SEISMOMETER AND ACCELEROMETER – A PAIR OF MEASURING INSTRUMENTS AT A SEISMIC STATION

Abstract

A modern broadband seismometer and seismic accelerometer measure different physical quantities of ground motion; the first measures velocity and the second, acceleration. Each has advantages and disadvantages, but when they are placed together and connected to a modern seismic six-channel acquisition unit, they form an advanced seismological measuring system. This system is capable of recording extremely weak seismic signals, as well as more powerful seismic shocks which occur in the vicinity of the seismic station. With both systems, the dynamic range of measurement is increased at this location, which will be shown by the data of an earthquake in the upper Soča valley in 2004. An additional reason for equipping earthquake stations with accelerometers and seismometers is for the duplication of the weakest part of the measurement system – the seismometer. From experience, we know that the seismometer is a weaker part of the equipment than the accelerometer. Quality control of equipment is the third reason why seismometers and accelerometers are installed together. Both meters overlap in a certain area of ground movement; this area is used to compare and check the measurements of both sensors.