
Study Predicts Large California Quake Within 30 Years
by
findingDulcinea Staff
California has released its first statewide earthquake forecast, predicting that it is “basically guaranteed” a large earthquake will strike within 30 years.
30-Second Summary
There is a 99.7 percent chance California will experience at least a magnitude 6.7 earthquake in the next three decades, according to the Uniform California Earthquake Rupture Forecast.
The prediction is the result of the combined efforts of the U.S. Geological Survey, the Southern California Earthquake Center and the California Geological Survey, who analyzed new data to calculate earthquake probabilities in California.
Scientists aren’t sure where or when the earthquake will occur, but chances are high that it will be in Southern California.
That region has had fewer quakes in the last 100 years than Northern California.
The southernmost part of the San Andreas fault, which hasn’t had a “stress-relieving” earthquake since 1680, “appears most primed to break,” according to the Los Angeles Times.
One of the last major urban earthquakes in California was the 1994 Northridge quake, and scientists are concerned that the coming quake could be at least that severe.
Meanwhile, researchers are urging residents to get ready now. “A big earthquake can happen tomorrow or it can happen ten years from now,” one researcher who participated in the project said.
This new forecast will be used to update seismic hazard maps to keep residents informed of the areas that have the greatest vulnerability to property damage in the event of an earthquake.
The prediction is the result of the combined efforts of the U.S. Geological Survey, the Southern California Earthquake Center and the California Geological Survey, who analyzed new data to calculate earthquake probabilities in California.
Scientists aren’t sure where or when the earthquake will occur, but chances are high that it will be in Southern California.
That region has had fewer quakes in the last 100 years than Northern California.
The southernmost part of the San Andreas fault, which hasn’t had a “stress-relieving” earthquake since 1680, “appears most primed to break,” according to the Los Angeles Times.
One of the last major urban earthquakes in California was the 1994 Northridge quake, and scientists are concerned that the coming quake could be at least that severe.
Meanwhile, researchers are urging residents to get ready now. “A big earthquake can happen tomorrow or it can happen ten years from now,” one researcher who participated in the project said.
This new forecast will be used to update seismic hazard maps to keep residents informed of the areas that have the greatest vulnerability to property damage in the event of an earthquake.
Headline Links: Calculating earthquake probabilities
Scientists who participated in the earthquake study acknowledged the decades of predictions that a “Big One” will hit California. “You have to realize this is a long pregnancy,” one researcher said. Earthquakes are generally expected along the southern San Andreas fault every 150 years, but there has not been a quake for 300 years.
Source: Los Angeles Times (free registration may be required)
Southern California experiences approximately 10,000 earthquakes a year, but most are too small to be felt, according to National Geographic. California has more than 300 fault lines and rests above two major tectonic plates, the Pacific and the North American.
Source: National Geographic
Historical Context: Major California earthquakes
On April 18, 1906, an earthquake struck San Francisco, devastating the city. Buildings collapsed, fires broke out and thousands of San Franciscans had to literally run for their lives. Photos and a history of the earthquake and its aftermath are available at the San Francisco Chronicle Web site.
Source: San Francisco Chronicle
The 1971 San Fernando earthquake measured a magnitude 6.6 and lasted 60 seconds. In that time, “earthquake-resistant” buildings were destroyed and $505 million of property damage occurred. Most deaths caused by the earthquake resulted from the collapse of the Veteran’s Administration hospital.
Source: U.S. Geological Survey
On Jan. 17, 1994, the Northridge earthquake showed that people could mitigate damage and save lives by improving the construction of buildings and other structures. The Southern California Earthquake Data Center offers several photographs of the damage caused by the Northridge earthquake.
Source: Southern California Earthquake Data Center
Related Topic: Earthquakes around the world
Scientists have recently recorded hundreds of earthquakes off the central Oregon coast. The quakes puzzle scientists because they are occurring in the middle of a tectonic plate rather than near tectonic boundaries. Researchers are planning to collect water samples from the area of the quakes to determine whether the cause is hydrothermal or tectonic.
Source: Science Daily
The most powerful earthquake ever recorded by seismic monitoring was the Great Chilean Earthquake of May 22, 1960. The magnitude 9.5 seismic event killed 1,655 people, injured 3,000, and left two million homeless. Effects of the quake were felt as far away as Hawaii, Japan, the Philippines and the west coast of the United States.
Source: U.S. Geological Survey
On Feb. 29, 1960, a magnitude 5.7 earthquake struck Agadir, Morocco. The 15-second event killed thousands and leveled parts of the city.
Source: findingDulcinea
The Pacific Disaster Center provides a history of earthquakes around the world that have caused significant damage.
Source: Pacific Disaster Center
Reference: What causes earthquakes?
One of the more perilous and baffling natural phenomena in the world is the earthquake. FindingDulcinea’s Netcetera examines the the science behind the earthquake and its various effects in history.
Source: findingDulcinea
The pulling apart and collision of tectonic plates under the earth’s surface cause earthquakes. Learn more about plate tectonics and earthquakes from MSNBC’s interactive feature, “What Causes Earthquakes?”
Source: MSNBC
Earthquake vibrations are recorded by instruments called seismographs. The magnitude of an earthquake is measured on the Richter Scale. The smallest earthquake people can generally feel is a magnitude two. Earthquakes measuring a magnitude six or more are usually considered major earthquakes.
Source: U.S. Geological Survey
Learn more about the Uniform California Earthquake Rupture Forecast at the Southern California Earthquake Center Web site.
Source: Southern California Earthquake Center

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