Significant Seismic Risk Potential From Buried Faults Beneath Almaty City, Kazakhstan, Revealed From High-Resolution Satellite DEMs
Significant Seismic Risk Potential From Buried Faults Beneath Almaty City, Kazakhstan, Revealed From High-Resolution Satellite DEMs
复制标题
高分辨率卫星 DEM 显示哈萨克斯坦阿拉木图市地下埋藏断层存在重大地震风险
DOI：
10.1029/2021ea001664
复制
发表时间：
2021
影响因子：
3.1
通讯作者：
Amey R
中科院分区：
文献类型：
--
作者：
Amey R
中亚天山地区的主要断裂具有较长的重复时间，但在大（7+）地震中失效。此外，在主断层之外可能存在较小的埋藏断层，这些断层没有被正确地表征，甚至没有被认为是活动的。这些都对哈萨克斯坦阿拉木图等沿着山脉前沿的城市构成威胁。在这里，我们探讨了阿拉木图的地震危险性和风险，从特定的地震场景。我们在当前人口和四个假设的近场断层情况下运行三个基于历史的地震情景（1887年Verny 7.3，1889年Chilik 8.0和1911年Chon Kemin 8.0）。通过从SPOT和Pleiades立体光学卫星图像制作高分辨率数字高程模型（DEM），我们识别了阿拉木图附近和下方的断层展布。我们评估了使用DEM估计城市建筑物高度的可行性，旨在更好地约束未来的曝光数据集。Pleiades和SPOT衍生的DEM都能在误差范围内找到大多数抽样建筑物的准确建筑物高度; Pleiades tri‐stereo在1 sigma内估计了15个建筑物高度中的80%，并且与现场测量高度的平均百分比差异最小（14%）。在阿拉木图北部褶皱下的一个盲冲断层上发生的中等规模的6.5级地震破裂是这里探讨的最具破坏性的场景，由于模型断层在阿拉木图下方延伸，估计有12，3005，000座完全损坏的建筑物，4，100 3，500人死亡，经济成本为4，700 2，700百万美元（一西格玛不确定性）。这突出了表征城市下方小断层的位置、范围、几何形状和活动的重要性。
Major faults of the Tien Shan, Central Asia, have long repeat times, but fail in large ( 7+) earthquakes. In addition, there may be smaller, buried faults off the major faults which are not properly characterized or even recognized as active. These all pose hazard to cities along the mountain range front such as Almaty, Kazakhstan. Here, we explore the seismic hazard and risk for Almaty from specific earthquake scenarios. We run three historical‐based earthquake scenarios (1887 Verny 7.3, 1889 Chilik 8.0 and 1911 Chon‐Kemin 8.0) on the current population and four hypothetical scenarios for near‐field faulting. By making high‐resolution Digital Elevation Models (DEMs) from SPOT and Pleiades stereo optical satellite imagery, we identify fault splays near and under Almaty. We assess the feasibility of using DEMs to estimate city building heights, aiming to better constrain future exposure datasets. Both Pleiades and SPOT‐derived DEMs find accurate building heights of the majority of sampled buildings within error; Pleiades tri‐stereo estimates 80% of 15 building heights within one sigma and has the smallest average percentage difference to field‐measured heights (14%). A moderately sized 6.5 earthquake rupture occurring on a blind thrust fault, under folding north of Almaty is the most damaging scenario explored here due to the modeled fault stretching under Almaty, with estimated 12,3005,000 completely damaged buildings, 4,100 3,500 fatalities and an economic cost of 4,700 2,700 Million US dollars (one sigma uncertainty). This highlights the importance of characterizing location, extent, geometry, and activity of small faults beneath cities.