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Southern California Earthquake Data Center

Earthquake Information

2001 Monthly Seismicity




January 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 971 earthquakes in January 2001. 205 of these were M2.0 & larger, 24 were M3.0 & larger, three were M4.0 & larger. The month’s largest earthquake was a ML4.4 on January 16, located in Mexico, 58 miles south of Yuma AZ. The month’s second largest earthquake was a ML4.3 on January 13, located 2 miles east of San Fernando. It was felt from Ventura to Hesperia & San Clemente, prompting 2,505 felt reports from 252 zip codes. The peak intensity was Modified Mercalli V. This quake had a ML4.1 aftershock about 24 minutes later at the same location, which was felt over almost the same area. There was also a ML2.7 on January 8, which prompted 186 felt responses. It was located 2 miles south of San Dimas. On January 29, there was a ML3.0 quake located 5 miles west-southwest of Corona. It produced 169 responses, from as far away as Pasadena & San Clemente.

February 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,101 earthquakes in February 2001. 201 of these were M2.0 & larger, 24 were M3.0 & larger, two were M4.0 & larger, one was M5.0 & larger. The month’s largest earthquake was a ML5.1 on February 10, located 4 miles north-northwest of the town of Big Bear Lake. The second largest, a ML4.2 occurred about 3h34m later, one of many aftershocks. The ML5.1 was felt in much of Southern California, from San Diego to Simi Valley to Ridgecrest. The peak intensity in the epicentral region was Modified Mercalli V. We received a total of 3,138 felt reports, form 450 zip codes. The ML4.2 aftershock was felt as far as the San Fernando Valley & Fallbrook. Only slightly more than three hours before the Big Bear ML5.1, there was a ML3.9 in the Little San Bernardino Mtns 8 miles north-northeast of Indio. It was felt as far away as Hesperia & San Diego, generating 229 felt reports. A ML3.3 earthquake on February 17, located 7 miles southwest of Idyllwild, prompted 335 felt reports from 60 zip codes, as far away as Norco.

March 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 936 earthquakes in March 2001. 202 of these were M2.0 & larger, 14 were M3.0 & larger. The month’s largest earthquake was a ML3.5 on March 17, located 19 miles south-southwest of Coso Junction. The most widely felt earthquake was the second largest, a ML3.4 on March 24, located 4 miles south-southeast of Rancho Cucamonga. This quake was felt from Apple Valley to Fullerton, with 242 felt reports from 53 zip codes. Also fairly widely felt was a ML3.1 on March 2, located 9 miles west-northwest of Devore. It was felt from Moreno Valley to Victorville, generating 113 felt reports.

April 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,152 earthquakes in April 2001. 395 of these were M2.0 & larger, 26 were M3.0 & larger, none were M4.0 & larger. The month’s largest earthquakes both had magnitudes of ML3.8 & were both located in the southern Owens Valley region. The first occurred on April 7 & was located 8 miles east-southeast of Coso Junction. The other one occurred on April 14. It was located 22 miles west of Coso Junction. The latter quake was reported felt in Porterville & the Lake Isabella area. Also of interest is a ML3.6 quake on April 13, located in the Chino Hills 7 miles west of Corona. It prompted 534 felt reports from as far away as San Clemente & Big Bear. The peak intensity was reported at Modified Mercalli V, in Yorba Linda.

May 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,228 earthquakes in May 2001. 356 of these were M2.0 & larger, 15 were M3.0 & larger, two were M4.0 & larger. The two largest earthquakes both occurred on May 17 & were both members of an active swarm in the Coso region, 18 miles south-southwest of Coso Junction. The magnitudes were ML4.3 & ML4.1. Both of these earthquakes were felt in Porterville, Lake Isabella, Trona & the northern Mojave Desert. Two ML3.8’s were also of interest. The first occurred on May 14, 2 miles west of Devore. This quake was widely felt from Ridgecrest to Escondido, generating 1,224 felt reports from 204 zip codes. The peak intensity was Modified Mercalli IV. The other ML3.8 occurred on May 23 & was located 7 miles southeast of Mt. San Gorgonio, or 7 miles north-northeast of Cabazon. There were 247 felt reports from as far as Escondido & San Clemente.

June 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 900 earthquakes in June 2001. 234 of these were M2.0 & larger, 12 were M3.0 & larger. The month’s largest earthquake was ML3.4 on June 13, located in Imperial Valley 6 miles northeast of Calexico. This quake was felt in Imperial, Holtville, Calexico & El Centro. Other earthquakes of interest include a M3.2 on June 8, 4 miles west of Devore, which was felt as far away as Apple Valley & Corona, and a ML3.0 on July 19, 2 miles north of Moreno Valley. The latter was felt as far as Temecula & Banning.

July 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 4,349 earthquakes in July 2001. 665 of these were M2.0 & larger, 61 were M3.0 & larger, five were M4.0 & larger, one was M5.0 & larger. All of the month’s largest quakes occurred in the Coso region, about 4 miles east of Coso Junction, as part of a significant swarm. The two largest events were a ML5.1 & a ML4.7, both on July 17. The ML4.8 was felt as far away as Big Bear & Yosemite National Park. The ML4.7 was reported from somewhat less far away, but there were reports from Victorville & Porterville. These quakes were a little over 52 minutes apart in time. The swarm ran from Jul 14 through until the end of September with a total of over 5,200 members. Also of interest was a ML3.9 on July 3, located 5 miles east of Big Bear City, which was felt as far away as Hemet & Ontario. There was also a ML3.8 quake on July 19, located 5 miles northwest of Devore. It prompted 635 felt reports ranging as far afield as San Clemente & Simi Valley.

August 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,965 earthquakes in August 2001. 226 of these were M2.0 & larger, 18 were M3.0 & larger, two were M4.0 & larger. The month’s two largest earthquakes, a ML4.4 & a ML4.2, both occurred on August 16 & were both located offshore about 5 miles south-southeast of San Clemente Island. The ML4.4 was felt as far away as Newbury Park, Victorville & San Diego. There were 1,232 felt reports. The ML4.2 was felt as far as Warner Springs. Also of interest was a ML3.6 on August 1 Greenwich time, July 31 local time, 5 miles southeast of Coso Junction. Due to its remote location, this quake did not generate much public interest. There was also a ML3.4 on August 28, located 7 miles south-southwest of Idyllwild. There were 94 felt reports from as far away as Phelan & Poway.

September 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,181 earthquakes in September 2001. 191 of these were M2.0 & larger, 18 were M3.0 & larger, one was M4.0 & larger. The month’s largest earthquake & the one with the most public interest, was a ML4.2 on September 9, located 1 mile southeast of Beverly Hills. It generated 3,925 felt reports from 396 zip codes, from Ventura to Lancaster to San Marcos. The peak intensity reported was Modified Mercalli VI in the epicentral area. The second largest earthquake of the month was a ML3.5 on September 1, in the San Jacinto fault zone 8 miles north-northwest of Borrego Springs. It was felt as far away as Chula Vista & San Clemente. On September 16, a ML3.1 located 3 miles northwest of Chino Hills generated 281 felt responses. On September 26, a ML2.8 located 2 miles west of Arcadia generated 273 responses.

October 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,424 earthquakes in October 2001. 206 of these were M2.0 & larger, 20 were M3.0 & larger, two were M4.0 & larger, one was M5.0 & larger. The largest earthquake of the month occurred on October 30 & was located in the San Jacinto Fault zone 10 miles east-southeast of Anza. The magnitude was ML5.1. It was felt as far away as San Diego, the Los Angeles Basin, Victorville & Twentynine Palms. There were 2,061 felt reports from 321 zip codes, with a peak intensity of Modified Mercalli V in the Anza & Warner Springs areas. The second largest was a ML4.0 on October 28, 4 miles northwest of Compton. The Compton quake was felt from Ventura to San Bernardino & Oceanside, with 1,481 responses from 255 zip codes. The peak intensity was IV in the epicentral area. A ML2.9 aftershock was also widely felt in the Los Angeles Basin. A few other small earthquakes generated significant public response. A ML2.9 earthquake on October 7, located near Silver Lake, was felt from Santa Monica to Pasadena & Long Beach. There were 639 responses from 101 zip codes. A ML2.5 aftershock on October 9 at the same location generated 360 responses. A ML2.9 earthquake on October 21 near Beverly Hills resulted in 812 felt reports from 91 zip codes from Simi Valley to Pasadena. A ML2.4 on October 23, also near Beverly Hills, was also widely felt.

November 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 1,195 earthquakes in November 2001. 183 of these were M2.0 & larger, 14 were M3.0 & larger, one was M4.0 & larger. The month’s largest earthquake was a ML4.1 on November 13, located 3 miles southeast of Bombay Beach. This Bombay Beach quake was the largest of swarm of 100 events, at the northern tip of the Brawley Seismic Zone near the San Andreas Fault. Because of the remote location of this earthquake, very few felt reports resulted.

December 2001 MAP GRAPH
    The Southern California Seismic Network recorded & analyzed 884 earthquakes in December 2001. 187 of these were M2.0 & larger, 17 were M3.0 & larger, three were M4.0 & larger, one was M5.0 & larger. The largest earthquake of the month, ML5.1, occurred on December 8 & was located in Mexico 53 miles south-southwest of Yuma AZ. This quake was felt as far away as Riverside, with most of the 353 reports coming from the San Diego area & Imperial Valley. The peak intensity of Modified Mercalli V occurred in the Salton City area. The ML5.1 quake was followed the next day by a ML4.9 aftershock. The largest earthquake in the Los Angeles metropolitan area was a M4.0 on December 14, located in the Chino Hills 5 miles southeast of Diamond Bar. It generated 1,792 felt reports from 255 zip codes ranging from Chatsworth to Lucerne Valley to Santa Ysabel. Peak intensity was IV in the epicentral area.



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Division of Geological and Planetary Sciences | California Institute of Technology