It’s only a matter of time before another significant earthquake comes to California. Since September is National Preparedness Month, here are a few tips and a historic look at our quakes.
Prepare and protect your home before an earthquake. Decrease your risk of damage and injury from an earthquake by identifying possible home hazards. Complete your earthquake plan by identifying and securing the following hazards:
You can learn about earthquake insurance at the California Department of Insurance.
If you have homeowners insurance in California, your company must offer to sell you earthquake insurance. It must offer this every other year.
There are limits on what earthquake insurance pays. The purpose of earthquake insurance is to help put a roof back over your head. It does not replace everything you lost.
The offer must be in writing. It must tell you the amounts it covers, the deductible and the premium.
You have 30 days to accept the offer.
The California Earthquake Authority provides the most earthquake insurance in California.
Learn more at:
This map is the National Seismic Hazard Model released earlier this year. The map displays the likelihood of damaging earthquake shaking in the United States over the next 100 years.
The rate of plate movement along the San Andreas Fault is approximately 1.3 inches each year – about the same rate your fingernails grow. A United States Geological Survey (USGS) report released in 2017 detailed a study of the southern San Andreas Fault. The study found evidence of 10 ground-rupturing earthquakes between magnitude 7.0 and 7.5 between 800 A.D. and 1857. Predictions based on the survey forecast a 16% chance of a magnitude 7.5 or larger earthquake near Kern County in the next 30 years.
The USGS cautions that although its most recent prediction model is vastly improved since the version in 2008, it is still an approximation. The USGS uses two kinds of scientific models to predict earthquake probability.
1. The earthquake rupture forecast shows where and when the Earth might slip along the state’s many faults.
2. The ground motion prediction model estimates the subsequent shaking given by one of the fault ruptures.
Below is a table of California’s significant earthquakes. These are earthquakes of magnitude greater than or equal to 6.5, or that caused loss of life or more than $200,000 in damage. The list is not adjusted for inflation. This table includes significant earthquakes having epicenters outside of California but within approximately 100 miles of California’s border. The list is from the most recent to 1933.
Above, the John Muir School in Long Beach, above, was damaged by a magnitude 6.4 earthquake on March 10, 1933. More than 230 school buildings were damaged by the quake which struck at 5:54 p.m. The devastation prompted the state to enact a series of earthquake building codes including one that mandated all school buildings be earthquake resistant.
The United States Geological Survey (USGS) estimates long-term quake hazards to give communities an assessment of risk in their area. More than two-thirds of the nation’s annualized earthquake losses will be in California, and in California, 80% of the losses will be in these 10 counties:
Top 10 counties by estimated annualized earthquake loss (percent of state total)
In the late 1980s, the USGS monitored 16 faults (the main ones). In 1994, the 6.7 Northridge earthquake occurred on an unrecognized fault line. The quake is said to be the costliest earthquake in U.S. history, and scientists began to search and monitor many other fault lines in the state. In 2017, there were 350 fault lines monitored.
Sources: U.S. Geological Survey, California Department of Conservation, Los Angeles Public Library, Working Group on California Earthquake Probabilities
