I love that seismology lets me study a fascinating natural process and use that knowledge to help people understand earthquakes and live with them safely. I combine observations of earthquakes with statistical models to assess hazards, evaluate earthquake predictions, seek to understand how geologic structures and tectonic forces cause earthquakes, and communicate that information to the public.
Andy Michael has been a geophysicist with the U.S. Geological Survey’s Earthquake Science Center since 1986. He combines observations of earthquake processes and statistical models to determine long-term and short-term earthquake probabilities, to evaluate proposed earthquake prediction methods, and to better understand how stress and structure function as part of the seismogenic process. A graduate of MIT (B.S., 1981) and Stanford University (M.S., 1983, Ph.D. 1986), he has authored over 100 papers and reports. He was the Editor-in-Chief of the Bulletin of the Seismological Society of America from 2004 to 2010. He also served the Society as President and on its Board of Directors.
His outreach efforts include founding the Earthquake Science Center web site, which became part of earthquake.usgs.gov, in order to facilitate the rapid dissemination of earthquake information and a lecture and performance titled “The Music of Earthquakes.” That lecture combines music and seismology and features “Earthquake Quartet #1,” his composition for voice, cello, trombone, and sonified seismograms. He is a founder of an online educational resource: The Community Online Resource for Statistical Seismicity Analysis.
He currently works on the USGS aftershock forecasts under the Earthquake Processes, Probabilities, and Occurrence Project, long-term hazards assessments as part of the National Seismic Hazard Model Project and is a member of the National Earthquake Prediction Evaluation Council.
For his service to the Seismological Society of America he received its Distinguished Service Award in 2011. For his career contributions, he received the Department of the Interior’s Distinguished Service Award in 2019.
Science and Products
Could the M7.1 Ridgecrest, CA Earthquake Sequence Trigger a Large Earthquake Nearby?
Operational Earthquake Forecasting – Implementing a Real-Time System for California
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 interactive viewer to improve operational aftershock forecasts
An efficient, analytic solution using order statistics for probabilistic seismic‐hazard assessment without the Poisson assumption
Prospective and retrospective evaluation of the U.S. Geological Survey public aftershock forecast for the 2019-2021 Southwest Puerto Rico Earthquake and aftershocks
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
An International Virtual Workshop on Global Seismology and Tectonics (IVWGST‐2020)
Global seismology and tectonics: A report on International Virtual Workshop on Global Seismology and Tectonics (IVWGST-2020)
The normal faulting 2020 Mw5.8 Lone Pine, Eastern California earthquake sequence
Pseudo-prospective evaluation of UCERF3-ETAS forecasts during the 2019 Ridgecrest sequence
Regionally Optimized Background Earthquake Rates from ETAS (ROBERE) for probabilistic seismic hazard assessment
Potential duration of aftershocks of the 2020 southwestern Puerto Rico earthquake
Ensembles of ETAS models provide optimal operational earthquake forecasting during swarms: Insights from the 2015 San Ramon, California swarm
OAF Tools - R package
Science and Products
- Science
Could the M7.1 Ridgecrest, CA Earthquake Sequence Trigger a Large Earthquake Nearby?
Release Date: SEPTEMBER 30, 2019 Two of the first questions that come to mind for anyone who just felt an earthquake are, “Will there be another one?” and “Will it be larger?”.Operational Earthquake Forecasting – Implementing a Real-Time System for California
It is well know that every earthquake can spawn others (e.g., as aftershocks), and that such triggered events can be large and damaging, as recently demonstrated by L’Aquila, Italy and Christchurch, New Zealand earthquakes. In spite of being an explicit USGS strategic-action priority (http://pubs.usgs.gov/of/2012/1088; page 32), the USGS currently lacks an automated system with which to forecast s... - Data
2017 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: 75
An interactive viewer to improve operational aftershock forecasts
The U.S. Geological Survey (USGS) issues forecasts for aftershocks about 20 minutes after most earthquakes above M 5 in the United States and its territories, and updates these forecasts 75 times during the first year. Most of the forecasts are issued automatically, but some forecasts require manual intervention to maintain accuracy. It is important to identify the sequences whose forecasts will bAuthorsGabrielle Madison Paris, Andrew J. MichaelAn 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. LlenosProspective and retrospective evaluation of the U.S. Geological Survey public aftershock forecast for the 2019-2021 Southwest Puerto Rico Earthquake and aftershocks
The Mw 6.4 Southwest Puerto Rico Earthquake of 7 January 2020 was accompanied by a robust fore‐ and aftershock sequence. The U.S. Geological Survey (USGS) has issued regular aftershock forecasts for more than a year since the mainshock, available on a public webpage. Forecasts were accompanied by interpretive and informational material, published in English and Spanish. Informational products inclAuthorsNicholas van der Elst, Jeanne L. Hardebeck, Andrew J. Michael, Sara McBride, Elizabeth VanacoreModeling 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 ShiroAn International Virtual Workshop on Global Seismology and Tectonics (IVWGST‐2020)
An International Virtual Workshop on Global Seismology and Tectonics (IVWGST‐2020) was organized by the Geoscience and Technology Division of Council of Scientific and Industrial Research—North East Institute of Science and Technology, Jorhat, India from 14 to 25 September 2020. This workshop predominantly catered to undergraduate, postgraduate, and Ph.D. students, scientists, and academicians froAuthorsSantanu Baruah, Chandan Dey, Prachurjya Borthakur, G. Narahari Sastry, Andrew J. MichaelGlobal seismology and tectonics: A report on International Virtual Workshop on Global Seismology and Tectonics (IVWGST-2020)
No abstract available.AuthorsSantanu Baruah, Chandan Dey, G. Narahari Sastry, Andrew J. MichaelThe normal faulting 2020 Mw5.8 Lone Pine, Eastern California earthquake sequence
The 2020 Mw 5.8 Lone Pine earthquake, the largest earthquake on the Owens Valley fault zone, eastern California, since the nineteenth century, ruptured an extensional stepover in that fault. Owens Valley separates two normal‐faulting regimes, the western margin of the Great basin and the eastern margin of the Sierra Nevada, forming a complex seismotectonic zone, and a possible nascent plate boundaAuthorsEgill Hauksson, Brian J. Olsen, Alex R. R. Grant, Jennifer R Andrews, Angela I. Chung, Susan E. Hough, Hiroo Kanamori, Sara McBride, Andrew J. Michael, Morgan T. Page, Zachary E. Ross, Deborah Smith, Sotiris ValkaniotisPseudo-prospective evaluation of UCERF3-ETAS forecasts during the 2019 Ridgecrest sequence
The 2019 Ridgecrest sequence provides the first opportunity to evaluate Uniform California Earthquake Rupture Forecast v.3 with epidemic‐type aftershock sequences (UCERF3‐ETAS) in a pseudoprospective sense. For comparison, we include a version of the model without explicit faults more closely mimicking traditional ETAS models (UCERF3‐NoFaults). We evaluate the forecasts with new metrics developedAuthorsWilliam J. Savran, Maximillian J. Werner, W. Marzocchi, David A. Rhoades, David D. Jackson, Kevin R. Milner, Edward H. Field, Andrew J. MichaelRegionally 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. MichaelPotential duration of aftershocks of the 2020 southwestern Puerto Rico earthquake
AbstractAftershocks (earthquakes clustered spatially and chronologically near the occurrence of a causative earthquake) are ongoing in southwestern Puerto Rico after a series of earthquakes, which include a magnitude 6.4 earthquake that occurred near Barrio Indios, Guayanilla, on January 7, 2020, and affected the surrounding area. This report estimates the expected duration of these aftershocks byAuthorsNicholas van der Elst, Jeanne L. Hardebeck, Andrew J. MichaelEnsembles 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. Michael - Software
OAF Tools - R package
This repository contains the source code for the oaftools package. The package creates visual tools to study aftershock behavior and the performance of the Operational Aftershock Forecasting system. The visual tools are: A global map, rendered by Leaflet to show the distribution of earthquakes with forecasts A local map, rendered by Leaflet to show the aftershock sequence and the aftershock zone