Near-field seismic displacement and tilt associated with the explosive activity of Stromboli
Near-field seismic displacement and tilt associated with the explosive activity of Stromboli
复制标题
与斯特龙博利爆炸活动相关的近场地震位移和倾斜
DOI：
10.4401/ag-3723
复制
发表时间：
1999
影响因子：
1
通讯作者：
T. Forbriger
中科院分区：
文献类型：
--
作者：
E. Wielandt;T. Forbriger
宽带地震记录在近场的Strombolian爆炸，在500米的距离，显示出明显的倾斜效果。倾斜信号在超过约50 s周期的水平分量中占主导地位，而在垂直分量中可以忽略不计。在地震检波器输出端的倾斜信号波形是由于地面位移引起的波形的双重时间积分。由于位移的波形是从垂直分量中已知的，因此可以重建水平地震记录中的倾斜信号的波形，并且可以利用线性回归将这两种贡献彼此分离。我们分析了1995年和1996年在斯特龙博利峰地区记录的数据。区域倾斜可以根据相距几十米的仪器之间的差异垂直位移来确定。用个别仪器测定的局部倾斜分散在区域值周围，最有可能是由于局部应变倾斜耦合。用Mogi（1958）关于均匀半空间中压力源的公式来解释结果。在爆炸前，震源移动了数十立方米的周围岩石; 1995年7月的典型体积为25立方米，1996年9月为60立方米。
Broadband seismic recordings in the near-field of Strombolian explosions, at 500 m distance, show pronounced effects of tilt. The tilt signal is predominant in the horizontal components beyond about 50 s period while it is negligible in the vertical component. The waveform of the tilt signal at the seismometer output is a double time integral of the waveform due to ground displacement. Since the waveform of the displacement is known from the vertical component, the waveform of the tilt signal in the horizontal seismogram can be reconstructed and both contributions can be separated from each other with a linear regression. We have analyzed data recorded in the summit region of Stromboli in 1995 and 1996. The regional tilt can be determined from the differential vertical displacement between instruments a few tens of meters apart. Local tilts determined with individual instruments scatter around the regional value, most probably due to local strain-tilt-coupling. Mogi's (1958) formulae for a pressure source in a homogeneous halfspace are used to interpret the results. The source displaces a volume of several tens of cubic meters of the surrounding rock before the explosive discharge; typical volumes were 25 m3 in July 1995 and 60 m3 in September 1996.