How do seismologists measure earthquakes?
In the United States, large-scale seismological networks are generally run by federal agencies (such as the USGS, the Bureau of Reclamation, and the Department of Energy), by state agencies, and by public and private universities. These networks are designed to monitor earthquake activity and to provide data for research into earth science problems. The Council of the National Seismic System is an organization of institutions involved in seismic monitoring with the goal of coordinating efforts to record and analyse seismic data. For example, UC Berkeley operates a seismic network in northern and central California for the purposes of monitoring seismic activity and furthering earthquake research. The seismographic instrumentation used in the Berkeley Digital Seismic Network (BDSN) includes broadband seismometers to sense weak ground motions and accelerometers to sense strong ground motions. Both types of sensors utilize force-feedback circuitry to determine the overall response, linear
