Seismic Noise Measurements in the Takinoue (Kakkonda) Geothermal Area (5)

On Direction of Arrival of Seismic Noise by the Cross-correlation Method

Abstract

We investigated the direction of arrival of seismic noise recorded at 65 observation points in the Kakkonda geothermal area, Iwate Prefecture, from 1983 to 1985. The cross-correlation method was adopted for the data processing in the frequency range of 3 to 11 Hz.
The results obtained in the study are summarised as follows.
1) No diurnal and secular variations of arrival direction of seismic noise in the Kakkonda geothermal area are observed.
2) Arrival directions obtained near the steam supply system change before and after the closure of the wellhead valve of geothermal production wells.
3) Arrival directions for seismic noise in the frequency range of 3 to 8 Hz showing large Fourier amplitude except just above the geothermal reservoir are well consistent with the direction to the geothermal reservoir.