Characterization of Seismic Noise in Venezuela Using Seismological Networks

Abstract

We present a seismic noise characterization in Venezuela using seismic records obtained by the stations of the Venezuelan Foundation of Seismological Research (FUNVISIS). To these records, we applied a power spectral analysis for a three-month time period between September and December 2016. The most representative values of the period ranges corresponding to cultural noise (0.1-1 s) and double frequency microseism (4-8 s) were extracted from each station to characterize the behavior of these phenomena across Venezuela. The values of cultural noise vary between -145 dB and -82 dB, showing their maximums in the western part of the country. Due to the confinement measures, a consequence of the COVID-19 pandemy, the daily activity of the population was reduced, resulting in a decrease in cultural noise of approximately 4 dB at the FUNV station. The double frequency microseism yielded amplitudes between -139.5 dB and -121.5 dB. These values increase in the sedimentary basins and decrease in the mountain systems of the Venezuelan Andes and the Caribbean. This behavior suggests that the geology of the region where the station is located has more influence on the amplitude values of double frequency microseism than the distance between the source and the station. The performance obtained by the RSSN stations is satisfying for locating local and regional earthquakes and failures have been identified at the stations BENV, JACV y TURV, which should be resolved soon.