A three-quarter watt seismic station

A low-power, low-cost instrument using slow speed, direct recording on magnetic tape provides continuous unattended seismic recording in excess of 1 month. The seismic signal is recorded at two gain levels separated by 26 db with a total dynamic range of greater than 70 db. A high-accuracy crystal clock with fully coded digital output and a crystal stabilized radio for reference time-signal reception provide timing to better than 0.1 sec throughout the recording period. Total power consumption is less than 34 watts which enables operation for 1 month on dry cell batteries. The weight of the complete system including seismometer and batteries is less than 100 lb. Ten instruments have been used to record seismic signals ranging from localized microearthquake activity to explosions and teleseismic events.