Andrew Michael
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
Subsurface structure and kinematics of the Calaveras-Hayward fault stepover from three-dimensional Vp and seismicity, San Francisco Bay region, California
Viscoelasticity, postseismic slip, fault interactions, and the recurrence of large earthquakes
Stress orientations at intermediate angles to the San Andreas Fault, California
Stress field variations in the Swiss Alps and the northern Alpine foreland derived from inversion of fault plane solutions
Is a powerful quake likely to strike in the next 30 years?
A shallow fault-zone structure illuminated by trapped waves in the Karadere-Duzce branch of the North Anatolian Fault, western Turkey
Quantitative analysis of seismic fault zone waves in the rupture zone of the 1992 Landers, California, earthquake: Evidence for a shallow trapping structure
A preliminary study on fine structures of Jiashi earthquake region and earthquake generating fault
Displaced rocks, strong motion, and the mechanics of shallow faulting associated with the 1999 Hector Mine, California, earthquake
Major quake likely to strike between 2000 and 2030
Birth of a fault: Connecting the Kern County and Walker Pass, California, earthquakes
Seismicity alert probabilities at Parkfield, California, revisited
Science and Products
- Science
- Data
- Publications
Filter Total Items: 77
Subsurface structure and kinematics of the Calaveras-Hayward fault stepover from three-dimensional Vp and seismicity, San Francisco Bay region, California
The Calaveras and Hayward faults are major components of the San Andreas fault system in the San Francisco Bay region. Dextral slip is presumed to transfer from the Calaveras fault to the Hayward fault in the Mission Hills region, an area of uplift in the contractional stepover between the two faults. Here the estimated deep slip rates drop from 15 to 6 mm/yr on the Calaveras fault, and slip beginAuthorsDavid M. Manaker, Andrew J. Michael, Roland BurgmannViscoelasticity, postseismic slip, fault interactions, and the recurrence of large earthquakes
The Brownian Passage Time (BPT) model for earthquake recurrence is modified to include transient deformation due to either viscoelasticity or deep post seismic slip. Both of these processes act to increase the rate of loading on the seismogenic fault for some time after a large event. To approximate these effects, a decaying exponential term is added to the BPT model's uniform loading term. The reAuthorsA.J. MichaelStress orientations at intermediate angles to the San Andreas Fault, California
There are currently two competing models for the frictional strength of the San Andreas Fault in California: the strong-fault model and the weak-fault model. The strong-fault model predicts the maximum horizontal compressive stress axis to be at low angles to the fault, while the relatively weak fault model predicts it to be at high angles. Previous studies have disagreed as to which model is suppAuthorsJeanne L. Hardebeck, Andrew J. MichaelStress field variations in the Swiss Alps and the northern Alpine foreland derived from inversion of fault plane solutions
This study is devoted to a systematic analysis of the state of stress of the central European Alps and northern Alpine foreland in Switzerland based on focal mechanisms of 138 earthquakes with magnitudes between 1 and 5. The most robust feature of the results is that the azimuth of the minimum compressive stress, S3, is generally well constrained for all data subsets and always lies in the NE quadAuthorsU. Kastrup, M.L. Zoback, N. Deichmann, Kenneth F. Evans, D. Giardini, A.J. MichaelIs a powerful quake likely to strike in the next 30 years?
No abstract available.AuthorsAndrew J. Michael, Stephanie L. Ross, Robert W. Simpson, Mary Lou Zoback, David P. Schwartz, Michael L. BlanpiedA shallow fault-zone structure illuminated by trapped waves in the Karadere-Duzce branch of the North Anatolian Fault, western Turkey
We discuss the subsurface structure of the Karadere-Duzce branch of the North Anatolian Fault based on analysis of a large seismic data set recorded by a local PASSCAL network in the 6 months following the Mw = 7.4 1999 Izmit earthquake. Seismograms observed at stations located in the immediate vicinity of the rupture zone show motion amplification and long-period oscillations in both P- and S-wavAuthorsY. Ben-Zion, Z. Peng, D. Okaya, L. Seeber, J.G. Armbruster, N. Ozer, A.J. Michael, S. Baris, M. AktarQuantitative analysis of seismic fault zone waves in the rupture zone of the 1992 Landers, California, earthquake: Evidence for a shallow trapping structure
We analyse quantitatively a waveform data set of 238 earthquakes recorded by a dense seismic array across and along the rupture zone of the 1992 Landers earthquake. A grid-search method with station delay corrections is used to locate events that do not have catalogue locations. The quality of fault zone trapped waves generated by each event is determined from the ratios of seismic energy in timeAuthorsZ. Peng, Y. Ben-Zion, A.J. Michael, L. ZhuA preliminary study on fine structures of Jiashi earthquake region and earthquake generating fault
It is very unusual that nine large earthquakes of similar magnitudes (M = 6.1-6.8) occured within a very small area and a very short period of time (1997-1998) in Jiashi of Xinjiang Province, Northwest China. This paper analyzes the observed data of the aftershocks in the Jiashi earthquake region for studying the generating mechanism and deep structural background of the Jiashi strong earthquake sAuthorsS.-L. Li, X. Zhang, Walter D. Mooney, X.-L. Lai, A.J. Michael, Y.-H. DuanDisplaced rocks, strong motion, and the mechanics of shallow faulting associated with the 1999 Hector Mine, California, earthquake
The paucity of strong-motion stations near the 1999 Hector Mine earthquake makes it impossible to make instrumental studies of key questions about near-fault strong-motion patterns associated with this event. However, observations of displaced rocks allow a qualitative investigation of these problems. By observing the slope of the desert surface and the frictional coefficient between these rocks aAuthorsAndrew J. Michael, Stephanie L. Ross, Heidi D. StennerMajor quake likely to strike between 2000 and 2030
No abstract available.AuthorsAndrew J. Michael, Stephanie L. Ross, David P. Schwartz, James W. Hendley, Peter H. StaufferBirth of a fault: Connecting the Kern County and Walker Pass, California, earthquakes
A band of seismicity transects the southern Sierra Nevada range between the northeastern end of the site of the 1952 MW (moment magnitude) 7.3 Kern County earthquake and the site of the 1946 MW 6.1 Walker Pass earthquake. Relocated earthquakes in this band, which lacks a surface expression, better delineate the northeast-trending seismic lineament and resolve complex structure near the Walker PassAuthorsGerald W. Bawden, A.J. Michael, L.H. KelloggSeismicity alert probabilities at Parkfield, California, revisited
For a decade, the U.S. Geological Survey has used the Parkfield Earthquake Prediction Experiment scenario document to estimate the probability that earthquakes observed on the San Andreas fault near Parkfield will turn out to be foreshocks followed by the expected magnitude 6 mainshocks. During this time, we have learned much about the seismogenic process at Parkfield, about the long-term probabilAuthorsA.J. Michael, L.M. Jones - Software