The participating hams send USGS "Did You Feel It?" or DYFI, reports after an earthquake via Winlink to hams outside the affected area, who then forward the reports to USGS over the internet. This allows real-time reports to be filed even if the quake has disrupted normal internet service to a given area.
According to Newsline, the DYFI system gathers data on macroseismic intensity, allowing researchers to more accurately determine where a quake was felt and at what intensity. The amateur radio involvement is coordinated by ARES (Amateur Radio Emergency Service) groups in California, Arizona, Washington State, Hawaii and Mexico.