SCEC Community Fault Model (CFM)

<strong>Introduction</strong> The SCEC Community Fault Model (CFM) is an object-oriented, three-dimensional representation of active faults in southern California and adjacent offshore basins. For each fault object, the CFM provides triangulated surface representations (t-surfs) in several resolutions, fault traces in several different file formats (shape files, GMT plain text, and GoogleEarth kml), and complete metadata including references used to constrain the surfaces. The CFM faults are defined based on all available data including surface traces, seismicity, seismic reflection profiles, well data, geologic cross sections, and various other types of data and models. The CFM serves the Southern California Earthquake Center (SCEC) as a unified resource for physics-based fault systems modeling, strong ground-motion prediction, and probabilistic seismic hazards assessment (e.g., UCERF3). Together with the Community Velocity Model (CVM-H 15.1.0), the CFM comprises SCEC's Unified Structural Representation of the Southern California crust and upper mantle (Shaw et al., 2015). <strong>Current Model Version: CFM6.1</strong> The current version of the SCEC Community Fault Model version 6.1 (CFM6.1) and is partially the result of a community evaluation of CFM5.3. CFM6.1 serves as the latest update to Plesch et al. (2007) and builds on previous CFM releases. New to CFM6.1 are two additional separate and fully-documented sub models: the ruptures and alternatives model. In total, CFM6.1 comprises the following components: The CFM6.1 Preferred Model: a set of 443 fault objects that constitute the preferred set of active faults in southern California. The CFM6.1 Rupture Model: a set of 13 fault objects assembled from the CFM6.1 preferred model that ruptured during selected significant historic events. These are not earthquake source models, but are representations of the entire fault surfaces where a significant historic rupture occurred. This model is intended to indicate which CFM fault objects were involved with selected significant historic ruptures. The CFM6.1 Alternatives: a set of 38 alternative representations where structural differences have been proposed that could potentially significantly impact fault mechanics and associated seismic hazards. These alternative representations were selected based on community rankings following a comprehensive evaluation of the CFM that took place in May of 2022. Including all sub models, the CFM6.1 incorporates 494 fully-documented objects. If you use the CFM, we would appreciate you citing the DOI where the archive is stored. <strong>CFM6.1 Change Log</strong> CFM6.1 differs from CFM6.0 in several ways, as described below. The Southern San Andreas fault was updated to the dipping model based on Fuis et al., (2012) which also contains a portion of the Banning fault. SAFS-SAFZ-MULT-Southern_San_Andreas_fault_and_Banning-CFM6 is now the preferred representation. Naming of this object is challenging because this object contains both what is typically referred to as the Southern San Andreas fault and a portion of the Banning fault. This is included in the metadata comments. SAFS-SAFZ-COAV-Southern_San_Andreas_fault-CFM4 (Steeply dipping) is now an alternative representation, SAFS-SAFZ-COAV-Southern_San_Andreas_fault-ALT6. The East Shoreline fault has been shortened to not extend north of Mecca Hills. SAFS-SAFZ-COAV-East_Shoreline_fault-CFM6 is the preferred version (same name in CFM6.0) and now no longer extends north of Mecca Hills. This is consistent with Janecke et al. (2019) where north of Mecca Hills the fault presence and location is mapped as speculative. The longer SAFS-SAFZ-COAV-East_Shoreline_fault-CFM5 is now provided as an alternative, SAFS-SAFZ-COAV-East_Shoreline_fault-ALT6. The Malibu Coast fault (east segment) has been truncated and merges with the Malibu Coast fault (west segment) and no longer extends farther to the west. The object name, WTRA-SFFS-SMMT-Malibu_Coast_fault_east-CFM6, remains the same. <strong>Directory Structure and Contents of the CFM6 Archive</strong> The archive directory structure is as follows: <strong>doc/</strong><br> Documentation and metadata, which include an MS Excel spreadsheet with detailed metadata about each fault surface. Metadata for the preferred, rupture, and alternative models are provided in separate but otherwise identically formatted sheets within the file. All faults contain references to the works that helped to define the 3D fault surface geometry. More information about the metadata columns is provided in doc/README.txt <strong>obj/preferred/<br> obj/ruptures/<br> obj/alternatives/</strong><br> These directories contain the model components for the preferred, rupture, and alternative models, respectively. Each model contains an identical directory structure, which is described below using the preferred model as an example. <strong>obj/preferred/native/</strong><br> The CFM6.1 preferred fault surfaces in gocad tsurf format using the native mesh. The native mesh uses a variable mesh resolution. Smaller triangles generally indicate where a fault is well-constrained by data. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711). <strong>obj/preferred/500m/</strong><br> The CFM6.1 preferred fault surfaces with a semi-regularized mesh of ~500m resolution in gocad tsurf format. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711). <strong>obj/preferred/1000m/</strong><br> The CFM6.1 preferred fault surfaces with a semi-regularized mesh of ~1000m resolution in gocad tsurf format. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711). <strong>obj/preferred/2000m/</strong><br> The CFM6.1 preferred fault surfaces with a semi-regularized mesh of ~2000m resolution in gocad tsurf format. All tsurf files are provided in UTM zone 11 using the NAD27 datum (EPSG:26711). <strong>obj/preferred/traces/</strong><br> Fault traces and upper tip lines (for blind faults) of the CFM6.1 preferred faults. While the CFM6.1 is a 3D model, it is often useful to make map-based visualizations of the model. The traces and blind faults are provided in several different formats described below. <strong>obj/preferred/traces/gmt/</strong><br> Fault traces and blind faults in Generic Mapping Tools multisegment ASCII format (i.e., plain text). .lonLat - Longitude/Latitude coordinates (WGS84 datum)<br> .utm - UTM zone 11 NAD27 datum (EPSG:26711) <strong>obj/preferred/traces/kml/</strong><br> Fault traces and blind faults in Google Earth .kml format (WGS84 datum). The kml files also contain selected metadata, which pops up if a fault is clicked on in the Google Earth interface. <strong>obj/preferred/traces/shp/</strong><br> Fault traces and blind faults in GIS shapefile format. Longitude/Latitude coordinates (WGS84 datum). <strong>CFM Contributors</strong> The current and past versions of the CFM would not be possible without contributions from numerous SCEC community members. We would like to thank the following CFM contributors: Christine Benson, William Bryant, Sara Carena, Michele Cooke, James Dolan, Jessica Don, Gary Fuis, Eldon Gath, Judith Hubbard, Susanne Janecke, Yuval Levy, Lisa Grant Ludwig, Egill Hauksson, Thomas Jordan, Marc Kamerling, Mark Legg, Scott Lindvall, Harold Magistrale, Scott Marshall, Jonathan Matti, Craig Nicholson, Nathan Niemi, Michael Oskin, Sue Perry, George Planansky, Andreas Plesch, Thomas Rockwell, John Shaw, Peter Shearer, Christopher Sorlien, M. Peter Süss, John Suppe, Jerry Treiman, Franklin Wolfe, Robert Yeats, and every colleague that has participated in a CFM community evaluation. We could not make the CFM without this community effort. <strong>CFM Evaluators</strong> Before assembling CFM6.1, a team of SCEC colleagues participated in a rigorous evaluation of CFM5.3 in April-May of 2022. This evaluation was open to the SCEC community and focused on 23 critical fault representations where different proposed interpretations have the potential to significantly affect seismic hazards. This evaluation resulted in 14 new fault representations in the CFM6.1 preferred model. The lower ranked representations are now provided in the CFM6.1 alternative model. We would like to thank the following CFM evaluators for volunteering their time and expertise to this process: Sinan Akçiz, Sara Carena, Michele Cooke, Tim Dawson, Jessica Don, Austin Elliot, Erik Frost, Gary Fuis, Athanassios Ganas, Eldon Gath, Alex Hatem, Susanne Janecke, Marc Kamerling, Christodoulos Kyriakopoulos, Mark Legg, Karen Luttrell, Chris Madugo, Scott Marshall, Andrew Meigs, Craig Nicholson, Nate Onderdonk, Alba Rodríguez Padilla, Andreas Plesch, Kate Scharer, John Shaw, Chris Sorlien, Franklin Wolfe, Doug Yule, Judy Zachariasen. <strong>References</strong> ● Evans, W. S., Plesch, A., Shaw, J. H., Pillai, N. L., Yu, E., Meier, M., &amp; Hauksson, E. (2020). A Statistical Method for Associating Earthquakes with Their Source Faults in Southern California. Bulletin of the Seismological Society of America, 110(1), 213-225. doi: 10.1785/0120190115. SCEC Contribution 9057 ● Hauksson, E., Yang, W., and Shearer, P. M., "Waveform Relocated Earthquake Catalog for Southern California (1981 to 2011)"; Bull. Seismol. Soc. Am., Vol. 102, No. 5, pp.2239-2244, October 2012, doi: 10.1785/0120120010 SCEC Contribution 1528 ● Plesch, A., et al. (2007). "Community Fault Model (CFM) for Southern California." Bulletin of the Seismological Society of America 97: 1793-1802. SCEC Contribution 1134 ● Plesch, A., Marshall, S. T., Nicholson, C., Shaw, J. H., Maechling, P. J., &amp; Su, M. (2020, 08). The Community Fault Model version 5.3 and new web-based tools. Poster Presentation at 2020 SCEC Annual Meeting. SCEC Contribution 10547 ● Shaw, J. H., Plesch, A., Tape, C., Suess, M., Jordan, T. H., Ely, G., Hauksson, E., Tromp, J., Tanimoto, T., Graves, R., Olsen, K., Nicholson, C., Maechling, P. J., Rivero, C., Lovely, P., Brankman, C. M., &amp; Munster, J. (2015). Unified Structural Representation of the southern California crust and upper mantle. Earth and Planetary Science Letters, 415, 1-15. doi: 10.1016/j.epsl.2015.01.016. SCEC Contribution 2068引言 南加州地震中心社区断层模型（SCEC Community Fault Model, CFM）是一款面向对象的三维模型，用于表征南加州及邻近近海盆地的活动断层。针对每个断层对象，CFM 提供多种分辨率的三角化曲面表示（t-surfs）、多种文件格式的断层迹线（包括形状文件、通用制图工具（Generic Mapping Tools, GMT）纯文本格式以及谷歌地球（GoogleEarth）kml 格式），以及包含曲面约束依据的完整元数据。CFM 中的断层基于所有可用数据定义，包括地表迹线、地震活动性、地震反射剖面、测井数据、地质剖面以及其他各类数据与模型。CFM 作为南加州地震中心（Southern California Earthquake Center, SCEC）的统一资源，服务于基于物理的断层系统建模、强地面运动预测以及概率地震危险性评估（如UCERF3）。结合社区速度模型（Community Velocity Model, CVM-H 15.1.0），CFM 共同构成了 SCEC 的南加州地壳与上地幔统一结构表征（Shaw 等, 2015）。 当前模型版本：CFM6.1 SCEC 社区断层模型当前版本为 6.1（CFM6.1），其部分内容源于对 CFM5.3 的社区评估。CFM6.1 是对 Plesch 等（2007）的最新更新，基于此前的 CFM 版本迭代而来。CFM6.1 新增了两个独立且完全文档化的子模型：破裂模型与备选模型。总体而言，CFM6.1 包含以下组件： 1. CFM6.1 优选模型：包含 443 个断层对象，构成南加州活动断层的优选集合。 2. CFM6.1 破裂模型：从 CFM6.1 优选模型中选取的 13 个断层对象，对应历史上发生过重大破裂事件的断层。该模型并非地震震源模型，而是表征曾发生重大历史破裂的完整断层表面，用于指示哪些 CFM 断层对象参与了选定的重大历史破裂事件。 3. CFM6.1 备选模型：包含 38 种备选表征方案，这些方案提出了可能显著影响断层力学与相关地震危险性的结构差异。这些备选表征基于 2022 年 5 月开展的 CFM 全面评估后的社区投票结果筛选而来。 若包含所有子模型，CFM6.1 共计纳入 494 个完全文档化的对象。若您使用 CFM 数据集，烦请引用数据存档的 DOI 编号。 CFM6.1 更新日志 如下所述，CFM6.1 与 CFM6.0 存在多处差异： 1. 南圣安德烈亚斯断层已更新为基于 Fuis 等（2012）提出的倾滑模型，该模型同时包含班宁断层（Banning fault）的一部分。当前优选表征为 SAFS-SAFZ-MULT-Southern_San_Andreas_fault_and_Banning-CFM6。由于该对象同时涵盖通常所称的南圣安德烈亚斯断层与班宁断层的一部分，其命名存在一定挑战，相关说明已纳入元数据注释。此前的 SAFS-SAFZ-COAV-Southern_San_Andreas_fault-CFM4（陡倾模型）现已作为备选表征 SAFS-SAFZ-COAV-Southern_San_Andreas_fault-ALT6 提供。 2. 东海岸线断层（East Shoreline fault）已被缩短，不再向北延伸至梅卡丘陵（Mecca Hills）以北。当前优选版本为 SAFS-SAFZ-COAV-East_Shoreline_fault-CFM6（与 CFM6.0 同名），现已调整为不向北延伸至梅卡丘陵以北，这与 Janecke 等（2019）的研究成果一致，该研究表明梅卡丘陵以北的断层存在与位置均为推测性的。原更长版本 SAFS-SAFZ-COAV-East_Shoreline_fault-CFM5 现已作为备选模型 SAFS-SAFZ-COAV-East_Shoreline_fault-ALT6 提供。 3. 马里布海岸断层（东段）已被截断，并与马里布海岸断层（西段）合并，不再向西延伸更远。其对象名称 WTRA-SFFS-SMMT-Malibu_Coast_fault_east-CFM6 保持不变。 CFM6.1 存档目录结构与内容 存档的目录结构如下： - doc/：文档与元数据，包含一份微软 Excel（MS Excel）电子表格，其中记录了每个断层曲面的详细元数据。优选模型、破裂模型与备选模型的元数据分别存储于该文件内的不同工作表中，格式完全一致。所有断层条目均附有用于定义其三维曲面几何形态的参考文献。元数据列的更多说明可参考 doc/README.txt 文件。 - obj/preferred/、obj/ruptures/、obj/alternatives/：分别存储优选模型、破裂模型与备选模型的组件。每个模型的目录结构完全一致，下文以优选模型为例进行说明。 - obj/preferred/native/：存储 CFM6.1 优选断层曲面的 gocad tsurf 格式文件，采用原生网格。原生网格使用可变分辨率，三角形尺寸越小代表该断层受数据约束程度越高。所有 tsurf 文件均采用 UTM 11 坐标系，基准面为 NAD27（EPSG:26711）。 - obj/preferred/500m/：存储 CFM6.1 优选断层曲面的 gocad tsurf 格式文件，采用约 500 米分辨率的半规则化网格。所有 tsurf 文件均采用 UTM 11 坐标系，基准面为 NAD27（EPSG:26711）。 - obj/preferred/1000m/：存储 CFM6.1 优选断层曲面的 gocad tsurf 格式文件，采用约 1000 米分辨率的半规则化网格。所有 tsurf 文件均采用 UTM 11 坐标系，基准面为 NAD27（EPSG:26711）。 - obj/preferred/2000m/：存储 CFM6.1 优选断层曲面的 gocad tsurf 格式文件，采用约 2000 米分辨率的半规则化网格。所有 tsurf 文件均采用 UTM 11 坐标系，基准面为 NAD27（EPSG:26711）。 - obj/preferred/traces/：存储 CFM6.1 优选断层的断层迹线与上尖端线（针对隐伏断层）。尽管 CFM6.1 是三维模型，但通常需要基于该模型制作地图可视化成果。迹线与隐伏断层文件提供了多种格式，如下所述： - obj/preferred/traces/gmt/：存储通用制图工具（GMT）多段线 ASCII 格式（即纯文本格式）的断层迹线与隐伏断层文件，包含两种子格式：.lonLat 为经纬度坐标（WGS84 基准面）；.utm 为 UTM 11 坐标系，NAD27 基准面（EPSG:26711）。 - obj/preferred/traces/kml/：存储谷歌地球（GoogleEarth）.kml 格式的断层迹线与隐伏断层文件（WGS84 基准面）。该 kml 文件包含选定的元数据，在谷歌地球界面中点击断层时会弹出相关信息。 - obj/preferred/traces/shp/：存储地理信息系统（GIS）形状文件格式的断层迹线与隐伏断层文件，采用经纬度坐标（WGS84 基准面）。 CFM 贡献者 CFM 的当前与历史版本离不开众多 SCEC 社区成员的贡献。特此感谢以下 CFM 贡献者：Christine Benson、William Bryant、Sara Carena、Michele Cooke、James Dolan、Jessica Don、Gary Fuis、Eldon Gath、Judith Hubbard、Susanne Janecke、Yuval Levy、Lisa Grant Ludwig、Egill Hauksson、Thomas Jordan、Marc Kamerling、Mark Legg、Scott Lindvall、Harold Magistrale、Scott Marshall、Jonathan Matti、Craig Nicholson、Nathan Niemi、Michael Oskin、Sue Perry、George Planansky、Andreas Plesch、Thomas Rockwell、John Shaw、Peter Shearer、Christopher Sorlien、M. Peter Süss、John Suppe、Jerry Treiman、Franklin Wolfe、Robert Yeats，以及所有参与过 CFM 社区评估的同仁。若无社区的共同努力，我们无法构建 CFM 数据集。 CFM 评估者 在组装 CFM6.1 之前，一支 SCEC 同事团队于 2022 年 4 月至 5 月对 CFM5.3 开展了严格评估。该评估面向 SCEC 社区开放，重点关注 23 处关键断层表征，这些表征的不同解释方案可能显著影响地震危险性评估结果。本次评估最终为 CFM6.1 优选模型新增了 14 处断层表征，排名较低的表征方案现已纳入 CFM6.1 备选模型。特此感谢以下自愿投入时间与专业知识参与本次评估的 CFM 评估者：Sinan Akçiz、Sara Carena、Michele Cooke、Tim Dawson、Jessica Don、Austin Elliot、Erik Frost、Gary Fuis、Athanassios Ganas、Eldon Gath、Alex Hatem、Susanne Janecke、Marc Kamerling、Christodoulos Kyriakopoulos、Mark Legg、Karen Luttrell、Chris Madugo、Scott Marshall、Andrew Meigs、Craig Nicholson、Nate Onderdonk、Alba Rodríguez Padilla、Andreas Plesch、Kate Scharer、John Shaw、Chris Sorlien、Franklin Wolfe、Doug Yule、Judy Zachariasen。 参考文献 1. Evans, W. S., Plesch, A., Shaw, J. H., Pillai, N. L., Yu, E., Meier, M., & Hauksson, E. (2020). 一种用于南加州地震与震源断层关联的统计方法. 《地震学会会刊》(Bulletin of the Seismological Society of America), 110(1), 213-225. doi: 10.1785/0120190115. SCEC 贡献编号 9057 2. Hauksson, E., Yang, W., & Shearer, P. M. (2012). 南加州地震波形重定位目录（1981 至 2011年）. 《地震学会会刊》(Bulletin of the Seismological Society of America), 第102卷, 第5期, 2239-2244页, 2012年10月. doi: 10.1785/0120120010. SCEC 贡献编号 1528 3. Plesch, A., et al. (2007). 南加州社区断层模型（CFM）. 《地震学会会刊》(Bulletin of the Seismological Society of America) 97: 1793-1802. SCEC 贡献编号 1134 4. Plesch, A., Marshall, S. T., Nicholson, C., Shaw, J. H., Maechling, P. J., & Su, M. (2020, 08). 社区断层模型5.3版与新型网络工具. 2020年SCEC年会海报展示. SCEC 贡献编号 10547 5. Shaw, J. H., Plesch, A., Tape, C., Suess, M., Jordan, T. H., Ely, G., Hauksson, E., Tromp, J., Tanimoto, T., Graves, R., Olsen, K., Nicholson, C., Maechling, P. J., Rivero, C., Lovely, P., Brankman, C. M., & Munster, J. (2015). 南加州地壳与上地幔统一结构表征. 《地球与行星科学快报》(Earth and Planetary Science Letters), 415, 1-15. doi: 10.1016/j.epsl.2015.01.016. SCEC 贡献编号 2068