Earthquake Commentary for September, 1998

Map of recent earthquake activity

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07:52 PDT, Wednesday, September 30

We did have a small quake that was felt last night. It occurred at 8:50 pm, 5 miles south-southeast of Rancho Cucamonga. The magnitude was M2.7. Note that the original, automatic magnitude estimate was only M2.3, clearly too small. A few people in the epicentral area felt the quake.

09:43 PDT, Tuesday, September 29

There were two quakes worth mentioning overnight. The first was a M2.7 at 11:46 pm, located 11 miles north of the town of Lake Isabella.

The other one was a M2.5 at 2:34 am, in the Mojave Desert, 26 miles east-southeast of Barstow.

Neither quake was, as far as we know, felt.

09:52 PDT, Monday, September 28

We had two quakes in the M2.5+ range over the weekend. The first was a M2.5 at 6:25 am on Saturday, located 4 miles north of Cabazon, in the San Gorgonion Pass.

The second event was a Landers aftershock, a M2.7 located 25 miles north of Yucca Valley, at 9:30 am the same day, Saturday.

Neither event was, as far as we know, felt by the public.

09:54 PDT, Friday, September 25

We recorded and analysed 177 earthquakes in the past week. Click here to see a summary and map .

09:28 PDT, Thursday, September 24

At 2:47 pm yesterday, there was a M2.5 quake, located 6 miles west of Mt. San Gorgonio. It was an aftershock of the August 16 M4.8 quake in the same area.

At 8:58 pm last night, there was a M2.8 quake in the Owens Valley, 9 miles north of Lone Pine.

The third small quake of interest occurred at 4:41 am today, 4 miles south of Woodland Hills. The magnitude was M2.6. Note that this epicenter is outside the aftershock zone of the Northridge quake, so this morning's quake is not an aftershock.

So far, we have not received any public inquiries about any to these three quakes.

10:48 PDT, Wednesday, September 23

There were two quakes in the upper M2's overnight. The first occurred at 11:28 pm at the northern end of Death Valley. It's magnitude was M2.9. Because of the remoteness of the epicenter, it probably was not felt.

The second event of note occurred at 8:34 am this morning, 2 miles north-northwest of Wrightwood. That magnitude was M2.7. Although we have received no inquiries, the quake could easily have been felt in Wrightwood.

15:02 PDT, Monday, September 21

At 6:33 am this morning, there was a M2.8 located 21 miles southeast of San Clemente Island, or 52 miles west of San Diego. It was almost certainly not felt.

16:59 PDT, Friday, September 18

We had a M2.5 Landers aftershock at 8:02 pm last night, located 10 miles north of Yucca Valley.

18:54 PDT, Thursday, September 17

We recorded and analysed 187 earthquakes in the past week. Click here to see a summary and map .

Contact the U.S. Geological Survey in Menlo Park for further information on the recent cluster of Parkfield earthquakes.

09:27 PDT, Wednesday, September 16

At 9:35 pm last night, there was a M2.7 located 8 miles southeast of Anza. This epicenter is near the San Jacinto fault zone, which is several kilometers wide in that area.

15:12 PDT, Monday, September 14

At 2:05 pm today, we had a M2.6 quake 23 miles southwest of Shoshone. This epicenter is in the Death Valley region.

10:13 PDT, Monday, September 14

The only quakes over the weekend that exceeded M2.5 magnitude were:

A M2.5 at 1:41 am on Saturday, located 7 miles north of the town of Lake Isabella.

A M2.7 at 8:03 am on Sunday, located 13 miles north-northeast of Trona.

A M2.7 at 10:11 am on Sunday, located 22 miles east of Coalinga.

As far as we know, none of them were felt.

17:47 PDT, Thursday, September 10

We recorded and analysed 232 earthquakes in the past week. Click here to see a summary and map .

09:42 PDT, Thursday, September 10

There was also a M3.1 quake this morning, at 8:43 am, in the San Jacinto fault zone 11 miles east-northeast of Borrego Springs (in the Borrego Badlands). The focal mechanism was strike-slip, as expected for the San Jacinto. Today's quake occurred close to the epicenter of a Mw6.4 in 1954.

08:41 PDT, Thursday, September 10

The Coso Range experienced a small quake at 2:39 am this morning. It was a M2.7 and was located 16 miles east of Coso Junction, which is on Rt. 395 at the southern end of Owens Valley. The Coso Range is a geothermal area and a very common source of small quakes, up to the M5 range, of which there have been three in the past two years.

15:33 PDT, Wednesday, September 09

At 12:43 pm today, a M2.7 quake occurred in the San Gorgonio Pass, 1 mile west-northwest of Cabazon. This epicenter is very close to the Banning fault, which is the southern branch of the San Andreas in that area. We don't have any reports that today's quake was felt.

16:40 PDT, Tuesday, September 08

At 4:17 pm today, there was a M2.5 located 4 miles east-southeast of Lake Henshaw, near the Elsinore fault zone. We have had no inquiries.

14:22 PDT, Tuesday, September 08

At 11:27 pm on Thursday, there was a M2.6 located 8 miles north-northeast of Barstow. It was an aftershock of the Mw7.3 Landers earthquake of June 28, 1992.

We also had some small Mt. San Gorgonio quakes on the weekend. These included a M2.5 at 5:56 am on Friday and a M2.8 at 3:21 pm on Saturday, both located 7 miles west-northwest of Mt. San Gorgonio. They are aftershocks of the M4.8 on August 16 quake at the same location.

On Sunday, at 3:49 pm, there was a M2.9 under the San Joaquin Valley, 26 miles south of Fresno.

We have not received any reports that any of these small quakes were felt.

18:50 PDT, Thursday, September 03

We recorded and analysed 206 earthquakes in the past week. Click here to see a summary and map .

Last updated 07:52 PDT September 30, 1998
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