Results of Analysis of the Data of Microseismic Survey at Lanzarote Island, Canary, Spain

Abstract

From the data of a microseismic survey of the Lanzarote Island territory (Canary Archipelago) we obtained a microseisms amplitude distribution in the frequency range 0.3-12.5 Hz. We found a distinguished anomaly such as an amplitude depression, whose size and magnitude depend on the frequency. After studying the statistical and polarization properties of microseism signals we proposed a model explaining this depression, based on the presence of a rigid intrusive body in the center of the island. Results of our survey coincided well with independent detailed gravity survey results whose interpretation also implies the presence of intrusion. We estimated shear-wave velocity for the rocks of intrusion and for surrounding rocks using microseismic data.

On the repeatability and consistency of three-component ambient vibration array measurements

“…De Angelis (2008) reports significant disturbance of the noise spectra between 2 and 8 Hz by strong tropical rainfall on Montserrat. Gurrola et al (1990), Withers et al (1996), Cara et al (2003), Gorbatikov et al (2004) and Mucciarelli et al (2005) describe increased noise levels in different frequency ranges, from 0.1 up to 60 Hz, with increased wind speed. In contrast, Fyen (1990) finds no measurable effect of wind on the noise spectra between 2 and 20 Hz averaged over the individual stations of the NORESS array (radius of 1.5 km).…”

“…At higher frequencies, starting above 1 Hz, the contrasting properties of anthropogenic noise during day and night time as well as during weekdays and weekends were investigated (Fyen 1990;Yamanaka et al 1993;Gorbatikov et al 2004;McNamara and Buland 2004;Bonnefoy-Claudet et al 2006a;Guillier et al 2007;Hanssen and Bussat 2008;Vassalo et al 2008). Furthermore, Burtin et al (2008) observe diurnal as well as seasonal fluctuations in ambient vibration spectral amplitudes between 2 and 15 Hz correlating with varying runoff and amount of bedload transport along a river with steep relief in the Himalayas.…”