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Evan Hirakawa

Evan Hirakawa is a geophysicist in the Earthquake Hazards Program.

Science and Products

Impact of sedimentary basins on Green’s functions for static slip inversion

Earthquakes often occur in regions with complex material structure, such as sedimentary basins or mantle wedges. However, the majority of co-seismic modelling studies assume a simplified, often homogeneous elastic structure in order to expedite the process of model construction and speed up calculations. These co-seismic forward models are used to produce Green’s functions for finite-fault inversi
Authors
Leah Langer, Stephen Beller, Evan Tyler Hirakawa, Jeroen Tromp
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Kinematic rupture and 3D wave propagation simulations of the 2019 Mw 7.1 Ridgecrest, California, earthquake

We model the kinematic rupture process of the 2019 MwMw 7.1 Ridgecrest, California, earthquake using numerical simulations to reproduce the elastodynamic wave field observed by inertial seismometers, high‐rate Global Navigation Satellite System stations, and borehole strainmeters. This was the largest earthquake in Southern California in 20 yr and was widely felt throughout the region. The MwMw 7.
Authors
Evan Tyler Hirakawa, Andrew Barbour
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center
link
Image Collage of Landsat, pollinator, and volcanologist

Crustal Characterization

The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
By
Natural Hazards Mission Area, Earthquake Hazards Program
link

Crustal Characterization

The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
Learn More

San Francisco Bay region 3D seismic velocity model v21.0

This three-dimensional (3D) seismic velocity model includes a detailed domain covering the greater San Francisco Bay urban region and a regional domain at a coarser resolution covering a larger region. Version 21.0 is a re-release of v08.3.0 in a new storage scheme. The model was constructed by assigning elastic properties (density, Vp, Vs, Qp, and Qs) to grids of points based on the geologic unit
By
Natural Hazards Mission Area, Earthquake Hazards Program, Geologic Hazards Science Center

San Francisco Bay region 3D seismic velocity model v21.1

This three-dimensional (3D) seismic velocity model includes a detailed domain covering the greater San Francisco Bay urban region and a regional domain at a coarser resolution covering a larger region. Version 21.1 updates only the detailed domain with adjustments to the elastic properties east and north of the San Francisco Bay. There are no changes to the underlying 3D geologic model or the regi
By
Natural Hazards Mission Area, Earthquake Hazards Program, Geologic Hazards Science Center

Science and Products

Impact of sedimentary basins on Green’s functions for static slip inversion

Earthquakes often occur in regions with complex material structure, such as sedimentary basins or mantle wedges. However, the majority of co-seismic modelling studies assume a simplified, often homogeneous elastic structure in order to expedite the process of model construction and speed up calculations. These co-seismic forward models are used to produce Green’s functions for finite-fault inversi
Authors
Leah Langer, Stephen Beller, Evan Tyler Hirakawa, Jeroen Tromp
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Kinematic rupture and 3D wave propagation simulations of the 2019 Mw 7.1 Ridgecrest, California, earthquake

We model the kinematic rupture process of the 2019 MwMw 7.1 Ridgecrest, California, earthquake using numerical simulations to reproduce the elastodynamic wave field observed by inertial seismometers, high‐rate Global Navigation Satellite System stations, and borehole strainmeters. This was the largest earthquake in Southern California in 20 yr and was widely felt throughout the region. The MwMw 7.
Authors
Evan Tyler Hirakawa, Andrew Barbour
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center
link
Image Collage of Landsat, pollinator, and volcanologist

Crustal Characterization

The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
By
Natural Hazards Mission Area, Earthquake Hazards Program
link

Crustal Characterization

The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
Learn More

San Francisco Bay region 3D seismic velocity model v21.0

This three-dimensional (3D) seismic velocity model includes a detailed domain covering the greater San Francisco Bay urban region and a regional domain at a coarser resolution covering a larger region. Version 21.0 is a re-release of v08.3.0 in a new storage scheme. The model was constructed by assigning elastic properties (density, Vp, Vs, Qp, and Qs) to grids of points based on the geologic unit
By
Natural Hazards Mission Area, Earthquake Hazards Program, Geologic Hazards Science Center

San Francisco Bay region 3D seismic velocity model v21.1

This three-dimensional (3D) seismic velocity model includes a detailed domain covering the greater San Francisco Bay urban region and a regional domain at a coarser resolution covering a larger region. Version 21.1 updates only the detailed domain with adjustments to the elastic properties east and north of the San Francisco Bay. There are no changes to the underlying 3D geologic model or the regi
By
Natural Hazards Mission Area, Earthquake Hazards Program, Geologic Hazards Science Center