The Inverness Public Utility District is participating in a seismic monitoring program sponsored by the United States Geological Survey, the district announced last week. During earthquakes, a small seismograph the size of a shoebox bolted to the floor in a storage closet at district headquarters will send seismic data through a wireless Internet signal to the survey. The data will quickly be incorporated into Shakemaps, a program that provides maps of close to real-time ground motion and shaking intensity, helping the federal agency assess potential damage after the event, record variation in ground motion and understand why certain structures were damaged. Two other seismographs are now used in the county to measure ground motion from the San Andreas Fault, which runs through Tomales Bay—one on Nicasio Valley Road and one in San Rafael.