From: andy@pangea.Stanford.EDU (Andy Michael USGS Guest)
Newsgroups: sci.geo.geology,ca.earthquakes
Subject: N. CA, USA, and World Quake Report 11/5-11/92
Date: 13 Nov 92 00:05:59 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
November 5 - 11, 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 11,
1992 the U.S. Geological Survey office in Menlo Park recorded 24
earthquakes of magnitude one (M1) and greater within the San Francisco Bay
area shown in Figure 1.  Five were as large as M2.0.  This week's total
compares to 27 earthquakes that were recorded during the previous 7-day
period, six of which were as large as M2. 
    A M2.3 earthquake occurred in the central Santa Cruz Mountains late
last Friday afternoon (#2 in Fig. 1).  Earthquakes of this size are often
not even felt but in this case, felt reports were received from many
people in the Santa Cruz and Boulder Creek areas.  The earthquake itself
occurred several miles west of the northernmost extent of Loma Prieta
aftershocks and apparently was not on the Loma Prieta segment.  
    The creeping segment of the San Andreas was quite active during the
week with earthquakes noted from Watsonville (#4/1) to south of San Juan
Bautista (#4/1).  The largest earthquakes on this segment occurred early
last Thursday morning: a M2.6 and a M2.4 that were located about 4 miles
west of San Juan Bautista (#1/1).  
    The only other earthquake of note in the Bay Area was a M1.6 Monday
night on the central Hayward, approximately 5 miles east of Oakland
(#3/1). 
    
Northern California

   Seismicity was again rather low throughout much of northern and central
California during the past week.  The exception to this was in the Geysers
geothermal area east of Cloverdale where a M3.0 occurred early Wednesday
morning (#6/2).  It was preceded by six M2 earthquakes during the previous
week which, added to the M3 event, produced the most active week here
since mid-September. 
    The San Andreas fault system was largely quiet during the week.   To
the north activity was limited to a pair of M2's in the Cape Mendocino
area (#1/2), a M2.0 in the Coast range east of Willits, and a M2.3 north
of Lake Berryessa.  To the south, the only earthquake as large as M2 was a
M2.7 south of the Kettleman Hills area (#3/2).
    The eastern edge of the Sierra Nevada saw about the same level of
activity with a pair of M2's east of Mono Lake (#2/2), a M2.7 11 miles
southeast of Portola (#5/2), a M2.1 7 miles southeast of Markleeville
(#7/2), and a M2.1 about 20 miles southeast of Bishop.  A M2.7 occurred
beneath the central Sierra Nevada last Saturday about 38 miles northeast
of Fresno (#4/2).  This earthquake occurred at a depth of about 25 km,
deeper than is typical for most earthquakes in California except in this
area of the central Sierra Nevada where events as deep as 40 km have been
observed.

        
Long Valley Caldera
    
    Several small earthquakes occurred inside the caldera during the week,
most concentrated in an area along the southeast edge of the resurgent
dome, about a mile northeast of the Fish Hatchery (#2/3).  Only one of
these events was as large as M2, a M2.7 event that occurred Sunday night. 
Only one M2 event occurred south of the caldera, a M2.7 that occurred last
Friday morning about 2 miles south of Mt. Morrison (#1/3).  
   
USA Seismicity

    According to information provided by the National Earthquake
Information Service, there were no notable earthquakes in the lower 48
states during the past week, outside of the California area.  In
California, aftershocks to the M7.5 Landers earthquake continue to
dominate though they continue to decline in both magnitude and number. 
During the past week the largest aftershock was a M3.6 event early last
Friday morning that was felt in the Palm Desert area (#1/4).
            
The Planet Earth

    The largest earthquake worldwide was a Ms6.5 in the Fiji Island region
(#4/5).  The New Britain region of Papua New Guinea also experienced
numerous moderate earthquakes, the largest a Ms6.1 event (#1/5).  In the
northern Pacific, the Aleutian Island subduction zone experienced a pair
of M5 events, the largest a M5.9 on Wednesday afternoon (#6/5).  
    Central and southern Asia also experienced several notable earthquakes
including M5's in both Kyrgyzstan and Tajikistan (#2/5) and a Ms6.1 in the
Aegean Sea area that produced some damage in the epicentral area and was
strongly felt at Izmir, Turkey (#3/5).  A Mb4.6 earthquake occurred in
northern Egypt, an aftershock to the Mb5.9 in early October that caused
much death and injury in the Cairo area. 
    The west coast of South America was also active with a pair of M5
events near the coast of northern Chile (#5/5), a M5.1 in central Peru, a
M4.5 in northern Colombia, and a M4.3 beneath the central Gulf of
California (#2/4). 
    
 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 NOV  5 1119 51.44 36 51.47 121 35.98  8.26 86   .21  .3  .5 SJB   2.6
92 NOV  5 1332 30.56 36 51.50 121 35.89  7.51 81   .21  .3  .5 SJB   2.4
92 NOV  6  641 24.18 40 23.35 124 15.88 11.05 14 1 .12  .3  .5 MEN   1.9
92 NOV  6  840 15.12 37 59.05 118 34.85  3.79 31   .11 1.0 3.5 MOL   2.9
92 NOV  6 1243 32.53 38 49.80 122 48.42  1.32 20   .07  .2  .6 GEY   2.4

92 NOV  6 1428  6.16 37 32.62 118 51.43  9.60 27   .10  .4  .8 MOR   2.7
92 NOV  6 2353 13.44 38 47.56 122 47.62  0.88 15   .17  .4  .9 GEY   2.3
92 NOV  7  114 20.17 37 10.21 122  7.16  8.42 57   .14  .3  .6 BLM   2.3
92 NOV  7  941 55.55 38 50.46 122 49.37  2.59 18   .03  .2  .7 GEY   2.0
92 NOV  7 1409  4.45 39 29.75 122 56.40 11.02 14   .11  .4  .8 BAR   2.0

92 NOV  7 1804 29.84 35 47.03 119 55.71 13.74 47   .22  .5  .8 BAK   2.8
92 NOV  7 2202 40.88 37  9.41 119 19.94 24.71 22   .15  .9 1.4 KAI * 2.7
92 NOV  8   42 22.60 38 49.29 122 47.58  4.10 37   .16  .3  .6 GEY   2.3
92 NOV  8  825 23.21 37 38.85 118 51.31  5.75 33   .14  .3  .5 HCF   2.6
92 NOV  9  555 13.56 37 21.68 118  2.91  3.03 14   .17 2.2 4.0 DEV   2.1

92 NOV  9  628 41.76 40 23.97 124 32.20 18.41  8   .12 3.3  .6 MEN   2.7
92 NOV  9 1041 54.73 38 47.13 122 45.08  0.53 17   .08  .2  .8 GEY   2.0
92 NOV  9 1240  1.07 38 43.78 122 24.43  7.82 33   .23  .4 1.3 GVL   2.3
92 NOV  9 1320 17.96 38 46.49 122 54.56  2.98 40   .20  .3 1.4 GEY   2.4
92 NOV 10  902 27.66 36 56.10 121 40.14  8.16 70   .14  .2  .5 SJB   2.3

92 NOV 10 2056 52.01 39 40.72 120 20.65 20.42 12   .05 2.6 3.8 WAK   2.7
92 NOV 11  223 40.85 35 37.56 118 24.93 13.03 13   .07  .4 1.0 WWF   2.1
92 NOV 11  901 53.53 36 48.03 121 31.73  8.25 70   .21  .3  .6 SJB   2.1
92 NOV 11 1341 32.62 38 48.28 122 45.85  1.14 29   .13  .2  .7 GEY   3.0
92 NOV 11 1423 28.01 38  9.17 118 53.72  4.42 13   .10 1.6 8.5 MOL - 2.1

92 NOV 11 1812 35.90 38 38.83 119 39.82  5.15  9   .10 7.3 4.0 WAK - 2.3

         

 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
-------------------------------------------------------------------------------
NOV 05
150452.4  68.035N 145.799W  10G 4.2     1.0  61 NORTHERN ALASKA. ML 4.5 (AEIC).
                                                Felt (IV) at Arctic Village.
154227.9* 42.610N  45.217E  33N 4.4     0.8  11 EASTERN CAUCASUS
173841.8   5.310S 152.714E  33N 4.9     0.5  22 NEW BRITAIN REGION, P.N.G.
184151.5* 29.917N  31.176E  26* 4.6     0.9  20 EGYPT. MD 4.4 (RYD), 4.3 (HLW).
                                                Felt in the Cairo area.
191646.2* 29.671N  31.090E  29*         0.6  12 EGYPT. MD 4.1 (HLW).
195325.9   5.042S 152.528E  33N 5.8 6.1 1.3 132 NEW BRITAIN REGION, P.N.G.
222506.6   5.314S 152.736E  33N 5.4     0.7  22 NEW BRITAIN REGION, P.N.G.
223545.4* 36.324N 141.116E  33N 4.5     1.5  19 NEAR EAST COAST OF HONSHU, JAPAN

NOV 06
002748.6?  5.62 S 152.90 E  33N 4.6     0.7   7 NEW BRITAIN REGION, P.N.G.
011907.2?  5.36 S 152.86 E  33N 4.8     1.0  11 NEW BRITAIN REGION, P.N.G.
020059.0& 60.620N 142.310W   0               23 SOUTHERN ALASKA. <AEIC>. ML 3.5
072157.1* 40.983N  72.437E  33N 4.9     1.0  26 KYRGYZSTAN
074654.5* 57.948N 156.239W 116* 4.0     1.4  18 ALASKA PENINSULA
084015.0  38.000N 118.563W   5G         0.9  15 CALIFORNIA-NEVADA BORDER REGION.
                                                ML 2.8 (GS).
144701.4  34.042N 116.736W   5G         0.8  20 SOUTHERN CALIFORNIA. MD 3.6
        (PAS). ML 3.6 (GS). Felt in the Palm Desert area.
190809.4  38.026N  26.802E  18D 5.6 6.1 1.0  67 AEGEAN SEA. Some damage in the
        epicentral area. Felt strongly at Izmir, Turkey. 
202402.6  36.698N 116.315W   5G         1.3  14 CALIFORNIA-NEVADA BORDER REGION.
        ML 2.7 (GS). Felt at Beatty and in the Lathrop Wells area, Nevada.
205156.5* 10.834S  75.141W 150G 5.1     0.7  47 CENTRAL PERU

NOV 08
021727.9* 26.317N 109.823W  10G 4.6 4.3 1.3  19 GULF OF CALIFORNIA
034327.8? 14.71 S 179.73 W  33N 5.8 6.5 0.9  67 FIJI ISLANDS REGION
102301.1? 22.19 S  70.85 W  31D 5.4 4.9 0.6  52 NEAR COAST OF NORTHERN CHILE
102417.8*  6.636N  73.056W 154D 4.5     0.6  43 NORTHERN COLOMBIA
104122.6* 23.483S  70.013W  28D 5.2 4.6 0.9  51 NEAR COAST OF NORTHERN CHILE. MD
        5.3 (SAN). Felt (V) at Antofagasta and (IV) at Mejillones.
175242.9* 13.953N  92.721W  33N 4.8     0.6  35 OFF COAST OF CHIAPAS, MEXICO
181900.1? 33.91 N 142.05 E  45D 4.8     0.6  27 OFF EAST COAST OF HONSHU, JAPAN
205009.1* 38.699N  69.848E  33N 5.1     0.5  16 TAJIKISTAN

NOV 09
012714.7* 20.458S 174.458W  33N 4.8     0.6  19 TONGA ISLANDS
043846.9  61.592N 146.447W  48*         0.8  54 SOUTHERN ALASKA

NOV 10
021329.1* 17.420N  99.892W  33N 4.5     1.0  32 GUERRERO, MEXICO
095814.3  51.974N 177.614W  56  5.6 5.1 0.9  74 ANDREANOF ISLANDS, ALEUTIAN IS.
                                                Felt on Adak.

NOV 11
001848  Q  2.7  S 141.2  E  33N     5.8 0.8  54 NEAR N COAST OF NEW GUINEA, PNG.
003127  Q  7.1  S 155.9  E  33N     5.6 0.8  16 SOLOMON ISLANDS
212614  Q 51.3  N 179.2  W  33N     5.9 1.0  94 ANDREANOF ISLANDS, ALEUTIAN IS.


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.
Xref: sparky sci.geo.geology:2362 ca.earthquakes:1320