{"title":"复杂三维地震波传播的降阶建模","authors":"John M. Rekoske, Dave A. May, Alice-Agnes Gabriel","doi":"arxiv-2409.06102","DOIUrl":null,"url":null,"abstract":"Elastodynamic Green's functions are an essential ingredient in seismology as\nthey form the connection between direct observations of seismic waves and the\nearthquake source. They are also fundamental to various seismological\ntechniques including physics-based ground motion prediction and kinematic or\ndynamic source inversions. In regions with established 3D models of the Earth's\nelastic structure, 3D Green's functions can be computed using numerical\nsimulations of seismic wave propagation. However, such simulations are\ncomputationally expensive which poses challenges for real-time ground motion\nprediction. Here, we use a reduced-order model (ROM) approach that enables the\nrapid evaluation of approximate Green's functions. The ROM technique developed\napproximates three-component surface velocity wavefields obtained from\nnumerical simulations of seismic wave propagation. We apply our ROM approach to\na 50 km x 40 km area in the greater Los Angeles area accounting for topography,\nsite effects, 3D subsurface velocity structure, and viscoelastic attenuation.\nThe ROM constructed for this region enables rapid computation (0.001 CPU hours)\nof complete, high-resolution, 0.5 Hz surface velocity wavefields that are\naccurate for a shortest wavelength of 1.0 km. Using leave-one-out cross\nvalidation, we measure the accuracy of our Green's functions in both the\ntime-domain and frequency-domain. Averaged across all sources and receivers,\nthe error in the rapid seismograms is less than 0.01 cm/s. We demonstrate that\nthe ROM can accurately and rapidly reproduce simulated seismograms for\ngeneralized moment tensor sources in our region, as well as kinematic sources\nby using a finite fault model of the 1987 Mw 5.9 Whittier Narrows earthquake as\nan example. We envision that our rapid, approximate Green's functions will be\nuseful for constructing rapid ground motion synthetics with high spatial\nresolution.","PeriodicalId":501270,"journal":{"name":"arXiv - PHYS - Geophysics","volume":"410 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Reduced-order modeling for complex 3D seismic wave propagation\",\"authors\":\"John M. Rekoske, Dave A. 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引用次数: 0
摘要
弹性动力格林函数是地震学的基本要素,因为它们构成了地震波直接观测结果与震源之间的联系。它们也是各种地震学技术的基础,包括基于物理的地动预测和运动学顺序动力源反演。在建立了地球弹性结构三维模型的地区,可以使用地震波传播的数值模拟计算三维格林函数。然而,这种模拟计算成本高昂,给实时地动预测带来了挑战。在此,我们采用了一种降低阶数模型(ROM)方法,可以快速评估近似格林函数。所开发的 ROM 技术可近似计算地震波传播数值模拟中获得的三分量表面速度波场。我们将 ROM 方法应用于大洛杉矶地区 50 km x 40 km 的区域,考虑了地形、场地效应、三维地下速度结构和粘弹性衰减。为该区域构建的 ROM 能够快速计算(0.001 CPU 小时)完整的高分辨率 0.5 Hz 表面速度波场,该波场在最短波长为 1.0 km 时是精确的。我们采用 "留一 "交叉验证的方法,测量了格林函数在时域和频域的精度。对所有震源和接收器进行平均,快速地震图的误差小于 0.01 厘米/秒。我们以 1987 年 Mw 5.9 Whittier Narrows 地震的有限断层模型为例,证明 ROM 可以准确、快速地再现本地区广义矩张量震源的模拟地震图以及运动震源的模拟地震图。我们预计,我们的快速近似格林函数将有助于构建具有高空间分辨率的快速地动合成模型。
Reduced-order modeling for complex 3D seismic wave propagation
Elastodynamic Green's functions are an essential ingredient in seismology as
they form the connection between direct observations of seismic waves and the
earthquake source. They are also fundamental to various seismological
techniques including physics-based ground motion prediction and kinematic or
dynamic source inversions. In regions with established 3D models of the Earth's
elastic structure, 3D Green's functions can be computed using numerical
simulations of seismic wave propagation. However, such simulations are
computationally expensive which poses challenges for real-time ground motion
prediction. Here, we use a reduced-order model (ROM) approach that enables the
rapid evaluation of approximate Green's functions. The ROM technique developed
approximates three-component surface velocity wavefields obtained from
numerical simulations of seismic wave propagation. We apply our ROM approach to
a 50 km x 40 km area in the greater Los Angeles area accounting for topography,
site effects, 3D subsurface velocity structure, and viscoelastic attenuation.
The ROM constructed for this region enables rapid computation (0.001 CPU hours)
of complete, high-resolution, 0.5 Hz surface velocity wavefields that are
accurate for a shortest wavelength of 1.0 km. Using leave-one-out cross
validation, we measure the accuracy of our Green's functions in both the
time-domain and frequency-domain. Averaged across all sources and receivers,
the error in the rapid seismograms is less than 0.01 cm/s. We demonstrate that
the ROM can accurately and rapidly reproduce simulated seismograms for
generalized moment tensor sources in our region, as well as kinematic sources
by using a finite fault model of the 1987 Mw 5.9 Whittier Narrows earthquake as
an example. We envision that our rapid, approximate Green's functions will be
useful for constructing rapid ground motion synthetics with high spatial
resolution.