3D Simulations of M 7 Earthquakes on the Wasatch Fault, Utah, Part I: Long-Period (0-1 Hz) Ground Motion
3D Simulations of M 7 Earthquakes on the Wasatch Fault, Utah, Part I: Long-Period (0-1 Hz) Ground Motion
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犹他州瓦萨奇断层上的 7 级地震的 3D 模拟，第一部分：长周期 (0-1 Hz) 地面运动
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发表时间：
2011
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通讯作者：
H. Magistrale
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作者：
D. Roten;K. Olsen;J. C. Pechmann;V. Cruz‐Atienza;H. Magistrale
摘要我们预测了Wasatch断层湖城段7级地震时盐湖盆地（SLB）的地震动。首先，我们生成一套真实的源表示通过模拟自发破裂过程中的平面，垂直断层交错网格分裂节点有限差分（FD）方法。剪切应力的初始分布是适合于倾斜正断层的区域深度相关剪切应力和与先前破裂相关的随机产生的残余剪切应力场的总和。从自发破裂的情况下的滑动率的历史被投射到一个详细的三维模型几何形状的WFSLC，我们开发的地质观测的基础上。接下来，我们模拟0- 1-Hz波传播从六个源模型与3DFD代码，使用最新版本的Wasatch前社区速度模型。水平频谱加速度在两秒钟（2-S SA）揭示了强大的沿走向破裂方向的影响，单边破裂，以及显着放大的低速沉积物的断层上盘侧。对于断裂成核的南端附近的部分，我们得到2-S SA的高达1.4克的SLC市中心附近，由断裂方向和盆地边缘的影响相结合所造成的。平均3-s SA和2-s SA从六种情况下，一般是一致的值预测的四个下一代衰减模型。
Abstract We predict ground motions in the Salt Lake basin (SLB) during M 7 earthquakes on the Salt Lake City segment of the Wasatch fault (WFSLC). First we generate a suite of realistic source representations by simulating the spontaneous rupture process on a planar, vertical fault with the staggered-grid split-node finite-difference (FD) method. The initial distribution of shear stress is the sum of both a regional depth-dependent shear stress appropriate for a dipping, normal fault and a stochastically generated residual shear stress field associated with previous ruptures. The slip-rate histories from the spontaneous rupture scenarios are projected onto a detailed 3D model geometry of the WFSLC that we developed based on geological observations. Next, we simulate 0- to 1-Hz wave propagation from six source models with a 3DFD code, using the most recent version of the Wasatch Front Community Velocity model. Horizontal spectral accelerations at two seconds (2-s SAs) reveal strong along-strike rupture direction effects for unilateral ruptures, as well as significant amplifications by the low-velocity sediments on the hanging-wall side of the fault. For ruptures nucleating near the southern end of the segment, we obtain 2-s SAs of up to 1.4 g near downtown SLC, caused by a combination of rupture-direction and basin-edge effects. Average 3-s SAs and 2-s SAs from the six scenarios are generally consistent with values predicted by four next-generation attenuation models.