Sean Kamran Ahdi (Former Employee)
Science and Products
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as...
Updated Compilation of VS30 Data for the United States Updated Compilation of VS30 Data for the United States
VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30...
Filter Total Items: 19
2023 Earthquake Ground-Motion Workshop for the Central and Eastern United States, with a focus on the Gulf and Atlantic Coastal Plains—Agenda and abstracts 2023 Earthquake Ground-Motion Workshop for the Central and Eastern United States, with a focus on the Gulf and Atlantic Coastal Plains—Agenda and abstracts
The U.S. Geological Survey held a virtual workshop December 7–8, 2023, to share research and ideas about earthquake ground motions in the Central and Eastern United States, with a focus on the Atlantic and Gulf Coastal Plains. The workshop was organized to learn about potential regionalization of ground-motion characteristics (source, path, and site), consider new explanatory variables...
Authors
Oliver S. Boyd, Julie A. Herrick, Ashly Cabas, Sean Kamran Ahdi
The 2023 U.S. National Seismic Hazard Model: Subduction ground motion models The 2023 U.S. National Seismic Hazard Model: Subduction ground motion models
The US Geological Survey National Seismic Hazard Models (NSHMs) are used to calculate earthquake ground-shaking intensities for design and rehabilitation of structures in the United States. The most recent 2014 and 2018 versions of the NSHM for the conterminous United States included major updates to ground-motion models (GMMs) for active and stable crustal tectonic settings; however...
Authors
Sanaz Rezaeian, Peter M. Powers, Jason M. Altekruse, Sean Kamran Ahdi, Mark D. Petersen, Allison Shumway, Arthur D. Frankel, Erin A. Wirth, James Andrew Smith, Morgan P. Moschetti, Kyle Withers, Julie A. Herrick
Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs...
Authors
Sean Kamran Ahdi, Brad T. Aagaard, Morgan P. Moschetti, Grace Alexandra Parker, Oliver S. Boyd, William J. Stephenson
The influence of anthropogenic regulation and evaporite dissolution on earthquake-triggered ground failure The influence of anthropogenic regulation and evaporite dissolution on earthquake-triggered ground failure
Remote sensing observations of Searles Lake following the 2019 moment magnitude 7.1 Ridgecrest, California, earthquake reveal an area where surface ejecta is arranged in a repeating hexagonal pattern that is collocated with a solution-mining operation. By analyzing geologic and geotechnical data, here we show that the hexagonal surface ejecta is likely not a result of liquefaction...
Authors
Paula Madeline Burgi, Eric M. Thompson, Kate E. Allstadt, Kyle Dennis Murray, Henry Mason, Sean Kamran Ahdi, Devin Katzenstein
The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States
We update the ground-motion characterization for the 2023 National Seismic Hazard Model (NSHM) for the conterminous United States. The update includes the use of new ground-motion models (GMMs) in the Cascadia subduction zone; an adjustment to the central and eastern United States (CEUS) GMMs to reduce misfits with observed data; an updated boundary for the application of GMMs for...
Authors
Morgan P. Moschetti, Brad T. Aagaard, Sean Kamran Ahdi, Jason M. Altekruse, Oliver S. Boyd, Arthur D. Frankel, Julie A. Herrick, Mark D. Petersen, Peter M. Powers, Sanaz Rezaeian, Allison Shumway, James Andrew Smith, William J. Stephenson, Eric M. Thompson, Kyle Withers
Recent applications of the USGS National Crustal Model for Seismic Hazard Studies Recent applications of the USGS National Crustal Model for Seismic Hazard Studies
The U.S. Geological Survey is developing the National Crustal Model (NCM) for seismic hazard studies to facilitate modeling site, path, and source components of seismic hazard across the conterminous United States. The NCM is composed of a 1km grid of geophysical profiles, extending from the Earth’s surface into the upper mantle. It is constructed from a threedimensional (3D) geologic...
Authors
Oliver S. Boyd, James Andrew Smith, Morgan P. Moschetti, Brad T. Aagaard, Robert Graves, Evan Tyler Hirakawa, Sean Kamran Ahdi
Science and Products
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as...
Updated Compilation of VS30 Data for the United States Updated Compilation of VS30 Data for the United States
VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30...
Filter Total Items: 19
2023 Earthquake Ground-Motion Workshop for the Central and Eastern United States, with a focus on the Gulf and Atlantic Coastal Plains—Agenda and abstracts 2023 Earthquake Ground-Motion Workshop for the Central and Eastern United States, with a focus on the Gulf and Atlantic Coastal Plains—Agenda and abstracts
The U.S. Geological Survey held a virtual workshop December 7–8, 2023, to share research and ideas about earthquake ground motions in the Central and Eastern United States, with a focus on the Atlantic and Gulf Coastal Plains. The workshop was organized to learn about potential regionalization of ground-motion characteristics (source, path, and site), consider new explanatory variables...
Authors
Oliver S. Boyd, Julie A. Herrick, Ashly Cabas, Sean Kamran Ahdi
The 2023 U.S. National Seismic Hazard Model: Subduction ground motion models The 2023 U.S. National Seismic Hazard Model: Subduction ground motion models
The US Geological Survey National Seismic Hazard Models (NSHMs) are used to calculate earthquake ground-shaking intensities for design and rehabilitation of structures in the United States. The most recent 2014 and 2018 versions of the NSHM for the conterminous United States included major updates to ground-motion models (GMMs) for active and stable crustal tectonic settings; however...
Authors
Sanaz Rezaeian, Peter M. Powers, Jason M. Altekruse, Sean Kamran Ahdi, Mark D. Petersen, Allison Shumway, Arthur D. Frankel, Erin A. Wirth, James Andrew Smith, Morgan P. Moschetti, Kyle Withers, Julie A. Herrick
Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs...
Authors
Sean Kamran Ahdi, Brad T. Aagaard, Morgan P. Moschetti, Grace Alexandra Parker, Oliver S. Boyd, William J. Stephenson
The influence of anthropogenic regulation and evaporite dissolution on earthquake-triggered ground failure The influence of anthropogenic regulation and evaporite dissolution on earthquake-triggered ground failure
Remote sensing observations of Searles Lake following the 2019 moment magnitude 7.1 Ridgecrest, California, earthquake reveal an area where surface ejecta is arranged in a repeating hexagonal pattern that is collocated with a solution-mining operation. By analyzing geologic and geotechnical data, here we show that the hexagonal surface ejecta is likely not a result of liquefaction...
Authors
Paula Madeline Burgi, Eric M. Thompson, Kate E. Allstadt, Kyle Dennis Murray, Henry Mason, Sean Kamran Ahdi, Devin Katzenstein
The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States
We update the ground-motion characterization for the 2023 National Seismic Hazard Model (NSHM) for the conterminous United States. The update includes the use of new ground-motion models (GMMs) in the Cascadia subduction zone; an adjustment to the central and eastern United States (CEUS) GMMs to reduce misfits with observed data; an updated boundary for the application of GMMs for...
Authors
Morgan P. Moschetti, Brad T. Aagaard, Sean Kamran Ahdi, Jason M. Altekruse, Oliver S. Boyd, Arthur D. Frankel, Julie A. Herrick, Mark D. Petersen, Peter M. Powers, Sanaz Rezaeian, Allison Shumway, James Andrew Smith, William J. Stephenson, Eric M. Thompson, Kyle Withers
Recent applications of the USGS National Crustal Model for Seismic Hazard Studies Recent applications of the USGS National Crustal Model for Seismic Hazard Studies
The U.S. Geological Survey is developing the National Crustal Model (NCM) for seismic hazard studies to facilitate modeling site, path, and source components of seismic hazard across the conterminous United States. The NCM is composed of a 1km grid of geophysical profiles, extending from the Earth’s surface into the upper mantle. It is constructed from a threedimensional (3D) geologic...
Authors
Oliver S. Boyd, James Andrew Smith, Morgan P. Moschetti, Brad T. Aagaard, Robert Graves, Evan Tyler Hirakawa, Sean Kamran Ahdi