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
Understanding Fluid Injection Induced Seismicity
Data Release for Latency Testing of Wireless Emergency Alerts intended for the ShakeAlert earthquake early warning system for the West Coast of the United States of America
2017 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes
2016 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes
An efficient, analytic solution using order statistics for probabilistic seismic‐hazard assessment without the Poisson assumption
Modeling the occurrence of M ∼ 5 caldera collapse-related earthquakes in Kīlauea volcano, Hawai'i
2021 U.S. National Seismic Hazard Model for the State of Hawaii
A big problem for small earthquakes: Benchmarking routine magnitudes and conversion relationships with coda-envelope-derived Mw in southern Kansas and northern Oklahoma
Regionally Optimized Background Earthquake Rates from ETAS (ROBERE) for probabilistic seismic hazard assessment
#EarthquakeAdvisory: Exploring discourse between government officials, news media and social media during the Bombay Beach 2016 Swarm
Ensembles of ETAS models provide optimal operational earthquake forecasting during swarms: Insights from the 2015 San Ramon, California swarm
Improving earthquake forecasts during swarms with a duration model
Updated California aftershock parameters
2018 one‐year seismic hazard forecast for the central and eastern United States from induced and natural earthquakes
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
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
- Science
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 mechanical - Data
Data Release for Latency Testing of Wireless Emergency Alerts intended for the ShakeAlert earthquake early warning system for the West Coast of the United States of America
ShakeAlert, the earthquake early warning (EEW) system for the West Coast of the United States, attempts to provides crucial warnings before strong shaking occurs. However, because the alerts are triggered only when an earthquake is already in progress, and the alert latencies and delivery times are platform dependent, the time between these warnings and the arrival of shaking is variable. The Shak2017 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes
We produced a one-year 2017 seismic hazard forecast for the central and eastern United States from induced and natural earthquakes that replaces the one-year 2016 forecast, and evaluated the 2016 seismic hazard forecast to improve future assessments. The 2016 forecast indicated high seismic hazard (greater than 1% probability of damaging ground shaking in 1 year) in portions of Oklahoma/Kansas, th2016 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes
A one-year seismic hazard forecast for the Central and Eastern United States (CEUS), based on induced and natural earthquakes, has been produced by the U.S. Geological Survey. 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 for the year 2016. This assessment - Publications
Filter Total Items: 20
An efficient, analytic solution using order statistics for probabilistic seismic‐hazard assessment without the Poisson assumption
Standard approaches to probabilistic seismic‐hazard assessment (PSHA) assume that earthquakes are random, independent events that follow a Poisson distribution of occurrences in a given time period (Cornell, 1968). To overcome the limitations of the Poisson assumption, such as ignoring earthquake clustering, we introduce an analytic method for PSHA that uses order statistics to allow for arbitraryAuthorsAndrew J. Michael, Andrea L. LlenosModeling the occurrence of M ∼ 5 caldera collapse-related earthquakes in Kīlauea volcano, Hawai'i
During the 2018 Kīlauea eruption and caldera collapse, M ∼ 5 caldera collapse earthquakes occurred almost daily from mid-May until the beginning of August. While caldera collapses happen infrequently, the collapse-related seismicity damaged nearby structures, and so these events should be included in a complete seismic hazard assessment. Here, we present an approach to forecast the seismic hazardAuthorsAndrea L. Llenos, Andrew J. Michael2021 U.S. National Seismic Hazard Model for the State of Hawaii
The 2021 U.S. National Seismic Hazard Model (NSHM) for the State of Hawaii updates the two-decades-old former model by incorporating new data and modeling techniques to improve the underlying ground shaking forecasts of tectonic-fault, tectonic-flexure, volcanic, and caldera collapse earthquakes. Two earthquake ground shaking hazard models (public policy and research) are produced that differ in hAuthorsMark D. Petersen, Allison Shumway, Peter M. Powers, Morgan P. Moschetti, Andrea L. Llenos, Andrew J. Michael, Charles Mueller, Arthur Frankel, Sanaz Rezaeian, Kenneth S. Rukstales, Daniel E. McNamara, P. Okubo, Yuehua Zeng, Kishor Jaiswal, Sean Kamran Ahdi, Jason M. Altekruse, Brian ShiroA big problem for small earthquakes: Benchmarking routine magnitudes and conversion relationships with coda-envelope-derived Mw in southern Kansas and northern Oklahoma
Earthquake magnitudes are widely relied upon measures of earthquake size. Although moment magnitude (MwMw) has become the established standard for moderate and large earthquakes, difficulty in reliably measuring seismic moments for small (generally Mw<4Mw<4) earthquakes has meant that magnitudes for these events remain plagued by a patchwork of inconsistent measurement scales. Because of this,AuthorsDavid R. Shelly, Kevin Mayeda, Justin Barno, Katherine M. Whidden, Morgan P. Moschetti, Andrea L. Llenos, Justin Rubinstein, William L. Yeck, Paul S. Earle, Rengin Gök, William R. WalterRegionally Optimized Background Earthquake Rates from ETAS (ROBERE) for probabilistic seismic hazard assessment
We use an epidemic‐type aftershock sequence (ETAS) based approach to develop a regionally optimized background earthquake rates from ETAS (ROBERE) method for probabilistic seismic hazard assessment. ROBERE fits parameters to the full seismicity catalog for a region with maximum‐likelihood estimation, including uncertainty. It then averages the earthquake rates over a suite of catalogs from which fAuthorsAndrea L. Llenos, Andrew J. Michael#EarthquakeAdvisory: Exploring discourse between government officials, news media and social media during the Bombay Beach 2016 Swarm
Communicating probabilities of natural hazards to varied audiences is a notoriously difficult task. Many of these challenges were encountered during the 2016 Bombay Beach, California, swarm of ~100 2≤M≤4.3 earthquakes, which began on 26 September 2016 and lasted for several days. The swarm’s proximity to the southern end of the San Andreas fault caused concern that a larger earthquake could be triAuthorsSara McBride, Andrea L. Llenos, Morgan T. Page, Nicholas van der ElstEnsembles of ETAS models provide optimal operational earthquake forecasting during swarms: Insights from the 2015 San Ramon, California swarm
Earthquake swarms, typically modeled as time-varying changes in background seismicity that are driven by external processes such as fluid flow or aseismic creep, present challenges for operational earthquake forecasting. While the time decay of aftershock sequences can be estimated with the modified Omori law, it is difficult to forecast the temporal behavior of seismicity rates during a swarm.AuthorsAndrea L. Llenos, Andrew J. MichaelImproving 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 statistics of previous swarms in a given region. We demonstrAuthorsAndrea L. Llenos, Nicholas van der ElstUpdated 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 mainshocks in California. Here, we update the “generic” parameters for California through a fAuthorsJeanne L. Hardebeck, Andrea L. Llenos, Andrew J. Michael, Morgan T. Page, Nicholas van der Elst2018 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. Rates of earthquakes across the United States M≥3.0 greAuthorsMark D. Petersen, Charles Mueller, Morgan P. Moschetti, Susan M. Hoover, Kenneth S. Rukstales, Daniel E. McNamara, Robert A. Williams, Allison Shumway, Peter M. Powers, Paul S. Earle, Andrea L. Llenos, Andrew J. Michael, Justin L. Rubinstein, Jack Norbeck, Elizabeth S. CochranForecasting 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. RukstalesNon-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.