How does the USGS know that the seismograph is functioning properly?
At the beginning of each day, the seismograph will call our servers and send the previous day’s computer log. This is a record of each action the seismograph has taken. Once a day, the sensor and record electronics are tested with a calibration signal. At regular intervals, usually once an hour, a short state-of-health message is sent with information about the internal batteries, memory usage, temperature, etc.
