 122 48.82 0.20 7 .08 .6 1.2 GEY 1.2 93 MAY 20 411 26.51 38 49.73 122 48.78 1.24 9 .05 .3 1.1 GEY 1.3 93 MAY 20 519 4.92 38 49.64 122 47.37 0.02 14 .07 .2 1.0 GEY * 1.5 93 MAY 20 651 31.55 37 40.35 118 50.01 4.95 9 .04 .8 1.5 HCF 1.3 Table 2. Eureka Valley Earthquakes(M>3.0) Preliminary Locations --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 93 MAY 17 2320 49.22 37 10.24 117 46.47 6.75 35 .15 1.2 2.1 DEVD 6.1 93 MAY 17 2325 38.96 37 7.76 118 11.20 10.60 8 .11 6.2 9.8 DEVD 3.9 93 MAY 17 2342 5.14 37 2.86 117 47.52 0.38 25 .17 8.110.0 DEVD 4.0 93 MAY 17 2351 56.55 37 9.04 117 42.63 0.15 22 .29 5.2 7.2 DEVD 4.1 93 MAY 17 2354 11.24 37 10.77 117 57.13 9.20 15 .07 4.1 1.3 DEVD 3.4 93 MAY 18 0 7.74 37 10.28 117 51.06 8.80 24 .12 4.6 2.0 DEVD 3.6 93 MAY 18 9 42.61 37 7.90 117 45.14 0.70 30 .15 1.9 5.5 DEVD 3.2 93 MAY 18 13 55.75 37 7.09 117 48.48 9.06 18 .16 2.6 2.2 DEVD 3.6 93 MAY 18 18 12.24 37 10.09 117 50.03 5.49 24 .13 3.9 2.0 DEVD 3.5 93 MAY 18 24 43.04 37 10.62 117 49.07 6.78 23 .15 8.9 2.6 DEVD 3.1 93 MAY 18 56 12.99 37 7.03 118 0.30 0.00 18 .3117.9 8.0 DEVD 3.8 93 MAY 18 103 6.43 37 9.13 117 45.72 2.78 22 .12 1.3 2.9 DEVD 4.8 93 MAY 18 110 36.47 37 14.06 117 48.97 1.32 28 .20 4.4 5.2 DEVD 3.6 93 MAY 18 122 1.40 37 11.59 117 43.37 0.12 23 .19 2.5 5.3 DEVD 3.0 93 MAY 18 125 34.23 37 5.05 117 48.84 4.77 30 .14 1.3 2.3 DEVD 3.1 93 MAY 18 127 4.67 37 8.27 117 51.16 0.01 26 .28 5.213.8 DEVD 3.3 93 MAY 18 129 18.45 37 8.34 118 1.02 6.60 18 .12 6.9 5.6 DEVD 3.8 93 MAY 18 151 18.14 37 9.04 117 47.21 0.00 20 .21 5.7 6.8 DEVD 3.0 93 MAY 18 157 53.67 37 13.66 117 50.26 0.00 24 .17 7.4 5.3 DEVD 3.1 93 MAY 18 224 19.32 37 6.90 117 51.00 9.51 24 .15 3.5 2.3 DEVD 3.0 93 MAY 18 232 33.25 37 14.90 117 59.95 3.95 20 .14 5.5 3.5 DEVD 3.2 93 MAY 18 307 48.89 37 4.57 117 49.14 3.80 29 .14 1.3 2.0 DEVD 3.5 93 MAY 18 316 54.02 37 7.57 117 50.77 6.87 25 .18 2.0 2.6 DEVD 3.0 93 MAY 18 351 34.43 37 8.55 117 49.42 7.11 29 .16 1.5 1.8 DEVD 3.9 93 MAY 18 410 28.41 37 11.87 117 49.44 0.00 23 .22 5.7 6.6 DEVD 3.1 93 MAY 18 417 50.18 37 13.44 117 49.32 7.38 25 .18 5.1 2.9 DEVD 3.0 93 MAY 18 439 8.91 37 14.69 117 57.86 7.64 21 .14 5.1 2.4 DEVD 3.0 93 MAY 18 510 47.29 37 10.02 117 47.94 5.74 25 .14 2.0 1.6 DEVD 3.7 93 MAY 18 703 25.81 37 3.63 117 43.51 0.28 18 .1610.1 6.2 DEVD 3.1 93 MAY 18 819 24.89 37 5.53 117 49.32 5.63 29 .16 1.0 2.0 DEVD 3.8 93 MAY 18 904 43.06 37 0.08 117 44.86 0.00 10 .07 1.6 6.8 DEVD 3.1 93 MAY 18 1028 59.22 37 6.73 117 54.00 6.65 21 .15 6.7 2.7 DEVD 3.7 93 MAY 18 1056 15.57 37 1.14 117 45.03 0.00 24 .23 2.5 9.6 DEVD 3.7 93 MAY 18 1104 54.73 37 8.68 117 46.89 0.00 28 .16 1.6 5.7 DEVD 3.2 93 MAY 18 1439 46.24 37 6.65 117 51.99 5.00 9 .1613.4 4.6 DEVD 3.4 93 MAY 18 1453 13.32 37 13.98 117 49.71 6.61 24 .15 4.6 2.7 DEVD 3.3 93 MAY 18 1554 34.78 37 11.10 117 45.58 0.21 25 .20 2.2 8.0 DEVD 3.2 93 MAY 18 2057 49.78 37 8.53 117 54.80 6.51 26 .14 5.1 1.9 DEVD 3.1 93 MAY 18 2348 53.91 37 3.86 117 46.59 3.03 36 .15 1.0 2.4 DEVD 5.0 93 MAY 18 2357 42.67 37 8.05 117 54.08 0.50 63 .46 2.2 5.5 DEVD 4.4 93 MAY 19 12 18.02 37 6.84 117 52.04 5.26 32 .14 1.7 2.0 DEVD 3.1 93 MAY 19 317 48.28 37 8.21 117 46.95 2.33 29 .17 1.7 3.0 DEVD 3.6 93 MAY 19 320 58.06 37 8.84 117 47.37 6.07 28 .17 1.2 2.4 DEVD 4.4 93 MAY 19 442 49.57 37 8.97 117 48.27 7.31 28 .16 1.3 2.2 DEVD 3.3 93 MAY 19 1413 22.58 37 8.22 117 46.06 0.00 29 .16 1.6 4.6 DEVD 4.9 --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 93 MAY 19 1448 30.93 37 4.57 117 45.13 0.37 25 .22 3.4 7.9 DEVD 3.1 93 MAY 19 1624 50.13 37 8.16 117 50.07 0.08 30 .18 1.8 7.8 DEVD 3.2 93 MAY 20 117 54.51 37 11.41 117 45.71 1.59 32 .18 1.4 3.9 DEVD 4.0 93 MAY 20 123 6.06 37 12.10 117 46.13 0.67 25 .19 3.0 6.9 DEVD 3.4 93 MAY 20 614 5.08 37 12.28 117 50.10 4.69 22 .17 5.5 3.5 DEVD 3.0 TABLE 3. Data from National Earthquake Information Center (NEIC) UTC TIME LAT LONG DEP GS MAGS SD STA REGION AND COMMENTS HRMNSEC MB Msz USED ---------------------------------------------------------------------------- MAY 12 021228.6* 6.787N 126.683E 33N 4.7 4.3 1.2 36 MINDANAO, PHILIPPINE ISLANDS 072404.1 36.203N 114.013W 5G 2.9 0.8 22 SOUTHERN NEVADA. ML 3.5 (GS). 073316.9* 6.704N 126.721E 85? 4.6 1.1 33 MINDANAO, PHILIPPINE ISLANDS 090321.0? 7.08 N 128.08 E 33N 4.6 1.6 14 EAST OF PHILIPPINE ISLANDS 115914.8 20.351S 177.921W 532D 5.0 0.9 114 FIJI ISLANDS REGION 130644.0 3.826S 135.481E 33N 4.7 5.4 1.2 33 IRIAN JAYA REGION, INDONESIA 142231.4& 64.470N 146.970W 8 3.4 62 CENTRAL ALASKA. . ML 3.9 (AEIC). Felt at Delta Junction, Eielson, Fairbanks and Salcha. 150513.6* 7.048N 126.964E 33N 4.4 0.9 17 MINDANAO, PHILIPPINE ISLANDS 194806.4% 30.783S 117.075E 10G 0.6 5 WESTERN AUSTRALIA 205406.7? 14.02 N 92.19 W 33N 4.2 1.1 14 NEAR COAST OF CHIAPAS, MEXICO 233314.7? 48.70 N 153.10 E 78? 4.3 1.4 18 KURIL ISLANDS MAY 13 021910.1* 3.873N 95.275E 33N 4.3 1.0 13 OFF W COAST OF NORTHERN SUMATERA 023157.8? 9.10 S 160.43 E 86* 4.9 0.8 12 SOLOMON ISLANDS. Felt at Honiara. 070303.0& 40.350N 76.020W 5 3 PENNSYLVANIA. . Felt in the Reading area. 102440.5 61.981N 147.035W 60D 5.2 0.9 186 SOUTHERN ALASKA. ML 4.9 (AEIC), 4.9 (PMR). Felt (IV) at Chugiak, Eagle River, Palmer, Sutton, Valdez and Wasilla; (III) at Anchorage. 115947.2 54.972N 160.396W 34G 6.4 6.9 1.1 285 ALASKA PENINSULA. Mo=2.9*10**19 Nm (PPT). Items knocked from shelves at King Cove and Sand Point. Felt (VI) at Sand Point; (V) at False Pass and Perryville; (IV) at Cold Bay and King Cove; (III) at Chignik Lagoon; (II) at Kodiak. 161325.4 40.170N 109.033W 5G 1.2 10 UTAH. ML 3.0 (GS). 182044.8* 13.750N 39.847E 10G 4.8 0.8 25 ETHIOPIA 193200.1& 64.470N 146.980W 8 64 CENTRAL ALASKA. . ML 3.5 (AEIC), 3.5 (PMR). Felt at Alyeska Pump Station 8 and Salcha. 234138.3 55.050N 160.163W 33D 5.2 1.0 96 ALASKA PENINSULA. ML 5.3 (PMR). Felt (IV) at Sand Point and Perryville; (III) at Chignik Lagoon and Cold Bay. 235737.8? 21.54 S 65.73 W 275* 4.4 1.0 24 SOUTHERN BOLIVIA MAY 14 020351.4* 24.459N 109.019W 10G 4.2 1.3 32 GULF OF CALIFORNIA 100026.9 2.443N 126.668E 33N 5.0 4.5 1.0 32 NORTHERN MOLUCCA SEA 151442.3 60.530N 153.187W 179 0.8 70 SOUTHERN ALASKA 212945.0 10.777S 161.261E 23D 5.5 5.1 0.6 50 SOLOMON ISLANDS MAY 15 015539.0* 7.189N 126.701E 33N 5.5 5.2 0.8 40 MINDANAO, PHILIPPINE ISLANDS 030940.8 16.791N 98.449W 33N 5.8 0.9 115 NEAR COAST OF GUERRERO, MEXICO. Felt strongly at Mexico City. 031236.4 17.008N 98.360W 33N 6.0 5.7 1.1 65 GUERRERO, MEXICO. Felt strongly at Mexico City. 042044.7 15.088N 91.902W 132D 4.8 1.1 52 MEXICO-GUATEMALA BORDER REGION 052339.7* 27.924S 176.875W 33N 5.3 5.4 1.1 28 KERMADEC ISLANDS REGION 064751.9% 47.278N 11.241E 10G 0.6 5 AUSTRIA. ML 1.5 (VIE). 081834.4 37.643N 118.962W 5G 0.8 23 CALIFORNIA-NEVADA BORDER ML 3.1 082632.8* 16.966N 98.452W 33N 4.7 1.0 39 NEAR COAST OF GUERRERO, MEXICO 202612.3? 4.33 N 127.80 E 33N 5.0 4.9 1.3 27 TALAUD ISLANDS, INDONESIA 203920.0? 54.67 S 131.95 W 10G 5.1 5.5 1.3 15 PACIFIC-ANTARCTIC RIDGE. 215225.2 51.305N 178.645W 33N 6.3 6.7 1.2 191 ANDREANOF ISLANDS, ALEUTIAN IS. ML 6.1 (PMR). Mo=3.6*10**19 Nm (PPT). Felt (IV) on Adak and Amchitka. 220310.8 51.223N 178.577W 33N 5.0 1.0 30 ANDREANOF ISLANDS, ALEUTIAN IS. 221338.2 51.057N 178.421W 33N 5.4 1.0 58 ANDREANOF ISLANDS, ALEUTIAN IS. 223230.1 51.268N 178.738W 33N 5.2 1.1 72 ANDREANOF ISLANDS, ALEUTIAN IS. MAY 16 001930.5 46.879N 145.436E 353D 4.8 0.7 51 SEA OF OKHOTSK 031910.4 51.272N 178.477W 33N 5.4 4.3 1.1 78 ANDREANOF ISLANDS, ALEUTIAN IS. 033053.1 37.863N 113.427W 5G 0.9 13 UTAH. ML 3.1 (GS). 034218.5* 51.027N 178.433W 33N 5.0 1.3 18 ANDREANOF ISLANDS, ALEUTIAN IS. 034448.0 36.078N 117.582W 5G 1.1 28 CALIFORNIA-NEVADA BORDER, ML 3.3 053021.2 36.677N 116.102W 5G 0.8 16 CALIFORNIA-NEVADA BORDER, ML 3.2 063420.6 13.987N 92.525W 33N 4.7 4.6 0.9 50 OFF COAST OF CHIAPAS, MEXICO 080525.1& 63.800N 148.450W 107 34 CENTRAL ALASKA. . 135555.4 36.026N 117.607W 5G 0.8 13 CALIFORNIA-NEVADA BORDER, ML 2.5 153019.3& 28.810N 98.170W 5 3 SOUTHERN TEXAS. . mbLg 3.0 (GS). Felt in the Jourdanton area. 214450.1 15.199S 173.438W 33N 6.2 6.7 0.9 98 TONGA ISLANDS. Mo=9.0*10**18 Nm 220551.5* 51.108N 178.468W 33N 4.3 1.5 24 ANDREANOF ISLANDS, ALEUTIAN IS. 222748.4* 5.088S 151.714E 33N 5.1 1.1 20 NEW BRITAIN REGION, P.N.G. MAY 17 020836.4* 11.072N 124.500E 33N 4.9 0.8 15 LEYTE, PHILIPPINE ISLANDS 024218.2* 14.969S 173.659W 33N 4.8 0.6 18 SAMOA ISLANDS REGION 043242.0? 37.65 N 142.04 E 33N 4.9 1.1 36 OFF EAST COAST OF HONSHU, JAPAN 060614.1 55.128N 159.711W 33N 5.4 5.3 1.2 77 ALASKA PENINSULA. Felt at Chignik, Cold Bay, Perryville and Sand Point. 064330.2 63.209N 150.690W 131D 4.5 1.0 65 CENTRAL ALASKA. Felt (III) at Cantwell and (II) at Palmer. 071809.2? 55.95 N 164.44 E 33N 4.6 1.2 23 KOMANDORSKY ISLANDS REGION 084502.4 39.620N 118.020W 5G 1.0 27 NEVADA. ML 3.8 (GS). 150349.1? 5.54 S 152.39 E 33N 4.6 0.7 11 NEW BRITAIN REGION, P.N.G. 160255.8* 5.202S 151.913E 33N 5.9 6.5 0.9 59 NEW BRITAIN REGION, P.N.G. 161422.8* 4.769S 151.717E 33N 5.3 0.5 22 NEW BRITAIN REGION, P.N.G. 174041.4? 4.73 S 151.42 E 33N 5.2 0.7 12 NEW BRITAIN REGION, P.N.G. 180000.5* 15.210S 173.718W 33N 5.0 0.7 15 TONGA ISLANDS 232049.1 37.120N 117.796W 5G 6.0 0.9 75 CALIFORNIA-NEVADA BORDER REGION. ML 6.2 (BRK). MD 6.0 (PAS), 5.8 (GM). Felt over a wide area of California and Nevada from the San Francisco Bay area, Sacramento and Los Angeles, California to Carson City, Ely and Las Vegas, Nevada. 232534.0* 37.216N 117.788W 5G 0.6 10 CALIFORNIA-NEVADA BORDER REGION. ML 4.5 (GS). Felt slightly at Beatty, Nevada. 234206.0 37.083N 117.786W 5G 0.7 21 CALIFORNIA-NEVADA BORDER REGION. ML 4.0 (GS). 235157.4 37.096N 117.783W 5G 4.1 1.0 39 CALIFORNIA-NEVADA BORDER REGION. ML 4.1 (GS). MD 3.8 (PAS). MAY 18 010306.4 37.107N 117.746W 5G 4.9 0.9 59 CALIFORNIA-NEVADA BORDER REGION 013858.5* 5.235S 151.458E 33N 5.5 0.6 33 NEW BRITAIN REGION, P.N.G. 071754.3 50.995N 178.556W 20D 4.4 0.8 29 ANDREANOF ISLANDS, ALEUTIAN IS. 080419.3 61.169N 149.944W 54D 4.8 0.8 55 SOUTHERN ALASKA. ML 5.0 (AEIC). Felt widely in the Anchorage area. 094524.3& 40.350N 76.020W 5 5 PENNSYLVANIA. . mbLg 2.1 101935.1* 19.831N 122.436E 187? 6.3 1.1 57 PHILIPPINE ISLANDS REGION 234854.0 37.040N 117.768W 5G 5.0 0.8 64 CALIFORNIA-NEVADA BORDER REGION. Felt in Inyo and Tuolumne Counties, California. MAY 19 141322 Q 37.1 N 117.7 W 10G 5.0 0.7 36 CALIFORNIA-NEVADA BORDER REGION Notes: 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.