Andrea Llenos
I am a research geophysicist whose research focuses on developing earthquake rate models for seismic hazard forecasts. I use statistical methods to characterize earthquake rate changes in catalogs, investigating the impacts these variations have on short-term earthquake forecasts as well as long-term seismic hazard models.
Professional Experience
Research Geophysicist, US Geological Survey, Geologic Hazards Science Center, Golden, CO. 2020-present
Research Geophysicist (term), US Geological Survey, Earthquake Science Center, Menlo Park/Moffett Field, CA . 2015-2020
Mendenhall Postdoctoral Fellow, US Geological Survey, Earthquake Science Center, Menlo Park, CA. 2011-2015
Postdoctoral Scholar, Stanford University, Stanford, CA. 2010-2011
Graduate Research Assistant, Woods Hole Oceanographic Institution, Woods Hole, MA. 2004-2010
Visiting Researcher, Institute of Statistical Mathematics, Tokyo, Japan. 2008, 2009
Undergraduate Research Assistant, Dept. of Geo. Sci., Brown University, Providence, RI. 2002-2004
NSF-REU Intern, University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK. 2003
Undergraduate Research Assistant, Planetary Geosci., Brown University, Providence, RI. 2001
Fellowships and Awards
Excellent Reviewer Award for Earth, Planets and Space. 2019
Editors' Citation for Excellence in Refereeing for Geophysical Research Letters. 2016
USGS Mendenhall Postdoctoral Fellowship. 2011-2013
National Defense Science and Engineering Graduate Fellowship. 2005-2008
Hollister Fellowship, Woods Hole Oceanographic Institution. 2004-2005
Outstanding Student Award (in Mechanical Engineering). 2004
Undergraduate Research and Academics Award (in Geological Science). 2004
Education and Certifications
PhD, 2010, Marine Geophysics, MIT/Woods Hole Oceanographic Institution Joint Program in Oceanography
ScB, 2004, Geology-Physics/Mathematics (with honors), Brown University, magna cum laude
ScB, 2004, Engineering (Mechanical), Brown University
Science and Products
Forecasting the (un)productivity of the 2014 M 6.0 South Napa aftershock sequence
2017 One‐year seismic‐hazard forecast for the central and eastern United States from induced and natural earthquakes
Seismic‐hazard forecast for 2016 including induced and natural earthquakes in the central and eastern United States
Characterizing potentially induced earthquake rate changes in the Brawley Seismic Zone, southern California
2016 one-year seismic hazard forecast for the Central and Eastern United States from induced and natural earthquakes
Increasing seismicity in the U. S. midcontinent: Implications for earthquake hazard
Incorporating induced seismicity in the 2014 United States National Seismic Hazard Model: results of the 2014 workshop and sensitivity studies
Modeling earthquake rate changes in Oklahoma and Arkansas: possible signatures of induced seismicity
Near real-time monitoring of volcanic surface deformation from GPS measurements at Long Valley Caldera, California
Detecting aseismic strain transients from seismicity data
Non-USGS Publications**
**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
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Filter Total Items: 22
Forecasting the (un)productivity of the 2014 M 6.0 South Napa aftershock sequence
The 24 August 2014 Mw 6.0 South Napa mainshock produced fewer aftershocks than expected for a California earthquake of its magnitude. In the first 4.5 days, only 59 M≥1.8 aftershocks occurred, the largest of which was an M 3.9 that happened a little over two days after the mainshock. We investigate the aftershock productivity of the South Napa sequence and compare it with other M≥5.5 California stAuthorsAndrea L. Llenos, Andrew J. Michael2017 One‐year seismic‐hazard forecast for the central and eastern United States from induced and natural earthquakes
We produce a one‐year 2017 seismic‐hazard forecast for the central and eastern United States from induced and natural earthquakes that updates the 2016 one‐year forecast; this map is intended to provide information to the public and to facilitate the development of induced seismicity forecasting models, methods, and data. The 2017 hazard model applies the same methodology and input logic tree as tAuthorsMark D. Petersen, Charles Mueller, Morgan P. Moschetti, Susan M. Hoover, Allison Shumway, Daniel E. McNamara, Robert Williams, Andrea L. Llenos, William L. Ellsworth, Justin L. Rubinstein, Arthur F. McGarr, Kenneth S. RukstalesSeismic‐hazard forecast for 2016 including induced and natural earthquakes in the central and eastern United States
The U.S. Geological Survey (USGS) has produced a one‐year (2016) probabilistic seismic‐hazard assessment for the central and eastern United States (CEUS) that includes contributions from both induced and natural earthquakes that are constructed with probabilistic methods using alternative data and inputs. This hazard assessment builds on our 2016 final model (Petersen et al., 2016) by adding sensiAuthorsMark D. Petersen, Charles Mueller, Morgan P. Moschetti, Susan M. Hoover, Andrea L. Llenos, William L. Ellsworth, Andrew J. Michael, Justin L. Rubinstein, Arthur F. McGarr, Kenneth S. RukstalesCharacterizing potentially induced earthquake rate changes in the Brawley Seismic Zone, southern California
The Brawley seismic zone (BSZ), in the Salton trough of southern California, has a history of earthquake swarms and geothermal energy exploitation. Some earthquake rate changes may have been induced by fluid extraction and injection activity at local geothermal fields, particularly at the North Brawley Geothermal Field (NBGF) and at the Salton Sea Geothermal Field (SSGF). We explore this issue byAuthorsAndrea L. Llenos, Andrew J. Michael2016 one-year seismic hazard forecast for the Central and Eastern United States from induced and natural earthquakes
The U.S. Geological Survey (USGS) has produced a 1-year seismic hazard forecast for 2016 for the Central and Eastern United States (CEUS) that includes contributions from both induced and natural earthquakes. The model assumes that earthquake rates calculated from several different time windows will remain relatively stationary and can be used to forecast earthquake hazard and damage intensity forAuthorsMark D. Petersen, Charles S. Mueller, Morgan P. Moschetti, Susan M. Hoover, Andrea L. Llenos, William L. Ellsworth, Andrew J. Michael, Justin L. Rubinstein, Arthur F. McGarr, Kenneth S. RukstalesIncreasing seismicity in the U. S. midcontinent: Implications for earthquake hazard
Earthquake activity in parts of the central United States has increased dramatically in recent years. The space-time distribution of the increased seismicity, as well as numerous published case studies, indicates that the increase is of anthropogenic origin, principally driven by injection of wastewater coproduced with oil and gas from tight formations. Enhanced oil recovery and long-term productiAuthorsWilliam L. Ellsworth, Andrea L. Llenos, Arthur F. McGarr, Andrew J. Michael, Justin L. Rubinstein, Charles S. Mueller, Mark D. Petersen, Eric CalaisIncorporating induced seismicity in the 2014 United States National Seismic Hazard Model: results of the 2014 workshop and sensitivity studies
The U.S. Geological Survey National Seismic Hazard Model for the conterminous United States was updated in 2014 to account for new methods, input models, and data necessary for assessing the seismic ground shaking hazard from natural (tectonic) earthquakes. The U.S. Geological Survey National Seismic Hazard Model project uses probabilistic seismic hazard analysis to quantify the rate of exceedanceAuthorsMark D. Petersen, Charles S. Mueller, Morgan P. Moschetti, Susan M. Hoover, Justin L. Rubinstein, Andrea L. Llenos, Andrew J. Michael, William L. Ellsworth, Arthur F. McGarr, Austin A. Holland, John G. AndersonModeling earthquake rate changes in Oklahoma and Arkansas: possible signatures of induced seismicity
The rate of ML≥3 earthquakes in the central and eastern United States increased beginning in 2009, particularly in Oklahoma and central Arkansas, where fluid injection has occurred. We find evidence that suggests these rate increases are man‐made by examining the rate changes in a catalog of ML≥3 earthquakes in Oklahoma, which had a low background seismicity rate before 2009, as well as rate changAuthorsAndrea L. Llenos, Andrew J. MichaelNear real-time monitoring of volcanic surface deformation from GPS measurements at Long Valley Caldera, California
Long Valley Caldera in eastern California is an active volcanic area and has shown continued unrest in the last three decades. We have monitored surface deformation from Global Positioning System (GPS) data by using a projection method that we call Targeted Projection Operator (TPO). TPO projects residual time series with secular rates and periodic terms removed onto a predefined spatial pattern.AuthorsKang Hyeun Ji, Thomas A. Herring, Andrea L. LlenosDetecting aseismic strain transients from seismicity data
Aseismic deformation transients such as fluid flow, magma migration, and slow slip can trigger changes in seismicity rate. We present a method that can detect these seismicity rate variations and utilize these anomalies to constrain the underlying variations in stressing rate. Because ordinary aftershock sequences often obscure changes in the background seismicity caused by aseismic processes, weAuthorsAndrea L. Llenos, Jeffrey McGuireNon-USGS Publications**
Segall, P., A. L. Llenos, S.-H. Yun, A. M. Bradley, and E. M. Syracuse (2013), Time-dependent dike propagation from joint inversion of seismicity and deformation data, J. Geophys. Res. Solid Earth, 118, doi: 10.1002/2013JB010251.Llenos, A. L., and J. J. McGuire (2011), Detecting aseismic strain transients from seismicity data, J. Geophys. Res., 116, B06305, doi: 10.1029/2010JB007537.Llenos, A. L., J. J. McGuire, and Y. Ogata (2009), Modeling seismic swarms triggered by aseismic transients, Earth Planet. Sci. Lett., 281, 59-69, doi:10.1016/j.epsl.2009.02.011.Llenos, A. L., and J. J. McGuire (2007), Influence of fore-arc structure on the extent of great subduction zone earthquakes, J. Geophys. Res., 112, B09301, doi: 10.1029/2007JB004944.**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.