Detecting and locating volcanic tremors in Kamchatka based on correlations of continuous seismic records

Abstract:

Kamchatka peninsular is known for its very strong volcanic activity. At any given moment in time, at least one of Kamchatka volcanoes is erupting. Some of these eruptions are producing strong seismic tremors that may be recorded at large distances. We analyze daily cross-correlation computed from continuous records by permanent stations operating on the Kamchatka peninsular. Seismic waves generated by volcanic tremors are clearly seen on the cross-correlations between some pairs of stations as strong signals at frequencies between 0.2 and 2 Hz and with travel times typically shorter than those corresponding to inter-station propagation. We use a two-dimensional source-scanning algorithm based on summation of the envelops of cross-correlations to determine locations from with the strong seismic energy is continuously emitted. In an alternative approach, we explore the distinctive character of the cross-correlation waveforms corresponding to tremors emitted by different volcanoes and develop a matched-filter method for detecting volcanic tremors. Application of these methods allows us to detect tremors generated by Klyuchevskoy, Tolbatchik, and Gorely volcanoes and to monitor evolution of their intensity in time.