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Belle Philibosian

Belle Philibosian is a Research Geologist in the Earthquake Science Center.

Belle’s research focuses on the earthquake cycle, using methods from active tectonics and paleoseismology. Research activities include imagery-based and LiDAR-based fault mapping, paleoseismic trenching, GPS and InSAR observations, and coral microatoll paleogeodesy. Research goals include both scientific understanding and earthquake hazard assessment.

EDUCATION

2013    Ph.D. Geology, Division of Geological and Planetary Sciences, California Institute of Technology

2007    M.S. Geological Sciences, Department of Geological Sciences, University of Oregon

2005    B.S. Geology, Division of Geological and Planetary Sciences, California Institute of Technology

                       

EMPLOYMENT

2019–present   Research Geologist, Earthquake Science Center, U.S. Geological Survey

2016–2019       Mendenhall Postdoctoral Research Geologist, Earthquake Science Center, U.S. Geological Survey

2015–2016       Columbia Science Fellow, Columbia University

2013–2015       AXA Postdoctoral Researcher, Equipe de Tectonique, Institut de Physique du Globe de Paris

Science and Products

Filter Total Items: 17

Dendroseismological investigation of redwood trees along the North Coast section of the San Andreas Fault Dendroseismological investigation of redwood trees along the North Coast section of the San Andreas Fault

Sequoia sempervirens (coast redwood) tree rings have the potential to annually resolve late-Holocene earthquakes on the northern San Andreas Fault based on direct (e.g., physical damage) and indirect (e.g., co-seismic environmental change) impacts, but scarcity of suitable samples and challenges crossdating this long-lived species have limited progress. More precise dating of the pre...
Authors
Allyson L. Carroll, Belle E. Philibosian, Stephen C. Sillett, Marie E. Antoine, Özgür Kozaci
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Paleoseismology and paleogeodesy using coral microatolls Paleoseismology and paleogeodesy using coral microatolls

Establishing the rupture extent and slip distribution of individual paleo-earthquakes is vital for assessing fault behavior including the persistence of rupture segmentation, recurrence patterns, and similarity of successive events, key issues in both fault mechanics and hazard assessment. Techniques with high temporal and geodetic precision as well as a wide distribution of study sites...
Authors
Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Investigating past earthquakes with coral microatolls Investigating past earthquakes with coral microatolls

Intertidal corals (microatolls) preserve evidence of past uplift or subsidence with annual precision. Microatoll records are particularly useful along subduction zones, and can reveal past earthquake ruptures at a level of detail that is ordinarily limited to the instrumental era.
Authors
Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Quaternary-active faults and the role of inherited structures in the Sacramento-San Joaquin Delta, western Central Valley, northern California Quaternary-active faults and the role of inherited structures in the Sacramento-San Joaquin Delta, western Central Valley, northern California

Seismic sources and their associated hazards within the Sacramento-San Joaquin Delta region of north-central California are relatively poorly characterized as compared to other, more heavily studied regions of northern California, such as the San Francisco Bay Area. Here we present a synthesis of subsurface, bedrock geology, and geodetic datasets from the Delta and from the Coast Ranges...
Authors
Charles Cashman Trexler, Jack Willard, Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Investigating spatio-temporal variability of initial 230Th/232Th in intertidal corals Investigating spatio-temporal variability of initial 230Th/232Th in intertidal corals

One of the key factors in obtaining precise and accurate 230Th ages of corals, especially for corals with ages less than a few thousand years, is the correction for non-radiogenic 230Th based on an initial 230Th/232Th value (230Th/232Th0). Studies that consider coral 230Th/232Th0 values in intertidal environments are limited, and it is in these environments that corals have Th...
Authors
Hong-Wei Chiang, Belle E. Philibosian, Aron J. Meltzner, Chung-Che Wu, Chuan-Chou Shen, R. Lawrence Edwards, Chih-Kai Chuang, Bambang W. Suwargadi, Danny H. Natawidjaja
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Interaction between climate and tectonics in the northern Lesser Antilles inferred from the last interglacial shoreline on Barbuda island Interaction between climate and tectonics in the northern Lesser Antilles inferred from the last interglacial shoreline on Barbuda island

In the context of increasing evidence of plate interface coupling variability in subduction zones, there is a need to extend the short time window given by instrumental data and to gather data over multiple time and spatial scales. We hence investigated the long-term topography on Barbuda island, located in the northern part of the Lesser Antilles, west of the Caribbean subduction zone...
Authors
Jennifer Weil-Accardo, Nathalie Feuillet, Belle E. Philibosian, Abel Guihou, Eric Jacques, Guy Cabioch, Andre Anglade, Anne-Sophie Meriaux, Pierre Deschamps
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Non-USGS Publications**

Philibosian, B., K. Sieh, J.-P. Avouac, D. H. Natawidjaja, H.-W. Chiang, C.-C. Wu, C.-C. Shen, M. R. Daryono, H. Perfettini, B. W. Suwargadi, Y. Lu, and X. Wang (2017). Earthquake supercycles of the Mentawai segment of the Sunda Megathrust in the 17th century and earlier, Journal of Geophysical Research 122, doi:10.1002/2016JB013560.
Philibosian, B., K. Sieh, J.-P. Avouac, D. H. Natawidjaja, H.-W. Chiang, C.-C. Wu, H. Perfettini, C.-C. Shen, M. R. Daryono, and B. W. Suwargadi (2014). Rupture and variable coupling behavior of the Mentawai segment of the Sunda megathrust during the supercycle culmination of 1797 to 1833, Journal of Geophysical Research 119, doi: 10.1002/2014JB011200.
Philibosian, B., K. Sieh, D.H. Natawidjaja, H.-W. Chiang, C.-C. Shen, B.W. Suwargadi, E.M. Hill, and R.L. Edwards (2012). An ancient shallow slip event on the Mentawai segment of the Sunda Megathrust, Sumatra. Journal of Geophysical Research 117, B05401, doi:10.1029/2011JB009075.
Philibosian, B., and M. Simons (2011). A survey of volcanic deformation on Java using ALOS PALSAR interferometric time series. Geochemistry, Geophysics, Geosystems 12, Q11004, doi:10.1029/2011GC003775.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

Locations at Which Paleoseismological Studies Have Been Completed Along Principal Faults in the San Francisco Bay Area

Earthquake Geology and Paleoseismology Overview

The goals of USGS earthquake geology and paleoseismology research are 1) to make primary observations and develop ideas to improve our understanding of the geologic expression of active faulting, and 2) to acquire data that will improve the National Seismic Hazard Model. Geological research allows us to characterize faults, including the identification of secondary seismogenic structures, to study...
By
Natural Hazards Mission Area, Earthquake Hazards Program
Earthquake Geology and Paleoseismology Overview

Earthquake Geology and Paleoseismology Overview

The goals of USGS earthquake geology and paleoseismology research are 1) to make primary observations and develop ideas to improve our understanding of the geologic expression of active faulting, and 2) to acquire data that will improve the National Seismic Hazard Model. Geological research allows us to characterize faults, including the identification of secondary seismogenic structures, to study...
Learn More

Ring widths, scans of samples, and ancillary data from Sequoia sempervirens (coast redwood) trees and stumps at Fort Ross and Gualala, sampled for dendroseismology in 2021–2024 Ring widths, scans of samples, and ancillary data from Sequoia sempervirens (coast redwood) trees and stumps at Fort Ross and Gualala, sampled for dendroseismology in 2021–2024

Sequoia sempervirens (coast redwood) trees were sampled for a dendroseismological investigation along the North Coast Section of the San Andreas Fault, and the data were fully analyzed, interpreted, and discussed in a journal article and supplemental material (Carroll et al., 2025). Here, were provide data associated with this work: 1200 dpi resolution images of tree cores and stumps...
By
Earthquake Hazards Program

Point cloud and digital elevation data from terrestrial laser scanning of the San Andreas Fault and coast redwood trees near Fort Ross, California Point cloud and digital elevation data from terrestrial laser scanning of the San Andreas Fault and coast redwood trees near Fort Ross, California

These data are derived from laser scanning surveys of the San Andreas Fault and surrounding groves of trees in Fort Ross State Historic Park, California. Surveys were performed on May 13, 2013 and June 19–20, 2024. The second survey was performed specifically to document the morphology of trees that show signs of past earthquake damage, four of which were sampled for dendroseismology...
By
Earthquake Hazards Program

Digital elevation and point cloud data from laser scanning at the Gualala paleoseismic site along the San Andreas Fault Digital elevation and point cloud data from laser scanning at the Gualala paleoseismic site along the San Andreas Fault

These data are derived from laser scanning surveys of a paleoseismic investigation site along the north coast section of the San Andreas Fault near Gualala, CA. We performed three surveys with a terrestrial laser scanner at different stages of trench excavation in 2021. To generate more complete maps of the bare ground at the site, we also incorporated airborne laser scanner data from...
By
Earthquake Hazards Program

Full-resolution photomosaics of trench walls from the 2006 paleoseismic study of the San Andreas Fault at Coachella, California Full-resolution photomosaics of trench walls from the 2006 paleoseismic study of the San Andreas Fault at Coachella, California

The Coachella paleoseismic site is located on the San Andreas Fault along the northeast edge of the Coachella Valley in southern California, southwest of the intersection of Dillon Road and Avenue 44. In 2006, three benched trenches were excavated across the fault zone as part of an Alquist-Priolo fault investigation study by a private geotechnical firm (see APSI_003361 at https://maps
By
Earthquake Hazards Program

Lidar point cloud, GNSS, and raster data from near St. Helena, CA, March 30 and August 1, 2017 Lidar point cloud, GNSS, and raster data from near St. Helena, CA, March 30 and August 1, 2017

Text files: These data are text files of GNSS survey points collected along a trace of the West Napa Fault Zone near Ehler?s Lane north of St. Helena, California. Data were collected to aid in paleoseismic investigation of the suspected fault strand and to characterize local geomorphology. Data were collected on March 31, and August 1, 2017 using a Leica Viva GS15 survey grade GPS. The...
By
Earthquake Hazards Program, Geologic Hazards Science Center

Pre-existing features associated with active faulting in the vicinity of the 2019 Ridgecrest, California earthquake sequence Pre-existing features associated with active faulting in the vicinity of the 2019 Ridgecrest, California earthquake sequence

This dataset is composed of linear active tectonic and other relevant features (scarps, deflected drainages, and lineaments and contrasts in topography, vegetation, and ground color) mapped based on high-resolution topography, aerial/satellite imagery, and field observations. The mapping covers the area surrounding the 2019 Ridgecrest, California earthquake surface ruptures. Point...
By
Earthquake Hazards Program, National Cooperative Geologic Mapping Program, Geologic Hazards Science Center, Geosciences and Environmental Change Science Center
A woman and two men inspect and measure a large crack in the earth's surface
Women in Science - Responding to Ridgecrest, CA earthquake July 2019
Women in Science - Responding to Ridgecrest, CA earthquake July 2019
A woman and two men inspect and measure a large crack in the earth's surface

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Geologists with USGS, the California Geological Survey (CGS) and Naval Air Weapons Station China Lake (NAWS) worked together in response to the Ridgecrest earthquake sequence in California that occurred July 4-6, 2019. The earthquakes were large enough that the fault rupture reached the earth’s surface.

By
Natural Hazards Mission Area, Earthquake Hazards Program
A woman and two men inspect and measure a large crack in the earth's surface

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Geologists with USGS, the California Geological Survey (CGS) and Naval Air Weapons Station China Lake (NAWS) worked together in response to the Ridgecrest earthquake sequence in California that occurred July 4-6, 2019. The earthquakes were large enough that the fault rupture reached the earth’s surface.

By
Natural Hazards Mission Area, Earthquake Hazards Program

Science and Products

Filter Total Items: 17

Dendroseismological investigation of redwood trees along the North Coast section of the San Andreas Fault Dendroseismological investigation of redwood trees along the North Coast section of the San Andreas Fault

Sequoia sempervirens (coast redwood) tree rings have the potential to annually resolve late-Holocene earthquakes on the northern San Andreas Fault based on direct (e.g., physical damage) and indirect (e.g., co-seismic environmental change) impacts, but scarcity of suitable samples and challenges crossdating this long-lived species have limited progress. More precise dating of the pre...
Authors
Allyson L. Carroll, Belle E. Philibosian, Stephen C. Sillett, Marie E. Antoine, Özgür Kozaci
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Paleoseismology and paleogeodesy using coral microatolls Paleoseismology and paleogeodesy using coral microatolls

Establishing the rupture extent and slip distribution of individual paleo-earthquakes is vital for assessing fault behavior including the persistence of rupture segmentation, recurrence patterns, and similarity of successive events, key issues in both fault mechanics and hazard assessment. Techniques with high temporal and geodetic precision as well as a wide distribution of study sites...
Authors
Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Investigating past earthquakes with coral microatolls Investigating past earthquakes with coral microatolls

Intertidal corals (microatolls) preserve evidence of past uplift or subsidence with annual precision. Microatoll records are particularly useful along subduction zones, and can reveal past earthquake ruptures at a level of detail that is ordinarily limited to the instrumental era.
Authors
Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Quaternary-active faults and the role of inherited structures in the Sacramento-San Joaquin Delta, western Central Valley, northern California Quaternary-active faults and the role of inherited structures in the Sacramento-San Joaquin Delta, western Central Valley, northern California

Seismic sources and their associated hazards within the Sacramento-San Joaquin Delta region of north-central California are relatively poorly characterized as compared to other, more heavily studied regions of northern California, such as the San Francisco Bay Area. Here we present a synthesis of subsurface, bedrock geology, and geodetic datasets from the Delta and from the Coast Ranges...
Authors
Charles Cashman Trexler, Jack Willard, Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Investigating spatio-temporal variability of initial 230Th/232Th in intertidal corals Investigating spatio-temporal variability of initial 230Th/232Th in intertidal corals

One of the key factors in obtaining precise and accurate 230Th ages of corals, especially for corals with ages less than a few thousand years, is the correction for non-radiogenic 230Th based on an initial 230Th/232Th value (230Th/232Th0). Studies that consider coral 230Th/232Th0 values in intertidal environments are limited, and it is in these environments that corals have Th...
Authors
Hong-Wei Chiang, Belle E. Philibosian, Aron J. Meltzner, Chung-Che Wu, Chuan-Chou Shen, R. Lawrence Edwards, Chih-Kai Chuang, Bambang W. Suwargadi, Danny H. Natawidjaja
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Interaction between climate and tectonics in the northern Lesser Antilles inferred from the last interglacial shoreline on Barbuda island Interaction between climate and tectonics in the northern Lesser Antilles inferred from the last interglacial shoreline on Barbuda island

In the context of increasing evidence of plate interface coupling variability in subduction zones, there is a need to extend the short time window given by instrumental data and to gather data over multiple time and spatial scales. We hence investigated the long-term topography on Barbuda island, located in the northern part of the Lesser Antilles, west of the Caribbean subduction zone...
Authors
Jennifer Weil-Accardo, Nathalie Feuillet, Belle E. Philibosian, Abel Guihou, Eric Jacques, Guy Cabioch, Andre Anglade, Anne-Sophie Meriaux, Pierre Deschamps
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Non-USGS Publications**

Philibosian, B., K. Sieh, J.-P. Avouac, D. H. Natawidjaja, H.-W. Chiang, C.-C. Wu, C.-C. Shen, M. R. Daryono, H. Perfettini, B. W. Suwargadi, Y. Lu, and X. Wang (2017). Earthquake supercycles of the Mentawai segment of the Sunda Megathrust in the 17th century and earlier, Journal of Geophysical Research 122, doi:10.1002/2016JB013560.
Philibosian, B., K. Sieh, J.-P. Avouac, D. H. Natawidjaja, H.-W. Chiang, C.-C. Wu, H. Perfettini, C.-C. Shen, M. R. Daryono, and B. W. Suwargadi (2014). Rupture and variable coupling behavior of the Mentawai segment of the Sunda megathrust during the supercycle culmination of 1797 to 1833, Journal of Geophysical Research 119, doi: 10.1002/2014JB011200.
Philibosian, B., K. Sieh, D.H. Natawidjaja, H.-W. Chiang, C.-C. Shen, B.W. Suwargadi, E.M. Hill, and R.L. Edwards (2012). An ancient shallow slip event on the Mentawai segment of the Sunda Megathrust, Sumatra. Journal of Geophysical Research 117, B05401, doi:10.1029/2011JB009075.
Philibosian, B., and M. Simons (2011). A survey of volcanic deformation on Java using ALOS PALSAR interferometric time series. Geochemistry, Geophysics, Geosystems 12, Q11004, doi:10.1029/2011GC003775.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

Locations at Which Paleoseismological Studies Have Been Completed Along Principal Faults in the San Francisco Bay Area

Earthquake Geology and Paleoseismology Overview

The goals of USGS earthquake geology and paleoseismology research are 1) to make primary observations and develop ideas to improve our understanding of the geologic expression of active faulting, and 2) to acquire data that will improve the National Seismic Hazard Model. Geological research allows us to characterize faults, including the identification of secondary seismogenic structures, to study...
By
Natural Hazards Mission Area, Earthquake Hazards Program
Earthquake Geology and Paleoseismology Overview

Earthquake Geology and Paleoseismology Overview

The goals of USGS earthquake geology and paleoseismology research are 1) to make primary observations and develop ideas to improve our understanding of the geologic expression of active faulting, and 2) to acquire data that will improve the National Seismic Hazard Model. Geological research allows us to characterize faults, including the identification of secondary seismogenic structures, to study...
Learn More

Ring widths, scans of samples, and ancillary data from Sequoia sempervirens (coast redwood) trees and stumps at Fort Ross and Gualala, sampled for dendroseismology in 2021–2024 Ring widths, scans of samples, and ancillary data from Sequoia sempervirens (coast redwood) trees and stumps at Fort Ross and Gualala, sampled for dendroseismology in 2021–2024

Sequoia sempervirens (coast redwood) trees were sampled for a dendroseismological investigation along the North Coast Section of the San Andreas Fault, and the data were fully analyzed, interpreted, and discussed in a journal article and supplemental material (Carroll et al., 2025). Here, were provide data associated with this work: 1200 dpi resolution images of tree cores and stumps...
By
Earthquake Hazards Program

Point cloud and digital elevation data from terrestrial laser scanning of the San Andreas Fault and coast redwood trees near Fort Ross, California Point cloud and digital elevation data from terrestrial laser scanning of the San Andreas Fault and coast redwood trees near Fort Ross, California

These data are derived from laser scanning surveys of the San Andreas Fault and surrounding groves of trees in Fort Ross State Historic Park, California. Surveys were performed on May 13, 2013 and June 19–20, 2024. The second survey was performed specifically to document the morphology of trees that show signs of past earthquake damage, four of which were sampled for dendroseismology...
By
Earthquake Hazards Program

Digital elevation and point cloud data from laser scanning at the Gualala paleoseismic site along the San Andreas Fault Digital elevation and point cloud data from laser scanning at the Gualala paleoseismic site along the San Andreas Fault

These data are derived from laser scanning surveys of a paleoseismic investigation site along the north coast section of the San Andreas Fault near Gualala, CA. We performed three surveys with a terrestrial laser scanner at different stages of trench excavation in 2021. To generate more complete maps of the bare ground at the site, we also incorporated airborne laser scanner data from...
By
Earthquake Hazards Program

Full-resolution photomosaics of trench walls from the 2006 paleoseismic study of the San Andreas Fault at Coachella, California Full-resolution photomosaics of trench walls from the 2006 paleoseismic study of the San Andreas Fault at Coachella, California

The Coachella paleoseismic site is located on the San Andreas Fault along the northeast edge of the Coachella Valley in southern California, southwest of the intersection of Dillon Road and Avenue 44. In 2006, three benched trenches were excavated across the fault zone as part of an Alquist-Priolo fault investigation study by a private geotechnical firm (see APSI_003361 at https://maps
By
Earthquake Hazards Program

Lidar point cloud, GNSS, and raster data from near St. Helena, CA, March 30 and August 1, 2017 Lidar point cloud, GNSS, and raster data from near St. Helena, CA, March 30 and August 1, 2017

Text files: These data are text files of GNSS survey points collected along a trace of the West Napa Fault Zone near Ehler?s Lane north of St. Helena, California. Data were collected to aid in paleoseismic investigation of the suspected fault strand and to characterize local geomorphology. Data were collected on March 31, and August 1, 2017 using a Leica Viva GS15 survey grade GPS. The...
By
Earthquake Hazards Program, Geologic Hazards Science Center

Pre-existing features associated with active faulting in the vicinity of the 2019 Ridgecrest, California earthquake sequence Pre-existing features associated with active faulting in the vicinity of the 2019 Ridgecrest, California earthquake sequence

This dataset is composed of linear active tectonic and other relevant features (scarps, deflected drainages, and lineaments and contrasts in topography, vegetation, and ground color) mapped based on high-resolution topography, aerial/satellite imagery, and field observations. The mapping covers the area surrounding the 2019 Ridgecrest, California earthquake surface ruptures. Point...
By
Earthquake Hazards Program, National Cooperative Geologic Mapping Program, Geologic Hazards Science Center, Geosciences and Environmental Change Science Center
A woman and two men inspect and measure a large crack in the earth's surface
Women in Science - Responding to Ridgecrest, CA earthquake July 2019
Women in Science - Responding to Ridgecrest, CA earthquake July 2019
A woman and two men inspect and measure a large crack in the earth's surface

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Geologists with USGS, the California Geological Survey (CGS) and Naval Air Weapons Station China Lake (NAWS) worked together in response to the Ridgecrest earthquake sequence in California that occurred July 4-6, 2019. The earthquakes were large enough that the fault rupture reached the earth’s surface.

By
Natural Hazards Mission Area, Earthquake Hazards Program
A woman and two men inspect and measure a large crack in the earth's surface

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Women in Science - Responding to Ridgecrest, CA earthquake July 2019

Geologists with USGS, the California Geological Survey (CGS) and Naval Air Weapons Station China Lake (NAWS) worked together in response to the Ridgecrest earthquake sequence in California that occurred July 4-6, 2019. The earthquakes were large enough that the fault rupture reached the earth’s surface.

By
Natural Hazards Mission Area, Earthquake Hazards Program
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