1994 Northridge Earthquake
Buildings collapsed as a result of the earthquake
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 Los Angeles
Las Vegas
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| Date | January 17, 1994 |
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| Origin time | 4:30:55 a.m. PST |
| Duration | 10–20 seconds |
| Magnitude | 6.7 Mw |
| Depth | 11.4 mi (18.3 km) |
| Epicenter | 34°12′47″N 118°32′13″W / 34.213°N 118.537°WCoordinates: 34°12′47″N 118°32′13″W / 34.213°N 118.537°W |
| Type | Blind thrust |
| Areas affected |
Greater Los Angeles Area Southern California United States |
| Total damage | $13–$44 billion |
| Max. intensity | IX (Violent) |
| Peak acceleration | 1.82g horizontal |
| Casualties | 57 killed > 8,700 injured |
The 1994 Northridge earthquake occurred on January 17, at 4:30:55 a.m. PST and had its epicenter in Reseda, a neighborhood in the north-central San Fernando Valley region of Los Angeles, California. It had a duration of approximately 10–20 seconds. The blind thrust earthquake had a moment magnitude (Mw) of 6.7, which produced ground acceleration that was the highest ever instrumentally recorded in an urban area in North America, measuring 1.8g (16.7 m/s2) with strong ground motion felt as far away as Las Vegas, Nevada, about 220 miles (360 km) from the epicenter. The peak ground velocity at the Rinaldi Receiving Station was 183 cm/s (4.09 mph or 6.59 km/h), the fastest peak ground velocity ever recorded. In addition, two 6.0 Mwaftershocks occurred, the first about one minute after the initial event and the second approximately 11 hours later, the strongest of several thousand aftershocks in all. The death toll was 57, with more than 8,700 injured. In addition, property damage was estimated to be between $13 and $40 billion, making it one of the costliest natural disasters in U.S. history.
The earthquake struck in the San Fernando Valley about 20 miles (31 km) northwest of downtown Los Angeles. Although given the name "Northridge", the epicenter was located in the community of Reseda; it took several days to pinpoint the epicenter in detail (both communities are neighborhoods of the City of Los Angeles). This was the first instance with a hypocenter directly beneath a U.S. city since the 1933 Long Beach earthquake.
The National Geophysical Data Center placed the hypocenter's geographical coordinates at 34°12′47″N 118°32′13″W / 34.21306°N 118.53694°W and at a depth of 11.4 miles (18.3 km). It occurred on a previously undiscovered fault, now named the Northridge blind thrust fault (also known as the Pico thrust fault). Several other faults experienced minor rupture during the main shock and other ruptures occurred during large aftershocks, or triggered events.
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