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|duration = 10–20 seconds〔(USGS Response to an Urban Earthquake -- Northridge ‘94 )〕 |date = |origintime = 4:30:55 PST〔http://earthquake.usgs.gov/earthquakes/states/events/1994_01_17.php〕 |magnitude = 6.7 Mw |depth = |location = |type = Blind thrust |countries affected = Greater Los Angeles Area Southern California United States |damage = $13–$40 billion〔 |intensity = IX (''Violent'')〔 |PGA = 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 was centered 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,〔(Northridge Earthquake ) Southern California Earthquake Data Center. Retrieved October 6, 2006.〕 measuring 1.8''g'' (16.7 m/s2)〔USGS Earthquake Information for 1994 ("Significant Earthquakes of the World 1994" )〕 with strong ground motion felt as far away as Las Vegas, Nevada, about 220 miles (360 km) from the epicenter. The peak ground velocity in this earthquake at the Rinaldi Receiving Station was 183 cm/s〔http://earthquake.usgs.gov/earthquakes/shakemap/background.php ShakeMap Scientific Background〕 (4.09 mph or 6.59 km/h), the fastest peak ground velocity ever recorded. In addition, two 6.0 Mw aftershocks 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.〔(【引用サイトリンク】author=Douglas Dreger )〕 The death toll was 57, with more than 5,000 injured. In addition, earthquake-caused property damage was estimated to be between $13 and $40 billion, making it one of the costliest natural disasters in U.S. history. ==Epicenter== 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. This was the first earthquake with a hypocenter directly beneath a US city since the 1933 Long Beach earthquake.〔(【引用サイトリンク】title=Significant Earthquakes and Faults, Northridge Earthquake )〕 The National Geophysical Data Center placed the hypocenter's geographical coordinates at and at a depth of 11.4 miles (18.3 km).〔National Geophysical Data Center ()“JANUARY 17 1994 NORTHRIDGE EARTHQUAKE”〕 The earthquake occurred on a previously undiscovered fault, now named the Northridge blind thrust fault (also known as the Pico thrust fault).〔(Northridge Earthquake 10th Anniversary )〕 Several other faults experienced minor rupture during the main shock and other ruptures occurred during large aftershocks, or triggered slip earthquakes.〔() Southern California Earthquake Data Center. Significant Earthquakes and Faults, Northridge Earthquake. Retrieved December 6, 2013〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「1994 Northridge earthquake」の詳細全文を読む スポンサード リンク
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