トレンド成分の発生を抑えた地震記録の積分手法による変位波形計算

摘要

近年では，高密度観測網の展開により，膨大な強震記録が得られるようになった。特に，変位波形は地動の動きを知る上で大変貴重なデータであり，様々な場面に利用される。変位波形を得るためには，加速度波形を2回積分して求める必要がある。%Computing a residual displacement by measured acceleration is important for understanding the characteristics of an earthquake. However, such a residual displacement is not necessarily be obtained with a good accuracy. It is partly because the low-frequency component dominating the behavior of the residual displacement is often affected by the sensor's tilt and the measurement error. In this paper, a new methodology to get the acceleration without those undesirable effects is proposed. In addition, the integration method in frequency domain for computing displacement from the obtained acceleration is proposed, considering causality as a constraint to avoid the numerical error. Using these techniques, the estimation of residual displacement of Iwate-Miyagi Nairiku Earthquake (2008) is attempted.