Annemarie Baltay

I study how physical measures of earthquakes and the earth control ground motions measured at distance, and how ground motion observations can be used to gain insight on the earthquake source and path. I am particularly interested in earthquake stress drop: how it is measured, what is the variability, and how that all relates to ground motion data and models. I am also focused on physical components and uncertainty of ground-motion prediction equations (GMPEs), a critical building block in hazard maps. Reducing the variability and uncertainty in GMPEs is imperative to building better hazard maps, as well as for performing more accurate site-specific hazard studies for critical facilities. Currently, I am working towards physical explanations for variability in the source, site, and path components in ground motions. Ultimately we will develop models for predicting those effects from geophysical observables, such as stress drop (for source), site velocity profiles and attenuation (for site), and whole-path attenuation (for path). I am also involved in the USGS-led ShakeAlert earthquake early warning project, which aims to alert the U.S. West coast for earthquake ground motion before it arrives at a user's location; as part of that project, I work on the best ways to model ground motion and associated uncertainty in early warning. 

Education

2011                      Ph.D. Geophysics, Department of Geophysics, Stanford University

2008                      M.S. Geophysics, Department of Geophysics, Stanford University

2005                      B.A. Applied Mathematics, Yale University

Appointments

2015 - present      Research Geophysicist, U.S. Geological Survey, Moffett Field, Mountain View, CA

2013 - 2015          Mendenhall Postdoctoral Scholar, U.S. Geological Survey, Menlo Park

2012                      Postdoctoral Scholar, Department of Geophysics, Stanford University

2012                      Instructor, Understanding Natural Hazards, Quantifying Risk and Increasing Resilience in Highly Urbanized                                                 Regions, Department of Geology, Stanford University

2010                      Summer Intern for Europe Earthquake Model Development, Risk Management Solutions, Newark, CA

2009                      Graduate Student Researcher through NSF EAPSI, Department of Earth and Planetary Sciences, University of Tokyo

Honors and Activities

2019                      Presidential Early Career Award for Scientists and Engineers (PECASE)

2018                      Charles F. Richter Early Career Award, Seismological Society of America

2017 - present       CISN ShakeMap Data/Integration Working Group

2016 - present       Co-leader, Southern California Earthquake Center Planning Committee, Ground Motion focus group 

Publications _{^{(*indicates supervisee/student/postdoc)}}

Baltay, A. S. and T. C. Hanks (2019), Jack Boatwright’s Last Science, Seism. Res. Lett., 90 (4): 1444–1445. doi: 10.1785/0220190086  [Link]

*Klimasewski, A., V. Sahakian, A. Baltay, J. Boatwright, J. B. Fletcher and L. Baker, κ0 and Broadband Site Spectra in Southern California from Source Model‐Constrained Inversion. Bulletin of the Seismological Society of America ; 109 (5): 1878–1889. doi: 10.1785/0120190037

Cochran, E. S., J. Bunn, S. E. Minson, A. Baltay, D. L. Kilb, Y. Kodera, and M. Hoshiba (2019), Event detection success of the PLUM earthquake early warning algorithm in southern California, in review at Bull. Seismol. Soc. Amer., 10.1785/0120180326.

*Sahakian, V., A. Baltay, T. Hanks, J. Buehler, F. Vernon, D. Kilb (2018), Ground-Motion Residuals, Path Effects, and Crustal Properties, J. of Geophys. Res., 10.1029/2018JB016796

Baltay, A. S., T. C. Hanks and N. A. Abrahamson (2019), Stress drops from Arias intensity ground motions, J. of Geophys. Res., 10.1029/2018JB016753 [Link]

Minson, S. E., A. S. Baltay, E. S. Cochran, T. C. Hanks, M. T. Page, S. K. McBride, K. R. Milner and M-A. Meier (2019), The Limits of Earthquake Early Warning: Accuracy and Best Alerting Strategy, Scientific Reports, 9:2478, 10.1038/s41598-019-39384-y

Given, D.D., Allen, R.M., Baltay, A.S., Bodin, P., Cochran, E.S., Creager, K., Gee, L.S., Hauksson, E., Heaton, T.H., Hellweg, M., Murray, J.R., Thomas, V.I., Toomey, D., and Yelin, T.S., (2018), Revised technical implementation plan for the ShakeAlert system—An earthquake early warning system for the West Coast of the United States: U.S. Geological Survey Open-File Report 2018–1155, 42 p., 10.3133/ofr20181155

*Sahakian, V., D. Melgar, L. Quíntanar, L. Ramírez-Guzman, X. Pérez-Campos, A. Baltay (2018), Ground Motions from the 7 and 19 September Tehuantepec and Puebla-Morelos, Mexico Earthquakes, Bull. Seismol. Soc. of Am., 10.1785/012018108

*Little, G., A. M. Thomas and A. S. Baltay (2018), Using tectonic tremor to constrain seismic-wave attenuation in Cascadia, Geophys. Res. Lett., 10.1029/2018GL079344

Cochran, E.S., Aagaard, B.T., Allen, R.M., Andrews, J., Baltay, A.S., Barbour, A.J., Bodin, P., Brooks, B.A., Chung, A., Crowell, B.W., Given, D.D., Hanks, T.C., Hartog, J.R., Hauksson, E., Heaton, T.H., McBride, S., Meier, M-A., Melgar, D., Minson, S.E., Murray, J.R., Strauss, J.A., and Toomey, D., (2018), Research to improve ShakeAlert earthquake early warning products and their utility: U.S. Geological Survey Open-File Report 2018–1131, 17 p.,  10.3133/ofr20181131

Thompson, E. M. and A. S. Baltay (2018), The case for mean rupture distance in ground‐motion estimation, Bull. Seismol. Soc. of Am., 10.1785/0120170306

*Sahakian, V., A. Baltay, T. Hanks, J. Buehler, F. Vernon, D. Kilb (2018), Decomposing leftovers: Event, path, and site residuals for a small-magnitude ANZA- region GMPE, Bull. Seismol. Soc. of Am., 10.1785/0120170376

Moschetti, M. P., N. Luco, A. D. Frankel, M. D. Petersen, B. T. Aagaard, A. S. Baltay, M. L. Blanpied, O. S. Boyd, R. W. Briggs, R. D. Gold, R. W. Graves, S. H. Hartzell, S. Rezaeian, W. J. Stephenson, D. J. Wald, R. A. Williams, K. B. Withers (2018), Integrate Urban‐Scale Seismic Hazard Analyses with the U.S. National Seismic Hazard Model, Seism. Res. Lett., 89 (3), 10.1785/0220170261

Minson, S. E., M.-A. Meier, A. S. Baltay, T. C. Hanks, E. S. Cochran (2018), The limits of earthquake early warning: Timeliness of ground motion estimates. Sci. Adv. 4, eaaq0504

Baltay, A. S., T. C. Hanks and N. A. Abrahamson (2017), Uncertainty, variability and earthquake physics in Ground-Motion Prediction Equations, Bull. Seis. Soc. Am., 107(4), 10.1785/0120140023 10.1785/0120160164 [Link] 

Baltay, A. S. and J. Boatwright (2015), Ground-motion observations of the 2014 South Napa Earthquake, Seism. Res. Lett., 86(2A), doi: 10.1785/0220140232 [Link]

Brocher, T.M., Baltay, A. S., Hardebeck, J. L., Pollitz, F. F., Murray, J. R., Llenos, A. L., Schwartz, D. P., Blair, J. L., Ponti, D. J., Lienkaemper, J. J., Langenheim, V. E., Dawson, T. E., Hudnut, K. W., Shelly, D. R., Dreger, D., Boatwright, J., Aagaard, B. T., Wald, D. J., Allen, R. M., Barnhart, W. D., Knudsen, K. L., Brooks, B. A., and Scharer, K. M. (2015), The M6.0 24 August 2014 South Napa Earthquake, Seism. Res. Lett., 86(2A), doi: 10.1785/0220150004.

Baltay, A. S. and T. C. Hanks (2014), Understanding the magnitude dependence of PGA and PGV in NGA-West2 Data, Bull. Seis. Soc. Am.,104(6), doi: 10.1785/0120130283 [Link]

Bozorgnia, Y., N. A. Abrahamson, L. Al Atik, T. D. Ancheta, G. A. Atkinson, J. W. Baker, A. S. Baltay, et al., (2014), NGA-West2 Research Project, Earthquake Spectra, doi: http://dx.doi.org/10.1193/072113EQS209M [Link]

Yabe, S., A. S. Baltay, S. Ide and G. C. Beroza, (2014) Seismic-wave attenuation determined from tectonic tremor in multiple subduction zones, Bull. Seis. Soc. Am., 104(4), doi:10.1785/0120140023 [Link]

Baltay, A. S., G. C. Beroza and S. Ide (2014), Radiated energy of great earthquakes from teleseismic empirical Green’s function deconvolution, Pure Appl. Geophs., doi:10.1007/s00024-014-0804-0 [Link]

Baltay, A. S., T. C. Hanks and G. C. Beroza (2013) Stable Stress Drop Measurements and their Variability: Implications for Ground-Motion Prediction, Bull. Seism. Soc. Am., 103(1), doi: 10.1785/0120120161. [Link]

Baltay, A. S. and G. C. Beroza (2013), Ground motion prediction from tremor, Geophys. Res. Lett, doi:10.1029/2013GL058506 [Link]

Ide, S., A. Baltay and G. C. Beroza, (2011) Shallow Dynamic Overshoot and Energetic Deep Rupture of the 2011 Mw 9.0 Tohoku-Oki Earthquake, Science 332, 6036, pp 1426 - 1429, doi:10.1126/science.1207020. [Link]

Baltay, A., S. Ide, G. Prieto, and G. C. Beroza, (2011) Variability in Earthquake Stress Drop and Apparent Stress, Geophys. Res. Lett. 38, L06303, doi:10.1029/2011GL046698 [Link]

Baltay, A., G. Prieto, and G. C. Beroza, (2010) Radiated seismic energy from coda measurements indicates no scaling in apparent stress with seismic moment, J. Geophys. Res. 115(B8), 1-12, doi:10.1029/2009JB006736 [Link]