Shaking Caused by Some Fast and Slow Moving Faults

Abstract:

For many years this meeting has been held in a place that looks fun, but is not safe. The reason is that there are many faults near our meeting place. For this work we looked at these faults and tried to figure out how big their shaking might be. One thing that controls the shaking is how far the slip reaches along the fault, how fast the fault slip is, and how big the fault slip is. An interesting thing about the faults near our meeting place is that while some of them are locked most of the time and do not move, others slowly move all of the time. This slow moving might or might not make it so that the sudden ground shaking, when it does happen, is not as strong, or does not last as long. If we look at news and books from the old days, and read the work by people who look under ground to find out how faults moved in the past, the story does not look good. For our own work, we used computers. We told the computers everything that we know, then the computers went to work to figure things out for us. Sometimes using a computer can lead to wrong ideas, but our computer learned how to do things well. Our computer told us that the shaking near our meeting place might be pretty bad, especially if the slow slip does not change how the faults act when they slip quickly. So, if you live or work near our meeting place, or are near other places with faults that move quickly: Be ready and have a plan. And when the shaking starts, Drop, Cover, and Hold On.