Reporter's Notes: The Hayward Fault
Updated: On March 11, 2011, a massive 8.8 magnitude earthquake hit the Pacific Ocean nearby Northeastern Japan. The quake, and a tsunami that followed, caused massive damage and loss of life. The news put quake prone California on alert. While many of us would rather not think about the possibility of another major quake, we are surrounded by active faults. One East Bay fault has scientists especially concerned.
It's been called the most dangerous fault in the U.S. The Hayward Fault runs 40 miles, from San Pablo Bay to Fremont, through some of the most densely populated areas in the country. Every 140 years for the past two thousand the Hayward Fault has jolted the East Bay. Geologists have figured out the regular history of these quakes by carbon dating trenches along the fault. A lesser known cousin of the San Andreas the Hayward fault is a creeper. Basically, it moves, slowly, along the surface but deep inside… it's locked until tension builds up and and it slips. It appears that it is time for the fault to slip again. The last major earthquake on the Hayward fault was 1868. Scientists believe that the temblor registered 7.0 in magnitude. Hayward and San Leandro were devastated. But if the quake were to happen today, it would be a much different story.
I met Mary Lou Zoback out at the Fremont Bart station, which sits right on top of the Hayward Fault. She pointed out cracks in the parking lot from the creeping fault. Zoback is a geophysicist who worked 28 years at the U.S. Geological Survey and who has done catastrophe modeling of risky residential buildings. Her company estimates that a 6.8 quake, or bigger, on the Hayward Fault could cause a disaster on par with Hurricane Katrina, causing 168 billion dollars in damage and leaving at least 200,000 homeless.
A number of public buildings in the east bay are undergoing retrofitting to make them more structurally sound. Area hospitals have until 2013 to meet seismic safety standards. There is a state inventory of public schools prone to collapse in a major quake, but no such list exists for private schools. And retrofitting standards for risky residences are confusing. I talked with Jim Cook, of Bay Area Retrofit. He says existing codes are unclear and there really is no specific licensing for seismic home retrofitters. Cook has been fighting local governments for years to improve seismic safety standards.
Homeowners can have their home evaluated but what if you are a renter? Many apartments and condos can collapse in earthquakes because they have parking or open commercial space on the first floor making this story weak or "soft." According to the Association of Bay Area Governments Earthquake and Hazards Program, soft-story apartment buildings were responsible for about two-thirds of the 46,000 uninhabitable housing units in the 1991 Northridge earthquake. In the Bay Area, unreinforced masonry (older buildings constructed of brick, stone or cement blocks) continues to be a threat.
The thought of a big earthquake is scary enough, never mind the chaos that can happen in the aftermath. But the damage from a large earthquake has repercussions that can last for a very long time. We can still see the scars from the 1989 Loma Prieta earthquake. Downtown Santa Cruz is not yet fully rebuilt and retrofitting continues on the Bay Bridge. We can prevent a lot of damage up front by shoring up our buildings and creating a family disaster plan and an earthquake kit. The Hayward Earthquake Alliance has put together some really helpful information on how to prepare for a major quake.