Development of the Seismo Site starts with two force sensors. One sensor is oriented to capture movement in the north-south direction, the other is oriented to capture east-west movement. Sensors and associated electronics are small, and fit in an electronics housing that measures 5 inches in outside diameter.

The accelerometers are based on the hinge sensor, mounted vertically and having a 3 gm weight glued to its movable hinge. By knowing the weight output of the sensor when it is at rest, and knowing its output at +1G, -1G, and at the 5G extremes, an output graph can be constructed.

Sensor output is sent to a serial converter where it is processed and sent to the serial port of a PC. A Quake Log program is loaded into the PC and it provides calibration routines, a date and time stamp event monitoring capability.