Skip to main content
U.S. flag

An official website of the United States government

Belle Philibosian

The focus of my research is to understand the earthquake cycle, using techniques drawn from the fields of active tectonics and paleoseismology. In various projects I have employed imagery- and LiDAR-based fault mapping, paleoseismic trenching, GPS and InSAR observations, and coral microatoll paleogeodesy.  I pursue the dual goals of scientific understanding and hazard assessment of earthquakes.

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

link
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
link

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

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.conservatio
By
Earthquake Hazards Program

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 data are de
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

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 locations of fie
By
Earthquake Hazards Program, National Cooperative Geologic Mapping Program, Geologic Hazards Science Center, Geosciences and Environmental Change Science Center

2017b high resolution seismic imaging of the West Napa Fault Zone, St. Helena, California

In September 2017, the U.S. Geological Survey acquired high resolution P- and S-wave seismic data across the suspected trace of the West Napa Fault zone in St. Helena, California, approximately 70 m north of the previous seismic survey conducted in April 2017 (Chan et al., 2018). We acquired seismic reflection, refraction, and guided-wave data along a 75-m-long profile across the expected trend of

2017 seismic imaging of the West Napa Fault Zone, St. Helena, California

In April 2017, the U.S. Geological Survey acquired high resolution P- and S-wave seismic data across the suspected trace of the West Napa Fault zone in St. Helena, California. We acquired seismic reflection, refraction, and guided-wave data along a 215-m-long profile across the expected trend of the West Napa Fault zone. To acquire the reflection and refraction data, we co-located shots and geopho
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, Earthquake Hazards
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, Earthquake Hazards

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 concentrations 100–1
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

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. Following
Authors
Jennifer Weil-Accardo, Nathalie Feuillet, Belle E. Philibosian, Abel Guihou, Eric Jacques, Guy Cabioch, André Anglade, Anne-Sophie Mériaux, Pierre Deschamps
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Photomosaics and logs associated with study of West Napa Fault at Ehlers Lane, north of Saint Helena, California

The West Napa Fault has previously been mapped as extending ~45 kilometers (km) from northern Vallejo to southern Saint Helena, California, dominantly running along the western edge of Napa Valley. A zone of fault strands (some previously unmapped) along a ~15-km section of the fault ruptured during the 2014 magnitude 6.0 South Napa earthquake, illustrating the need for further investigation of th
Authors
Belle E. Philibosian, Robert R. Sickler, Carol S. Prentice, Alexandra J. Pickering, Patrick Gannon, Kiara N. Broudy, Shannon A. Mahan, Jazmine N. Titular, Eli A. Turner, Cameron Folmar, Sierra F. Patterson, Emilie E. Bowman
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center, Geosciences and Environmental Change Science Center

20th-century strain accumulation on the Lesser Antilles megathrust based on coral microatolls

The seismic potential of the Lesser Antilles megathrust remains poorly known, despite the potential hazard it poses to numerous island populations and its proximity to the Americas. As it has not produced any large earthquakes in the instrumental era, the megathrust is often assumed to be aseismic. However, historical records of great earthquakes in the 19th century and earlier, which were most li
Authors
Belle E. Philibosian, Nathalie Feuillet, Jennifer Weil-Accardo, Eric Jacques, Abel Guihou, Anne-Sophie Mériaux, André Anglade, Jean-Marie Saurel, Sébastien Deroussi
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Creep on the Sargent Fault over the past 50 yr from alignment arrays with implications for slip transfer between the Calaveras and San Andreas Faults, California

The 55‐km‐long Sargent fault connects the creeping Calaveras fault with the locked San Andreas fault through the Santa Cruz Mountains west of Gilroy, California. The position of the Sargent fault between these two faults may have implications for slip transfer and strain accumulation between a creeping and locked fault. The detection and measurement of creep on the Sargent fault would indicate whe
Authors
Daniel Mongovin, Belle E. Philibosian
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Documentation of Surface Fault Rupture and Ground‐Deformation Features Produced by the 4 and 5 July 2019 Mw 6.4 and Mw 7.1 Ridgecrest Earthquake Sequence

The MwMw 6.4 and MwMw 7.1 Ridgecrest earthquake sequence occurred on 4 and 5 July 2019 within the eastern California shear zone of southern California. Both events produced extensive surface faulting and ground deformation within Indian Wells Valley and Searles Valley. In the weeks following the earthquakes, more than six dozen scientists from government, academia, and the private sector carefully
Authors
Daniel J. Ponti, James Luke Blair, Rosa Carla M, Kate Thomas, Alexandra Pickering, Sinan Akciz, Stephen J. Angster, Jean-Philipe Avouac, Jeffrey Bachhuber, Steven Bacon, Nicolas C. Barth, S. Bennett, Kelly Blake, Stephan Bork, Benjamin A. Brooks, Thomas Bullard, Paul A. Burgess, Colin Chupik, Timothy E. Dawson, Michael DeFrisco, Jaime E. Delano, Stephen B. DeLong, James D. Dolan, Andrea Donnellan, Christopher DuRoss, Todd Ericksen, Erik Frost, Gareth J. Funning, Ryan D. Gold, Nicholas A Graehl, Carlos Gutierrez, Elizabeth Haddon, Alexandra Elise Hatem, John Helms, Janis Hernandez, Christopher S. Hitchcock, Peter Holland, Kenneth W. Hudnut, Katherine J. Kendrick, Richard D Koehler, Ozgur Kozaci, Tyler C. Ladinsky, Robert Leeper, Christopher Madugo, Maxime Mareschal, James McDonald, Devin McPhillips, Christopher Milliner, Daniel Mongovin, Alexander Morelan, Stephanie Nale, Johanna Nevitt, Matt O'Neal, Brian J. Olsen, Michael Oskin, Salena Padilla, Jason Patton, Belle E. Philibosian, Ian Pierce, Cynthia Pridmore, Nathaniel Roth, David Sandwell, Katherine Scharer, Gordon G. Seitz, Drake Singleton, Bridget Smith-Konter, Eleanor Spangler, Brian J. Swanson, Jessica Thompson Jobe, Jerome Treiman, Francesca Valencia, Joshua Vanderwal, Alana Williams, Xiaohua Xu, Judith Zachariasen, Jade Zimmerman, Robert Zinke
By
Natural Hazards Mission Area, Earthquake Hazards Program, National Cooperative Geologic Mapping Program, Earthquake Science Center, Geosciences and Environmental Change Science Center

Evidence of previous faulting along the 2019 Ridgecrest, California earthquake ruptures

The July 2019 Ridgecrest earthquake sequence in southeastern California was characterized as surprising because only ~35% of the rupture occurred on previously mapped faults. Employing more detailed inspection of pre-event high-resolution topography and imagery in combination with field observations, we document evidence of active faulting in the landscape along the entire fault system. Scarps, de
Authors
Jessica Thompson Jobe, Belle E. Philibosian, Colin Chupik, Timothy E. Dawson, Scott E. K. Bennett, Ryan D. Gold, Christopher DuRoss, Tyler C. Ladinsky, Katherine J. Kendrick, Elizabeth Haddon, Ian Pierce, Brian J. Swanson, Gordon G. Seitz
By
Natural Hazards Mission Area, Earthquake Hazards Program, National Cooperative Geologic Mapping Program, Earthquake Science Center, Geologic Hazards Science Center, Geosciences and Environmental Change Science Center

Segmentation and supercycles: A catalog of earthquake rupture patterns from the Sumatran Sunda Megathrust and other well-studied faults worldwide

After more than 100 years of earthquake research, earthquake forecasting, which relies on knowledge of past fault rupture patterns, has become the foundation for societal defense against seismic natural disasters. A concept that has come into focus more recently is that rupture segmentation and cyclicity can be complex, and that a characteristic earthquake model is too simple to adequately describ
Authors
Belle E. Philibosian, Aron J. Meltzner
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center, Subduction Zone Science

Surface displacement distributions for the July 2019 Ridgecrest, California earthquake ruptures

Surface rupture in the 2019 Ridgecrest, California, earthquake sequence occurred along two orthogonal cross faults and includes dominantly left‐lateral and northeast‐striking rupture in the Mw 6.4 foreshock and dominantly right‐lateral and northwest‐striking rupture in the Mw 7.1 mainshock. We present >650 field‐based, surface‐displacement observations for these ruptures and synthesize our results
Authors
Christopher DuRoss, Ryan D. Gold, Timothy E. Dawson, Katherine Scharer, Katherine J. Kendrick, Sinan Akciz, Stephen J. Angster, Jeffery Bachhuber, Steven Bacon, Scott E. K. Bennett, Luke Blair, Benjamin A. Brooks, Thomas Bullard, W. Paul Burgess, Colin Chupik, Michael DeFrisco, Jaime Delano, James D. Dolan, Erik Frost, Nick Graehl, Elizabeth Haddon, Alexandra Elise Hatem, Janis Hernandez, Christopher S. Hitchcock, Kennth Hudnut, Jessica Thompson Jobe, Richard D Koehler, Ozgur Kozaci, Tyler C. Ladinsky, Christopher Madugo, Devin McPhillips, Christopher Milliner, Alexander Morelan, Brian Olson, Jason Patton, Belle E. Philibosian, Alexandra J. Pickering, Ian Pierce, Daniel J. Ponti, Gordon G. Seitz, Eleanor Spangler, Brian J. Swanson, Kate Thomas, Jerome Treiman, Francesca Valencia, Alana Williams, Robert Zinke
By
Natural Hazards Mission Area, Earthquake Hazards Program, National Cooperative Geologic Mapping Program, Earthquake Science Center, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center

Coupling of Indo-Pacific climate variability over the last millennium

The Indian Ocean Dipole (IOD) impacts climate and rainfall across the world, and most severely in nations surrounding the Indian Ocean1-4. The frequency and intensity of positive IOD events increased during the 20th Century5 and may continue to intensify in a warming world6; however, confidence in future IOD changes is limited by known biases in model representations of the IOD7 and the lack of in
Authors
Nerilie J. Abram, Nicky M. Wright, Bethany Ellis, Bronwyn C. Dixon, Jennifer B. Wurtzel, Matthew H. England, Caroline C. Ummenhofer, Belle E. Philibosian, Sri Yudawati Cahyarini, Tsai-Luen Yu, Chuan-Chou Shen, Hai Cheng, R. Lawrence Edwards, David Heslop
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

San Andreas fault earthquake chronology and Lake Cahuilla history at Coachella, California

The southernmost ~100 km of the San Andreas fault has not ruptured historically. It is imperative to determine its rupture history to better predict its future behavior. This paleoseismic investigation in Coachella, California, establishes a chronology of at least five and up to seven major earthquakes during the past ~1100 yr. This chronology yields a range of average recurrence intervals between
Authors
B. Philibosian, T. Fumal, R. Weldon
By
Natural Hazards Mission Area, Earthquake Hazards Program, Earthquake Science Center

Photomosaics and logs of trenches on the San Andreas Fault near Coachella, California

The Coachella paleoseismic site is located on the San Andreas Fault along the northeast edge of the Coachella Valley in southern California east of Dillon Road and south of Avenue 44. Three benched trenches, a total of more than 950 m, were excavated across the fault zone as part of an Alquist-Priolo fault investigation study. These trenches exposed a thick section of latest Holocene lacustrine, f
Authors
Belle Philibosian, Thomas E. Fumal, Ray J. Weldon, Katherine J. Kendrick, Katherine M. Scharer, Sean P. Bemis, Reed J. Burgette, Beth A. Wisely

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.

Science and Products