The Northridge Earthquake: Learning about the last big one in California
Seven Seconds to Change a City: The power of a blind thrust fault
The Northridge Quake
Memories of Northridge Earthquake PDF
The Northridge Earthquake was one of the most destructive earthquakes in Los Angeles history. It changed quake history at 4:31AM on January 17, 1994. The primary duration was seven seconds, although there was shaking that lasted as long as 20 seconds. Even though from a magnitude perspective, this wasn’t a huge quake on the Magnitude Scale (6.7), due to the nature of the quake (blind thrust fault), it was one of the most power quakes ever measured in an urban area of North America.
One of the more interesting facts about this quake is that it wasn’t centered in Northridge, but rather in nearby Reseda. The fault involved is called the Pico Thrust Fault.
The official death toll was established at 57 people. More than 8,700 people were injured, and 1,600 of those people required hospitalization. The Northridge Meadows apartment complex was one of the well-known affected areas – and in part contributed to the name of the event. Unfortunately, 16 people were killed as a result of the building’s collapse. The Northridge Fashion Center and California State University, Northridge also sustained very heavy damage. The earthquake gained worldwide attention because of damage to the vast freeway network, which served millions of commuters on a daily basis.
The most notable damage to a freeway was to the Santa Monica Freeway, Interstate 10, known as the busiest freeway in the United States, congesting nearby surface roads for three months while the roadway was repaired. Farther north, the Newhall Pass interchange of Interstate 5 (the Golden State Freeway) and State Route 14 (the Antelope Valley Freeway) collapsed as it had 23 years earlier in the 1971 Sylmar earthquake even though it had been rebuilt with improved structural components. One life was lost in the Newhall Pass interchange collapse.
Portions of a number of major roads and freeways, including Interstate 10 over La Cienega Boulevard, and the interchanges of Interstate 5 with California State Route 14, 118, and Interstate 210, were closed because of structural failure or cracks in the roadway.
An unusual side effect of the Northridge earthquake was an outbreak of coccidioidomycosis, more commonly known as Valley fever, a respiratory disease caused by inhaling airborne spores of a species of fungus unique to the American southwest. The number of reported cases (203) in Ventura County was roughly 10 times the normal rate in the eight weeks following the earthquake and three people died.
The Northridge earthquake led to a number of legislative changes. The estimate on losses continues to be debated, but was between $20 and $25 billion dollars. As a result, many insurance companies either stopped offering or severely restricted earthquake insurance in California (and elsewhere). In response, the California Legislature created the California Earthquake Authority (CEA), which is a publicly managed but privately funded organization that offers minimal coverage. A substantial effort was also made to reinforce freeway bridges against seismic shaking, and a law requiring water heaters to be properly strapped was passed in 1995.