Planning microearthquake investigations in regions of nuclear power plant sites

In a selected region where an important structure such as nuclear power plant, high dam or a large industrial complex is planned, it is necessary to carry out systematic seismic investigations starting well before the construction phase and extending preferably over the whole operating life time of the plant. This paper highlights the importance of such investigations that are related to seismicity and seismotectonic status of the region through acquisition of data of microearthquakes constituted by very small seismic signals of relatively low magnitude but high frequency of occurrence. The procedure for establishing small aperture telemetered microearthquake network interfaced to a centralized digital recording and data processing facility is described. A scheme is presented wherein the data generated by continuous regional seismic monitoring are analysed using estimates of source location, signal duration magnitude, b-value profile, power spectra, spatiotemporal changes in seismicity, local crustal structure and other pertinent parameters for seismotectonic assessment of the region. (author). 33 refs