The LASA sensing system design, installation, and operation

The implementation of the LASA sensing system is the subject of the following paper. The selection of the geographical area has already been treated. The design of the sensing system, the establishment of system specifications, and the selection of components are discussed. The installation of the seismograph systems is described in some detail. This includes the drilling and casing of 504 two-hundred foot wells and 21 five-hundred foot wells, the trenching of 3 000 000 feet of cable, and the installation and calibration of the 525 seismometers and amplifiers. To meet the operational requirements the 525 sensing circuits were equalized to the same system sensitivity, 20 millivolts per millimicron of earth motion which corresponds roughly to the saturation of a typical amplifier by the signal generated by a magnitude 7.75 event [1]. The maintenance phase has been initiated and is described.