1971 San Fernando earthquake
| 1971 San Fernando earthquake | |||
|---|---|---|---|
|
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| date | February 9, 1971 | ||
| Magnitude | 6.6 M W | ||
| depth | 8.4 km | ||
| epicenter | 34 ° 24 '43 " N , 118 ° 24' 0" W | ||
| country | Southern California , USA | ||
| Affected places |
Sylmar |
||
| dead | 65 | ||
The San Fernando Earthquake of 1971 (also known as Sylmar earthquake occurred) to February 9, 1971 at 6:00:55 am local time (14:00 UTC ) in the San Fernando Valley near Sylmar, a suburb of Los Angeles , with a magnitude M w of 6.6.
The earthquake is known by different names. Seismologists call it the "San Fernando earthquake", as does the United States Geological Survey (USGS). "Sylmar quake" or "Sylmar earthquake" is the name the quake was initially given by the local news media as the worst damage occurred at the Olive View Medical Center in Sylmar. Those affected by the quake also called it "February Ninth", the "February 9th" quake.
Location of the earthquake
The Southern California Earthquake Data Center located the hypocenter at a depth of 8.4 km, the epicenter was on the other side of the San Gabriel Mountains as seen from Sylmar in the Iron Canyon in the area of Sand Canyon , Canyon Country . Due to the location of the epicenter between Sylmar and San Fernando , these settlement areas were most affected by damage, as was the northeastern part of the San Fernando Valley.
The earthquake was triggered by a rupture on the San Fernando Fault Zone , a cluster of north- dipping , steep faults on the southeastern edge of the San Gabriel Mountains. It created an incoherent zone of surface fractures with a mean horizontal and vertical offset of one meter. A series of strong aftershocks included four magnitude 5 quakes.
Damage
The earthquake claimed 65 lives and caused more than $ 500 million in property damage, including the destruction of two hospitals, two highway junctions and part of the lower dam of Van Norman Lake . The damage to the dam gave rise to fears that it might collapse in part or in whole. A source of great confusion was the fact that various agencies ordered a complete evacuation of 40,000 people and others a voluntary evacuation of areas of the San Fernando Valley below the dam. Communication was made difficult by the disruption of telephone and power lines. The water supply also partially collapsed.
Most of the victims involved the collapse of the Veterans Administration Hospital in San Fernando, where 49 people died. The Olive View Hospital in Sylmar, which had opened just a month earlier, was pushed almost half a meter from its foundations, causing the first floor to collapse and three patients and one employee perishing under the rubble.
Twelve flyovers collapsed, including the intersection of Interstate 5 and Interstate 210 ( Foothill Freeway ), where two people were killed. The recently completed Newhall Pass Interchange , the junction of Interstate 5 ( Golden State Freeway ) and California State Route 14 ( Antelope Valley Freeway ), was also destroyed by the earthquake. The Newhall Pass Interchange was rebuilt with reinforced components, but collapsed 23 years later in the Northridge earthquake of 1994.
Landslides were widespread and caused severe damage to the San Gabriel Mountains.
legislation
In response to the earthquake, building regulations were tightened. In 1972 the Alquist Priolo Special Studies Zone Act was passed accordingly . This prohibits the erection of buildings on active faults in order to reduce the risk of building destruction through breakdowns.
See also
Individual evidence
- ↑ a b c San Fernando Earthquake. ( Memento of the original from February 1, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Southern California Earthquake Data Center
- ↑ Historic Earthquakes: San Fernando, California, 1971 02 09 14:00 UTC Magnitude 6.6 Intensity XI ( Memento of the original from August 8, 2006 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Feb. 9, 1971 'Sylmar' Earthquake Instrumental Intensity Map . Santa Clarita Valley Historical Society . Retrieved November 23, 2008.
- ↑ Killer Quake. ( Memento of the original from March 18, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Herald Examiner article, Vol. 5, No. 318, Tuesday, February 9, 1971, on the Los Angeles Fire Department Historical Archive website
Web links
- Earthquake. Documentary (28 min) from 1973 about the earthquake, United States Department of Agriculture
- Historic Earthquakes: San Fernando, California, 1971 02 09 14:00 UTC Magnitude 6.6 Intensity XI. Detailed information from the United States Geological Survey
- San Fernando Earthquake, February 1971. Photos of the damage, United States Geological Survey ( Memento of October 27, 2007 in the Internet Archive )