Because the first floor almost collapsed, the building was leaning to the north by almost two feet, and three of the four concrete stair towers fell away from the main building. The 1971 San Fernando (a.k.a. Some canals in the area of the dams were damaged and not usable, and dikes experienced slumping but these did not present a hazard. 8 x 10 in. [25], Following many of California's major earthquakes, lawmakers have acted quickly to develop legislation related to seismic safety. Severe structural damage caused by the San Fernando earthquake corresponds to an intensity of IX, and locally X, and so it appears that the 1893 shock was the lesser of the two. The frontal fault system at the base of the San Gabriel Mountains extends from the San Jacinto Fault Zone in the east to offshore Malibu in the west, and is defined primarily by moderate to shallow north-dipping faults, with a conservative vertical displacement estimated at 4,000–5,000 feet (1,200–1,500 m). Two were due to power failure of life-support systems and one, that of an employee who was struck by part of the collapsing building as he or she tried to exit the building, was a direct result of the destruction. [16], The areas that were affected by the strongest shaking were the outlying communities north of Los Angeles that are bounded by the northern edge of the San Fernando Valley at the base of the San Gabriel Mountains. As had happened following other earthquakes in California, legislation related to building codes was once again revised, with laws that specifically addressed the construction of homes or businesses near known active fault zones. The difference in rigidity at the second floor was proposed as a cause of the considerable damage to the lower levels. By that time, much of the area had been built over; new base maps were available, and many new roads provided road cuts to give new looks at the geology. Schools were affected, as they had been during the 1933 Long Beach earthquake, but this time amended construction styles improved the outcome for the thousands of school buildings in the Los Angeles area. Twenty-six buildings that were built prior to 1933 had been constructed following the local building codes and did not require seismic-resistant designs. In 1969, the California Division of Mines and Geology published Map Sheet 15, entitled Preliminary reconnaissance map of major landslides, San Gabriel Mountains, California, by D. M. Morton and R. Streitz. Analysis revealed that the earthquake triggered over 1,000 landslides. [11], Prominent surface faulting trending N72°W was observed along the San Fernando Fault Zone from a point south of Sylmar, stretching nearly continuously for 6 miles (9.7 km) east to the Little Tujunga Canyon. The unincorporated districts of Newhall, Saugus, and Solemint Junction had moderate damage, even to newer buildings. The event affected a number of health-care facilities in Sylmar, San Fernando, and other densely populated areas north of central Los Angeles. Considerable damage was seen in localized portions of the valley and also in the foothills of the San Gabriel Mountains above the fault block. The most frequently-encountered type of slide was the surficial (less than 3 feet (0.91 m) thick) debris slides and were most often encountered on terrain consisting of sedimentary rock. All these buildings had been previously inspected with regard to the requirements of the Act, and many were reinforced or rebuilt at that time, but earthquake engineering experts recommended further immediate refurbishment or demolition after a separate evaluation was done after the February 1971 earthquake, and within a year and a half the district followed through with the direction with regard to about 100 structures. [10], Several key attributes of the event were shared with the 1994 Northridge earthquake, considering both were brought about by thrust faults in the mountains north of Los Angeles, and each resulting earthquake being similar in magnitude, though no surface rupture occurred in 1994. [19], The Veterans Administration Hospital entered into service as a tuberculosis hospital in 1926 and became a general hospital in the 1960s. The near total failure of the Lower Van Norman Dam resulted in the evacuation of tens of thousands of downstream residents, though an earlier decision to maintain the water at a lower level may have contributed to saving the dam from being overtopped. [9], The San Fernando earthquake occurred on February 9, 1971, at 6:00:41 am Pacific Standard Time (14:00:41 UTC) with a strong ground motion duration of about 12 seconds. The event was one in a series that affected Los Angeles county in the late 20th century. The greatest number of slides were centered to the southwest of the mainshock epicenter and close to the areas where surface faulting took place. The 1971 San Fernando earthquake with a 6.6 magnitude and large aftershocks caused over $500 million in damages and destruction to infrastructure; including the collapsed freeway overpasses on the Interstate freeways 5, 14, and 210, destruction of several hospitals in the North Los Angeles area, and damage to the Van Norman Dam in Granada Hills. When it was apparent that the landslide potential of the hillsides, though great, did not threaten any urban areas, the geologists turned their attention to the study of geologic effects--so often ephemeral--and to other geologic hazards that may have been developed or increased by the earthquake. Several instances of failure or collapse at the site took place and two men were killed while driving in a pickup truck as a result. As we go to press one month later, 65 lives have been charged to it, and damage has been estimated at more than half a billion dollars. Because of its consequences, the San Fernando earthquake was a major earthquake from the engineering point of view, even though it was only a moderate shock in seismological terms. 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. [21], Differential ground motion and strong shaking (MMI VIII (Severe)) were responsible for serious damage to the Sylmar Juvenile Hall facility and the Sylmar Converter Station (both located close to the Upper Van Norman lake). 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 measured at 6.6 at its epicenter. Soil liquefaction played a role within confined areas of the slide, but it was not responsible for all the motion at the site, and tectonic slip of faults in the area was also excluded as a cause. February 9, 1971, Granada Hills, CA. [19], On the grounds, there were cracks in the pavement and soil, but no surface faulting. Full Record Title: DAMAGE SURVEY, SAN FERNANDO EARTHQUAKE OF FEBRUARY 9, 1971. Sylmar) earthquake (Mw = 6.6) occurred in the early morning hours of February 9. The 1979 Imperial Valley and 1987 Whittier Narrows earthquakes were presented as gainful events that were recorded during that period, because both produced valuable data that increased knowledge of how moderate events affect buildings. Among those attending, in addition to Division personnel, were representatives from the California Institute of Technology, the U S. Geological Survey, the National Ocean Survey (a part of the National Oceanic and Atmospheric Administration), the University of California at Santa Barbara, the University of Southern California, California State College at Los Angeles, and the University of Washington; from several state agencies-the Division of Oil and Gas, the Division of Highways, the Department of Water Resources; from Los Angeles County and from Los Angeles City; as well as from several private consulting firms. Service breaks, main breaks and shattered mains in the water pipe system are shown, respectively, by solid points, and by small and large open circles. Olive View Hospital, a county-owned structure, is such a lesson. Derrumbe del paso elevado, 1971 El terremoto de San Fernando de 1971 produjo, mayormente, daños en los pasos elevados de las carreteras y los hospitales. Three Division geologists had an especial interest in the area, as well as especial expertise. We must hurry to learn what we can, and to put to use what we know, while our luck holds.... M.R.H. Seismologists call it the San Fernando earthquake.USGS 'Sylmar Quake' or 'Sylmar earthquake' is the name initially given to the event by local media outlets, because the worst damage … [25], At Los Angeles High School (20 mi (32 km) from Pacoima Dam) where the exterior walls of the main pre-Field Act building (constructed 1917) were unreinforced brick masonry, long portions of the parapet and the associated brick veneer broke off and some fragments fell through the roof to a lower floor, while other material landed on an exit stairway and into a courtyard area. Earthquake Damage Earthquake And Tsunami California History Southern California Vintage California San Andreas Fault San Francisco Earthquake San Fernando Valley Local History [20], Both the Upper and Lower Van Norman dams were severely damaged as a result of the earthquake. [28][29], The San Gabriel Mountains with the Veterans Hospital complex in center (above) and selected cities with reported felt intensity in the United States (below), Ground level and overhead view of the scarp at the Foothill Nursing Home, Los Angeles Department of Water and Power, Interstate 210 and State Route 210 (California), List of Los Angeles Unified School District schools, "Preliminary strong-motion results from the San Fernando earthquake of February 9, 1971", "Tectonic setting of the San Gabriel mountains", "Seismically triggered landslides in the area above the San Fernando Valley", "The study of earthquake questions related to Veterans Administration hospital facilities", "Damage to constructed works, associated with soil movements and foundation failures", "Ground displacement at San Fernando Valley Juvenile Hall and the Sylmar Converter Station", "Highway damage in the San Fernando earthquake", "Earthquake damage to freeway structures", "History of the Alquist-Priolo Earthquake Fault Zoning Act, California, USA", "San Fernando 1971: M 6.6 - 10km SSW of Agua Dulce, CA", "Seismological studies of the San Fernando earthquake and their tectonic implications", "Strong motion data from the San Fernando, California, earthquake of February 9, 1971", "Pattern of faulting and nature of fault movement in the San Fernando earthquake", "Building damage in the San Fernando Valley", Historic Earthquakes – San Fernando, California, California Geological Survey – About CSMIP, Veterans Memorial Community Regional Park, Los Angeles County Department of Parks and Recreation, https://en.wikipedia.org/w/index.php?title=1971_San_Fernando_earthquake&oldid=1001027502, Geology of Los Angeles County, California, February 1971 events in the United States, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, This page was last edited on 17 January 2021, at 22:28. 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… The California Strong Motion Instrumentation Program was initiated in 1971 with the goal of maximizing the volume of data by furnishing and maintaining instruments at selected lifeline structures, buildings, and ground response stations. The hospital buildings, the freeway overpasses, and the Sylmar Juvenile Hall were on coarse alluvium that overlay thousands of feet of loosely consolidated sedimentary material. [27], California Strong Motion Instrumentation Program, Prior to the San Fernando earthquake, some structural engineers had already believed that the existing groundwork for seismic design required enhancement. Nursing homes also were affected. Besides those credited as authors, virtually all staff members in the Los Angeles office participated in the study: Wilma Ashby, Pat Caldwell, George Cleveland, Bill Edgington, Jim Evans, Don Fife, Cathy Govaller, Cliff Gray, Ed Kiessling, and Paul Morton. This paper compares the distribution of damage from the San Fernando, 1971, and Northridge, 1994, earthquakes. Most of the masonry and reinforced concrete buildings constructed after 1933 withstood the shaking and most did not collapse, but in 1972 a resolution came forth to abandon the site and the remaining structures were later demolished, the site becoming a city park. The Indian Hills Medical Center, the Foothill Medical Building, and the Pacoima Lutheran Professional building were heavily damaged. Other sites throughout the Los Angeles area had been instrumented as a result of local ordinances, and an extraordinary amount of strong motion data was recorded, more so than any other event up until that time. Charlie Bishop came from San Francisco, as well as several staff members from Sacramento-Quint Aune, Chief Wes Bruer, Bob Matthews, and Bennie Troxel. As much as 5 ft (1.5 m) of lateral motion was observed on either end of the slide, and trenches that were excavated during the examination at the site revealed that some of the cracks were up to 15 ft (4.6 m) deep. [19], Most of the buildings at the Los Angeles County–owned, 880-bed hospital complex had been built before the adoption of new construction techniques that had been put in place after the 1933 Long Beach earthquake. Find art you love and shop high-quality art prints, photographs, framed artworks and posters at Art.com. The shaking surpassed building code requirements and exceeded what engineers had prepared for, and although most dwellings in the valley had been built in the prior two decades, even modern earthquake-resistant structures sustained serious damage. Damage from the San Fernando, 1971, earthquake. 100% satisfaction guaranteed. Black and white photograph. The two facilities, located near Grapevine and Weldon canyons that channel water and debris off the Sierra Madre Mountains, are lined by steep ridges and have formed alluvial fans at their mouths. It had been established that these zones had a higher likelihood of experiencing strong ground acceleration, and the plan was made to furnish the selected VA hospitals with two instruments. On Interstate 5, the most significant damage was between the Newhall Pass interchange on the north end and the I-5 / I-405 interchange in the south, where subsidence at the bridge approaches and cracking and buckling of the roadway made it unusable. • The epicenter of the magnitude 6.6 disastrous earthquake was in the foothills of the San Gabriel Mountains, at the northeastern edge of the Valley. On February 9, 1971, a magnitude 6.6 earthquake in California’s San Fernando Valley claimed 65 lives. This destructive earthquake occurred in a sparsely populated area of the San Gabriel Mountains, near San Fernando. Scarps ran along the sidewalk and across the property. Dr. Morton's paper herein describes an additional 1,000 landslides generated by the earthquake--most of them west of the area previously mapped, but many in Big Tujunga Canyon, the site of already mapped slides. They paid particular attention to hillsides that might give way in aftershocks, causing more havoc than already existed. Freeway interchanges collapsed (killing two men in a pickup truck under one fallen overpass), reservoirs were in danger of imminent failure, forcing people living below them to evacuate, and houses and commerical buildings collapsed or caught fire. The buildings at both facilities were constructed with mixed styles, but engineers were unable to thoroughly study the buildings' responses because they were not outfitted with instruments for recording strong ground motion, and this prompted the Veterans Administration to later install seismometers at its high-risk sites. The San Fernando earthquake has been extensively studied by many seismologists, geologists, and earthquake engineers. Earthquake damage at Olive View Hospital, Sylmar, 1971 Creator Unknown Date Created and/or Issued 1971-02 2001-08-27 Publication Information California State University, Northridge. "Anytime" came Feb. 9, 1971, when the Santa Clarita and San Fernando valleys were devastated by the 6.6-magnitude "Sylmar" earthquake, aka San Fernando earthquake, whose actual epicenter was in the Iron Canyon section of Sand Canyon in the SCV. Also known as the Sylmar Earthquake, this earthquake occurred on the San Fernando fault zone, a zone of thrust faulting which broke the surface in the Sylmar-San Fernando Area. They were supported by aircraft: a fixed wing chartered plane and a helicopter provided and manned by the U. S. Marine Corps. The earthquake was generated by thrust faulting on the Sierra Madre fault. Intact blocks of embankment material moved tens of feet on liquefied hydraulic fill shell material (figures D-8-1 and D-8-2). [23], While the Newhall Pass interchange was still under construction at the time of the earthquake, the requisite components of the overpass were complete. The area where the heaviest effects were present was limited by geographical features on the three remaining margins, with the Santa Susana Mountains on the west, the Santa Monica Mountains and the Los Angeles River to the south, and along the Verdugo Mountains to the east. Ground displacement at the site was ruled out as a major cause of the failure, and in addition to the fallen sections and a crane that was struck during the collapse, other portions of the overpass were also damaged. This stipulation ultimately found its way into the Uniform Building Code as an appendix several years later. Damage was locally severe in the northern San Fernando Valley and surface faulting was extensive to the south of the epicenter in the mountains, as well as urban settings along city streets and neighborhoods. A state of emergency in California after the most serious earthquake since the San … [20], Few strong motion seismometer installations were present outside of the western United States prior to the San Fernando earthquake but, upon a recommendation by the Earthquake and Wind Forces Committee, the Veterans Administration entered into an agreement with the Seismological Field Service (then associated with NOAA) to install the instruments at all VA sites in Uniform Building Code zones two and three. Although instruments had recorded a force of .33g during the 1940 El Centro earthquake, building codes only required structures to withstand a lateral force of .1g as late as the 1960s. In the southern California area--from Point Arguello to Nevada and from the Mexican border to Owens Valley--seismic records suggest that 37 shocks of this magnitude or greater might be expected in a century; indeed, one might expect two shocks with a magnitude of 8.0 or more. 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