Broad-band seismic analysis and modeling of the 2015 Taan Fjord, Alaska landslide using Instaseis
Broad-band seismic analysis and modeling of the 2015 Taan Fjord, Alaska landslide using Instaseis
复制标题
DOI：
10.1093/gji/ggy086
复制
发表时间：
2018-06-01
影响因子：
2.8
通讯作者：
Ekstrom, Goran
中科院分区：
文献类型：
--
作者：
Gualtieri, Lucia;Ekstrom, Goran
我们对2015年10月17日在Icy Bay（阿拉斯加）附近发生的大规模山体滑坡产生的地震信号进行了宽带分析。该事件产生了全球记录的地震信号。使用Instaseis，一个最近开发的工具，快速计算完整的宽带合成地震图，我们模拟了地震波之间的传播事件和位于滑坡周围的5个地震台站。通过对5-200 s宽频带地震记录的模拟，反演了滑坡时变点力的时间历程。我们计算了滑坡力历史的宽带谱，发现它有一个约100 s的转折周期，对应于滑动的持续时间。与标准地震相比，滑坡力谱在转角频率以下衰减为，而在较高频率处的频谱振幅与ω-2成比例，类似于在地震中看到的频谱衰减速率。从反演的力的历史和最后的运行距离的估计，我们推导出的质量，轨迹和特性的滑坡动力学与质心，如加速度，速度，位移和摩擦。从卫星图像推断出类似于900米的有效跑出距离，我们估计滑坡质量类似于1.5亿公吨。
We carry out a broad-band analysis of the seismic signals generated by a massive landslide that occurred near Icy Bay (Alaska) on 2015 October 17. The event generated seismic signals recorded globally. Using Instaseis, a recently developed tool for rapid computation of complete broad-band synthetic seismograms, we simulate the seismic wave propagation between the event and five seismic stations located around the landslide. By modeling the broad-band seismograms in the period band 5-200 s, we reconstruct by inversion a time-varying point force to characterize the landslide time history. We compute the broad-band spectrum of the landslide force history and find that it has a corner period of about 100 s, corresponding to the duration of sliding. In contrast with standard earthquakes, the landslide force spectrum below the corner frequency decays as., while the spectral amplitudes at higher frequencies is proportional to omega-2, similar to the rate of spectral decay seen in earthquakes. From the inverted force history and an estimate of the final run-out distance, we deduce the mass, the trajectory and characteristics of the landslide dynamics associated with the centre of mass, such as acceleration, velocity, displacement and friction. Inferring an effective run-out distance of similar to 900 m from a satellite image, we estimate a landslide mass of similar to 150 million metric tons.