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Publications (168)
The San Andreas Fault system, known for its frequent seismic activity, provides an extensive dataset for earthquake studies. The region's well-instrumented seismic networks have been crucial in advancing research on earthquake statistics, physics, and subsurface Earth structures. In recent years, earthquake data from California has become increasin...
The ShakeAlert earthquake early warning (EEW) system partners along with U.S. Geological Survey (USGS) licensed operators deliver EEW alerts to the public and trigger automated systems when a significant earthquake is expected to impact California, Oregon, or Washington. ShakeAlert’s primary goal is to provide usable warning times before the arriva...
Detecting offshore earthquakes in real time is challenging for traditional land-based seismic networks due to insufficient station coverage. Application of distributed acoustic sensing (DAS) to submarine cables has the potential to extend the reach of seismic networks and thereby improve real-time earthquake detection and earthquake early warning (...
In the field of ground-motion modeling, the availability of densely sampled ground-motion data is becoming key to mapping repeatable source, path, and site effects to enable ground-motion models (GMMs) to more accurately predict shaking from future earthquakes. This is particularly important because the field is moving toward nonergodic GMMs with s...
This paper presents a novel approach to extract scientifically valuable information about Earth's physical phenomena from unconventional sources, such as multi-modal social media posts. Employing a state-of-the-art large language model (LLM), Gemini 1.5 Pro's (Reid et al. 2024), we estimate earthquake ground shaking intensity from these unstructure...
The U.S. Geological Survey (USGS)-operated ShakeAlert® system is the United States West Coast earthquake early warning system (Given et al., 2018). In this study we detail ShakeAlert’s performance during some of the largest events seen by the system thus far. Statewide public alerting using ShakeAlert messages was authorized in California in Octobe...
The central San Andreas Fault (CSAF) exhibits a simple linear large-scale fault geometry, yet seismic and aseismic deformation features vary in a complex way along the fault. Here we investigate fault zone behaviors using geodetic observation, seismicity and microearthquake focal mechanisms. We employ an improved focal-mechanism characterization me...
This paper presents a novel approach for estimating the ground shaking intensity using social media data and CCTV footage. Employing the Gemini Pro (Reid et al. 2024) model, a multi-modal language model, we demonstrate the ability to extract relevant information from unstructured data utilizing generative AI and natural language processing. The mod...
The central San Andreas Fault (CSAF) exhibits a simple linear large-scale fault geometry, yet seismic and aseismic deformation features vary in a complex way along the fault. Here we investigate fault zone behaviors using geodetic observation, seismicity and microearthquake focal mechanisms. We employ an improved focal-mechanism characterization me...
The field of structural health monitoring (SHM) faces a fundamental challenge related to accessibility. While analytical and empirical models and laboratory tests can provide engineers with an estimate of a structure’s expected behavior under various loads, measurements of actual buildings require the installation and maintenance of sensors to coll...
MyShake is a free citizen science smartphone app that provides a range of features related to earthquakes. Features available globally include rapid postearthquake notifications, live maps of earthquake damage as reported by MyShake users, safety tips, and various educational features. The app also uses the accelerometer in the mobile device to det...
Distributed acoustic sensing (DAS) is being explored in a variety of environments as a promising technology for the recording of seismic signals in dense array configurations. There is a particular interest for deploying DAS arrays on the ocean floor, presenting formidable challenges for conventional seismology. Taking advantage of the availability...
Tsunamis cause significant damage and loss of life, particularly for the nearest communities, where the tsunami may arrive in minutes. These local communities often do not receive an informed or timely alert under traditional warning pathways. In response, numerous tsunami early warning (TEW) algorithms have been developed with the goal of providin...
Accurate earthquake focal mechanisms are essential for solving fault zone structure, estimating stress variations, and assessing seismic hazards. Small earthquakes' focal mechanisms are usually solved using P‐wave first‐motion polarities and/or S‐/P‐wave amplitude ratios, which are limited due to the low signal‐to‐noise ratio of small‐earthquake wa...
Timely alerts sent through earthquake early warning (EEW) programs allow those alerted to take protective actions to mitigate their risk from potentially damaging shaking. Over the past few years, ShakeAlert, the EEW program focused on the west coast of the contiguous United States, has grown, alerting communities within California, Oregon, and Was...
MyShake is a free citizen science and public safety smartphone application that delivers the United States ShakeAlert program’s Earthquake Early Warning to the public in the states of California, Oregon, and Washington. Although smartphone notifications have long been a component of the ShakeAlert warning delivery plan, very little data has been pu...
After significant earthquakes, we can see images posted on social media platforms by individuals and media agencies owing to the mass usage of smartphones these days. These images can be utilized to provide information about the shaking damage in the earthquake region both to the public and research community, and potentially to guide rescue work....
MyShake is a free citizen science smartphone app that provides a range of features related to earthquakes. Features available globally include rapid post-earthquake notifications, live maps of earthquake damage as reported by MyShake users, safety tips and various educational features. The app also uses the accelerometer to detect earthquake shakin...
Public-private partnerships provide a method for vastly expanding sensor networks
Optical polarization-based sensing is applied to multiple submarine cables around the world. Earthquakes are detected by their shear waves at the closest fiber section. Synchronized detection on multiple cables enables potential localization of major earthquakes.
Cite this article as Medina, M., R During 2020, the National Seismological Center (CSN) implemented an earthquake early warning system (EEWS) for northern Chile. From a seismological point of view, this area is considered to be one of the largest seismic gaps in Chile, where an M w ∼9:0 earthquake is expected in a region with a population of more t...
After significant earthquakes, we can see images posted on social media platforms by individuals and media agencies owing to the mass usage of smartphones these days. These images can be utilized to provide information about the shaking damage in the earthquake region both to the public and research community, and potentially to guide rescue work....
S U M M A R Y The Transportable Array in south-central Alaska spans several subduction zone features: backarc, forearc and volcanic arc, making it an ideal tool to study subduction zone anisotropy. Shear wave splitting analysis of 157 local earthquakes of m b ≥ 3.0 that occurred between 2014 and 2019 yields 210 high-quality measurements at 23 stati...
The MyShake project aims to build a global smartphone seismic network to facilitate large-scale earthquake early warning and other applications by leveraging the power of crowdsourcing. The MyShake mobile application first detects earthquake shaking on a single phone. The earthquake is then confirmed on the MyShake servers using a “network detectio...
The MyShake project aims to build a global smartphone seismic network to facilitate large-scale earthquake early warning (EEW) and other applications by leveraging the power of crowdsourcing. The MyShake mobile application first detects earthquake shaking on a single phone. The earthquake is then confirmed on the MyShake servers using a “network de...
The MyShake app began delivering earthquake early warning alerts to users in California on October 17, 2019. The app delivers alerts from ShakeAlert when the estimated magnitude is 4.5 or greater to phones in the Modified Mercalli Intensity (MMI) III or greater zone. MyShake users receive the alerts, but also serve as citizen seismologists for the...
The MyShake Platform is an operational framework to provide earthquake early warning (EEW) to people in earthquake prone regions. It is unique among approaches to EEW as it is built on existing smartphone technology to both detect earthquakes and issue warnings. It therefore has the potential to provide EEW wherever there are smartphones, and there...
The MyShake project aims to build a global smartphone seismic network to facilitate large-scale earthquake early warning and other applications by leveraging the power of crowdsourcing. The MyShake mobile application first detects earthquake shaking on a single phone. The earthquake is then confirmed on the MyShake servers using a "network detectio...
The MyShake project aims to build a global smartphone seismic network to facilitate large-scale earthquake early warning and other applications by leveraging the power of crowdsourcing. The MyShake mobile application first detects earthquake shaking on a single phone. The earthquake is then confirmed on the MyShake servers using a "network detectio...
MyShake harnesses private and personal smartphones to build a global seismic network. It uses the accelerometers embedded in all smartphones to record ground motions induced by earthquakes, returning recorded waveforms to a central repository for analysis and research. A demonstration of the power of citizen science, MyShake expanded to six contine...
The processes that accompany the death of an oceanic plate, as a ridge nears a trench, remain enigmatic. How the plate might reorganize, fragment, and eventually be captured by one of the bounding plates are among the unresolved details. We present a tomographic model of the Pacific Northwest from onshore and offshore seismic data that reveals a ho...
Earthquake early warning (EEW) is the delivery of ground shaking alerts or warnings. It is distinguished from earthquake prediction in that the earthquake has nucleated to provide detectable ground motion when an EEW is issued. Here we review progress in the field in the last 10 years. We begin with EEW users, synthesizing what we now know about wh...
Alaska provides an ideal tectonic setting for investigating the interaction between subduction and asthenospheric flow. Within the span of a few hundred kilometers along strike, the geometry of the subducting Pacific plate varies significantly and terminates in a sharp edge. Furthermore, the region documents a transition from subduction along the A...
The ElarmS Earthquake Early Warning System (EEWS) is a point-source, network-based EEWS that has been under development since early 2006. ElarmS was one of the original US West Coast ShakeAlert algorithms. Recently, significant modifications were made to the code that resulted in ElarmS version 3.0 (E3), which was deployed on the ShakeAlert product...
MyShake harnesses private/personal smartphones to build a global seismic network. It uses the accelerometers embedded in all smartphones to record ground motions induced by earthquakes, returning recorded waveforms to a central repository for analysis and research. A demonstration of the power of citizen science, MyShake expanded to 6 continents wi...
Geodetic earthquake early warning (EEW) algorithms complement point‐source seismic systems by estimating fault‐finiteness and unsaturated moment magnitude for the largest, most damaging earthquakes. Because such earthquakes are rare, it has been difficult to demonstrate that geodetic warnings improve ground motion estimation significantly. Here, we...
Geodetic earthquake early warning (EEW) algorithms complement point-source seismic systems by estimating fault-finiteness and unsaturated moment magnitude for the largest, most damaging earthquakes. Because such earthquakes are rare, it has been difficult to demonstrate that geodetic warnings improve ground motion estimation significantly. Here, we...
Earthquake Early Warning (EEW) systems can effectively reduce fatalities, injuries, and damages caused by earthquakes. Current EEW systems are mostly based on traditional seismic and geodetic networks, and exist only in a few countries due to the high cost of installing and maintaining such systems. The MyShake system takes a different approach and...
The UC Berkeley’s Earthquake Alert System (ElarmS) is a network-based earthquake early warning (EEW) algorithm that was one of the original algorithms developed for the U.S. west coast-wide ShakeAlert EEW system. Here we describe the latest update to the algorithm, ElarmS version 3.0 (ElarmS-3 or E3). A new teleseismic filter has been developed for...
Displacement waveforms derived from Global Navigation Satellite System (GNSS) data have become more commonly used by seismologists in the past 15 yrs. Unlike strong‐motion accelerometer recordings that are affected by baseline offsets during very strong shaking, GNSS data record displacement with fidelity down to 0 Hz. Unfortunately, fully processe...
MyShake is a global seismic platform that uses private citizens' smartphones to detect earthquakes and record both ground shaking and users' experiences. The goal is to reduce earthquake risk and provide users with a resource for earthquake science and information. It is powered by the participation of users, therefore, its success as a global netw...
This article gives an overview of machine learning (ML) applications in MyShake-a crowdsourcing global smartphone seismic network. Algorithms from classification, regression, and clustering are used in the MyShake system to address various problems, such as artificial neural network (ANN) and convolutional neural network (CNN) to distinguish earthq...
The moment evolution of large earthquakes is a subject of fundamental interest to both basic and applied seismology. Specifically, an open problem is when in the rupture process a large earthquake exhibits features dissimilar from those of a lesser magnitude event. The answer to this question is of importance for rapid, reliable estimation of earth...
Earthquake Early Warning Systems (EEWS) are often challenged when the earthquakes occur outside the seismic network or where the station density is sparse. In these situations, poor locations and large alert delays are more common due to the limited azimuthal coverage and the time required for the wavefield to reach the minimum number of seismic st...
Supporting Information S1
Alaska has been a site of subduction and terrane accretion since the mid-Jurassic. The area features abundant seismicity, active volcanism, rapid uplift, and broad intraplate deformation, all associated with subduction of the Pacific plate beneath North America. The juxtaposition of a slab edge with subducted, overthickened crust of the Yakutat ter...
The devastating 2017 Puebla quake provides an opportunity to assess how citizens perceive and use the Mexico City earthquake early warning system.
MyShake is a global crowdsourcing smartphone seismic network to monitor and detect earthquakes. After it got released to the public in 2016, we arrived at more than 300,000 downloads with more than 800 detected earthquakes globally within 2 years. Machine learning plays a critical role in MyShake that makes everything happen. In this presentation,...
Reducing the False Alert Problem in Earthquake Early Warning: ElarmS Version 3.0
This article presents the results of a shaker test of the Millikan Library in Pasadena, California, using sensors inside smartphones to demonstrate their potential usage as a way to monitor health states of buildings. This approach to structural health monitoring could allow many more commercial and residential buildings to be monitored because it...
Since 1990, nearly one million people have died from the impacts of earthquakes. Reducing those impacts requires building a local seismic culture in which residents are aware of earthquake risks and value efforts to mitigate harm. Such efforts include earthquake early warning (EEW) systems that provide seconds to minutes notice of pending shaking....
GNSS-based earthquake early warning (EEW) algorithms estimate fault-finiteness and unsaturated moment magnitude for the largest, most damaging earthquakes. Because large events are infrequent, algorithms are not regularly exercised and insufficiently tested on few available datasets. We use 1300 realistic, time-dependent, synthetic earthquakes on t...
We present a 3-D model of upper mantle seismic discontinuity structure below Cascadia using a receiver function Kirchhoff migration method. A careful analysis of the primary and multiple reverberated phases allows imaging of the Juan de Fuca plate dipping below the North American continent. The subducting slab is observed as an eastward dipping sig...
Current operational Earthquake Early Warning Systems (EEWS) acquire data with networks of single seismic stations, and compute source parameters assuming earthquakes to be point sources. For large events, the point-source assumption leads to an underestimation of magnitude, and the use of single stations leads to large uncertainties in the location...
ElarmS Earthquake Early Warning System Updates and Performance
The boundary between Earth's strong lithospheric plates and the underlying mantle asthenosphere corresponds to an abrupt seismic velocity decrease and electrical conductivity increase with depth, perhaps indicating a thin, weak layer that may strongly influence plate motion dynamics.The behavior of such a layer at subduction zones remains unexplore...
Scenario ruptures and ground motion simulation are important tools for studies of expected earthquake and tsunami hazards during future events. This is particularly important for large (Mw8+) and very large (Mw8.5+) events for which observations are still limited. In particular, synthetic waveforms are important to test the response of earthquake a...
The southern Alaskan margin captures a transition between compression and strike-slip dominated deformation, accretion of the over-thickened Yakutat terrane, termination of Aleutian arc magmatism and the enigmatic Wrangell Volcanic Field. The extent of subduction and mantle structure below this region is uncertain, with important implications for v...
MyShake is a global smartphone seismic network that harnesses the power of crowdsourcing. In the first 6 months since the release of the MyShake app, there were almost 200,000 downloads. On a typical day about 8,000 phones provide acceleration waveform data to the MyShake archive. The on-phone app can detect and trigger on P-waves and is capable of...
Earthquake early warning systems (EEWS) are being operated and tested
increasingly around the globe in recent years. Following the Israeli government’s decision
to build an EEWS in Israel, and as the Californian EEWS (ShakeAlert) moves
toward its operational phase, we demonstrate implementation of one of its three
algorithms, ElarmS, to the Israel...
Earthquake early warning (EEW) is the rapid detection of earthquakes underway and the alerting of people and infrastructure in harms way. Public warning systems are now operational in Mexico and Japan, and smaller-scale systems deliver alerts to specific users in Turkey, Taiwan, China, Romania, and the United States. The warnings can arrive seconds...
We are building a seismic network that harnesses the accelerometers in personal smartphones to record earthquake shaking data for research, hazard information and warnings. We developed an android application – MyShake, that running on the phone that has the function to distinguish earthquake shakings from daily human activities based on the differ...
We are exploring applying the techniques used in social network analysis back to seismic network. We try to characterize networked structures in terms of nodes (seismic station) and the ties or edges (relationships between the stations, e.g. similarities between the waveforms, characterized by the correlation coefficient) that connect them. We use...
We are exploring applying the techniques used in social network analysis back to seismic network. We try to characterize networked structures in terms of nodes (seismic station) and the ties or edges (relationships between the stations, e.g. similarities between the waveforms, characterized by the correlation coefficient) that connect them. We use...
We are exploring applying the techniques used in social network analysis back to seismic network. We try to characterize networked structures in terms of nodes (seismic station) and the ties or edges (relationships between the stations, e.g. similarities between the waveforms, characterized by the correlation coefficient) that connect them. We use...
We are exploring applying the techniques used in social network analysis back to seismic network. We try to characterize networked structures in terms of nodes (seismic station) and the ties or edges (relationships between the stations, e.g. similarities between the waveforms, characterized by the correlation coefficient) that connect them. We use...
We are exploring applying the techniques used in social network analysis back to seismic network. We try to characterize networked structures in terms of nodes (seismic station) and the ties or edges (relationships between the stations, e.g. similarities between the waveforms, characterized by the correlation coefficient) that connect them. We use...
Israel proximity to the Dead Sea Transform (DST) have led the Israeli government to initiate the building of an Earthquake Early Warning System (EEWS). The prime objective of this research is to implement, adjust and validate the ElarmS EEWS for the Israeli Seismological Network (ISN). Our approach for analyzing ElarmS performances with the non-EEW...
Most of the current EEWS utilize conventional seismic stations, housing high quality accelerometers and/or velocity-meters, and consider an earthquake as a point source. For large events, this point-source assumption leads to an underestimation of magnitudes. Recently, Meng et al. (2014) showed that it was possible to back-trace array waveforms in...
We demonstrate a flexible strategy for local tsunami warning that relies on regional geodetic and seismic stations. Through retrospective analysis of four recent tsunamigenic events in Japan and Chile, we show that rapid earthquake source information, provided by methodologies developed for earthquake early warning, can be used to generate timely e...
Large magnitude earthquakes in urban environments continue to kill and injure tens to hundreds of thousands of people, inflicting lasting societal and economic disasters. Earthquake early warning (EEW) provides seconds to minutes of warning, allowing people to move to safe zones and automated slowdown and shutdown of transit and other machinery. Th...
We present a novel 3-D pre-stack Kirchhoff depth migration (PKDM) method for teleseismic receiver functions. The proposed algorithm considers the effects of diffraction, scattering and traveltime alteration caused by 3-D volumetric heterogeneities. It is therefore particularly useful for imaging complex 3-D structures such as dipping discontinuitie...
The 2015 Mw8.3 Illapel, Chile earthquake is the latest megathrust event on the central segment of that subduction zone. It generated strong ground motions and a large (up to 11m runup) tsunami which prompted the evacuation of more than 1 million people in the first hours following the event. Observations during recent earthquakes suggest that these...
Israel is located adjacent to the Dead Sea Transform (DST) capable of producing earthquakes with maximal magnitudes of M7.5-M7.8 and a recurrence time for a M6 and M7 earthquake on the order of 100 and 1000 years, respectively. The most recent destructive earthquake along the DST was the 1927 ML 6.2 earthquake near Jericho, leading to 285 deaths an...
We designed an android app that harnesses the accelerometers in personal smartphones to record earthquake-shaking data for research, hazard information and warnings. The app has the function to distinguish earthquake shakings from daily human activities based on the different patterns behind the movements. It also can be triggered by the traditiona...
We designed an android app that harnesses the accelerometers in personal smartphones to record earthquake-shaking data for research, hazard information and warnings. The app has the function to distinguish earthquake shakings from daily human activities based on the different patterns behind the movements. It also can be triggered by the traditiona...
Overview of MyShake project in simple ways.
Tectonic plates are underlain by a low-viscosity mantle layer, the asthenosphere. Asthenospheric flow may be induced by the overriding plate or by deeper mantle convection. Shear strain due to this flow can be inferred using the directional dependence of seismic wave speeds-seismic anisotropy. However, isolation of asthenospheric signals is challen...
We have constructed an automated routine to identify prominent bursts of tectonic tremor and locate their source region during time periods of raised amplitude in the tremor passband. This approach characterizes 62 episodes of tectonic tremor between 2005 and 2011, with tremor epicenters forming a narrow band spanning the entire length of the Casca...
Earthquake early warning studies are shifting real-time seismology in earthquake science. They provide methods to rapidly assess earthquakes to predict damaging ground shaking. Preventing false alarms from these systems is key. Here we developed a simple, robust algorithm, Authorizing GRound shaking for Earthquake Early warning Systems (AGREEs), to...
GPS instruments are non-inertial and directly measure displacements with respect to a global reference frame, while inertial sensors are affected by systematic offsets - primarily tilting - that adversely impact integration to displacement. We study the magnitude scaling properties of peak ground displacement (PGD) from high-rate GPS networks at ne...
Real-time high-rate geodetic data have been shown to be useful for rapid earthquake response systems during medium to large events. The 2014 Mw 6.1 Napa, California earthquake is important because it provides an opportunity to study an event at the lower threshold of what can be detected with GPS. We show the results of GPS-only earthquake source p...
The Mw 6.0 South Napa earthquake, which occurred at 10:20 UTC 24 August 2014 was the largest earthquake to strike the greater San Francisco Bay area since the Mw 6.9 1989 Loma Prieta earthquake. The rupture from this right‐lateral earthquake propagated mostly unilaterally to the north and up‐dip, directing the strongest shaking toward the city of N...
It is generally accepted that mantle plumes are responsible for hotspot chains and as such provide insight to mantle convection processes. Among all the hotspots, the Hawaiian chain is a characteristic example that has been extensively explored. However, many questions remain. If a plume does exist beneath the Hawaiian chain, what is the shape, siz...
We investigate the merits of the more recently developed finite frequency approach to tomography against the more traditional and approximate ray theoretical approach for state of the art seismic models developed for western North America. To this end, we employ the spectral element method to assess the agreement between observations on real data a...
ElarmS Earthquake Early Warning System Updates
Seismic hazard mitigation encompasses a suite of approaches to reduce the impact of earthquakes on our society. Since the development of earthquake seismology and earthquake engineering at the beginning of the twentieth century, the probability that any one person dies in an earthquake has been reduced by a factor of 3. This is at least in part a t...
Recently, progress has been made to demonstrate feasibility and benefits of including real-time GPS (rtGPS) in earthquake early warning and rapid response systems. Most concepts, however, have yet to be integrated into operational environments. The Berkeley Seismological Laboratory runs an rtGPS based finite fault inversion scheme in real-time. Thi...
Moment magnitudes for large earthquakes (Mw≥7.0) derived in real-time from near field seismic data can be underestimated due to instrument limitations, ground tilting, and saturation of frequency/amplitude-magnitude relationships. Real-time high-rate GPS resolves the build-up of static surface displacements with the S-Wave arrival (assuming non-sup...
Earthquake early warning (EEW) systems that issue warnings prior to the arrival of strong shaking are essential in mitigating earthquake hazard. Currently operating EEW systems work on point-source assumptions and are of limited effectiveness for large events, for which ignoring finite-source effects result in magnitude underestimation. Here, we ex...
