At 12:20 pm and 12:27 pm today, two more aftershocks have occurred
to last night’s M4.2. The first had a magnitude of M3.6, and was
felt in the northern San Fernando Valley. The second had a magnitude
of M3.1.
January 30, 2002
January 29, 2002
Commentary
Comments Off
Commentary
Another small Simi/Valencia quake has been felt, an aftershock of last
night’s M4.2. This one was a M2.7
at 11:20 am today, located 6 miles north-northeast of Simi Vallley.
It was felt in Valencia, Simi Valley, and Canyon Country.
Comments Off
Commentary
There has been a M3.0 this morning, located offshore about 24 miles
south of the east end of Santa Cruz Island. The time was 7:31 am.
It is not expected that anyone will have felt this quake, due to its
distance from shore.
Comments Off
Commentary
A series of quakes occurred last night to the northwest of
San Fernando Valley. The largest ones were a M4.2 at 9:53 pm, a M3.9
at 10:00 pm, and a M3.8 at 10:08 pm. These were located about
halfway between Simi Valley and Valencia. There have been 11 smaller
aftershocks as well at this location.
All three of the largest quakes were felt fairly widely, the M4.2 as
far away as Antelope Valley, the Grapevine area, and Orange County.
The peak Modified Mercalli Intensity was IV. The M3.9 was felt as
far as Ventura and Pasadena, and also had a peak Intensity of IV, over
a smaller area.
The question of whether these quakes are Northridge aftershocks or
not will certainly arise, and may not be so easy to answer.
Technically, aftershocks continue at an ever decreasing rate until
the number of quakes per week, month, or whatever is down to the
level it was before the mainshock. For a quake the size of
Northridge, that can be many years later. In fact, the Northridge
sequence is still visible on current seismicity maps, so aftershocks
are really still going on. These might be some of them. On the
other hand, San Fernando Valley may be getting on with its seismic
life, so to speak.
Oddly enough, in the past week, there has been a smattering of tiny
quakes strewn over the San Fernando Valley. All these were less than
M2.0, and so were not felt by residents. Normally, when we see such
a scattered distribution, we expect to find the “quakes” are caused
by wind or other extraneous noise, or telemetry problems. These
quakes, however, are real and correctly located. Their appearance
before the Simi Valley/Valencia activity is probably coincidence, but
it’s worth a note in the commentary.
Comments Off
January 25, 2002
Commentary
Southern California Earthquakes in the Past Week
Kate Hutton ,
Seismological Laboratory
Lucy Jones,
U. S. Geological Survey
California Institute of Technology
January 25, 2002
Kate Hutton ,
Seismological Laboratory
Lucy Jones,
U. S. Geological Survey
California Institute of Technology
January 25, 2002
The time period covered is 4 pm on Thursday, January 17 (PST)
through 4 pm on Thursday, January 24 (PST). During this period
we dectected and analysed 192 earthquakes. Click
here to see a map.
The table below lists the quakes during the past week
that were M2.0 or larger in the central part of the coverage area.
Times are local times; if you want Greenwich Mean Time, add 7 hrs
to the Pacific Daylight Time or 8 hrs to the Pacific Standard Time
listed.
Mag. Local Date Local Time Lat. Long. Depth Descriptive location
-------------------------------------------------------------------------------------------
9749637 2.0 2002/01/17 20:09:52 34 22.5 N 116 28.1 W 5.6 29 km (18 mi) N of Yucca Valley, CA
9749653 2.1 2002/01/17 23:58:10 33 51.9 N 116 9.4 W 8.4 18 km (11 mi) NNE of Indio, CA
9749669 3.5 2002/01/18 01:23:49 32 24.6 N 115 5.7 W 7.0 47 km (29 mi) SE of Calexico, CA
9749673 2.8 2002/01/18 01:28:53 32 15.3 N 115 1.1 W 7.0 62 km (38 mi) SW of Yuma, AZ
9749677 2.1 2002/01/18 01:33:11 33 58.2 N 116 52.5 W 19.5 5 km ( 3 mi) N of Banning, CA
9749681 2.3 2002/01/18 01:42:13 32 25.3 N 115 5.6 W 7.0 47 km (29 mi) SE of Calexico, CA
9749685 2.6 2002/01/18 01:46:42 32 25.5 N 115 6.2 W 7.0 46 km (28 mi) SE of Calexico, CA
9749781 2.7 2002/01/18 09:52:04 32 9.7 N 115 25.7 W 7.0 57 km (35 mi) S of Calexico, CA
9749793 2.1 2002/01/18 10:29:22 33 41.4 N 116 48.8 W 15.3 11 km ( 7 mi) WSW of Idyllwild, CA
9749941 2.7 2002/01/18 22:12:52 32 25.2 N 115 6.4 W 7.0 46 km (28 mi) SE of Calexico, CA
9749953 2.3 2002/01/18 22:48:15 32 25.1 N 115 5.9 W 7.0 46 km (29 mi) SE of Calexico, CA
9749981 2.3 2002/01/19 01:27:53 32 6.1 N 114 57.7 W 7.0 74 km (46 mi) SSW of Yuma, AZ
9750225 2.1 2002/01/19 20:22:46 32 13.8 N 115 19.8 W 7.0 51 km (32 mi) SSE of Calexico, CA
9750269 2.2 2002/01/19 21:18:21 34 36.5 N 116 16.6 W 5.8 53 km (33 mi) N of Joshua Tree, CA
9750361 2.6 2002/01/19 23:38:22 32 13.0 N 115 19.1 W 7.0 53 km (33 mi) SSE of Calexico, CA
9750665 2.2 2002/01/20 06:36:34 34 59.2 N 116 56.4 W 6.1 13 km ( 8 mi) NE of Barstow, CA
9750829 2.8 2002/01/20 07:08:52 34 28.6 N 117 47.2 W 2.0 20 km (12 mi) NW of Wrightwood, CA
FELT
9750841 2.9 2002/01/20 08:28:59 32 24.5 N 115 6.5 W 7.0 46 km (29 mi) SE of Calexico, CA
9750925 2.1 2002/01/20 09:41:21 32 24.7 N 115 3.3 W 7.0 50 km (31 mi) SE of Calexico, CA
9751089 2.2 2002/01/21 02:06:45 33 46.9 N 116 10.2 W 7.0 9 km ( 5 mi) NNE of Indio, CA
9751229 2.5 2002/01/21 03:46:18 36 3.1 N 117 52.4 W 2.7 7 km ( 4 mi) E of Coso Junction, CA
9751393 2.8 2002/01/21 10:23:15 33 10.9 N 116 2.6 W 5.2 9 km ( 6 mi) ENE of Ocotillo Wells, CA
9751397 2.0 2002/01/21 10:47:42 33 41.8 N 118 17.0 W 7.0 1 km ( 1 mi) SE of Pt. Fermin San Pedro, CA
9751769 3.3 2002/01/22 00:39:30 34 32.4 N 118 58.2 W 24.2 17 km (10 mi) NNW of Fillmore, CA
FELT in Ventura, Ojai, Santa Paula, Castaic areas
9751841 2.0 2002/01/22 10:14:56 33 36.3 N 117 57.3 W 13.6 2 km ( 1 mi) WSW of Newport Beach, CA
9751849 2.1 2002/01/22 11:11:14 34 32.4 N 118 58.2 W 21.7 17 km (10 mi) NNW of Fillmore, CA
12259768 2.3 2002/01/22 14:10:27 33 49.8 N 117 38.5 W 7.1 9 km ( 5 mi) SW of Corona, CA
12271480 2.1 2002/01/23 02:30:42 32 18.7 N 115 16.3 W 7.0 45 km (28 mi) SSE of Calexico, CA
12271488 2.1 2002/01/23 02:48:57 32 22.1 N 115 16.5 W 7.0 39 km (24 mi) SSE of Calexico, CA
12271528 2.0 2002/01/23 06:52:22 32 32.0 N 115 45.6 W 3.8 29 km (18 mi) WSW of Calexico, CA
9752217 2.2 2002/01/23 14:46:11 32 31.9 N 115 45.6 W 3.8 29 km (18 mi) WSW of Calexico, CA
12275508 2.1 2002/01/23 22:47:52 35 2.6 N 116 57.6 W 2.1 18 km (11 mi) NNE of Barstow, CA
12275520 2.3 2002/01/24 02:58:08 32 19.7 N 115 13.6 W 7.0 45 km (28 mi) SSE of Calexico, CA
12279448 2.8 2002/01/24 13:01:36 32 32.1 N 115 44.9 W 5.3 28 km (17 mi) WSW of Calexico, CA
12279452 2.2 2002/01/24 13:03:47 32 31.9 N 115 45.0 W 4.6 28 km (18 mi) WSW of Calexico, CA
-------------------------------------------------------------------------------------------
Comments Off
January 23, 2002
Commentary
At 8:48 pm last night, a couple of very sensitive people felt a
small quake in Beverly Hills. The magnitude was M1.8. (Note that
the real-time computer systems initially located this quake in
Studio City, which is wrong. With very small quakes, it is easy for
the computers to be confused by seismic noise due to human activity,
wind, noisy communications lines, etc.)
Comments Off
January 22, 2002
Commentary
A M3.3 quake occurred just after midnight this morning, at 12:39 am,
10 miles north-northwest of Fillmore. The quake was slightly felt
in the Ventura, Ojai, Santa Paula and Castaic areas.
Comments Off
January 21, 2002
Commentary
Another M2.8 quake occurred this morning (Monday), 5 miles
east-northeast of Ocotillo Wells. The time was 10:23 am. So far
we have no reports of it being felt.
Comments Off
January 20, 2002
Commentary
There was a small felt earthquake this morning, at 7:08 am, 13 miles
northwest of Wrightwood. It was felt in the epicentral area.
Comments Off
Commentary
Two more felt quakes occurred in the Simi Valley sequence late this
morning: a M3.5 just before 10:48 am and a M3.0 just before 10:59 am.
Both were felt, the first one as far away as Pasadena.