1994 Northridge earthquake
 The underpass of the I-10 Freeway at La Cienega Blvd. This image shows the collapsed section of the freeway. | |
| UTC time | ?? |
|---|---|
| Magnitude | 6.7 Mw |
| Depth | 17.0 km (10.6 mi) |
| Epicenter | 34°12′25″N 118°32′06″W / 34.207°N 118.535°W |
| Areas affected |  United States (Southern California) |
| Max. intensity | IX - Ruinous |
| Casualties | 72 killed over 8,700 injured |
The Northridge earthquake occurred on January 17, 1994 at 4:31 AM Pacific Standard Time in Reseda, a neighborhood in the city of Los Angeles, California, lasting for about 20 seconds.[1] The earthquake had a "strong" moment magnitude of 6.7, but the ground acceleration was one of the highest ever instrumentally recorded in an urban area in North America.[2] Seventy-two deaths were attributed to the earthquake, with over 9,000 injured. In addition, the earthquake caused an estimated $20 billion in damage, making it one of the costliest natural disasters in U.S. history.[3]
Epicenter
The earthquake struck in the San Fernando Valley about 20 miles (31 km) northwest of downtown Los Angeles near the community of Northridge. The actual epicenter of the quake was in Reseda, near the intersection of Reseda Blvd. and Saticoy St. However, it took several days to pinpoint the epicenter with accuracy, and in the meantime the media had already dubbed it "The Northridge Earthquake." The name stuck, in part due to the extensive damage and loss of life in Northridge. The National Geophysical Data Center places the hypocenter's geographical coordinates at 34°12′47″N 118°32′13″W / 34.21306°N 118.53694°W and a depth of 17 km (10.56 mi). Despite the area's proximity to the San Andreas Fault, the Northridge quake did not occur along this fault, but rather on a previously-undiscovered blind thrust fault.
Damage and fatalities
Damage occurred up to 85 miles (125 km) away, with the most damage in the west San Fernando Valley, and the cities of Santa Monica, Simi Valley and Santa Clarita. It is estimated that at least 57 people died as a result of the earthquake and as many as 72 deaths were attributed to the quake. More than 8,700 were injured including 1,600 that required hospitalization.[4] The Northridge Meadows apartment complex was one of the well-known affected areas in which sixteen people were killed as a result of the building's collapse. The Northridge Fashion Center also sustained very heavy damage—most notably, the collapse of parking structures. The earthquake also gained worldwide attention because of damage to the vast freeway network, which serves millions of commuters everyday. The most notable of this damage 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 freeway was repaired. Further north, Interstate 5 (the Golden State Freeway) and State Route 14 (the Antelope Valley Freeway) collapsed and had to be rebuilt. The Newhall Pass interchange of Interstate 5 and State Route 14 collapsed as it had 23 years earlier during the 1971 Sylmar earthquake even though it had been rebuilt with improved structural components.[5] One life was lost in the Newhall Pass interchange collapse: LAPD motorcycle officer Clarence W. Dean fell 40 feet from the damaged connector from southbound 14 to southbound I-5 along with his motorcycle. Because of the early morning darkness, he was unaware that the elevated roadway beneath him had dropped, and was unable to stop in time to avoid the fall and died instantly. When the interchange was rebuilt again one year later, it was renamed the Clarence Wayne Dean Memorial Interchange in his honor.
Additional damage occurred about 50 miles south in Anaheim as the scoreboard at Anaheim Stadium collapsed onto several hundred seats. The stadium was empty at the time. Although several commercial buildings also collapsed, loss of life was minimized because of the early morning hour of the quake, and because it occurred on a Federal holiday (Martin Luther King, Jr. Day). Also, because of known seismic activity in California, area building codes dictate that buildings incorporate structural design intended to withstand earthquakes. However, the damage caused by the earthquake revealed that some structural specifications did not perform as well as expected. Because of this building codes were revised. Some structures were not red-tagged until months after the earthquake because damage was not immediately apparent.
The quake produced unusually strong ground accelerations in the range of 1.0 g. Damage was also caused by fire and landslides. The Northridge earthquake was notable for striking almost the same area as the MW 6.6 San Fernando (Sylmar) Earthquake. Some estimates of total damage range as high as $25 billion.
Most casualties and damage occurred in multi-story wood frame buildings (e.g. the three-story Northridge Meadows apartment building). In particular, buildings with an unsteady first floor (such as those with parking areas on the bottom) performed poorly. Numerous fires were also caused by broken gas pipes due to houses shifting off foundations or unsecured water heaters falling over.[6] In the San Fernando Valley, several underground gas and water mains were severed, and there were some streets where there were fires burning through floods. As is common in earthquakes, unreinforced masonry buildings and houses on steep slopes suffered damage. However, school buildings (K-12), which are required to be reinforced against earthquakes, in general survived fairly well.
Base isolation
Before the Northridge earthquake occurrence, a heavy damping mechanism sometimes incorporated in vibration control technologies and, particularly, in base isolation devices was considered a valuable source of suppressing vibrations thus enhancing a building's seismic performance. However, for the very pliant systems such as base isolated structures, with a relatively low bearing stiffness but with a high damping, the so-called "damping force" turned out to be the main pushing force at this strong earthquake. This resulted in the "base isolation" buildings performing far worse than promised, and much worse than average buildings.[7]
Valley Fever outbreak
An unusual effect of the Northridge earthquake was an outbreak of coccidioidomycosis (Valley Fever), a respiratory disease caused by inhaling airborne spores. The number of cases (203) in Ventura County was roughly 10 times the normal rate in the eight weeks following the earthquake and three people died. It is thought that the spores were carried in large clouds of dust created by seismically triggered landslides. Most of the cases occurred immediately downwind of the landslides.[8]
Hospitals affected
Eleven hospitals suffered structural damage and were damaged or unusable after the earthquake.[4] Not only were they unable to serve their local neighborhoods, they had to transfer out their inpatient populations, which further increased the burden on nearby hospitals that were still operational. As a result, the state legislature passed a law requiring all California hospitals to ensure that their acute care units and emergency rooms would be in earthquake-proof structures by January 1, 2005.
Television, Movie & Music productions affected
The quake stopped production of movies and TV shows filming in the area at the time, most notably The Simpsons season 6's first two episodes "Bart of Darkness" and "Lisa's Rival". ABC's General Hospital, which tapes in Los Angeles, was also heavily affected by the Northridge earthquake. The set, which is at ABC Television Center, suffered major damage via partial collapse and water damage. Also, the season five episode of Seinfeld, The Pie, was due to begin shooting on the day of the earthquake before stage sets were damaged.
All of the earthquake sequences in the Wes Craven movie New Nightmare were actually filmed a month prior to the Northridge quake. The real quake struck only weeks before film was completed. Subsequently, a team was sent out to film footage of the actual quake damaged areas of the city. The cast and crew thought that the scenes that were filmed before the real quake struck were a bit overdone, but when viewed after the real quake hit, they were horrified by the realism of it.[9]
Michael Jackson had been due to begin recording of his new album HIStory on the day of the earthquake. A recording studio had just been refurbished at a cost of "several" million US dollars, but Jackson's entourage moved recording to New York City. They returned to the new studio in Los Angeles some six months later.
Transportation affected
Portions of a number of major roads and freeways, including the interchange of Interstate 5 with California State Route 14, Interstate 10, and California State Route 118, were closed because of structural failure or collapse. Rail service was briefly interrupted, with full Amtrak and expanded Metrolink service resuming in stages in the days after the quake. All MTA bus lines operated service with detours and delays on the day of the quake except for Line 243, which ran along DeSoto and Winnetka Avenues near the epicenter. Many flights schedules were altered after the quake, due to a water tower collapse at Los Angeles International Airport. Other airports in the Los Angeles Area were also closed including Burbank Glendale Pasedena Airport (now Bob Hope Airport) and Van Nuys Airport, which is near the epicenter, the control tower suffered from radar failure and panel collapse.
Real Estate affected
When the earthquake occurred, real estate values were negatively affected for a short time. Real estate appraiser and crisis consultant Randall Bell writes in his book Real Estate Damages, "When the Northridge earthquake occurred, real estate values in the San Fernando Valley were generally declining due to a regional economic downturn. Immediately following the earthquake, most pending sales of real estate in the San Fernando Valley were postponed until damage assessments could be completed. Values of damaged properties were negatively impacted for a short period while they were repaired. Undamaged properties experienced no long-term loss in values. Adjacent areas such as the Conejo Valley to the east experienced an upsurge in occupancy for short-term housing such as apartments and rental homes while displaced homeowners sought temporary residences as repair projects were completed."
Bell continues, "Residential buyer confidence experienced a short downturn with little or no long-term implications, but the investor market for large commercial properties required more time for buyer confidence to recover...The negative impacts on real estate directly from the Northridge earthquake were short-lived and generally related to repair costs and temporary loss of use, although some structures were destroyed."[10]
Universities, Colleges, Schools affected
California State University, Northridge was the only major university near the epicenter. Many campus buildings were heavily damaged and a parking structure collapsed; as a result, many classes were moved to temporary structures. Los Angeles Unified School District closed local schools throughout the area, classes were rescheduled for a couple of days. University of California, Los Angeles and other universities were also shut down.
Entertainment & Sports affected
Universal Studios Hollywood shut down the Earthquake attraction, based on the 1974 motion picture Earthquake, It was closed for the second time since the Loma Prieta Earthquake, The Anaheim Stadium which is far away from the epicenter suffered some damage, and the scoreboard fell into the seats. Disneyland was shut down after the quake, but only for inspections. The Los Angeles Memorial Coliseum suffered minor damage. In Hollywood, water collapses and curfews caused the city to postpone all public events for the next several days.
Other Buildings affected
The United States Postal Service suspended all mail service throughout the Los Angeles area for few days, Los Angeles Public Library shut down most of its branches, books were knocked down after the quake. Many Los Angeles Museums including the Art Deco Building in Hollywood, were closed. Many Shopping Malls including the Sherman Oaks Galleria and Other Shopping malls were also shut down.
Radio & Television affected
The earthquake knocked Los Angeles's radio and television stations off the air, later they went back on the air for earthquake coverage.
Legislative changes
The Northridge earthquake led to a number of legislative changes. Due to the large amount lost by insurance companies because of the earthquake, most 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.[11] 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.
See also
References
- ^ USGS Response to an Urban Earthquake -- Northridge ‘94
- ^ Northridge Earthquake Southern California Earthquake Data Center, Accessed October 6, 2006
- ^ "Northridge Earthquake". http://nisee.berkeley.edu/northridge/. 2005. Retrieved 2008-10-23.
{{cite web}}: External link in|publisher= - ^ a b Executive Summary
- ^ Public Roads On-Line (Summer 1994): The Northridge Earthquake: Progress Made, Lessons learned in Seismic-Resistant bridge Design
- ^ Secure Your Stuff: Water Heater
- ^ Valentin Shustov, PhD, PE. "The 1994 Northridge earthquake: seismic base isolationj". Archived from the original on 2009-07-21. Retrieved 2009-07-04.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help)CS1 maint: multiple names: authors list (link) - ^ Coccidioidmycosis Outbreak
- ^ http://www.imdb.com/title/tt0111686/trivia
- ^ Bell, Randall. Real Estate Damages. p. 216–217.
- ^ California Earthquake Authority (CEA) Version 2.0
External links
