This data release is composed of three crustal (as opposed to subduction zone) geologic input datasets for the 2023 Alaska update to the U.S. National Seismic Hazard Model (NSHM): 1) fault section vector line data, 2) fault zone vector polygon data, and 3) accompanying earthquake geology attributes.

The U.S. National Seismic Hazard Model (NSHM) for the state of Alaska was updated in 2023 as part of the 50-state NSHM update. The new model incorporates more than 15 years of additional science since the release of the previous model in 2007 and has been reviewed by a six-member review panel and a supplementary eight-member team of ground motion model developers. This time-independent probabilistic seismic hazard model applies new earthquake catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling relations, geologic and geodetic deformation models, and ground motion models. This data release supports the 2023 Alaska NSHM and includes the seismicity catalogs used to develop the model, hazard curves and uniform-hazard ground motions for the state of Alaska, and multiple period response spectra for the Alaska test sites.

The U.S. National Seismic Hazard Model (NSHM) for the state of Alaska was updated in 2023 as part of the 50-state NSHM update. The new model incorporates more than 15 years of additional science since the release of the previous model in 2007 and has been reviewed by a six-member review panel and a supplementary eight-member team of ground motion model developers. This time-independent probabilistic seismic hazard model applies new earthquake catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling relations, geologic and geodetic deformation models, and ground motion models. This data release supports the 2023 Alaska NSHM and includes the seismicity catalogs used to develop the model, hazard curves and uniform-hazard ground motions for the state of Alaska, and multiple period response spectra for the Alaska test sites.

The U.S. National Seismic Hazard Model (NSHM) for the state of Alaska was updated in 2023 as part of the 50-state NSHM update. The new model incorporates more than 15 years of additional science since the release of the previous model in 2007 and has been reviewed by a six-member review panel and a supplementary eight-member team of ground motion model developers. This time-independent probabilistic seismic hazard model applies new earthquake catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling relations, geologic and geodetic deformation models, and ground motion models. This data release supports the 2023 Alaska NSHM and includes the seismicity catalogs used to develop the model, hazard curves and uniform-hazard ground motions for the state of Alaska, and multiple period response spectra for the Alaska test sites.

The U.S. National Seismic Hazard Model (NSHM) for the state of Alaska was updated in 2023 as part of the 50-state NSHM update. The new model incorporates more than 15 years of additional science since the release of the previous model in 2007 and has been reviewed by a six-member review panel and a supplementary eight-member team of ground motion model developers. This time-independent probabilistic seismic hazard model applies new earthquake catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling relations, geologic and geodetic deformation models, and ground motion models. This data release supports the 2023 Alaska NSHM and includes the seismicity catalogs used to develop the model, hazard curves and uniform-hazard ground motions for the state of Alaska, and multiple period response spectra for the Alaska test sites.

This dataset contains earthquake catalogs compiled for Alaska from U.S. Geolgical Survey (USGS) Advanced National Seismic System (ANSS) Comprehensive Earthquake Catalog (ComCat) (USGS, 2017) and Natural Resources Canada (NRCan) Canadian National Earthquake Database (NRCan, 1985) catalog searches and processed following the methods of Mueller (2019) and Llenos et al. (2024). Catalogs are deculstered using multiple methods and segregated into crustal, subduction interface, and subduction intraslab catalogs using Slab2 (Hayes, 2018).

This data release documents proposed updates to geologic inputs (faults) for the upcoming 2023 National Seismic Hazard Model (NSHM). This version (1.0) conveys differences between 2014 NSHM fault sources and those recently released in the earthquake geology inputs for the U.S. National Seismic Hazard Model (NSHM) 2023, version 1.0 data release by Hatem et al. (2021). A notable difference between the 2014 and 2023 datasets is that slip rates are provided at points for 2023 instead of generalized along the entire fault section length as in 2014; consequently, slip rates are not provided for fault sections in the draft 2023 dataset. Geospatial data (shapefile, kml and geojson) are provided in this data release with each fault distinguished as either “addition” for newly added faults, “revised” for faults that have undergone geometry changes, or “no change” for fault geometries that have remained the same as in the 2014 NSHM.

This Data Release contains version 3.0 of two related earthquake geology databases for use in the 2023 U.S. National Seismic Hazard Model. The databases are: 1) A fault sections database (“NSHM23_FSD_v3”), which depicts the geometry of faults capable of hosting independent earthquakes, and 2) an earthquake geology site information database (“NSHM23_EQGeoDB_v3”), which contains fault slip rate constraints at points. These databases cover the 12 western U.S. states: Washington, Oregon, California, Idaho, Nevada, Arizona, Montana, Wyoming, Colorado, New Mexico and Texas. Datasets containing crustal fault information for Alaska and the central and eastern United States were prepared by Bender and others, 2021 and Thompson Jobe and others, 2023 in separate efforts. The two databases are broken into separate child items from this landing page. The databases are provided as geospatial data (.SHP, .KML, and GeoJSON file formats) and tables (.CSV format). Reference information, including change log, version notes, and a README, are included as "Attached Files" below this Summary. Versioning These databases are updated as of December 2023 (version 3.0), which supersede the databases release in February 2022 (version 2.0) and the January 2021 (version 1.0) preliminary datasets. After significant testing by many user groups, this version 3.0 data release contains minor changes. The specific changes made in the fault sections database (FSD) from version 2.0 (2022) to version 3.0 (2023; this release) are outlined in "NSHM23_FSD_v2-v3_VersionChanges.txt." The changes to the EQGeoDB involve fixing typos and further populating the reference list to include UCERF3 references; the authors acknowledge Scott Marshall (Appalachian State University) for uncovering these additional references. Note on the Cheraw fault: At the time of original compilation (2020-2021), the Cheraw fault of Colorado was included in the western U.S. fault sections database. During model implementation, the Cheraw fault was instead treated as a central and eastern U.S. fault. To maintain consistency with earlier releases, we retain the Cheraw fault geometry and attributes in this table. For more information, please review Shumway and others., in press manuscript about CEUS fault implementation. For more information on how these datasets were compiled, please refer to our manuscript publication, Hatem and others, 2022. References Cited Bender, A.M., Haeussler, P.J. and Powers, P.M., 2021, Geologic inputs for the 2023 Alaska update to the U.S. National Seismic Hazard Model (NSHM) (ver. 2.0, February 2023): U.S. Geological Survey data release, https://doi.org/10.5066/P97NRR0F Hatem, A.E., Collett, C.M., Briggs, R.W., Gold, R.D., Angster, S.J., Field, E.H., Powers, P.M. and the Earthquake Geology Working Group, 2022, Simplifying complex fault data for systems-level analysis: Earthquake geology inputs for US NSHM 2023. Scientific data, 9(1), 506. https://doi.org/10.1038/s41597-022-01609-7 Shumway, A.M., Petersen, M.D., Powers, P.M., Toro, G., Altekruse, J. M., Herrick, J.A., Rukstales, K.S., Thompson Jobe, J.A., Hatem, A.E., and Girot, D.L., in press, Earthquake Rupture Forecast Model Construction for the 2023 U.S. 50-State National Seismic Hazard Model Update: Central and Eastern U.S. Fault-Based Source Model. Seismological Research Letters. Thompson Jobe, J.A., Hatem, A.E., Gold, R.D., DuRoss, C., Reitman, N.G., Briggs, R.W., and Collett, C.M., 2022, Earthquake geology inputs for the National Seismic Hazard Model (NSHM) 2023 (central and eastern United States), version 1.0: U.S. Geological Survey data release, https://doi.org/10.5066/P94HLE5G

This Data Release contains version 3.0 of two related earthquake geology databases for use in the 2023 U.S. National Seismic Hazard Model. The databases are: 1) A fault sections database (“NSHM23_FSD_v3”), which depicts the geometry of faults capable of hosting independent earthquakes, and 2) an earthquake geology site information database (“NSHM23_EQGeoDB_v3”), which contains fault slip rate constraints at points. These databases cover the 12 western U.S. states: Washington, Oregon, California, Idaho, Nevada, Arizona, Montana, Wyoming, Colorado, New Mexico and Texas. Datasets containing crustal fault information for Alaska and the central and eastern United States were prepared by Bender and others, 2021 and Thompson Jobe and others, 2023 in separate efforts. The two databases are broken into separate child items from this landing page. The databases are provided as geospatial data (.SHP, .KML, and GeoJSON file formats) and tables (.CSV format). Reference information, including change log, version notes, and a README, are included as "Attached Files" below this Summary. Versioning These databases are updated as of December 2023 (version 3.0), which supersede the databases release in February 2022 (version 2.0) and the January 2021 (version 1.0) preliminary datasets. After significant testing by many user groups, this version 3.0 data release contains minor changes. The specific changes made in the fault sections database (FSD) from version 2.0 (2022) to version 3.0 (2023; this release) are outlined in "NSHM23_FSD_v2-v3_VersionChanges.txt." The changes to the EQGeoDB involve fixing typos and further populating the reference list to include UCERF3 references; the authors acknowledge Scott Marshall (Appalachian State University) for uncovering these additional references. Note on the Cheraw fault: At the time of original compilation (2020-2021), the Cheraw fault of Colorado was included in the western U.S. fault sections database. During model implementation, the Cheraw fault was instead treated as a central and eastern U.S. fault. To maintain consistency with earlier releases, we retain the Cheraw fault geometry and attributes in this table. For more information, please review Shumway and others., in press manuscript about CEUS fault implementation. For more information on how these datasets were compiled, please refer to our manuscript publication, Hatem and others, 2022. References Cited Bender, A.M., Haeussler, P.J. and Powers, P.M., 2021, Geologic inputs for the 2023 Alaska update to the U.S. National Seismic Hazard Model (NSHM) (ver. 2.0, February 2023): U.S. Geological Survey data release, https://doi.org/10.5066/P97NRR0F Hatem, A.E., Collett, C.M., Briggs, R.W., Gold, R.D., Angster, S.J., Field, E.H., Powers, P.M. and the Earthquake Geology Working Group, 2022, Simplifying complex fault data for systems-level analysis: Earthquake geology inputs for US NSHM 2023. Scientific data, 9(1), 506. https://doi.org/10.1038/s41597-022-01609-7 Shumway, A.M., Petersen, M.D., Powers, P.M., Toro, G., Altekruse, J. M., Herrick, J.A., Rukstales, K.S., Thompson Jobe, J.A., Hatem, A.E., and Girot, D.L., in press, Earthquake Rupture Forecast Model Construction for the 2023 U.S. 50-State National Seismic Hazard Model Update: Central and Eastern U.S. Fault-Based Source Model. Seismological Research Letters. Thompson Jobe, J.A., Hatem, A.E., Gold, R.D., DuRoss, C., Reitman, N.G., Briggs, R.W., and Collett, C.M., 2022, Earthquake geology inputs for the National Seismic Hazard Model (NSHM) 2023 (central and eastern United States), version 1.0: U.S. Geological Survey data release, https://doi.org/10.5066/P94HLE5G

Gridded seismic hazard curve data, gridded ground motion data, and mapped gridded ground motion values are available for the 2007 Alaska Seismic Hazard Model. Time-independent probabilistic seismic hazard data and maps of Alaska and the Aleutians for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 1.0 and 2.0 second spectral acceleration at probability levels of 2 percent in 50 years (annual probability of 0.000404), 5 percent in 50 years (annual probability of 0.001026), and 10 percent in 50 years (annual probability of 0.0021) assuming firm rock soil conditions at 760 m/s are available. Development of the 2007 Alaska Seismic Hazard Model is documented in the USGS Open-File Report 2007-1043 (https://pubs.usgs.gov/of/2007/1043/). This dataset is considered a legacy dataset. The original dataset was uploaded to the USGS website at the time of publication of the seismic hazard model (2007) but was later moved over the the USGS ScienceBase Catalog (2019). The original dataset was assumed to be complete and accurate, but may contain inconsistencies when compared to more recent, actively maintained datasets.