Earthquake Preparedness

The threat of major and damaging earthquakes in the San Francisco Bay Area is a fact.

The violent shaking of the ground produces the greatest property losses and personal injuries.

The U.S. Geological Survey reports that:

San Francisco Bay area:

Within the next 30 years the probability is:

• 72% that an earthquake measuring magnitude 6.7
• 51% that an earthquake measuring magnitude 7
• 20% that an earthquake measuring magnitude 7.5

Plonowski worked as a F.E.M.A. Damage Assessor following the Loma Prieta Earthquake of 1989.  He surveyed over 80 quake-damaged houses from the epicenter in the Santa Cruz Mountains up through the S.F. Peninsula for emergency relief funding.  "It was an extraordinarily valuable experience for a young architect, to see first-hand what severe, seismic ground-shaking forces can do to a house or building.  In addition to witnessing the damage, "I learned more about people than about buildings during my stint with F.E.M.A.   Definitely one of the more interesting periods of my career." 

Plonowski and team are certified by the California Earthquake Authority (C.E.A.) to help Bay Area homeowners who wish to seismically retrofit their houses.  

We have over 30 years of experience designing and installing seismic force-resisting structural systems such as foundations, shear walls and hold-downs, as well as bracing,  retrofitting anchor bolts, etc.

Is your house earthquake ready?

In a Brace + Bolt retrofit, the foundation is bolted to the frame of the house, and if there is a crawl space (or cripple wall), it is braced with plywood or OSB sheathing.  This helps prevent the house from sliding or toppling off its foundation during an earthquake, which is exactly what happened to the two houses in the above photos.