| 講演要旨(和文) | | 2015年4月から6月，サウジアラビアAl Wasseフィールドにおいて弾性波アクロス震源と地震計アレイを用いたタイムラプス観測を行った．P波部分の波形・振幅はほとんど変化が見られなかったが，P波部分の相互相関解析によって2か月半の間に最大で1.5ミリ秒の走時変化が検出された．一方で後続波は非常に大きい波形と振幅の変化を示した．後続波はレイリー波からなると考えられるが，時間変化は極めて局所的であり，気温変動による日周変化の他に地下水の汲み上げに伴う帯水層の変動に起因している可能性がある． |
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| | 講演要旨(英文) | | In Al Wasse field in the Kingdom of Saudi Arabia, we carried out the time-lapse study using an ACROSS seismic source and a geophone array from April to June, 2015. The amplitude and/or waveform change of P-wave portions are extremely small. The cross-correlation analysis of P-wave portions suggests that the temporal change of P-wave travel time could be 1.5 ms during two and half moths. On the other hand, later arrivals show much large change of waveforms and amplitude. Temporal changes in the later arrivals probably dominated by Raleigh waves are much localized and could be caused by movement of the aquifer layer due to water pumping besides the temperature effect causing the daily variation. |
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