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
  April 22 - 28, 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  
    
    It's been a very quiet week here beside the Bay. For the 7-day period
ending at midnight on Wednesday, April 28, 1993 the U.S. Geological Survey
office in Menlo Park recorded just 13 earthquakes of magnitude one (M1)
and greater within the San Francisco Bay area shown in Figure 1.  Only one
was as large as M2.0.  This is the lowest weekly total in the past five
months.  By contrast, 26 earthquakes were  recorded during the previous
7-day period, six of which were as large as M2. 
   The lone M2 earthquake occurred late last Thursday night along the
northern Hayward fault about 2 miles east of Berkeley (#1 in Fig. 1).  The
Hayward fault is generally considered to be a "locked" fault, accumulating
strain rather than releasing it in numerous smaller earthquakes, as is the
case on the creeping segment of the San Andreas.  However, there are a
couple of areas of the Hayward fault that experience occasional
earthquakes in the M1-3 range.  The area east of Berkeley that experienced
the M2.3 last Friday night is one of those areas.  The most recent
comparable activity here was a pair of M2.4 events on March 24 and a M2.2
a week later, on March 31.
    Both the San Andreas and Calaveras faults were quiet during the week
with only a few scattered M1 events.   
      
Northern & Central California

    The low level of activity seen in the Bay Area extended through much
of the rest of northern and central California with no earthquakes as
large as M3 in either region.  Central California in particular was
unusually quiet with only two M2.0 earthquakes, one just northeast of
Coalinga, the other about 22 miles southwest of Lone Pine in the southern
Sierra Nevada.
   Northern California saw M2 earthquakes in many of the usual places,
including a pair of deep earthquakes beneath the Klamath Mountains.  The
first of the deep events occurred last Saturday morning, a 23 km-deep
event that was located about 26 miles southeast of Eureka (#4/2).  It was
followed Monday morning by a 42 km-deep earthquake located about 44 miles
west-southwest of Redding (#6/2).  It's worth mentioning that a pair of
deep earthquakes also occurred during the previous week:  a 32 km-deep
event on the 15th located 30 miles southeast of Eureka and a 30 km-deep
event on the 19th located 45 miles east of Eureka.  
   Cape Mendocino experienced four M2 earthquakes during the week, the
largest a M2.9 last Sunday evening (#5/2).  A M2.1 occurred two days
earlier in the eastern Gorda Plate, about 42 miles west of Eureka (#3/2). 
  
Long Valley Caldera
    
   The increased seismicity within the caldera that has been observed
during the past 4 weeks declined markedly with nothing larger than two
M2.0 events on the southern rim (#2/3).  These were part of a small
cluster of small earthquakes that occurred Monday morning along the
southern rim of the caldera, 1-2 km east of a slightly more energetic
cluster during the previous week.   
   Activity south of the caldera was also down from the previous week with
a pair of M2's southeast of Mt. Crocker (#1/3) and a M2.1 near the
southwest side of Convict Lake (#3/3).     
  
USA Seismicity
   
   According to information provided by the National Earthquake
Information Center (NEIC), there were several notable earthquakes in the
lower 48 states during the past week.  Most newsworthy were a pair of
moderate earthquakes south of the Grand Canyon that were widely felt in
Arizona and Utah (#2/4).  The first of these was a M4.8 that occurred
early Sunday morning about 30 miles south of Grand Canyon Village, the
main visitors center for the National Park.  It was felt strongly at
Flagstaff (90 miles to the south) and as far away as Phoenix and St.
George Utah.  It was followed early Thursday morning by a M5.5 that
briefly knocked out electrical power at the National Park and that was
reported to have shaken some people in Flagstaff out of their beds.  No
reports of injury or serious damage were immediately available.
   Earlier in the week, a M3.9 occurred in the Salmon River Mountains of
north-central Idaho (#1/4).  A slightly smaller M3.6 occurred Wednesday
afternoon in the New Madrid area of the central U.S.  The NEIC location
places this earthquake just south of Reelfoot Lake in northwestern
Tennessee (#4/4). 
    
The Planet Earth  (April 19 - April 29)
  
   The planet was fairly quiet during the past week, at least with respect
to seismic activity.  There were no large earthquakes during the week, ie.
none as large as M6.0.  The largest earthquake was a Ms5.7 on the mid-
ocean ridge separating the Australian and Antarctic plates (#2/5). 
Interestingly, a Ms5.2 occurred later in the week along the mid-ocean
ridge separating the Australian and Pacific plates (#5/5).  
   Other earthquakes of note include a M5.3 in the Kodiak Island region of
Alaska that was felt at Old Harbor (#4/5), a Ms4.8 on the central East
Pacific Rise (#3/5), and a Mb4.4 in the Afghanistan-Tajikistan border
region (#1/5).

 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 APR 22  806 31.43 39 28.52 122 59.61  9.84 45 1 .11  .2  .4 BAR   2.4
93 APR 22  934 26.05 38 49.27 122 49.65  1.68 16   .07  .3  .6 GEY   1.5
93 APR 22 1015 21.97 37 39.86 118 54.16  5.22  8   .04  .6  .8 DOM   1.2
93 APR 22 1126  7.15 38 47.74 122 48.39  4.95  8   .10 1.4 1.1 GEY   1.1
93 APR 22 1242 36.02 37 33.98 118 28.74 11.32 22 1 .08  .3  .6 CHV   1.5

93 APR 22 1359 56.26 37 38.19 118 53.23  5.57  7   .09 1.4 1.7 SMO   1.9
93 APR 22 1453 23.77 38 51.24 122 50.97  4.17 10 2 .08  .5 1.5 GEY   1.4
93 APR 22 1540 46.55 37 39.30 118 54.36  5.01 18   .11  .4  .6 DOM   1.8
93 APR 22 1546 23.60 37  0.67 121 27.80  7.77 20   .07  .3  .7 CYS   2.5
93 APR 22 1606  5.97 37 39.54 118 54.38  4.49 10 1 .08  .5  .6 DOM   1.0

93 APR 22 1713  8.65 37 28.09 118 50.08  7.20 30 3 .10  .5 1.1 MOR   1.7
93 APR 22 2206 57.31 37 39.10 118 54.48  5.65 19 2 .11  .4  .5 DOM   1.5
93 APR 22 2249 23.07 37 38.59 118 46.87  9.76  8   .14 5.3 5.1 EMO   1.2
93 APR 22 2352 56.42 37 31.15 118 48.29 14.38 20   .09  .5 1.0 MOR   1.4
93 APR 23    2 11.48 38 48.26 122 46.29  1.75  9   .15  .9 1.6 GEY   1.5

93 APR 23  311 21.33 38 48.85 122 48.53  4.25 11   .04  .3  .4 GEY   1.3
93 APR 23  315 40.43 37 25.97 118 37.23 10.48 31 3 .09  .3  .6 RVL   1.6
93 APR 23  329 32.12 38 47.32 122 46.32  6.55  9   .08  .6 1.1 GEY   1.2
93 APR 23  432 57.50 40  8.58 123 51.12 20.78  9 1 .17 1.0 1.3 MEN   1.4
93 APR 23  601 45.39 37 38.97 118 52.10  8.60 12 2 .03  .5  .8 SMO    .9

93 APR 23  757 24.65 39 52.42 122 25.40 31.06  9 2 .17 1.7 3.7 SAC   1.7
93 APR 23  833 32.98 36 22.23 120 44.29 12.28 18 1 .11  .5  .4 CRV   1.4
93 APR 23  941 30.71 36 47.34 121 28.15  5.05 19 1 .16  .4  .7 SJB   1.0
93 APR 23 1111  4.56 36 11.50 120 45.19  7.43 27 3 .16  .5  .6 BIT   1.8
93 APR 23 1214 52.62 39 37.31 123 38.94  0.01 17 1 .16  .6 2.6 PAR-  1.6

93 APR 23 1733 47.50 37 40.91 119 26.07 18.46 16 3 .14  .5 2.6 KAI   2.1
93 APR 23 1800 39.99 38 47.82 122 48.24  3.04 12   .05  .3  .6 GEY   1.7
93 APR 23 1819 18.69 38  4.09 120 24.57  0.87  8   .08  .6 9.6 YOS - 1.5
93 APR 23 1823 27.19 38 48.73 122 48.07  2.72  8   .02  .4  .5 GEY   1.1
93 APR 23 2017 46.62 40 17.50 124 28.52 20.91 10 1 .12 1.7  .6 MEN   2.0

93 APR 23 2255 38.27 39 58.66 120 43.15  0.03 23   .29 2.2 4.5 WAK * 2.2
93 APR 24  202 31.90 35 49.57 120 22.40  6.49 12   .02  .3  .4 GOL   1.3
93 APR 24  317 30.85 36 44.69 121 27.14  7.89 45   .22  .4  .8 SJB   1.8
93 APR 24  409 34.82 40 17.34 124 23.33 21.32 13 1 .10 1.3  .4 MEN   1.8
93 APR 24  416 51.39 40 55.55 124 57.31  5.97 13   .10 3.4 4.8 DEL   2.1

93 APR 24  441  4.51 35 51.79 120 24.20  5.40 19 2 .07  .4  .4 GOL   1.4
93 APR 24  622 41.33 37 52.00 122 14.30 10.59 52 4 .18  .2  .7 HAY   2.4
93 APR 24  806 46.11 36 44.26 121  5.25  1.27 22   .30  .7 5.2 ORT   1.2
93 APR 24  902 46.88 37 35.26 121 48.67  8.97 19 1 .10  .3  .6 SUN   1.1
93 APR 24 1114 13.22 40 23.57 124 14.22 11.18 16 1 .07  .2  .3 MEN   1.6

93 APR 24 1308 49.80 36 28.58 121  0.38  1.40 17   .10  .3 1.1 BIT   1.3
93 APR 24 1352 10.12 37 37.92 118 48.75  3.58  7 1 .02 2.1 1.8 HCF   1.1
93 APR 24 1506  7.38 37 38.20 118 48.52  3.97  8 2 .06 1.2 1.2 HCF   1.3
93 APR 24 1513 48.58 37 37.94 118 51.96  3.63 17 2 .09  .3  .7 SMO   1.8
93 APR 24 1539  3.86 37 36.97 118 51.34 14.75  7   .15 2.811.7 SMO - 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 APR 24 1656 49.87 37 39.66 118 50.94  5.66 11   .06  .6  .7 HCF   1.2
93 APR 24 1814 11.73 36 22.39 120 56.91  7.19 28 1 .06  .2  .6 BIT   1.9
93 APR 24 1814 24.77 38 48.48 122 49.58  1.88  7   .04  .3  .6 GEY   1.2
93 APR 24 1848 51.12 40 40.82 123 42.05 23.08 19 2 .08  .3  .4 EUR   2.0
93 APR 24 1908 10.20 37 31.97 121 40.18  4.41 13   .06  .3  .7 HAM   1.0

93 APR 24 1915 17.31 37 33.55 118 28.04 10.40 12 1 .04  .4  .7 CHV   1.1
93 APR 24 1931 31.20 37 33.51 118 49.28 11.55 21   .13  .5  .9 MOR   1.8
93 APR 24 2235 40.68 38 50.23 122 49.07  3.24  9   .03  .6  .8 GEY   1.3
93 APR 24 2354 20.49 37 23.56 121 44.55  3.37 10 1 .09  .5 1.1 ALU   1.3
93 APR 25    5 24.66 36 12.63 120 18.80 10.39 30   .12  .3  .4 COA   2.1

93 APR 25   19  6.60 38 47.92 122 48.59  4.78 13   .10  .4  .7 GEY   1.4
93 APR 25   31 22.81 37 34.50 118 51.56  9.70 16   .13  .5  .9 MOR   1.1
93 APR 25   49 21.22 36 58.15 121 35.89  2.00 35   .16  .3  .6 SAR   1.5
93 APR 25  401 31.93 40  2.05 122 52.17  4.93  7 2 .13  .8 5.2 KLA   1.2
93 APR 25  406 32.31 39 29.28 122  0.40 18.04 11   .06  .5 1.1 SAC   1.7

93 APR 25  511 47.24 37 37.92 118 51.99  9.56 13 1 .13  .6  .9 SMO   1.5
93 APR 25  626 28.98 36  0.93 120 33.46  4.12  8 2 .03  .4 1.4 SLA   1.2
93 APR 25  923 11.19 40 24.21 124 33.92 13.97 14 1 .10 1.4  .4 MEN   1.8
93 APR 25  937 32.18 36 33.53 121  5.44  9.62 18 2 .08  .4  .8 BVL    .9
93 APR 25 1018 31.81 39 19.69 122 49.47  9.11 46 1 .15  .3 1.0 BAR   2.4

93 APR 25 1043 36.02 37 36.74 118 28.43 10.45 18 1 .09  .4  .8 CHV   1.4
93 APR 25 1157  1.25 37 38.46 118 52.70  9.11 12 1 .07  .6 1.1 SMO   1.0
93 APR 25 1211 50.65 37 33.87 118 46.95  6.95 11 1 .08  .5  .9 MOR    .9
93 APR 25 1354 41.58 38 47.58 122 46.59  2.91 10   .09  .4  .9 GEY   1.1
93 APR 25 1708 25.88 39 20.96 122 53.58  7.63 17   .04  .3 1.3 BAR   1.6

93 APR 25 1823 48.21 39 19.67 122 49.72  5.26 12   .04  .3 2.5 BAR-  1.6
93 APR 25 2147 23.58 37 28.86 118 48.76  8.66 31 2 .12  .4  .9 MOR   2.2
93 APR 25 2242 52.66 37 37.60 118 52.11  2.60 16   .10  .3  .5 SMO   1.9
93 APR 25 2301 16.88 37 28.85 118 48.73  8.36 34 2 .11  .4 1.0 MOR   2.2
93 APR 26  104 31.31 36 29.85 121  4.48  4.54 19 1 .05  .3 1.1 BIT   1.1

93 APR 26  119 36.37 40 24.71 124 25.51 10.47 12 1 .06  .9  .4 MEN   1.4
93 APR 26  334 19.09 40 17.94 124 16.71 10.18 23 2 .14  .4  .2 MEN   2.8
93 APR 26  605 19.20 38 48.83 122 48.31  4.49 40   .15  .3  .5 GEY   2.2
93 APR 26  614 47.10 38 48.92 122 48.00  4.69 26   .12  .3  .6 GEY   1.8
93 APR 26  614 58.38 38 48.97 122 48.30  3.88 10   .02  .3  .5 GEY   2.1

93 APR 26  813 52.21 37 37.39 118 52.01  4.24  8   .09  .5 1.4 SMO   1.3
93 APR 26  930 45.71 36 14.26 120 21.02  9.81 23   .15  .4  .4 COA   1.4
93 APR 26  949 14.51 38 50.42 122 49.30  3.49 17   .10  .3 1.2 GEY   1.7
93 APR 26  958  4.36 36 28.33 121 47.52 17.66 13 1 .07 1.0  .8 SUR   1.2
93 APR 26 1152 22.36 37  6.66 121 49.42  3.20 24   .09  .3  .4 LOM   1.1

93 APR 26 1200 23.97 37 38.14 118 48.57  3.42  9   .05  .4  .9 HCF   1.3
93 APR 26 1237  4.30 37 37.37 118 51.96  3.89  9   .10  .5 1.3 SMO   1.6
93 APR 26 1333 24.86 40 17.38 123  7.17 42.16 37 2 .16  .3 1.0 KLA   2.6
93 APR 26 1333 26.66 37 37.30 118 52.16  2.87 33 1 .12  .3  .4 SMO   2.0
93 APR 26 1405 30.96 39 55.71 120 52.26  5.15 17 2 .34 2.113.5 WAK * 2.1

--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 APR 26 1457 45.92 38 32.66 118 22.08  7.97 11   .4027.825.0 NEV - 2.2
93 APR 26 1458 13.36 38 18.56 118 25.65  8.05 10   .35 9.029.4 MOL - 1.9
93 APR 26 1520 23.26 37 37.23 118 52.12  3.03 32 1 .13  .3  .5 SMO   2.1
93 APR 26 1623  3.90 37 39.14 118 54.60  6.27  9   .03  .6  .9 DOM   1.1
93 APR 26 1658 26.10 37 28.48 118 48.82  9.17 18   .08  .6 1.1 MOR   1.2

93 APR 26 1727 29.76 37 37.23 118 52.30  3.09 13   .05  .3  .4 SMO   1.5
93 APR 26 1727 43.04 37 37.16 118 52.18  3.32  9   .04  .4  .6 SMO   1.7
93 APR 26 1737 14.57 37 37.45 118 52.21  3.07  7   .04  .5  .7 SMO   1.3
93 APR 26 1738 31.64 37 37.47 122  0.83 12.18 21 2 .11  .4  .8 HAY   1.5
93 APR 26 1851 46.05 37 36.67 118 55.35  4.19 10   .05  .5  .7 SHE    .9

93 APR 26 2020  8.26 36 48.73 121 31.82  6.74 48 1 .16  .3  .4 SJB   1.5
93 APR 26 2130 24.63 38 48.70 122 48.54  4.26  9   .03  .4  .6 GEY   1.3
93 APR 26 2130 57.82 38 48.64 122 48.23  5.68 12   .13  .5  .9 GEY   1.5
93 APR 26 2137 18.84 37 37.13 118 51.73  4.87  8   .03  .5  .7 SMO   1.0
93 APR 26 2339 57.91 37 37.86 118 48.67  3.41 16   .10  .4  .8 HCF   1.4

93 APR 27  152 10.50 37 38.78 118 55.76  8.80 10   .09  .6 1.4 SMO   1.2
93 APR 27  237 19.97 37 38.91 118 55.69  5.86 10   .10  .5 1.1 SMO   1.1
93 APR 27  954 43.80 39 17.43 123 14.07  6.67 19 1 .14  .3 1.4 MAA   1.4
93 APR 27 1448 49.60 36 24.85 118 22.53  0.19 19 1 .10  .5 1.2 WWF   2.4
93 APR 27 1549 35.86 38 47.79 122 46.45  2.37 10   .06  .3  .6 GEY   1.4

93 APR 27 2031 24.43 37 19.51 118 17.31 11.91 24   .14  .9 1.2 OWV   1.7
93 APR 27 2047 26.21 36 52.29 120 49.36  0.73 12   .11 1.1  .8 ORT   2.2
93 APR 27 2130 33.81 38 50.44 122 49.49  2.07  9   .07  .5  .8 GEY   1.4
93 APR 27 2203 48.15 36 35.15 121 11.04  3.44  8   .03  .4  .5 PIN   1.0
93 APR 27 2214 34.72 37 56.57 121 32.61 12.66 33 3 .21  .5 1.2 JQN   1.9

93 APR 27 2302 33.93 40 17.50 124 22.42 13.79 18 1 .10  .7  .4 MEN   2.2
93 APR 27 2333 51.67 37 37.74 118 52.05  3.54 11   .10  .4  .9 SMO   1.6
93 APR 28   19 17.25 37 15.34 118 39.16  6.62 25 3 .07  .5 1.8 KAI   1.6
93 APR 28   20 16.85 36 16.38 120 24.98  9.95 25 1 .10  .4  .6 COA   2.0
93 APR 28   26 56.39 37 48.80 122  2.67 12.24 21 2 .07  .3  .5 CON   1.4

93 APR 28  255  6.19 38 50.18 122 48.05  0.04 13   .15  .4 1.9 GEY * 1.7
93 APR 28  408 31.01 38 47.74 122 47.24  0.02 12   .11  .4 1.7 GEY * 1.7
93 APR 28  535 45.05 40 18.76 124 30.04 10.98 14 1 .13 1.1  .5 MEN   2.3
93 APR 28  727 38.80 35 44.38 118  3.16  4.07 10 1 .08  .4 2.1 WWF-  1.6
93 APR 28  744 29.63 37 39.82 118 53.80  5.49  8   .05  .8  .9 DOM   1.1

93 APR 28  811 19.02 37 35.88 118 51.62  8.22 10   .08 1.4 1.0 MOR   1.1
93 APR 28  943 45.35 38 49.05 122 46.31  0.89 15   .09  .3  .7 GEY   2.0
93 APR 28  943 52.13 37 35.22 118 52.09  7.35 20   .12  .5  .5 MOR   2.1
93 APR 28  945 38.08 38 49.29 122 45.95  0.11  8   .04  .3  .9 GEY   1.5
93 APR 28  946 13.46 38 48.88 122 46.46  1.41 32   .12  .2  .4 GEY   2.2

93 APR 28 1158 55.16 38 49.32 122 47.37  0.98  8   .04  .3  .6 GEY   1.5
93 APR 28 1243 49.05 37 38.13 118 51.78  3.96 20 1 .07  .3  .4 SMO   1.7
93 APR 28 1400 22.51 38 49.24 122 45.98  0.06 10   .10  .4  .9 GEY * 1.6
93 APR 28 1538 41.34 38 50.05 122 47.43  0.60 11   .15  .4 1.2 GEY   1.7
93 APR 28 1542 49.14 38 50.04 122 47.49  1.64  9   .06  .3  .7 GEY   1.3

--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 APR 28 1543 15.78 38 48.11 122 46.63  4.03  8   .01  .4  .7 GEY   1.2
93 APR 28 2002 42.68 37 31.96 118 48.47 14.79 13   .11  .7 1.4 MOR   1.5
93 APR 28 2034  0.71 37 38.14 118 51.94  3.61  9   .08  .5 1.0 SMO   1.7
93 APR 28 2038 50.17 37 38.64 118 52.17  0.09  8   .19  .5 7.1 SMO * 1.3
93 APR 28 2115 44.54 37 37.99 118 52.37  2.20  8   .06  .3  .6 SMO   1.2

93 APR 28 2317  6.70 37 31.66 118 25.53  8.96 12   .09  .6  .9 CHV   1.2
93 APR 29   15 58.46 37 37.97 118 52.21  2.18 12   .18  .4  .7 SMO   1.8
93 APR 29   40 37.39 37 29.36 118 31.67 12.05 23   .06  .3  .6 CHA   2.2
93 APR 29  452 28.15 38 41.11 122 46.22  5.59 10   .14  .5 1.3 NAP   1.1
93 APR 29  647 48.46 37 30.59 118 45.48  1.28 16   .15  .910.6 WCN - 1.7

93 APR 29  653  6.12 37 31.35 118 45.76  6.86 18   .12  .5 1.8 WCN   1.9

    
         
 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
--------------------------------------------------------------------------------

APR 20
015804.4? 33.34 N 141.02 E  33N 4.7     1.4  10 OFF EAST COAST OF HONSHU, JAPAN
031100.6? 36.69 N  71.90 E  33N 4.4     0.9  12 AFGHANISTAN-TAJIKISTAN BORD REG.
033838.6* 17.943N  62.704W  33N 4.4     0.8  23 LEEWARD ISLANDS
064450.6& 59.410N 153.160W 109               69 SOUTHERN ALASKA. <AEIC>.
081120.8? 54.33 S 144.08 E  10G     5.7 1.5  12 WEST OF MACQUARIE ISLAND
094306.1*  3.803N 128.405E  73? 4.7     0.8   9 NORTH OF HALMAHERA, INDONESIA
134212.1* 34.283N  26.451E  33N 4.3     1.4  16 CRETE. MD 4.3 (HLW).
161128.1& 60.110N 152.880W 111  3.8          86 SOUTHERN ALASKA. <AEIC>.
162620.4  20.586S 178.818W 592D 5.6     0.8 115 FIJI ISLANDS REGION
185642.8* 83.653N 113.823E  10G 4.1     1.3  15 NORTH OF SEVERNAYA ZEMLYA
221723.8?  7.05 N 125.09 E  51? 4.6     1.4  16 MINDANAO, PHILIPPINE ISLANDS
222449.5?  1.89 N 125.87 E 139? 4.6     0.6   6 NORTHERN MOLUCCA SEA

APR 21
003807.0& 61.270N 150.160W  38               52 SOUTHERN ALASKA. <AEIC>. ML 2.7
125825.4   0.011N 123.461E  96? 5.3     1.1  39 MINAHASSA PENINSULA, SULAWESI
174157.4* 52.242N 170.043W  33N 4.5     1.4  42 FOX ISLANDS, ALEUTIAN ISLANDS
203636.7* 51.636N 175.792W  43D 4.8     1.3  37 ANDREANOF ISLANDS, ALEUTIAN IS.
                                                Felt strongly on Adak.

APR 22
005939.6*  8.782S 108.048W  10G 4.9 4.8 1.0  50 CENTRAL EAST PACIFIC RISE
010538.1   4.031S 102.429E  70  5.5     0.9  40 SOUTHERN SUMATERA, INDONESIA
031849.6* 25.407S 179.598E 509D 4.8     0.8  42 SOUTH OF FIJI ISLANDS
060250.2& 60.890N 149.810W  26               51 KENAI PENINSULA, ALASKA. <AEIC>.
                                                ML 2.6 (AEIC), 2.6 (PMR).
062105.0*  4.552N  76.228W 100G 4.5     0.9  28 COLOMBIA
063612.4*  2.415N 127.274E  75D 5.2     1.1  17 NORTHERN MOLUCCA SEA
110329.5* 32.055N 115.108W   5G         1.2  16 CALIF.-BAJA CALIF. ML 3.9 
123156.3  10.669N  62.607W 100G 4.5     0.8  39 NEAR COAST OF VENEZUELA. MD 4.1
124554.9  56.891N 154.654W  35D 5.3     1.2 172 KODIAK ISLAND REGION. Felt (I)
                                                at Old Harbor.
152203.2& 62.500N 149.930W   4  2.6          43 CENTRAL ALASKA. <AEIC>. ML 3.0
160806.9* 24.280S  67.080W 171? 4.7     0.8   8 CHILE-ARGENTINA BORDER REGION
162527.3* 52.906N 170.247W 111* 4.3     1.1  33 FOX ISLANDS, ALEUTIAN ISLANDS
163354.9? 19.22 S 177.98 W 500G 4.8     0.4  10 FIJI ISLANDS REGION
172018.2% 33.141S  70.255W  10G         0.2   8 CHILE-ARGENTINA BORDER, MD 3.7 
180339.2? 16.18 S 167.58 E  33N 5.2 4.4 1.0   9 VANUATU ISLANDS
195315.3? 32.47 S  71.60 W  50G         0.4   8 COAST OF CENTRAL CHILE. MD 3.8 
201854.0  35.696N 137.495E   7  4.2     1.4  31 EASTERN HONSHU, JAPAN
210930.4& 61.420N 151.450W  90               68 SOUTHERN ALASKA. <AEIC>.
221519.1* 53.413S 159.245E  10G 5.3 5.2 1.3  15 MACQUARIE ISLANDS REGION
233441.1* 47.481N 152.534E 110* 4.7     0.9  31 KURIL ISLANDS

APR 23
095107.8  34.088N 116.860W   5G         0.7   7 SOUTHERN CALIFORNIA. ML 2.8
121445.2  44.501N 114.784W   5G         0.6  56 WESTERN IDAHO. ML 3.9 (GS), 
150817.6& 61.630N 150.670W  53               63 SOUTHERN ALASKA. <AEIC>. ML 2.9
160116.2? 32.21 S  70.26 W 120G         0.4   8 CHILE-ARGENTINA BORDER, MD 3.7 
164913.2? 32.06 S  70.11 W 130G         0.4   8 CHILE-ARGENTINA BORDER, MD 3.6 

APR 24
083607.1% 33.468S  70.206W 110G         0.2   9 CHILE-ARGENTINA BORDER, MD 3.4
090617.7% 42.571N 143.716E  75?         0.5   8 HOKKAIDO, JAPAN  REGION
092357.4? 32.13 S  69.91 W 130G         0.3   9 MENDOZA PROV.,ARGENTINA, MD 4.2 
095421.2  17.613S 179.765E 599D 5.5     0.8 100 FIJI ISLANDS
104920.5* 20.452S 178.728W 600G 4.8     1.0  19 FIJI ISLANDS REGION
154536.9* 11.825N 124.049E  33N 4.5     0.7  10 LEYTE, PHILIPPINE ISLANDS
175323.7% 32.819S  70.910W  70G         0.2   8 CHILE-ARGENTINA BORDER, MD 3.2 
203012.1* 27.367N  57.837E  33N 4.5     0.8  16 SOUTHERN IRAN

APR 25
000708.8* 15.377S 173.216W  33N 5.3 5.6 1.0  42 TONGA ISLANDS
092950.5  35.641N 112.157W  10G 4.8     1.2  47 WESTERN ARIZONA. Felt at
        Flagstaff, Grand Canyon Village and Phoenix. Also felt at St. George,
        Utah.
132957.6% 33.020S  71.073W  33N         0.3   8 COAST OF CENTRAL CHILE. MD 3.2 

APR 26
033405.8  60.709N 151.936W 105          0.8  62 KENAI PENINSULA, ALASKA

APR 27
071808.4  34.087N 117.190W  10G         1.1   9 SOUTHERN CALIFORNIA. ML 3.0
                                                (GS). Felt at San Bernardino.

APR 28
223959  Q 36.1  N  89.4  W  10G         0.7   7 NEW MADRID, MISSOURI  REGION.
                                                mbLg 3.6 (GS).

APR 29
082101  Q 35.6  N 112.1  W  10G 5.5     1.3  76 WESTERN ARIZONA


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.