What was the date of the California earthquake in 1971?
The magnitude 6.6 Sylmar earthquake shook Southern California on Feb. 9, 1971, causing significant damage and 64 deaths.
When was the Los Angeles earthquake in 1971?
Source: California Integrated Seismic Network On February 9, 1971 at 6:01 am PST, a devastating M6.6 earthquake struck the densely populated metropolitan area of Los Angeles, leaving death and destruction in its wake.
What is the biggest earthquake in Los Angeles?
What is the biggest earthquake recorded in Los Angeles? On March 17, 2014, a magnitude 4.4 earthquake occurred about two miles south-southeast of Encino. The earthquake was felt in Los Angeles, Ventura, San Bernardino and Orange counties. This was the largest earthquake in Los Angeles since the aftershocks of the 1994 Northridge quake.
What was Peru earthquake magnitude in 1970?
The earthquake in west-central Peru triggered a massive avalanche that swept downhill from a height of 18,000 feet. On the afternoon of May 31, 1970, an earthquake of magnitude 7.9 struck an area of more than 30,000 square miles in west-central Peru near the town of Chimbote about three hundred miles north of the capital, Lima.
How many earthquakes were there in 1971?
Like the previous year, 1971 had heightened seismic activity. 20 earthquakes exceeded magnitude 7 with 2 of those measuring above magnitude 8.
What caused the 1971 San Fernando earthquake?
The 1971 earthquake ruptured a subsection named the San Fernando Fault Zone, which extends from the western San Fernando Valley to Big Tujunga Wash, about 12 and a half miles (20 km) across. The San Fernando Fault is a thrust fault, which means a section of land above the fault moved up and over a region below it.
What date was the 1971 earthquake?
February 9, 19711971 San Fernando earthquake / Start date
What was the magnitude of the 1971 earthquake?
Looking Back on the San Fernando Earthquake 50 Years Later and What We Learned. EL SEGUNDO, Calif. — At 6 a.m. on February 9, 1971, a 6.6-magnitude earthquake struck the San Fernando Valley.
When was the worst earthquake in LA?
On the early morning of June 28, 1992, a magnitude 7.3 (Mw) earthquake—the largest Southern California earthquake in 40 years—struck, rupturing five different faults! Although its epicenter was in a sparsely populated area, it was said to have been felt throughout the Los Angeles area, Arizona, Nevada, and Idaho.
What was the strongest earthquake in California?
magnitude 6.0 earthquakeDozens of aftershocks followed, including some of magnitude 4.0 or greater. The magnitude 6.0 earthquake was the largest to hit the area since the magnitude 6.1 quake in 1994. Some viewers shared their reaction to the recent earthquake, many comparing it to the 1989 Loma Prieta earthquake in San Francisco.
What was the name of the 1972 earthquake?
1972 Nicaragua earthquakeThe 1972 Nicaragua earthquake occurred at 12:29:44 a.m. local time (06:29:44 UTC) on December 23 near Managua, the capital of Nicaragua....1972 Nicaragua earthquake.ManaguaUTC time1972-12-23 06:29:44Depth10 km (6.2 mi)Epicenter12.18°N 86.22°WAreas affectedNicaragua7 more rows
When was the last strong earthquake in California?
California's Largest Recorded Earthquakes Since 1800, Ranked by MagnitudeMagnitudeDateLocation7.1July 5, 2019Ridgecrest/Trona7.0May 18, 1940El Centro6.9Oct. 17, 1989Bay Area6.7Jan. 17, 1994Northridge12 more rows
Is Sierra Madre fault active?
The Sierra Madre fault zone is a south-vergent, active reverse fault that accommodates shortening between basins on the northern margin of the Los Angeles region and the San Gabriel Mountains.
Was there a 7.1 earthquake in California today?
A magnitude 7.1 earthquake struck southern California on July 5, 2019 at 8:20 p.m. local time (July 6 at 03:20 UTC). This event was centered near the July 4, 2019 magnitude 6.4 earthquake.
How big was the earthquake just now Long Beach?
M 6.4 - Long Beach, California Earthquake.
How many earthquakes happen a day?
The National Earthquake Information Center now locates about 20,000 earthquakes around the globe each year, or approximately 55 per day.
When was the San Fernando earthquake?
See also: California earthquake forecast and Earthquake rupture. 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 as recorded by seismometers, although the whole event was reported to have lasted about 60 seconds.
How many people died in the San Fernando earthquake?
Casualties. 58–65 dead. 200–2,000 injured. 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.
Where is the San Fernando fault zone?
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. Additional breaks occurred farther to the east that were in a more scattered fashion, while the western portion of the most affected area had less pronounced scarps, especially the detached Mission Wells segment. Although the complete Sierra Madre Fault Zone had previously been mapped and classified by name into its constituent faults, the clusters of fault breaks provided a natural way to identify and refer to each section. As categorized during the intensive studies immediately following the earthquake, they were labeled the Mission Wells segment, Sylmar segment, Tujunga segment, Foothills area, and the Veterans fault.
How many landslides were there in the San Fernando Valley?
Analysis revealed that the earthquake triggered over 1,000 landslides. Highly shattered rock was also documented along the ridge tops, and rockfalls (which continued for several days) were the result of both the initial shock and the aftershocks. Few of the slides that were logged from the air were also observed from the ground. 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 slides ranged from 49–984 feet (15–300 m) in length, and could be further categorized as rock falls, soil falls, debris slides, avalanches, and slumps. 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.
What reservoirs were damaged by the earthquake?
See also: Baldwin Hills Reservoir and Bull Creek (Los Angeles County) Both the Upper and Lower Van Norman dams were severely damaged as a result of the earthquake. The lower dam was very close to breaching, and approximately 80,000 people were evacuated for four days while the water level in the reservoir was lowered.
What are the faults in the San Gabriel Basin?
Moving eastward, there is the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, with active reverse faults ( San Cayetano, Red Mountain, Santa Susana, and Sierra Madre) all lining the north boundary.
How did the transverse ranges form?
The Transverse Ranges form the perimeter of a series of basins that begins with the Santa Barbara Channel on the west end. Moving eastward, there is the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin, with active reverse faults ( San Cayetano, Red Mountain, Santa Susana, and Sierra Madre) all lining the north boundary. A small number of damaging events have occurred, with three in Santa Barbara ( 1812, 1925, and 1978) and two in the San Fernando Valley (1971 and 1994 ), though other faults in the basin that have high Quaternary slip rates have not produced any large earthquakes.
What year did the San Fernando earthquake happen?
The 1971 San Fernando Earthquake damaged a pipe on the Maclay Reservoir outlet line in Sylmar.
Where was the San Fernando earthquake?
This map illustrates widespread shaking from the 1971 San Fernando earthquake in Southern California.
What hospital was damaged in the Sylmar earthquake?
Both the Veteran's Administration Hospital and Olive View Medical Center in Sylmar were severely damaged, accounting for many of the deaths. Much like the Northridge Earthquake 23 years later, the quake also tore apart freeway overpasses. But the threat of disaster didn't end when the shaking stopped.
How many people died in the San Fernando earthquake?
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. Also known as the Sylmar Earthquake, the magnitude-6.5 quake was reported on a Tuesday at about 6:01 a.m.
What was the name of the dam that collapsed after the San Fernando earthquake?
This aerial view shows a collapsed section of the lower Van Norman Dam after the 1971 San Fernando Earthquake. An aerial view of displaced railroad tracks in Sylmar after the 1971 San Fernando Earthquake. A view inside Olive View Medical Center after the 1971 San Fernando Earthquake.
When was the Sylmar earthquake?
Below, a look back at the 1971 Sylmar Earthquake.
What happened to the 405 freeway?
Residents along the 405 Freeway were evacuated for days until the dam was shored up and determined to be safe. The aftermath led to major changes for building construction and the Alquist-Priolo Act. It bans construction on active faults in California. Below, a look back at the 1971 Sylmar Earthquake.
Where was the earthquake in Los Angeles?
The epicenter of the earthquake was in the vicinity of Magic Mountain, about six miles northeast of Sylmar, at a depth of about seven miles. The shock was felt for 300 miles along the southern California coastal region and as far inland as Las Vegas, Nevada. The greatest damage was in the San Fernando area northwest of Los Angeles. The earthquake resulted in 65 deaths and more than 2,000 people injured. Property damage losses totaled more than half a billion dollars.
How many people died in the San Fernando earthquake?
The greatest damage was in the San Fernando area northwest of Los Angeles. The earthquake resulted in 65 deaths and more than 2,000 people injured.
How far did the San Fernando fault extend?
Movement along the fault reached the surface during the earthquake and extended 12.5 miles from the San Fernando-Sylmar area in the northern San Fernando Valley to Big Tujunga Wash in the Sunland area. Along this zone, many additional structures sitting on top of the fault zone were severely damaged directly by fault movement at the surface.
What is the California Geological Survey?
The California Geological Survey reviews the geotechnical and seismic aspects of hospital and public school construction throughout California. The 1971 earthquake illustrated the need for better coordination between scientists, engineers, and emergency responders and led to the establishment of the first Earthquake Clearinghouse.
Is California safe from the earthquake?
California is safer because of the 1971 earthquake. Visit our Story Map: Remembering the San Fernando Earthquake of 1971 to see then-and-now photos, and to learn more about the Alquist-Priolo Earthquake Fault Zoning Act, one of four pieces of major legislation that resulted from the earthquake.
Tectonic setting
Central Chile lies on the destructive plate boundary where the Nazca Plate is being subducted beneath the South American Plate. The rate of convergence at this boundary in central Chile is about 74 mm per year. The boundary has a long history of destructive earthquakes and damaging tsunamis.
Earthquake
The focal mechanism and hypocentral depth of this earthquake are consistent with rupture along the plate interface. The aftershock locations spread from the epicenter westwards towards the trench.
Damage
The earthquake caused widespread damage across central Chile, with the port city of Valparaíso being the most affected. A total of 83 people were killed, a further 447 were injured and 40,000 made homeless.
What was the magnitude of the earthquake in 1971?
The 1971 Tuscania earthquake is an earthquake that occurred on February 6, 1971 near the town of Tuscania in Lazio, Italy. It had a body wave magnitude of 4.6. Despite being a moderate magnitude this event caused major destruction. 24 people were killed, 150 were injured and about 5,000 homeless. 40 homes were destroyed and 1,678 were damaged.
What buildings were damaged by the earthquake?
Among those structures sustaining serious damage were the 8th century St. Peter's Church and the 12th century Basilica of St. Mary Major, both recently restored. The heavy damage sustained was due to the shallow depth of the earthquake and poorly constructed buildings.
Where did the 6.7 earthquake happen?
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. The quake took place at 6 am under the town of Sylmar.
How many people died in the 1994 Northridge earthquake?
During the Northridge earthquake in January 1994, more than 50 people were killed and the quake caused damage worth $35 billion. It also occurred on a hitherto unknown fault, albeit a different one from the San Fernando fault (see Figure 2). Such faults, which are unknown but can produce devastating quakes, are called blind thrust faults. Following these to earthquakes, geologists are now sure that many more of these hidden faults crisscross deep beneath the San Fernando Valley. 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. (hra135)
What is the red line on the Northridge quake?
The red line is the fault on which the Northridge quake occurred in 1994. The two blue lines mark the faults which ruptured in the San Fernando earthquake 46 years ago today. The colored dots represent locations of the respective aftershocks of each quake.
How long did the evacuees stay in the dam?
More than 80,000 people living downstream had to leave their homes for four days, while engineers frantically shored up the dam and lowered the water level. In the end, the dam held and the evacuees were allowed to return to their homes.
Did the San Gabriel Mountains have earthquakes?
Geologists had known for a long time that the San Gabriel Mountains above the San Fernando Valley were riddled with faults. 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.
Overview
The 1971 San Fernando earthquake (also known as the 1971 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 magnitude of 6.5 on the Ms scale and 6.6 on the Mw scale, and a maximum Mercalli intensity of XI (Extreme). The event was one in a series tha…
Tectonic setting
The San Gabriel Mountains are a 37.3 mi (60.0 km) long portion of the Transverse Ranges and are bordered on the north by the San Andreas Fault, on the south by the Cucamonga Fault, and on the southwest side by the Sierra Madre Fault. The San Bernardino, Santa Ynez, and Santa Monica Mountains are also part of the anomalous east–west trending Transverse Ranges. The domain of the ranges stretches from the Channel Islands offshore to the Little San Bernardino Mountains, 3…
Earthquake
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 as recorded by seismometers, although the whole event was reported to have lasted about 60 seconds. The origin of faulting was located five miles north of the San Fernando Valley. Considerable damage was seen i…
Damage
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. The unincorporated districts of Newhall, Saugus, and Solemint Junction had moderate damage, even to newer buildings. The area where the heaviest effec…
Aftermath
Following many of California's major earthquakes, lawmakers have acted quickly to develop legislation related to seismic safety. After the M6.4 1933 Long Beach earthquake, the Field Act was passed the following month, and after the 1989 Loma Prieta earthquake, the Seismic Hazards Mapping Act and Senate Bill 1953 (hospital safety requirements) were established. Following the San Fern…
See also
• 1994 Northridge earthquake, a magnitude 6.7 quake which affected many of the same areas
• California State Route 126
• Interstate 105 (California)
• List of earthquakes in 1971
Further reading
• Bouchon, M. (1978). "A dynamic source model for the San Fernando earthquake". Bulletin of the Seismological Society of America. 68 (6): 1555–1576. doi:10.1785/BSSA0680061555. S2CID 132403783.
External links
• San Fernando Earthquake – Southern California Earthquake Center
• Historic Earthquakes – San Fernando, California – United States Geological Survey
• California Geological Survey – About CSMIP – California Department of Conservation