Ground shaking caused by the sudden release of accumulated strain by an abrupt shift of rock along a fracture in the earth or by volcanic or magmatic activity, or other sudden stress changes in the earth.
If you live or work in the San Francisco Bay region, this handbook explains why you should be concerned with earthquakes, what you can expect during and after a quake, and what you need to do beforehand to be safe and reduce property damage.
With high property damage, loss of life and fire damage were relatively low. Why? The legal system encourages builders to follow code, the electrical grid was shut down early, and emergency response management was very effective.
Fact sheet describing plans for a San Andreas Fault Observatory at Depth (SAFOD) by drilling into the fault to install instruments for long-term monitoring near the location of the magnitude 6 Parkfield earthquakes.