Mutual Coupling Between Meteorological Parameters and Secondary Microseisms

Abstract

The basic scientific question of this study was: do other mechanisms exist for excitation of secondary microseisms aside from the widely accepted mechanism by non-linear interactions of respective ocean waves. Here we use continuous broadband data from secondary microseisms recorded at the Ostrava-Krásné Pole, Czech Republic (OKC) seismic station to create a massive seismological database. Except for seismological data, various meteorological features and their mutual relations were analysed: temperature, the so called ¡§shifted¡¨ temperature, air density, changes of atmospheric pressure, and synoptic situations. These analyses prove that maximum amplitudes of microseisms were observed during winter, while minimum amplitudes occured in summer months. The annual variations of microseisms amplitudes could not be explained by annual variations of storm activity above the North Atlantic. In addition, current analyses also aim at quantitative and quantitative evaluation of synoptic situations for triggering individual microseismic anomalies. Some of the meteorological features, namely the distribution of low pressures above northern Europe and high-pressure areas in Central Europe make it easy to explain most of the microseismic extremes. Here we pay special attention to the influence of large earthquakes, which usually induce slow deformation waves. We conclude that at least three mechanisms of microseism generation are possible: (1) the function of atmospheric pressure at sea level in the North Atlantic, (2) the effects of spreading of thermoelastic waves in the rock mass and (3) deformation waves induced by large earthquakes.