Annemarie Baltay
Full name: Annemarie Baltay Sundstrom
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, as well as chair the Ground Motion Working Group and collaborate on the PLUM algorithm development.
Professional Experience
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
Education and Certifications
2011 Ph.D. Geophysics, Department of Geophysics, Stanford University
2008
Science and Products
Shaking, Damage and Failure
Earthquake Early Warning – Fine-Tuning for Best Alerts
Incorporating intensity distance attenuation into PLUM ground-motion-based earthquake early warning in the United States: The APPLES configuration
Applications of nonergodic site response models to ShakeAlert case studies in the Los Angeles area
Estimates of k0 and effects on ground motions in the San Francisco Bay area
What to expect when you are expecting earthquake early warning
Spatially continuous models of aleatory variability in seismic site response for southern California
Estimates of kappa in the San Francisco Bay area
Real-time earthquake detection and alerting behavior of PLUM ground-motion-based early warning in the United States
Empirical map-based nonergodic models of site response in the greater Los Angeles area
Earthquake early warning for estimating floor shaking levels of tall buildings
Alert optimization of the PLUM earthquake early warning algorithm for the western United States
The impact of 3D finite‐fault information on ground‐motion forecasting for earthquake early warning
Shaking is almost always a surprise: The earthquakes that produce significant ground motion
Science and Products
- Science
Shaking, Damage and Failure
Engineers require accurate estimates of strong ground motion in order to design structures to resist earthquake loads and reduce loss of life and property from damaging earthquakes. In addition, engineers need recordings of structural response to validate their design methodologies. In order to improve seismic hazard assessments, we need to advance our understanding of the physical processes that...Earthquake Early Warning – Fine-Tuning for Best Alerts
Release Date: OCTOBER 8, 2019 The goal of an earthquake early warning (EEW) system is to provide an alert to people and automatic systems after an earthquake begins but before the shaking reaches their location. As the USGS and its partners are developing an EEW system, called ShakeAlert®, for the West Coast, the benefits, costs, capabilities, and limitations are being investigated. Two recent... - Publications
Filter Total Items: 39
Incorporating intensity distance attenuation into PLUM ground-motion-based earthquake early warning in the United States: The APPLES configuration
We develop Attenuated ProPagation of Local Earthquake Shaking (APPLES), a new configuration for the United States West Coast version of the Propagation of Local Undamped Motion (PLUM) earthquake early warning (EEW) algorithm that incorporates attenuation into its ground-motion prediction procedures. Under APPLES, instead of using a fixed radius to forward-predict observed peak ground shaking to thAuthorsJessie K. Saunders, Elizabeth S. Cochran, Julian Bunn, Annemarie S. Baltay, Sarah E. Minson, Colin T O'RourkeApplications of nonergodic site response models to ShakeAlert case studies in the Los Angeles area
In this study, we explore whether the Parker and Baltay (2022) site response models for the Los Angeles (LA) basin region can improve ground‐motion forecasts in the U.S. Geological Survey ShakeAlert earthquake early warning system (hereafter ShakeAlert). We implement the peak ground acceleration and peak ground velocity site response models of Parker and Baltay (2022) in ShakeAlert via the earthquAuthorsRongrong Lin, Grace Alexandra Parker, Jeffrey McGuire, Annemarie S. BaltayEstimates of k0 and effects on ground motions in the San Francisco Bay area
Ground‐motion studies are a key component of seismic hazard analyses and often rely on information of the source, path, and site. Extensive research has been done on each of these parameters; however, site‐specific studies are of particular interest to seismic hazard studies, especially in the field of earthquake engineering, as near‐site conditions can have a significant impact on the resulting gAuthorsTara Nye, Valerie J. Sahakian, Elias King, Annemarie S. Baltay, Alexis KlimasewskiWhat to expect when you are expecting earthquake early warning
We present a strategy for earthquake early warning (EEW) alerting that focuses on providing users with a target level of performance for their shaking level of interest (for example, ensuring that users receive warnings for at least 95 per cent of the occurrences of that shaking level). We explore the factors that can affect the accuracy of EEW shaking forecasts including site conditions (which caAuthorsSarah E. Minson, Elizabeth S. Cochran, Jessie Kate Saunders, Sara McBride, Stephen Wu, Annemarie S. Baltay, Kevin R. MilnerSpatially continuous models of aleatory variability in seismic site response for southern California
We develop an empirical, spatially continuous model for the single-station within-event (ϕSS) component of earthquake ground motion variability in the Los Angeles area. ϕSS represents event-to-event variability in site response or remaining variability due to path effects not captured by ground motion models. Site-specific values of ϕSS at permanent seismic network stations were estimated during oAuthorsGrace Alexandra Parker, Annemarie S. Baltay, Eric M. ThompsonEstimates of kappa in the San Francisco Bay area
Site characterization is a critical component of seismic hazards studies, especially in the development and use of ground motion models (GMMs). One such parameter, kappa (Κ0), represents local site attenuation and effectively describes regional variations in ground motion [1]. However, estimates of Κ0 are limited. We estimate the site parameter Κ0 for 296 broadband and accelerometer stations in thAuthorsTara A. Nye, Valerie J. Sahakian, E.L. King, Annemarie S. Baltay, Alexis KlimasewskiReal-time earthquake detection and alerting behavior of PLUM ground-motion-based early warning in the United States
We examine the real‐time earthquake detection and alerting behavior of the Propagation of Local Undamped Motion (PLUM) earthquake early warning (EEW) algorithm and compare PLUM’s performance with the real‐time performance of the current source‐characterization‐based ShakeAlert System. In the United States (U.S.), PLUM uses a two‐station approach to detect earthquakes. Once a detection is confirmedAuthorsJessie Kate Saunders, Sarah E. Minson, Annemarie S. Baltay, Julian J Bunn, Elizabeth S. Cochran, Deborah L. Kilb, Colin T O'Rourke, Mitsuyuki Hoshiba, Yuki KoderaEmpirical map-based nonergodic models of site response in the greater Los Angeles area
We develop empirical estimates of site response at seismic stations in the Los Angeles area using recorded ground motions from 414 M 3–7.3 earthquakes in southern California. The data are from a combination of the Next Generation Attenuation‐West2 project, the 2019 Ridgecrest earthquakes, and about 10,000 newly processed records. We estimate site response using an iterative mixed‐effects residualsAuthorsGrace Alexandra Parker, Annemarie S. BaltayEarthquake early warning for estimating floor shaking levels of tall buildings
This article investigates methods to improve earthquake early warning (EEW) predictions of shaking levels for residents of tall buildings. In the current U.S. Geological Survey ShakeAlert EEW system, regions far from an epicenter will not receive alerts due to low predicted ground‐shaking intensities. However, residents of tall buildings in those areas may still experience significant shaking dueAuthorsS. Farid Ghahari, Annemarie S. Baltay, Mehmet Çelebi, Grace Alexandra Parker, Jeffrey McGuire, Ertugrul TacirogluAlert optimization of the PLUM earthquake early warning algorithm for the western United States
We determine an optimal alerting configuration for the propagation of local undamped motion (PLUM) earthquake early warning (EEW) algorithm for use by the U.S. ShakeAlert system covering California, Oregon, and Washington. All EEW systems should balance the primary goal of providing timely alerts for impactful or potentially damaging shaking while limiting alerts for shaking that is too low to beAuthorsElizabeth S. Cochran, Jessie Kate Saunders, Sarah E. Minson, Julian Bunn, Annemarie S. Baltay, Debi Kilb, Colin T O'Rourke, Mitsuyuki Hoshiba, Yuki KoderaThe impact of 3D finite‐fault information on ground‐motion forecasting for earthquake early warning
We identify aspects of finite‐source parameterization that strongly affect the accuracy of estimated ground motion for earthquake early warning (EEW). EEW systems aim to alert users to impending shaking before it reaches them. The U.S. West Coast EEW system, ShakeAlert, currently uses two algorithms based on seismic data to characterize the earthquake’s location, magnitude, and origin time, treatiAuthorsJessica R. Murray, Eric M. Thompson, Annemarie S. Baltay, Sarah E. MinsonShaking is almost always a surprise: The earthquakes that produce significant ground motion
Although small earthquakes are expected to produce weak shaking, ground motion is highly variable and there are outlier earthquakes that generate more shaking than expected—sometimes significantly more. We explore datasets of M 0.5–8.3 earthquakes to determine the relative impact of frequent, smaller-magnitude earthquakes that rarely produce strong ground motion, to rare, large earthquakes that alAuthorsSarah E. Minson, Annemarie S. Baltay, Elizabeth S. Cochran, Sara McBride, Kevin R. Milner