北海道大学地球物理学研究報告 = Geophysical bulletin of Hokkaido University;第72号

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上杵臼ひずみ高精度記録からの鋸歯状成分の除去について

雨宮, 晋一郎;高波, 鐵夫;北川, 源四郎

Permalink : http://hdl.handle.net/2115/38156
JaLCDOI : 10.14943/gbhu.72.231

Abstract

Recently, high precision high frequency A/D converter system was installed for the strainmeters in Urakawa Seismological Observatory, Kami-Kineusu, Urakawa, Hokkaido, Japan. The record could be used as seismogram with very wide frequency-band as well as measuring geodetic deformation. However, a peculiar saw-shape wave was found in the record and it prevents from extracting the component of seismic waves. In this paper, we develop a statistical model for decomposing the observed strainmeter time series into two components: one is the low-frequency component that consists of the effect of air pressure and earth tide, and the other is the saw-shape component, which is the high-frequency component consisting of random noise and the seismic wave. The method was applied to several data set and verified that it can reasonably decompose the time series and extract seismic waves. The possibility of improving the model and the cause of the saw-shape wave are also discussed.

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