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Long Beach Earthquake

Long Beach Earthquake

Date: March 10, 1933

Location: Long Beach, CA

The March 10th SE of Long Beach earthquake occurred at exactly 5:54 PM. It occurred south of Los Angeles and had its epicenter on the Newpoprt-Inglewood Fault, southeast of the Long Beach, California. This earthquake which caused lots of damages had 6.4 moment magnitude and a maximum of VIII Mercalli Intensity (Severe). Throughout southern California, damages to buildings were widespread. Around $40 million worth of damages resulted from the earthquake and around 115-120 people died. Most of the fatalities happened as people ran out of their buildings and a large of them was hit by falling debris.

The damages caused by the earthquake

Even though in terms of magnitude the earthquake was moderate, it caused lots of damages to the weak buildings particularly from south of Los Angeles to Laguna Beach. A large percentage of the damages occurred in the densely populated Long Beach city on the southern facing Los Angeles County city. The damages also extended to industrial area southern of the downtown Los Angeles.

The unfavorable geological conditions including landfill, water soaked alluvium alongside poorly constructed buildings heightened the level of damages. At Long Beach, lots of buildings collapsed, a lot of water-tanks fall off the roofs and many houses were lifted from their foundations. Among the buildings which incurred severe damages were school buildings.

Even though the Long Beach City and the neighboring communities suffered greatly, people in San Joaquin Valley and Baja also felt the earthquake. The earthquake damaged several docks at the Los Angeles Harbor and according to the US National Geographic Survey; the Catalina Channel sank around 359 feet. Bricks broke down in San Pedro from downtown businesses ornate facades. Throughout, the Long Beach earthquake area, the community recovery highly benefited from Army, American Legion, Navy and many volunteers assistance.

The earthquakes aftermath

Following the earthquake, people realized the importance of earthquake resistant structures within California. The Long Beach earthquake damaged lots of school buildings. Around 230 school buildings either suffered severe damages, were judged as unsafe for occupation or were completely damaged. On April 10, 1933, the California Stage Legislature passed Field Act which mandated that all school buildings must be earthquake resistant. Possibly, if the earthquake occurred on school hours, then the number of deaths would be higher.

Other earthquakes in California

California has been a home for most of the highest magnitude earthquakes in the United States. The largest ever earthquake recorded within the United States had a magnitude of 9.2. This earthquake struck Prince William Sound, Alaska March 28, 1964 UTC. However the largest recorded earthquake worldwide had a magnitude of 9.5 (Mw) and was recorded in Chile on 22nd May 1960. Gaspar de Portola exploring expendition felt the first reported earthquake in California. This was in the year 1769. At the time, they were camping around 48 kilometers southeast of Los Angeles.

Other earthquakes in California include the Northridge Earthquake. This earthquake awoke people of Los Angeles area on 17th January 1994 at 4.30 am. The earthquake was the first to hit directly under the United States urban area since the Long Beach earthquake which occurred on 1933. The Northridge Earthquake, which took place on a blind thrust fault, produced the strongest ground motions that have been recorded in the urban settings of North America.

It also caused severe damages. Parking structures, major freeways and even office buildings collapsed. Moreover, the earthquake damaged numerous apartment buildings. In the Santa Monica areas and San Fernando Valley, the earthquake caused lots of damages to wood frame apartment houses, particularly to structures with lower level parking garages. The vertical and horizontal accelerations lifted buildings off their foundations and shifted walls laterally.

Fort Tejon Earthquake is also among the most severe earthquakes that affected California. It is often compared to San Francisco earthquake which happened in the year 1906. However, Fort Tejon earthquake caused larger mean ground movements than the 1906 one. Along the fault, horizontal displacement was 29.5 feet (9 meters). And the shock that hit San Andreas Fault north of Los Angeles caused tremors which people in the southern California and in Las Vegas felt. One person was reported dead after collapse of an adobe house. Fort Tejon Earthquake had a magnitude of 7.9 and happened on 9th January 1857.

Owens Valley Earthquake is also reported as an earthquake that caused lots of damages. The earthquake, which had a magnitude of 7.4 and took place on 26th march 1872, caused 27 deaths after several houses collapsed in Lone Pine, on the east of Sierra Nevada Mountains. The earthquake happened on early morning hours and its horizontal and vertical movements occurred on Owens Valley Fault. The earthquake moved the ground 7 meters (23 feet) horizontally and an average of 1 meter (3 feet) vertically. People in Nevada and California felt the earthquake. In addition to stopping clocks in San Diego, it caused around $250,000 property loss – a huge amount of money at the time.

San Fernando Earthquake also known as the Sylmar Earthquake took place on San Fernando Fault Zone – a thrust faulting zone that broke the surface on Sylmar-San Fernando Area. The surface rupture was around 19 Km (12 miles) long and the maximum slip was around 6 feet (2 meters). This quake caused around $500 million worth of damages and around 65 deaths. Most of these deaths resulted from the collapse of Veteran's Administration Hospital collapse. Some other hospitals which included the Olive View Community Hospital in Sylmar suffered severe damages. This earthquake also damaged newly built freeway overpasses.

Summary

California has many active faults which produce large earthquakes from time to time. The San Jacinto Fault zone situated in southern California has produced the largest number of earthquake events in the most recent history. Mendocino Triple Junction situated on the offshore of Northern California also produces many earthquakes above M6 from time to time. The 1857 Fort Tejon earthquake which had a magnitude of 7.9 is the largest ever recorded earthquake in the state.