Airborne LiDAR analysis and geochronology of faulted glacial moraines in the Tahoe-Sierra frontal fault zone reveal substantial seismic hazards in the Lake Tahoe region, California-Nevada, USA
Airborne LiDAR analysis and geochronology of faulted glacial moraines in the Tahoe-Sierra frontal fault zone reveal substantial seismic hazards in the Lake Tahoe region, California-Nevada, USA
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机载激光雷达分析和太浩山脉前断层冰川冰碛的地质年代学揭示了美国加利福尼亚州内华达州太浩湖地区存在重大地震危险
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Brent von Twistern
中科院分区：
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作者：
J. Howle;G. Bawden;R. Schweickert;R. Finkel;L. Hunter;R. S. Rose;Brent von Twistern
我们将高分辨率裸地机载光探测和测距 (LiDAR) 图像与现场观测和现代地质年代学相结合，以描述塔霍-山脉锋断层的特征，该断层形成了内华达山脉与太浩湖以西的盆地和山脉省之间的新构造边界。 LiDAR 图像清楚地描绘了活动的正断层，这些正断层沿着塔霍-塞拉锋断层带的 30 公里线性、右阶梯范围前沿，取代了晚更新世冰川碛石和全新世冲积层。在此，我们说明并描述了断层侧碛的构造地貌。我们开发了新的三维建模技术，利用高分辨率激光雷达数据来确定冰碛顶部和冲积层的构造位移。统计稳健的位移模型与位移 Tioga（20.8 ± 1.4 ka）和 Tahoe（69.2 ± 4.8 ka；73.2 ± 8.7 ka）冰碛的新年龄相结合，用于估计 Tahoe-Sierra 前断层沿线 17 个地点的最小垂直分离率。在研究区域北端附近，最小垂直分离率为 1.5 ± 0.4 毫米/年，这意味着太浩湖盆地地震矩的估计增加了两到三倍。从这项研究中，我们得出结论，潜在地震矩震级 (M w ) 范围为 6.3 ± 0.25 至 6.9 ± 0.25。滑坡和活动断层的密切空间关联表明滑坡是由地震引发的。我们的研究强调，塔霍-塞拉锋断层带来了巨大的地震和山体滑坡危险。
We integrated high-resolution bare-earth airborne light detection and ranging (LiDAR) imagery with field observations and modern geochronology to characterize the Tahoe-Sierra frontal fault zone, which forms the neotectonic boundary between the Sierra Nevada and the Basin and Range Province west of Lake Tahoe. The LiDAR imagery clearly delineates active normal faults that have displaced late Pleistocene glacial moraines and Holocene alluvium along 30 km of linear, right-stepping range front of the Tahoe-Sierra frontal fault zone. Herein, we illustrate and describe the tectonic geomorphology of faulted lateral moraines. We have developed new, three-dimensional modeling techniques that utilize the high-resolution LiDAR data to determine tectonic displacements of moraine crests and alluvium. The statistically robust displacement models combined with new ages of the displaced Tioga (20.8 ± 1.4 ka) and Tahoe (69.2 ± 4.8 ka; 73.2 ± 8.7 ka) moraines are used to estimate the minimum vertical separation rate at 17 sites along the Tahoe-Sierra frontal fault zone. Near the northern end of the study area, the minimum vertical separation rate is 1.5 ± 0.4 mm/yr, which represents a two- to threefold increase in estimates of seismic moment for the Lake Tahoe basin. From this study, we conclude that potential earthquake moment magnitudes (M w ) range from 6.3 ± 0.25 to 6.9 ± 0.25. A close spatial association of landslides and active faults suggests that landslides have been seismically triggered. Our study underscores that the Tahoe-Sierra frontal fault zone poses substantial seismic and landslide hazards.