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October 15, 2008

By Dr. John Parrish
State Geologist of California and head of the California Geological Survey

Next month, the Governor's annual 'Golden Guardian' statewide training exercise will bring together federal, state and local officials to test Southern California’s readiness for a 7.8 magnitude earthquake along the San Andreas Fault. Those of us in northern California should pay close attention.
 
Oct. 21 marks the 140th anniversary of the most recent major earthquake on the Hayward Fault, which lies 74 miles northward along the base of the East Bay Hills to San Pablo Bay, east of San Francisco. While 140 years doesn’t have the same distinction as a centennial or golden anniversary, scientific investigations show that the last five large earthquakes on the fault occurred about 140 years apart. Thus, it’s important that we recognize the anniversary and continue our preparation for the next significant seismic event.
 
The East Bay was relatively unpopulated in 1868 (only about 24,000 people), but the damage from the Hayward Fault quake was felt throughout northern California and Nevada.  Almost every building in Hayward was damaged or destroyed and 30 people were killed. Damage was also extensive in San Francisco, San Jose, Fremont and San Leandro.  Today, the Hayward Fault runs directly under densely populated areas (2.4 million people) and is crisscrossed by critical infrastructure. The California Geological Survey’s 1987 Earthquake Planning Scenario for a Magnitude 7.5 Earthquake on the Hayward Fault in San Francisco Bay Area anticipated 1,500 to 4,500 deaths, depending on the time of day, and three times the number of nonfatal casualties.

Although already-stringent building codes and practices have improved since 1989’s Loma Prieta earthquake and a significant amount of retrofitting has taken place on roadways and structures, it is estimated the next large Hayward Fault earthquake could cause at least $165 billion in damage to residential and commercial properties and impact more than five million people. The loss estimate doesn’t include damage to infrastructure, business disruption or the potential for post-quake fires.  More than 90 percent of the damage would be uninsured.
 
Science cannot predict earthquakes, nor may it ever be able to do so.  But we can say with absolute certainty that California is prone to earthquakes and the Hayward Fault is a known source of significant quakes, past and future. When it happens, we must be ready.

Take time to secure water heaters, major appliances and tall, heavy furniture to prevent them from toppling and store hazardous or flammable liquids, heavy objects and breakables on low shelves or in cabinets.

If you haven’t yet prepared a home or car survival kit that contains water, medical supplies, food, radio, flashlight, and other supplies, now is the time. Make sure that nothing has expired, including batteries, and remember that water should be changed every six months.  Families should also have a clear emergency plan so that everyone knows where to meet following an earthquake. 

As our fellow Californians across the south state test their emergency response capabilities and earthquake safety messages Nov. 13, take note. The more you know, the better prepared you will be.  Let’s work together to make preparation a priority.

For more information about how to prepare for the next significant seismic event, read “Living in Earthquake Country.” 


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Related Links:

Hayward Fault Fact Sheet

Earthquake Myths and Basics

California's Largest Earthquakes