Andrea Llenos
Biography
I am a research geophysicist at the Earthquake Science Center. In my research, I use statistical models and tests to characterize earthquake rate changes in catalogs and the processes that trigger them, both natural (e.g., slow slip or dike intrusions) and manmade (e.g., wastewater fluid injection). I am also interested in the impacts these variations have on short-term earthquake forecasts as well as longer term seismic hazard. Recent study areas include Oklahoma, Arkansas, the central and eastern US, Long Valley Caldera, Hawaii, the Bay Area in northern California and the Salton Trough in southern California.
Prior to the USGS, I worked as a postdoctoral scholar at Stanford University, modeling time-dependent dike propagation by jointly inverting seismicity and deformation data.
Education
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
Professional Experience
Research Geophysicist (term), US Geological Survey, Menlo Park, CA 2015-present
Mendenhall Postdoctoral Fellow, US Geological Survey, 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
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
Professional Societies, Memberships and Service
USGS Powell Center Working Group on Induced Seismicity (2012-2014)
American Geophysical Union (2004-present)
Seismological Society of America (2007-present)
Sigma Xi (2004-present)
Reviewer for NSF proposals, Journal of Geophysical Research, Geophysical Research Letters, Geophysical Journal International, Bulletin of the Seismological Society of America, Seismological Research Letters, Earth and Planetary Science Letters, Tectonophysics, Physical Review Leters, Science, Science Advances, Nature Geoscience, Earth Planets Space, Acta geodynamica et geomateria, International Journal of Earth Sciences, Science China Earth Sciences, Geofluids, Advances in Geophysics, Journal of Seismology, AGU Books, GSA Books.
Publications
Llenos, A. L., and A. J. Michael (2019), Ensembles of ETAS models provide optimal operational earthquake forecasting during swarms: Insights from the 2015 San Ramon, California swarm, Bull. Seismol. Soc. Am., doi: 10.1785/0120190020. https://pubs.geoscienceworld.org/ssa/bssa/article/doi/10.1785/0120190020/573839/Ensembles-of-ETAS-Models-Provide-Optimal
Llenos, A. L., and N. J. van der Elst (2019), Improving earthquake forecasts during swarms with a duration model, Bull. Seismol. Soc. Am., 109, 1148-1155, doi: 10.1785/0120180332. https://pubs.geoscienceworld.org/ssa/bssa/article/569753/improving-earthquake-forecasts-during-swarms-with
Hardebeck, J. L., A. L. Llenos, A. J. Michael, M. T. Page, and N. van der Elst (2018), Updated California aftershock parameters, Seismol. Res. Lett., 90, doi: 10.1785/0220180240. https://pubs.geoscienceworld.org/ssa/srl/article/90/1/262/567500/updated-california-aftershock-parameters
Petersen, M. D., C. S. Mueller, M. P. Moschetti, S. M. Hoover, K. S. Rukstales, D. E. McNamara, R. A. Williams, A. M. Shumway, P. M. Powers, P. S. Earle, A. L. Llenos, A. J. Michael, J. L. Rubinstein, J. H. Norbeck, and E. S. Cochran (2018), 2018 One-year seismic hazard forecast for the Central and Eastern United States from induced and natural earthquakes, Seismol. Res. Lett., 89, 1049-1061, doi: 10.1785/0220180005. http://pubs.geoscienceworld.org/ssa/srl/article/89/3/1049/529918/2018-one-year-seismic-hazard-forecast-for-the
Llenos, A. L., and A. J. Michael (2017), Forecasting the (Un)productivity of the 2014 M6.0 South Napa aftershock sequence, Seismol. Res. Lett., doi: 10.1785/0220170050. http://srl.geoscienceworld.org/content/early/2017/07/14/0220170050
Petersen, M. D., C. S. Mueller, M. P. Moschetti, S. M. Hoover, A. M. Shumway, D. E. McNamara, R. A. Williams, A. L. Llenos, W. L. Ellsworth, A. J. Michael, J. L. Rubinstein, A. F. McGarr, and K. S. Rukstales (2017), 2017 One-year seismic hazard forecast for the Central and Eastern United States from induced and natural earthquakes, Seismol. Res. Lett., 88, doi: 10.1785/0220170005. http://srl.geoscienceworld.org/content/early/2017/02/24/0220170005
Petersen, M. D., C. S. Mueller, M. P. Moschetti, S. M. Hoover, A. L. Llenos, W. L. Ellsworth, A. J. Michael, J. L. Rubinstein, A. F. McGarr, and K. S. Rukstales (2016), Seismic-hazard forecast for 2016 including induced and natural earthquakes in the Central and Eastern United States, Seismol. Res. Lett., 87, doi: 10.1785/0220160072. http://srl.geoscienceworld.org/content/early/2016/08/25/0220160072.abstract
Llenos, A. L., and A. J. Michael (2016), Characterizing potentially induced earthquake rate changes in the Brawley Seizmic Zone, southern California, Bull. Seismol. Soc. Am., 106, doi: 10.1785/0120150053. http://bssa.geoscienceworld.org/content/early/2016/08/18/0120150053
Petersen, M. D., C. S. Mueller, M. P. Moschetti, S. M. Hoover, A. L. Llenos, W. L. Ellsworth, A. J. Michael, J. L. Rubinstein, A. F. McGarr, and K. S. Rukstales (2016), 2016 One-year seismic hazard forecast for the Central and Eastern United States from induced and natural earthquakes, U. S. Geological Survey Open-File Report 2016-1035, 52 p. [Link]
Petersen, M. D., C. S. Mueller, M. P. Moschetti, S. M. Hoover, J. L. Rubinstein, A. L. Llenos, A. J. Michael, W. L. Ellsworth, A. F. McGarr, A. A. Holland, and J. G. Anderson (2015), Incorporating induced seismicity in the 2014 United States National Seismic Hazard Model - Results of 2014 workshop and sensitivity studies, U. S. Geological Survey Open-File Report 2015-1070, 69 p. [Link]
Brocher, T. M., A. S. Baltay, J. L. Hardebeck, F. F. Pollitz, J. R. Murray, A. L. Llenos, D. P. Schwartz, J. L. Blair, D. J. Ponti, J. J. Lienkaemper, V. E. Langenheim, T. E. Dawson, K. W. Hudnut, D. R. Shelley, D. Dreger, J. Boatwright, B. T. Aagaard, D. J. Wald, R. M. Allen, W. D. Barnhart, K. L. Knudsen, B. A. Brooks, K. M. Scharer (2015), The M6.0 24 August 2014 South Napa earthquake, Seismol. Res. Lett., 86, 309-326, doi: 10.1785/0220150004. [Link]
Ellsworth, W. L., A. L. Llenos, A. F. McGarr, A. J. Michael, J. L. Rubinstein, C. S. Mueller, M. D. Petersen, and E. Calais (2015), Increasing seismicity in the U. S. Midcontinent: Implications for earthquake hazard, The Leading Edge, 34, 6(2015), 618-626, doi:10.1190/tle34060618.1. [Link]
Ji, K. H., T. A. Herring, and A. L. Llenos (2013), Near real-time monitoring of volcanic surface deformation at Long Valley Caldera, California, Geophys. Res. Lett., 40, 1054-1058, doi: 10.1002/grl.50258.[Link]
Llenos, A. L., and A. J. Michael (2013), Modeling earthquake rate changes in Oklahoma and Arkansas: Possible signatures of induced seismicity, Bull. Seismol. Soc. Am., 103, 2850-2861, doi: 10.1785/0120130017. [Link]
Segall, P., A. L. Llenos, S.-H. Yun, A. M. Bradley, and E. Syracuse (2013), Time-dependent dike propagation from joint inversion of seismicity and deformation data, J. Geophys. Res., 118, doi:10.1002/2013JB010251. [Link]
Llenos, A. L., and J. J. McGuire (2011), Detecting aseismic strain transients from seismicity data, J. Geophys. Res., 116, B06305, doi: 10.1029/2010JB007537. [Link]
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. [Link]
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. [Link]
Science and Products
Understanding Fluid Injection Induced Seismicity
Fluid injection induced seismicity has been reported since the 1960s. There are currently more than 150,000 injection wells associated with oil and gas production in 34 states in the conterminous US. Pore pressure disturbance caused by injection is generally considered the culprit for injection induced seismicity, but, not all injection causes seismicity. It is not well understood what...
Improving earthquake forecasts during swarms with a duration model
Earthquake swarms present a challenge for operational earthquake forecasting because they are driven primarily by transient external processes, such as fluid flow, the behavior and duration of which are difficult to predict. In this study, we develop a swarm duration model to estimate how long a swarm is likely to last based on actuarial...
Llenos, Andrea L.; Van Der Elst, Nicholas Updated California aftershock parameters
Reasenberg and Jones (1989) introduced a statistical model for aftershock rate following a mainshock along with estimates of “generic” California parameter values based on past aftershock sequences. The Reasenberg and Jones (1989) model has been used for decades to issue aftershock forecasts following M≥5">M≥5...
Hardebeck, Jeanne L.; Llenos, Andrea L.; Michael, Andrew J.; Page, Morgan T.; Van Der Elst, Nicholas 2018 one‐year seismic hazard forecast for the central and eastern United States from induced and natural earthquakes
This article describes the U.S. Geological Survey (USGS) 2018 one‐year probabilistic seismic hazard forecast for the central and eastern United States from induced and natural earthquakes. For consistency, the updated 2018 forecast is developed using the same probabilistic seismicity‐based methodology as applied in the two previous forecasts....
Petersen, Mark D.; Mueller, Charles; Moschetti, Morgan P.; Hoover, Susan M.; Rukstales, Kenneth S.; McNamara, Daniel E.; Williams, Robert A.; Shumway, Allison; Powers, Peter M.; Earle, Paul S.; Llenos, Andrea L.; Michael, Andrew J.; Rubinstein, Justin L.; Norbeck, Jack; Cochran, Elizabeth S. 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...
Llenos, Andrea L.; Michael, Andrew J. 2017 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...
Petersen, Mark D.; Mueller, Charles; Moschetti, Morgan P.; Hoover, Susan M.; Shumway, Allison; McNamara, Daniel E.; Williams, Robert; Llenos, Andrea L.; Ellsworth, William L.; Rubinstein, Justin L.; McGarr, Arthur F.; Rukstales, Kenneth S. Seismic‐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...
Petersen, Mark D.; Mueller, Charles; Moschetti, Morgan P.; Hoover, Susan M.; Llenos, Andrea L.; Ellsworth, William L.; Michael, Andrew J.; Rubinstein, Justin L.; McGarr, Arthur F.; Rukstales, Kenneth S. Characterizing 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...
Llenos, Andrea L.; Michael, Andrew J.
2016 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...
Petersen, Mark D.; Mueller, Charles S.; Moschetti, Morgan P.; Hoover, Susan M.; Llenos, Andrea L.; Ellsworth, William L.; Michael, Andrew J.; Rubinstein, Justin L.; McGarr, Arthur F.; Rukstales, Kenneth S. Increasing 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...
Ellsworth, William L.; Llenos, Andrea L.; McGarr, Arthur F.; Michael, Andrew J.; Rubinstein, Justin L.; Mueller, Charles S.; Petersen, Mark D.; Calais, Eric
Incorporating 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...
Petersen, Mark D.; Mueller, Charles S.; Moschetti, Morgan P.; Hoover, Susan M.; Rubinstein, Justin L.; Llenos, Andrea L.; Michael, Andrew J.; Ellsworth, William L.; McGarr, Arthur F.; Holland, Austin A.; Anderson, John G. Modeling 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...
Llenos, Andrea L.; Michael, Andrew J. Near 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...
Ji, Kang Hyeun; Herring, Thomas A.; Llenos, Andrea L.