Teleseismic P, SV, and SH waves recorded by the WWSS and Canadian networks from the 1971 San Fernando, California earthquake (M L = 6.6) are modeled in the time domain to determine detailed features of the source as a prelude to studying the near and local field strong-motion observations. The San Fernando Earthquake ofFebruary 9, 1971, offered a unique opportunity to assess many ofthe important scientific, engineering, and human concerns associated with earthquakes in a modern urban environment. The 1971 San Fernando-Sylmar earthquake, which measured 6.7 on the Richter scale of ground motion, occurred on a buried fault that was later named the Sierra Madre fault. The 1971 earthquake was a massive disaster resulting in collapsed freeways, destroyed homes, and way too many ruined lives. Preparedness, Risks, and Hazards Southern California  |  The 1971 San Fernando Earthquake. The presence in California of major universities with strong and active earthquake research Such faults, which are unknown but can produce devastating quakes, are called blind thrust faults. Photo: E. Leyendecker, USGS. More chunks of earth collapsed with each new aftershock, reducing the height of the crown and bringing the water table dangerously close to the top of the dam (see Figure 1). It is evident, however, that more faults in the San Fernando Valley area may be active today than are now recognized." San Fernando earthquake Sylmar 6.6 Richter scale 1971 damage collapse building parking structure emergency temblor shake crack Major damage was concentrated at the Newhall Pass Interchange, which was under construction at the time of the 1971 San Fernando earthquake in Southern California. Earthquake Information Chronological Earthquake Index San Fernando Earthquake.  |  (The earthquake of 9-Feb-1971). But at 42 seconds after 6 a.m. on a Tuesday morning 25 years ago this week, Feb. 9, 1971, the Sylmar-San Fernando earthquake hit the Valley and … Earthquake Faults and Faulting The question of whether it is wise to live below a dam behind which millions of acre feet of water are stored is usually rather low on people's lists of daily worries. This earthen dam had partially liquefied and the top 30 feet of the edifice had crumbled. Following the San Fernando Earthquake, new seismic safety building codes and legislation such as the Alquist-Priolo Act, which bans development near active fault lines in California, were put into place. The southern California soil shook violently the morning of February 9, 1971. Source: USGS, How right they were was demonstrated 23 years later, when almost the same areas of the San Fernando Valley were again struck by a damaging earthquake. Mandatory Credit: Brue Cox/ The L.A. Times/ ME.Quake71.1.1Ð22Ðm2.7.$. Old footage of some of the destruction resulting from the 1971 San Fernando earthquake. The San Fernando earthquake caused approximately 65 deaths, up to 1,000 personal injuries, and resulted in over 500 million dollars in damages. Even more surprising was the location of the focus of the quake, which later came to be known as the San Fernando earthquake.  |  Today in Earthquake History, February 9, 2017  Categories:   In some areas it was offset more than 5 feet. Burbank, California - Wikipedia In the 1971 San Fernando earthquake, which took place along the western edge of the Sierra Madre Fault, surface ruptures were nearly 12 mi long, including one portion a few miles northwest of Glendale. The San Fernando earthquake, 1971: Assessed at Richter magnitude 6.6, it … the 1971 san fernando earthquake An hour before sunrise, at 6:01 AM, PST, on February 9, 1971, the San Fernando region was struck by one of the most devastating earthquakes in California history. The San Fernando earthquake of February 9, 1971, was a geologic phenomenon not unlike many similar earthquakes that occur every year around the world. The unanticipated thrust earthquake had a moment magnitude of 6.5 or 6.7 (as determined by several independent institutions) and had a maximum Mercalli intensity of XI (Extreme). The San Fernando Fault, located 6 mi northwest of Burbank's downtown, caused the 6.6 magnitude 1971 San Fernando earthquake. That’s because a fault with the provocative name of the Santa Susana thrust exhibited a lot of movement that day, with the result being an earthquake … Mandatory Credit: Al Markado/ The Los Angeles Times/ ME.Quake71.2.1Ð22Ðm2.7.$. The two blue lines mark the faults which ruptured in the San Fernando earthquake 46 years ago today. However, when you live in earthquake country, you might want to give the question a second thought. Mandatory Credit: Al Markado/ The Los Angeles Times, Los Angeles Times Contributor: Larry Sharkey (retired), The Ground Beneath our Feet: A Hundred Years of Earthquakes in Los Angeles.  |  The 1971 San Fernando earthquake shook loose a massive slide in the upstream slope of the Lower San Fernando Dam that lowered the crest about 30 feet. Most dams are constructed well and they are built for eternity. An hour before sunrise, at 6:01 AM, PST, on February 9, 1971, the San Fernando region was struck by one of the most devastating earthquakes in California history. Although the Richter magnitude of the tremblor was 6.6, … TYPE OF FAULTING: thrust TIME: February 9, 1971 / 6:01 am PST LOCATION: 34° 24.67' N, 118° 24.04' W MAGNITUDE: M W 6.5 DEPTH: 8.4 km FAULT INVOLVED: San Fernando fault zone; minor offset reported on the eastern Santa Susana fault zone The 1971 San Fernando earthquake, also known as Sylmar earthquake, struck the San Fernando Valley near Sylmar at 6:00:55 a.m. PST on February 9, 1971, with a magnitude of 6.6. The dam, which crumbled during the earthquake and during the following aftershocks, held approximately 3.6 billion gallons of water. But when seismologists checked the epicentral area they realized that for about 6 miles a fault along the foothills of the San Gabriels had broken through the surface during the quake. It also occurred on a hitherto unknown fault, albeit a different one from the San Fernando fault (see Figure 2). On Feb. 9, 1971, the deadly San Fernando Earthquake rattled Southern California, leaving more than 60 people dead and causing more than $500 million in property damage. Forty-six years ago today, the possibility of such a sudden dam burst was the hair-raising fear, in the chaos and devastation following the magnitude 6.7 earthquake that struck the San Fernando Valley north of Los Angeles. High Acceleration  |  Although the Richter magnitude of the tremblor was 6.6, ranking it as moderate to large, but not great, it shook a wide, heavily populated area, leaving death and destruction in its wake. 1971 San Fernando earthquake map via USGS The M6.5 earthquake, also known as the Sylmar earthquake, killed 65 people and injured 2,000. LA Times staff writers: Kenneth Reich, 2/4/1996/ Los Angeles Daily News writer: Dana Bartholomew. ", Figure 2: Earthquakes on two blind thrust faults caused severe damage in the San Fernando Valley. The unanticipated thrust earthquake had a magnitude of 6.5 on the Ms scale, and a maximum Mercalli intensity of XI (Extreme). The earthquake was the third major earthquake to occur in the state in 23 years (after the 1971 San Fernando Valley and 1989 San Francisco–Oakland earthquakes), the Northridge earthquake was the state's most destructive one since the San Francisco earthquake of 1906 and the one that cost the most expensive for reconstruction. My dad rushed us out and filmed some of the freeway damage. – and caused $553 million damage [in 1971 dollars, that would be about $3.28 billion in 2016 dollars]. The 1971 San Fernando earthquake (also known as the Sylmar earthquake) occurred in the early morning of February 9 in the foothills of the San Gabriel Mountains in southern California. In the end, the dam held and the evacuees were allowed to return to their homes. More than once have dams failed or were overtopped due to the shaking of large earthquakes - with devastating consequences for the people living downstream. Objects under such forces would have been weightless for a few seconds, like astronauts in space. It was the first strong quake to hit the area since the 1893 Pico Canyon quake, with an epicenter several miles west of Sylmar. The Newhall Pass was rebuilt and finished in 1973 with the institution of new earthquake safety standards and additional steel rebar reinforcement.  |  The Newhall Pass infrastructure project which is located northwest of the San Fernando Valley in Weldon Canyon and less than eight miles from two other major freeway interchanges, prompted Councilman Donald Lorenzen to criticize conglomeration of freeways and connectors as “putting too many eggs in one basket.” The majority of damage to freeway structures during the “Sylmar Quake” ranged from minor cracking and slanting to the complete destruction of major sections of the interchange bridges. Blind Thrust The two geologists Carl Wentworth and Robert Yerkes from the US Geological Survey in Pasadena later wrote that "the San Fernando fault was discovered to be active only when it ruptured the ground surface on February 9, 1971. It caused hospitals and schools to collapse, brought down sections of elevated freeways and cost 64 people their lives. United States Earthquakes, 1971 By Jerry L. Coffman and Carl A. von Hake Open-File report 84-971 Prepared in cooperation with National Oceanic and Atmospheric Administration, This report has not been reviewed for conformity with U.S. Geological Survey editorial standards. Some of the most spectacular damage occurred at Olive View Hospital in Sylmar, California, where 49 people died despite its supposedly earthquake … The 1971 earthquake was a massive disaster resulting in collapsed freeways, destroyed homes, and way too many ruined… But the threat of disaster didn't end when the shaking stopped. The 1971 San Fernando earthquake, also known as the “Sylmar Quake,” took place on the morning of February 9, 1971 around 6:01am. Bottom line: the 1971 Sylmar quake in Los Angeles produced the most destructive power of any earthquake in California since the Fort Tejon quake in 1857 (Richter 7.9). A little known fact was that the Van Norman … 1984 When seismologists checked their records they were utterly surprised. Within the southern California region alone, the historic record suggests that an earthquake of about this magnitude occurs on the average of once every four years ( Fig. But it was generally accepted that none of these demarcation lines between two separate geologic units were active, meaning that they had not produced any earthquakes recently. Dam failure However, twenty-one years later the Newhall Pass Interchange would collapse again in almost the exact same location during the 1994 Northridge earthquake. The San Fernando earthquake occurred in 1971 with a magnitude of 6.6. But even now, after further detailed studies, they are not sure whether they have identified all blind faults in the area or if the valley's inhabitants are in for more surprises. The earthquake caused over $500 million in damages, around 64 deaths, and critical destruction to the infrastructure of the region. The 1971 San Fernando earthquake (also known as the Sylmar earthquake) occurred in the early morning of February 9 in the foothills of the San Gabriel Mountains in southern California.The unanticipated thrust earthquake had a moment magnitude of 6.5 or 6.7 (as determined by several independent institutions) and had a maximum Mercalli intensity of XI (Extreme). Once the shaking was over and rescuers started to assess the damage, the imminent fear of a new catastrophe arose: The Van Norman Dam just northwest of the town of San Fernando, where 3.6 billion gallons of drinking water were stored, was severely damaged. 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