I am a Research Geophysicist with a background in geotechnical earthquake engineering and engineering geology. My research focuses on using data from near-surface geophysical methods for seismic site characterization. This information is used to estimate earthquake site response and ground motions, models of which are applied in the development of the USGS National Seismic Hazard Mapping Project.
Education
Ph.D., UCLA, 2018, Civil Engineering (Geotechnical Earthquake Engineering)
M.S., UCLA, 2014, Civil Engineering (Geotechnical Earthquake Engineering)
B.S., UCLA, 2013, Civil Engineering
B.S., UCLA, 2013, Geology/Engineering Geology
Publications
Google Scholar
Science and Products
COSMOS Ground-Motion Simulation Working Group workshops #1 and #2
These 2 workshops were held in response to interest generated from sessions on the use of simulated earthquake ground motions at the 2020 and 2021 Consortium of Organizations for Strong Motion Observation Systems (COSMOS) Technical Sessions. The discussions at the Technical Sessions highlighted desires to promote the use of simulated earthquake ground motions for engineering applications and the n
Authors
Brad T. Aagaard, Aysegul Askan, Sanaz Rezaeian, Sean Kamran Ahdi, Alan Yong
Implementation of basin models and sediment depth terms in the 2023 update of the U.S. National Seismic Hazard Model: Example from Reno, Nevada
We present a framework to evaluate the inclusion of candidate basin depth models in the U.S. Geological Survey National Seismic Hazard Model. We compute intensity measures (peak and spectral amplitudes) from uniformly processed earthquake ground motions in and around the basin of interest and compare these to ground-motion model (GMM) estimates over a range of oscillator periods. The GMMs use dept
Authors
Sean Kamran Ahdi, Morgan P. Moschetti, Brad T. Aagaard, Kaitlyn Abernathy, Oliver S. Boyd, William J. Stephenson
NGA-Subduction research program
This article summarizes the Next Generation Attenuation (NGA) Subduction (NGA-Sub) project, a major research program to develop a database and ground motion models (GMMs) for subduction regions. A comprehensive database of subduction earthquakes recorded worldwide was developed. The database includes a total of 214,020 individual records from 1,880 subduction events, which is by far the largest da
Authors
Yousef Bozorgnia, Norman A. Abrahamson, Sean Kamran Ahdi, Timothy D. Ancheta, Linda Al Atik, Ralph J Archuleta, Gail M. Atkinson, David M Boore, Kenneth W. Campbell, Brian S-J Chiou, Victor Contreras, Robert B. Darragh, Sahar Derakhshan, Jennifer L Donahue, Nick Gregor, Zeynep Gulerce, Izzat M Idriss, Chengxin Jiang, Tadahiro Kishida, Albert R. Kottke, Nicolas Kuehn, Dongyoup Kwak, Annie O-L Kwok, Person Lin, Jorge Macedo, Silvia Mazzoni, Saburoh Midorikawa, Sifat Muin, Grace Alexandra Parker, Sanaz Rezaeian, Hongjun Si, Walter J Silva, Jonathan P. Stewart, Melanie Walling, Katie Wooddell, Robert R Youngs
Relational database for horizontal‐to‐vertical spectral ratios
Frequency‐dependent horizontal‐to‐vertical spectral ratios (HVSRs) of Fourier amplitudes from three‐component recordings can provide useful information for site response modeling. However, such information is not incorporated into most ground‐motion models, including those from Next‐Generation Attenuation projects, which instead use the time‐averaged shear‐wave velocity (VSVS) in the upper 30 m
Authors
Pengfei Wang, Paolo Zimmaro, Tristan E Buckreis, Tatiana Gospe, Scott J Brandenberg, Sean Kamran Ahdi, Alan Yong, Jonathan P. Stewart
2021 U.S. National Seismic Hazard Model for the State of Hawaii
The 2021 U.S. National Seismic Hazard Model (NSHM) for the State of Hawaii updates the two-decades-old former model by incorporating new data and modeling techniques to improve the underlying ground shaking forecasts of tectonic-fault, tectonic-flexure, volcanic, and caldera collapse earthquakes. Two earthquake ground shaking hazard models (public policy and research) are produced that differ in h
Authors
Mark D. Petersen, Allison Shumway, Peter M. Powers, Morgan P. Moschetti, Andrea L. Llenos, Andrew J. Michael, Charles Mueller, Arthur Frankel, Sanaz Rezaeian, Kenneth S. Rukstales, Daniel E. McNamara, P. Okubo, Yuehua Zeng, Kishor Jaiswal, Sean Kamran Ahdi, Jason M. Altekruse, Brian Shiro
Horizontal-to-vertical spectral ratios from California sites: Open-source database and data interpretation to establish site parameters
Frequency-dependent horizontal-to-vertical spectral ratios (HVSR) of Fourier amplitudes from three-component recordings can provide information on one or more site resonant frequencies and relative levels of amplification at those frequencies. Such information is potentially useful for predicting site amplification but is not present in site databases that have been developed over the last 15–20 y
Authors
Pengfei Wang, Paolo Zimmaro, Tatiana Gospe, Sean Kamran Ahdi, Alan Yong, Jonathan P. Stewart
Science and Products
- Publications
COSMOS Ground-Motion Simulation Working Group workshops #1 and #2
These 2 workshops were held in response to interest generated from sessions on the use of simulated earthquake ground motions at the 2020 and 2021 Consortium of Organizations for Strong Motion Observation Systems (COSMOS) Technical Sessions. The discussions at the Technical Sessions highlighted desires to promote the use of simulated earthquake ground motions for engineering applications and the nAuthorsBrad T. Aagaard, Aysegul Askan, Sanaz Rezaeian, Sean Kamran Ahdi, Alan YongImplementation of basin models and sediment depth terms in the 2023 update of the U.S. National Seismic Hazard Model: Example from Reno, Nevada
We present a framework to evaluate the inclusion of candidate basin depth models in the U.S. Geological Survey National Seismic Hazard Model. We compute intensity measures (peak and spectral amplitudes) from uniformly processed earthquake ground motions in and around the basin of interest and compare these to ground-motion model (GMM) estimates over a range of oscillator periods. The GMMs use deptAuthorsSean Kamran Ahdi, Morgan P. Moschetti, Brad T. Aagaard, Kaitlyn Abernathy, Oliver S. Boyd, William J. StephensonNGA-Subduction research program
This article summarizes the Next Generation Attenuation (NGA) Subduction (NGA-Sub) project, a major research program to develop a database and ground motion models (GMMs) for subduction regions. A comprehensive database of subduction earthquakes recorded worldwide was developed. The database includes a total of 214,020 individual records from 1,880 subduction events, which is by far the largest daAuthorsYousef Bozorgnia, Norman A. Abrahamson, Sean Kamran Ahdi, Timothy D. Ancheta, Linda Al Atik, Ralph J Archuleta, Gail M. Atkinson, David M Boore, Kenneth W. Campbell, Brian S-J Chiou, Victor Contreras, Robert B. Darragh, Sahar Derakhshan, Jennifer L Donahue, Nick Gregor, Zeynep Gulerce, Izzat M Idriss, Chengxin Jiang, Tadahiro Kishida, Albert R. Kottke, Nicolas Kuehn, Dongyoup Kwak, Annie O-L Kwok, Person Lin, Jorge Macedo, Silvia Mazzoni, Saburoh Midorikawa, Sifat Muin, Grace Alexandra Parker, Sanaz Rezaeian, Hongjun Si, Walter J Silva, Jonathan P. Stewart, Melanie Walling, Katie Wooddell, Robert R YoungsRelational database for horizontal‐to‐vertical spectral ratios
Frequency‐dependent horizontal‐to‐vertical spectral ratios (HVSRs) of Fourier amplitudes from three‐component recordings can provide useful information for site response modeling. However, such information is not incorporated into most ground‐motion models, including those from Next‐Generation Attenuation projects, which instead use the time‐averaged shear‐wave velocity (VSVS) in the upper 30 mAuthorsPengfei Wang, Paolo Zimmaro, Tristan E Buckreis, Tatiana Gospe, Scott J Brandenberg, Sean Kamran Ahdi, Alan Yong, Jonathan P. Stewart2021 U.S. National Seismic Hazard Model for the State of Hawaii
The 2021 U.S. National Seismic Hazard Model (NSHM) for the State of Hawaii updates the two-decades-old former model by incorporating new data and modeling techniques to improve the underlying ground shaking forecasts of tectonic-fault, tectonic-flexure, volcanic, and caldera collapse earthquakes. Two earthquake ground shaking hazard models (public policy and research) are produced that differ in hAuthorsMark D. Petersen, Allison Shumway, Peter M. Powers, Morgan P. Moschetti, Andrea L. Llenos, Andrew J. Michael, Charles Mueller, Arthur Frankel, Sanaz Rezaeian, Kenneth S. Rukstales, Daniel E. McNamara, P. Okubo, Yuehua Zeng, Kishor Jaiswal, Sean Kamran Ahdi, Jason M. Altekruse, Brian ShiroHorizontal-to-vertical spectral ratios from California sites: Open-source database and data interpretation to establish site parameters
Frequency-dependent horizontal-to-vertical spectral ratios (HVSR) of Fourier amplitudes from three-component recordings can provide information on one or more site resonant frequencies and relative levels of amplification at those frequencies. Such information is potentially useful for predicting site amplification but is not present in site databases that have been developed over the last 15–20 yAuthorsPengfei Wang, Paolo Zimmaro, Tatiana Gospe, Sean Kamran Ahdi, Alan Yong, Jonathan P. Stewart