From: andy@pangea.Stanford.EDU (Andy Michael USGS Guest)
Newsgroups: sci.geo.geology,ca.earthquakes
Subject: N. CA, USA, and World Quake Report 10/29-11/4/92
Date: 6 Nov 92 00:25:52 GMT
Organization: Stanford Univ. Earth Sciences
NNTP-Posting-Host: pangea.stanford.edu

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
   October 29 - November 4, 1992

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  
    
    During the 7-day period ending at midnight on Wednesday, November 4,
1992 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.  Six were as large as M2.0, including a M3.3 event
south of San Juan Bautista.  This week's total compares to 16 earthquakes
that were recorded during the previous 7-day period, none of which were as
large as M2. 
   The moderate increase in activity over that of the previous week was
due to a small swarm on the creeping segment of the San Andreas, initiated
by the M3.3 mentioned above (#1 in Fig. 1).  This quake occurred at 9:00
am last Saturday morning and was felt as far south as Monterey and
Salinas.   It was followed within minutes by a M1.8 aftershock.  As of
midnight on Wednesday, a total of eight aftershocks larger than M1.0 have
occurred in this area, four of which were as large as M2.0.
   The only other M2 earthquake in the Bay Area occurred Tuesday night
about 8 miles south-southwest of Antioch (#2/1).  This M2.4 event appears
to have occurred on or near the Mount Diablo Fault, an extension of the
Greenville Fault that produced the M5.8 Livermore earthquake in 1980.
   Two small earthquakes are worth noting.  The first occurred last
Saturday morning, a M1.4 on the San Gregorio fault just east of Ano Nuevo
State Park.   The second occurred early Tuesday morning, a M1.6 event
beneath central San Pablo Bay (#3/1).  This small quake appears to have
occurred along the northern extension of the Hayward fault near where the
Hayward "steps over" to the Rogers Creek fault.  The Rogers Creek fault
extends from San Pablo Bay northwesterly to Santa Rosa.  
    
Northern California

   Seismicity was again rather low throughout much of northern and central
California during the past week.  The Cape Mendocino area, as usual,
produced many of the larger earthquakes.  The largest, a M3.0 last
Saturday, occurred 3 miles southwest of Petrolia near the Mendocino
fracture zone (#5/2).  Several M2 events followed on Monday, all on or
near the mapped trace of the fracture zone.  To the north, a M2.9 quake
occurred in the Gorda Plate near its juncture with the Cascadia subduction
zone (#2/2).   In addition, a pair of M2.4 earthquakes occurred east of
Eureka (#4/2).  Both had focal depths of about 24 km, suggesting they were
related to the subduction of the Gorda Plate beneath this leading edge of
the North American Plate.   
   The eastern margin of the Sierra Nevada experienced several M2
earthquakes during the past week, most notably a small cluster of events
along the northern and eastern edges of the Mono Basin (#6/2).  The
largest event in the area was a M2.9 event in the northern Chalfant
Valley, about 14 miles north of Bishop (#7/2).  In the southern Sierra
Nevada, a pair of M2 events occurred about 20 miles north of Lake Isabella
(#1/2). 
   The San Andreas in central California was largely quiet with only a
couple of M2 along the creeping segment and one M2 northwest of Coalinga. 
Parkfield was quiet at the M2 level, although a pair of M1.7 events
occurred Tuesday morning beneath the Middle Mountain area.  Because both
were shallow (2-3 km) they had no impact on the alert status devised for
the Parkfield Earthquake Prediction Experiment.      
        
Long Valley Caldera
    
   Seismicity increased slightly both within the caldera and in the Sierra
Nevada terrane to the south.  The south moat continued to experience
activity in the vicinity of the Fish Hatchery, the largest earthquake here
being a M2.1 last Saturday evening (#3/3).   The central resurgent dome,
which hasn't been active since early July, also experienced a couple of
earthquakes, the largest a M2.4 early Tuesday night (#5/3).  South of the
caldera, M2 events occurred northwest of Convict Lake (#4/3), southeast of
Laurel Mtn. (#2/3), and south of Grinnell Lake (#1/3).

USA Seismicity

    Outside of California, only two notable earthquakes occurred in the
lower 48 states, according to information provided by the National
Earthquake Information Service.  The first of these was a M3.0 that
occurred Monday in eastern Wyoming and was felt at Lusk, WY (#1/4).  
On Tuesday a M4.3 occurred in northwestern Utah that was felt at Brigham
City (#2/4).  
            
The Planet Earth

   The largest earthquakes during the past week occurred in the southwest
Pacific:   M6.4 events in both the Papua New Guinea area (#4/5) and in the
Vanuatu Islands area (#6/5).  Nearly as large was a M6.3 in the Balleny
Islands region south of Australia (#5/5).
   The eastern Pacific margin was also active during the week with a swarm
of earthquakes in the central Chile area, capped by a trio of M5 events
(#1/5).  M4 earthquakes occurred in northern Colombia and off the coasts
of both Guatemala and southern Mexico.
   Two notable earthquakes occurred in the Mediterranean region:  a M5.2
in southern Morocco (#3/5) and a M4.6 near the northern coast of Albania. 

    
 Table 1.  Central California Seismicity (M>2.0)

--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

92 OCT 29  809  0.44 35 59.16 118 22.22  4.02  9   .02  .4 2.7 WWF   2.1
92 OCT 29  941  7.85 41  8.40 125  5.29  5.03 16   .19 6.717.1 PON-- 2.9
92 OCT 29 1416 32.94 39 11.54 119 45.94  5.00  8   .09 3.4 9.6 WAK - 2.5
92 OCT 29 1449 55.20 37 27.34 118 50.87  7.52 30   .10  .4 1.1 MOR   2.8
92 OCT 30  658 11.78 39 16.87 122 49.10  7.76 21   .11  .3 1.3 BAR   2.4

92 OCT 31  330 35.41 40 38.04 123 43.15 23.34  9   .07  .4  .8 EUR   2.0
92 OCT 31  838 41.09 38 47.27 122 45.93  0.03 26   .25  .5 2.2 GEY * 2.8
92 OCT 31 1249 43.26 40 17.05 124 19.01  8.91 15   .18 1.1  .7 MEN   3.0
92 OCT 31 1700 30.10 36 47.82 121 31.73  9.80106   .21  .2  .4 SJB   3.3
92 OCT 31 1756 33.18 37 34.13 118 52.34  7.27 23   .09  .3  .7 MOR   2.1

92 NOV  1  612  2.20 37 38.09 118 52.46  5.31 24   .14  .4  .6 SMO   2.1
92 NOV  1  653 52.95 36 36.88 121 12.90  4.92 58   .11  .2  .5 PIN   2.2
92 NOV  1 1202 55.05 38  5.23 119  1.15 11.30 24   .12  .9 2.2 MOL   2.2
92 NOV  1 1221 41.60 38 46.96 122 45.08  0.66 12   .06  .3  .8 GEY   2.1
92 NOV  1 1316 50.30 36 12.90 120 25.24  6.33 25   .14  .3  .6 COA   2.0

92 NOV  1 1758 15.55 36 47.73 121 31.53  8.07 79   .22  .3  .5 SJB   2.5
92 NOV  2  309 16.29 36 47.61 121 31.50  8.58 74   .22  .3  .6 SJB   2.3
92 NOV  2  320  8.02 37 36.27 118 52.66 11.03 29   .10  .3  .5 SHE   2.1
92 NOV  2  619 27.11 37 27.30 118 50.86  6.79 29   .10  .4 1.1 MOR   2.3
92 NOV  2 1930 16.57 36  0.20 118 22.51  4.64 13   .04  .4 2.0 WWF   2.7

92 NOV  2 2332 18.38 40 17.14 124 20.17  9.65 14   .14 1.0  .6 MEN   2.8
92 NOV  3   32 32.92 40 47.19 123 57.40 24.64 13   .08  .6  .8 EUR   2.4
92 NOV  3  548 32.78 38 46.37 122 54.19  5.10 30   .15  .3  .7 GEY   2.5
92 NOV  3  738 27.58 40 20.23 124 33.35  0.13  8   .09 2.2 3.5 MEN   2.6
92 NOV  3  833 19.26 40 25.66 124 41.55 13.28  7   .09 5.1 2.0 MEN   2.3

92 NOV  3  935 48.70 37 54.13 121 50.85 16.24 39   .14  .3  .6 GRN   2.4
92 NOV  3 1126 54.78 36 48.98 121 32.76  6.37 47   .20  .3  .6 SJB   2.0
92 NOV  3 1225 52.87 37 33.13 118 26.15  7.08 26   .05  .3  .6 CHV   2.9
92 NOV  3 1431 48.94 38 46.49 122 54.54  3.22 30   .14  .3 1.2 GEY   2.5
92 NOV  4   19 31.90 36 19.98 120 54.60  8.49 17   .08  .3 1.0 BIT   2.3

92 NOV  4  644 17.19 37 39.19 118 54.15  1.48 12   .11  .4  .7 DOM   2.4
92 NOV  4  715 49.18 38 48.36 122 47.77  1.63 32   .15  .3  .5 GEY   2.5
92 NOV  4 1644 42.26 38  3.40 118 47.07  7.01  7   .04  .9 7.2 MOL - 2.1
92 NOV  4 1809 58.93 37 56.58 118 34.77  6.88 16   .13 1.6 4.7 MOL   2.0
92 NOV  4 1951 22.06 36 50.00 121 34.59  9.54 72   .19  .3  .5 SJB   2.5
    
     

 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
-------------------------------------------------------------------------------
OCT 29
133459.6& 63.270N 151.090W  14               35 CENTRAL ALASKA. <AEIC>. ML 2.6
140016.3*  2.197S 141.160E  33N 4.9 4.8 1.0  13 NEAR N COAST OF NEW GUINEA, PNG.
143917.1  29.274S  71.069W  46D 5.5 4.7 1.0  73 NEAR COAST OF CENTRAL CHILE. MD
                                                5.1 (SAN). Felt (V) at Coquimbo.
190550.4% 33.474S  70.561W  10G         0.7   9 CHILE-ARGENTINA BORDER REGION.
                                                MD 3.4 (SAN).
192907.0% 33.147S  70.235W  14*         0.3   6 CHILE-ARGENTINA BORDER REGION.
                                                MD 3.6 (SAN).
215607.3*  6.982N  76.440W  10G 4.8 4.5 1.4  52 NORTHERN COLOMBIA. MD 4.8 (UPA).
224444.3*  7.199N  76.704W  10G 4.9 4.1 1.2  53 NORTHERN COLOMBIA. MD 4.8 (UPA).

OCT 30
024949.0  29.937N 138.912E 402D 5.9     0.9 112 SOUTH OF HONSHU, JAPAN
053826.7  42.343N  19.125E  22D 4.6     0.8  32 NORTHWESTERN BALKAN REGION
082430.4* 17.301N 100.500W  33N 4.5     1.2  40 GUERRERO, MEXICO
104359.8  31.502N   4.551W  25D 5.1 5.2 1.2  73 MOROCCO
145618.3* 31.311S 178.199W  52D 5.3     1.1  19 KERMADEC ISLANDS REGION

OCT 31
113142.2* 20.191S 179.553W 638D 4.6     0.6  23 FIJI ISLANDS REGION
114548.3* 59.295N 153.226W 130?         0.3   9 SOUTHERN ALASKA
130614.7* 51.227N 178.523W  33N 4.6     1.2  24 ANDREANOF ISLANDS, ALEUTIAN IS.
143426.3*  2.129S 140.857E  33N 5.8 6.4 1.1  43 NEAR NORTH COAST OF IRIAN JAYA.
144627.7?  2.48 S 141.49 E  33N 5.8 6.2 1.4  30 NEAR N COAST OF NEW GUINEA, PNG.
152930.4*  2.359S 141.344E  33N 5.3     0.8  12 NEAR N COAST OF NEW GUINEA, PNG.
155339.9  33.954N 116.909W   5G         0.6  12 SOUTHERN CALIFORNIA. MD 3.0
170027.8  36.709N 121.717W  10G         0.7  13 CENTRAL CALIFORNIA. ML 3.2 (GS).
        Felt in the Monterey-Salinas area.

NOV 01
010500.9  35.291N 118.575W   5G         0.8   9 CENTRAL CALIFORNIA. MD 2.6
011253.5* 14.447S 166.535E  33N 5.2 4.7 0.7  29 VANUATU ISLANDS
045449.6? 13.37 N  90.08 W  33N 4.4     0.8  24 NEAR COAST OF GUATEMALA
072427.0?  5.60 S 154.67 E  33N 4.7     0.7  11 SOLOMON ISLANDS
082351.0  64.082N 149.837W 141  4.9     1.0  55 CENTRAL ALASKA
093643.1* 28.624S  69.141W 109D 5.6     0.7  64 CHILE-ARGENTINA BORDER REGION
174745.9?  2.13 S 140.90 E  29D 5.3 5.1 0.7  12 NEAR NORTH COAST OF IRIAN JAYA
211358.3  64.707N 147.534W  10G         0.5   8 CENTRAL ALASKA. ML 3.3 (AEIC).
        Felt at Fairbanks and North Pole.

NOV 02
065410.2* 42.740N 104.387W   5G         1.0   6 WYOMING. ML 3.0 (GS). Felt at
                                                Lusk.

NOV 04
015927  Q 61.3  S 154.6  E  10G     6.3 0.9  27 BALLENY ISLANDS REGION
181316  Q 14.1  S 167.4  E  33N     6.4 0.9  24 VANUATU ISLANDS
182209  Q 41.5  N 113.4  W  10G 4.3     0.6  15 UTAH
213236  Q 31.4  S  71.2  W  33N     5.7 0.8  77 NEAR COAST OF CENTRAL CHILE


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.