Earthquake Commentary for April, 2001

Map of recent earthquake activity

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16:53 PDT, Monday, April 30

Today, at 12:04 pm, a M2.7 earthquake was felt in the San Fernando area. The earthquake itself was located 2 miles northwest of the city of San Fernando, but was felt as far south as Burbank and Glendale. The weekend was quiet with only two earthquakes that could have possibly been felt (though we received no calls about them): a M2.6 at 9:09 on Sunday morning located 3 miles north-northeast of the town of Lake Isabella and a M2.6 on Saturday morning, at 2:30 am, located 6 miles east of Yorba Linda.

09:47 PDT, Friday, April 27

We have recorded and located 397 earthquakes in the last week. Click here to see a summary and map .

17:16 PDT, Monday, April 23

The Coso swarm is continuing; with 3 earthquakes over M3.0 occurring today. The first, and largest, was a M3.5 at 9:33 this morning followed by a M3.2 at 9:44. At 12:59 pm there was a M3.3. All are generally located 3 mi. SE of Coso Junction. We've received no reports that any of them were felt.

16:41 PDT, Saturday, April 21

We have recorded and located 334 earthquakes in the last week. Click here to see a summary and map .

16:52 PDT, Friday, April 20

This morning at 2:52 am there was a M3.4 located 5 miles west-southwest of Idyllwild. It's very possible this event was felt though we haven't received any calls about it. Early morning quakes tend to be felt more than expected mainly because people aren't bustling around as much. There are those though who could sleep through anything - even M6.7s!!!

14:26 PDT, Friday, April 20

Apologies. We are experiencing technical difficulties getting our catalog for this past week complete. Hopefully the Weekly Report and its map will be ready later today. If not, surely by Monday. Again, our apologies.

07:53 PDT, Wednesday, April 18

Yesterday at 4:47 pm, there was another member of the Pine Flat cluster, 25 north-northeast of Lake Isabella. Magnitude was M2.7.

Later in the evening, there was a cluster in the Imperial Valley, 1 to 2 miles southwest of Obsidian Butte. The largest two were a M3.0 at 7:23 pm and a M2.8 at 8:21 pm. A cluster is a very small swarm, just a grouping of earthquakes in space and time, for which there is no obvious mainshock. The Imperial Valley, especially the Brawley Seismic Zone, which connects the northern end of the Imperial fault with the southern end of the San Andreas fault, is an area very prone to swarms.

At 3:37 am, there was a M3.0 quake offshore, 27 miles east-northeast of San Clemente Island. Of all the quakes overnight, this was the only one that was reported felt, in Oceanside.

16:16 PDT, Tuesday, April 17

A small quake happened at 1:46 pm today, located in Imperial Valley 5 miles west-northwest of Obsidian Butte. Magnitude was M2.8. Shortly before that, at 12:39 pm, there was a M2.5 quake located 5 miles north-northwest of Cabazon. Neither was, as far as we know, felt.

07:33 PDT, Tuesday, April 17

At 10:42 pm last night, a Hector Mines aftershock occurred 28 miles north of Twentynine Palms. Magnitude was M3.0. There were no reports of it being felt.

16:59 PDT, Monday, April 16

On Saturday, at 7:51 am, there was a M3.5 quake, 25 miles north-northeast of Lake Isabella. It was reported felt in the Lake Isabella area and Porterville.

08:12 PDT, Friday, April 13

There were four small quakes overnight in our region that might be of interest:

The first occurred at 7:48 pm, 6 miles northwest of Parkfield. Magnitude was M3.4, and the quake was reported felt in San Luis Obispo, Los Osos, San Miguel, Shafter, and Paso Robles. The seismic information was furnished by the U.S. Geological Survey office in Menlo Park.

The second quake of interest was another Coso Range event: a M2.8 at 8:08 pm, 15 miles east of Coso Junction. We have not indication that it was felt by anyone.

The third was a M3.5 at 4:50 am, located 5 miles east-southeast of Yorba Linda. It was felt in most of Orange County, specifically Anaheim, Anaheim Hills, Orange, Yorba Linda, and West Covina. The focal mechanism was strike-slip.

Shortly afterwards, a M2.9 quake occurred in the Redlands area. This happened at 4:54 am. The 'felt' reports from Redlands and Yucaipa probably belong to this smaller quake.

17:31 PDT, Thursday, April 12

We have recorded and located 174 earthquakes in the last week. Click here to see a summary and map .

08:05 PDT, Thursday, April 12

At 5:21 pm, there was a M2.9 in the southern Sierra Nevada, 25 miles north-northeast of Lake Isabella. This is an uninhabited area, and the quake was not reported felt.

17:07 PDT, Wednesday, April 11

There has been another quake near Olancha at 4:55 pm this afternoon. The magnitude was 3.0 and the epicenter 9 miles east-northeast of Olancha, very close to the one early this afternoon.

13:43 PDT, Wednesday, April 11

At 12:53 pm today, there was another small quake in the southern Owens Valley, 11 miles east-northeast of Olancha. Magnitude was M2.9. The quake was apparently not felt.

08:20 PDT, Tuesday, April 10

Late yesterday afternoon, there were two small quakes of interest. The first occurred at 5:01 pm, 14 miles east of Coso Junction, in the ever prolific Coso Range. The magnitude was M3.1. This quake was felt in the town of Trona.

The second M3+ quake was a M3.1 Hector Mines aftershock, located 28 miles north of Joshua Tree. It occurred at 6:47 pm, and was not reported felt.

08:34 PDT, Monday, April 09

Saturday afternoon, at 6:25 pm, a M3.5 quake occurred in the Coso Range, 7 miles east-southeast of Coso Junction. It was not reported felt.

17:30 PDT, Thursday, April 05

We have recorded and located 151 earthquakes in the last week. Click here to see a summary and map .

15:27 PDT, Thursday, April 05

At 1:28 pm this afternoon, there was a M3.2 quake located 5 miles southwest of Beaumont. It was reported felt in Beaumont and Nuevo.

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Last updated 16:55 PDT April 30, 2001.