As part of the National Science Foundation (NSF) funded EarthScope project, the USArray Transportable Array (TA) in Alaska and western Canada deployed near 200 telemetered broadband seismic and infrasound stations. This systematic coverage of continental Alaska and northwest Canada has provided an unprecedented dataset for the seismological community. The primary scientific target of EarthScope has

Alaska is the last frontier and final destination for the National Science Foundation‐supported EarthScope USArray Transportable Array (TA) project. The goal of this project is to record earthquakes and image the structure of the North American continent. The Alaska TA consists of 283 broadband seismic stations evenly spaced about 85 km apart to cover the state of Alaska and into western Canada. The

Between 2014 and 2017, almost 200 new seismic stations were installed in Alaska and northwestern Canada as part of the EarthScope USArray Transportable Array. These stations currently provide an unprecedented capability for the detection and location of seismic events in regions with otherwise relatively sparse station coverage. Two interesting earthquake sequences in 2018 and 2019 in the northeastern

We examine three continuously recording data sets related to the aurora: all‐sky camera images, three‐component magnetometer data, and vertical‐component, broadband seismic data as part of the EarthScope project (2014 to present). Across Alaska there are six all‐sky cameras, 13 magnetometers, and >200 seismometers. The all‐sky images and magnetometers have the same objective, which is to monitor space

The Alaska Amphibious Community Seismic Experiment (AACSE) is a shoreline‐crossing passive‐ and active‐source seismic experiment that took place from May 2018 through August 2019 along an ∼700 km long section of the Aleutian subduction zone spanning Kodiak Island and the Alaska Peninsula. The experiment featured 105 broadband seismometers; 30 were deployed onshore, and 75 were deployed offshore in

We introduce a method for estimating crustal thickness and bulk crustal and upper‐mantle shear‐wave velocities directly from high‐quality measurements of fundamental‐mode Rayleigh‐wave dispersion in the period range from 10 to 40 s. The method is based on an approximate Rayleigh‐wave dispersion formula and provides fast results with minimal model parameterization. We apply the method to Rayleigh‐wave

Moho morphology in orogens provides important constraints on the rheology and density structure of the crust and underlying mantle. Previous studies of Moho geometry in the northern Canadian Cordillera (NCC) using very sparse seismic data have indicated a flat and shallow (⁠∼30–35 km⁠) Moho, despite an average elevation of >1000 m above sea level attributable to increased thermal buoyancy and lower

Azimuthal variations in receiver function conversions can image lithospheric structural contrasts and anisotropic fabrics that together compose tectonic grain. We apply this method to data from EarthScope Transportable Array in Alaska and additional stations across the northern Cordillera. The best‐resolved quantities are the strike and depth of dipping fabric contrasts or interfaces. We find a strong

We present two new seismic velocity models for Alaska from joint inversions of body‐wave and ambient‐noise‐derived surface‐wave data, using two different methods. Our work takes advantage of data from many recent temporary seismic networks, including the Incorporated Research Institutions for Seismology Alaska Transportable Array, Southern Alaska Lithosphere and Mantle Observation Network, and onshore

The 24 January 2020 Mw 6.7 earthquake in eastern Turkey was due to the reactivation of the strike‐slip faulting between the Arabian and Anatolian plates. To gain insight into the source regime and its relationship with historical earthquakes, we determined the coseismic slip distribution of this event by joint analyses of Interferometric Synthetic Aperture Radar and teleseismic observations. Inversion

With the strong 26 November 2019 earthquake that struck western Albania, several buildings collapsed, causing 51 casualties, mainly in the areas of Durrës and Thumanë. The destruction is attributed to several factors, including strong ground motion (⁠maximum peak ground acceleration=192 cm/s2 in Durrës), soil liquefaction, site amplification, poor building workmanship and construction quality, aging

We analyze the spatiotemporal evolution of seismicity during a sequence of moderate (an Mw 4.7 foreshock and Mw 5.8 mainshock) earthquakes occurring in September 2019 at the transition between a creeping and a locked segment of the North Anatolian fault in the central Sea of Marmara, northwest Turkey. To investigate in detail the seismicity evolution, we apply a matched‐filter technique to continuous

On 28 September 2018, Indonesia was struck by an MW 7.5 strike‐slip earthquake. An unexpected tsunami followed, inundating nearby coastlines leading to extensive damage. Given the traditionally non‐tsunamigenic mechanism, it is important to ascertain if the source of the tsunami is indeed from coseismic deformation, or something else, such as shaking induced landsliding. Here we determine the leading

Multiple fault segments ruptured during the 2014 Yutian earthquake, but the detailed source parameters and the mechanism of rupture complexity remain poorly understood. Here, we use high‐resolution TanDEM‐X satellite data and Satellite Pour l’Observation de la Terre‐6/7 images to map the coseismic ground deformation field of the event. We find that the majority of coseismic slip occurred in the upper

Human activity‐induced earthquakes are emerging as a global issue, and revealing its underlying mechanisms is essential for earthquake hazard mitigation and energy development. We investigated the relationship between the seismotectonic model and seismic sequences from moderate Mw 4.3 and Mw 5.2 earthquakes that occurred in February and September 2019, respectively, in the Weiyuan anticline of Sichuan

Earthquakes rarely occur at extremely shallow depths, for example, less than 2 km. Even for induced earthquakes that are typically shallower than tectonic events, only very small ones have been reported in such depths. The ML 4.9 earthquake (⁠Mw 4.3) that struck the Rongxian County, Sichuan, China on 25 February 2019 was an extremely shallow event. Seismological and geodetic data constrained the mainshock

We present regional earthquake magnitude conversion relations among different magnitude scales (⁠Mw⁠, Ms⁠, mb⁠, ML⁠, and MD⁠) for the Himalayan seismic belt developed from data of local, regional, and international seismological agencies (International Seismological Centre [ISC], National Earthquake Information Centre [NEIC], Global Centroid Moment Tensor Solution [CMT], International Data Centre [IDC]

We implemented an automatic procedure to update in near‐real time (daily to hourly) a homogeneous catalog of Italian instrumental seismicity to be used for forecasting experiments and other statistical analyses. The magnitudes of all events are homogeneously revalued to be consistent with Mw standard estimates made by the Global Centroid Moment Tensor project. For the time interval from 1960 to 15

Following the recommendations of an international committee (Allen et al., 2012), since October 2017, the Israeli Seismic Network has been undergoing significant upgrades, with 120 stations being added or upgraded throughout the country and the addition of two new datacenters. These enhancements are the backbone of the TRUAA project, assigned to the Geological Survey of Israel (GSI) by the Israeli

We compare the performance of a downhole distributed acoustic sensing (DAS) fiber‐optic array with that of conventional geophones. The downhole collocated arrays are part of the Frontier Observatory for Research in Geothermal Energy (FORGE) geothermal experiment, in which stimulation of the rock volume in an enhanced geothermal system (EGS) causes microseismic events. The DAS acquisition system yields

We present a 1D shear‐velocity model for Los Humeros geothermal field (Mexico) obtained from three‐component beamforming of ambient seismic noise, imaging for the first time the bottom of the sedimentary basement ∼5 km below the volcanic caldera, as well as the brittle‐ductile transition at ∼10 km depth. Rayleigh‐wave dispersion curves are extracted from ambient seismic noise measurements and inverted

P′P′ precursors have been used to detect discontinuities in the lower mantle of the Earth, but some seismic phases propagating along asymmetric ray paths or scattered waves could be misinterpreted as reflections from mantle discontinuities. By forward modeling in standard 1D Earth models, we demonstrate that the frequency content, slowness, and decay with distance of precursors about 180 s before P′P′

We present data and results of a passive seismic experiment that we operated between June 2016 and May 2018 in the Ngorongoro Conservation Area (northern Tanzania), located on the western side of the eastern branch of the Eastern African Rift (EAR) system. The motivation for this experiment is twofold: (1) investigating the extension of the Olduvai basin, referred to also as the “Cradle of Human Mankind

Northeastern Tibet is still in the primary stage of tectonic deformation and is the key area for studying the lateral expansion of the Tibetan plateau. In particular, the existence of lower crustal flow, southward subduction of the Asian lithosphere, and northward subduction of the Indian lithosphere beneath northeastern Tibet remains controversial. To provide insights into these issues, a high‐resolution

We perform 3D simulations of seismic wavefields to clarify effects of strong reductions of shallow velocities on long‐period seismic waves. The simulations use a reference Community Velocity Model of southern California and a modified version with strong velocity reductions in the top 500 m of the Los Angeles basin. Differences between wavefields generated by 10 earthquakes in the reference and perturbed

In May 1976, a devastating earthquake of magnitude Ms 6.5 occurred in Friuli, Italy, resulting in 976 deaths, 2000 injured, and 60,000 homeless. It is notable that, at the time of the earthquake, only one station was installed in the affected region. The resulting lack of information, combined with a dearth of mitigation planning for responding to such events, lead to a clear picture of the impact

Geological, historical, and geophysical observations show that the entire Himalayan arc is poised to produce a sequence of great earthquakes, possibly similar to that which occurred in the twentieth century along the Aleutian subduction zone. The human catastrophe in the densely populated countries astride the arc is likely to be unprecedented when these earthquakes occur.

Operational earthquake forecasts (OEFs) are represented as time‐dependent probabilities of future earthquake hazard and risk. These probabilities can be presented in a variety of formats, including tables, maps, and text‐based scenarios. In countries such as Aotearoa New Zealand, the U.S., and Japan, OEFs have been released by scientific organizations to agencies and the public, with the intent of

Himalayan earthquakes have deep societal and economic impact. In this article, we implement a surrogate method of nowcasting (Rundle et al., 2016) to determine the current state of seismic hazard from large earthquakes in a dozen populous cities from India and Pakistan that belong to the west‐northwest part of Himalayan orogeny. For this, we (1) perform statistical inference of natural times, intersperse

The populace of Los Angeles, California, was startled by shaking from the M 7.1 earthquake that struck the city of Ridgecrest located 200 km to the north on 6 July 2019. Although the earthquake did not cause damage in Los Angeles, the experience in high‐rise buildings was frightening in contrast to the shaking felt in short buildings. Observations from 560 ground‐level accelerometers reveal large variations

The shear‐wave velocity (⁠VS⁠) in soil is an important parameter to characterize dynamic soil properties. The Delaney Park downhole array was deployed in 2003 without measuring the shear‐ and compression‐wave velocity (⁠VS and VP⁠) profiles. Thornley et al. (2019) measured the VS and VP profiles using the downhole method after the sensor was removed from the 61 m borehole with casing in the array.

A reliable estimation of seismic hazard‐facing Mexico City from local earthquakes has suffered from poor seismic instrumentation, complex crustal structure, large and variable site amplification, and lack of knowledge of recurrence period of earthquakes on the mapped faults. Owing to recent improvement in local seismic networks, an earthquake swarm activity, which occurred in June–August 2019, was

In this article, we present a strong‐motion database from earthquakes recorded by the Earthquake Engineering Laboratory at the University of Costa Rica. The database consists of 2471 three‐component accelerograms from 155 digitally recorded events. It covers the last 20 yr of measurements, including records from the 5 September 2012 Mw 7.6 Nicoya earthquake. The engineering and seismological communities

Throughout the 2018 eruption of Kīlauea volcano (Hawai‘i), episodic collapses of a portion of the volcano’s summit caldera produced repeated Mw 4.9–5.3 earthquakes. Each of these 62 events was characterized by a very‐long‐period (VLP) seismic signal (⁠>40 s⁠). Although collapses in the later stage of the eruption produced earthquakes with significant amplitude clipping on near‐summit broadband seismometers

Spatial distribution of seismic intensity plays an important role in emergency response during and immediately after an earthquake. In this study, we propose a deep learning model to predict the seismic intensity based on only the observation records at the seismic stations in a surrounding area. The deep learning model is trained using the observation records at both the input and target stations

Seismic T waves, which result from transformation of hydroacoustic to seismic energy at coastlines, were investigated for two strong earthquakes. A 2014 Caribbean event generated seismic T waves that were detected at over 250 seismometers along the east coast of the U.S., primarily at seismic stations operated by the USArray Transportable Array. A 2006 Hawaiian event generated seismic T waves observed

Microseisms in frequencies of 0.05–0.5 Hz are a presentation of solid earth response to the ocean waves that are developed by atmospheric pressure change. The South China Sea provides a natural laboratory with a closed ocean environment to examine the influence of regional factors on microseism development as well as the nature of microseisms. The microseisms induced by typhoons crossing over the South

We propose a template‐matching workflow capable of improving detection sensitivity of a seismic network and demonstrate its performance on the local seismic network comprising Texas Seismological Network installations in West Texas. We use three earthquakes from three clusters as our templates. Template matching is applied to each station independently. Then, SeisComP3 scanloc associator groups the

Specifying the extent and location of rifted, crystalline Precambrian crust in the eastern United States is important for seismic hazard evaluation and for models that relate upper‐mantle structure to ancient tectonic features and ongoing tectonism. As currently depicted in the National Seismic Hazard Maps (NSHM), the western limit of Iapetan rifted crust is beneath the Appalachian plateau physiographic

The focal mechanism and source parameters of 41 local earthquakes (⁠Mw 4.0–5.1) that occurred in the Kachchh rift basin, which is seismically one of India’s most active intraplate regions, are determined to characterize various active fault systems in that region. The tectonics in the rift basin are heterogeneous and complex. In the present study, it was found that one‐third of the earthquakes exhibit

Recent M 3–5 earthquakes near Cushing, Oklahoma, provide observations of intensity up to eight with accompanying ground motions due to close‐in acceleration records at distances less than 30 km from the epicenters. Adding these observations to the existing Central and Eastern North America (CENA) ground‐motion intensity correlation equation (GMICE) database allows the updating of a CENA GMICE from

We developed a 3D elastic boundary element method computer code, called AstroSeis, to model seismic wavefields in a body with an arbitrary shape, such as an asteroid. Besides the AstroSeis can handle arbitrary surface topography, it can deal with a liquid core in an asteroid model. Both the solid and liquid domains are homogenous in our current code. For seismic sources, we can use single forces or

The horizontal‐to‐vertical spectral ratio (HVSR) for seismic ambient noise is a popular method that can be used to estimate the predominant frequency at a given site. In this article, we introduce the Incorporated Research Institutions for Seismology (IRIS) Data Management Center’s (DMC’s) openly available HVSR station toolbox. These tools offer a variety of ways to compute the spectral ratio by providing

Earthquake moment tensors and focal depths are crucial to assessing seismic hazards and studying active tectonic and volcanic processes. Although less powerful than strong earthquakes (M 7+), moderately strong earthquakes (M 5–6.5) occur more frequently and extensively, which can cause severe damages in populated areas. The inversion of moment tensors is usually affected by insufficient local waveform

Seismic waveforms are essential for seismology but are clipped when their actual amplitudes are too high to be faithfully recorded by seismometers. The clipping effects are popular for both big earthquakes and small earthquakes within a short epicentral distance. Here, we illustrate potential risks of direct usage of clipped waveforms by examining the frequency leakage and show the failure of bandpass

Matched‐filtering (template‐matching) is an effective method for detecting clustered seismicity such as aftershocks, low‐frequency earthquakes, repeating earthquakes, and tectonic and volcanic swarms. Several groups have developed efficient codes implementing matched‐filter methods and demonstrated that earthquake catalogs can be substantially expanded using these methods. Here, we present a near‐real‐time

In this article, the original accounts of the first 19 earthquakes—occurring before A.D. 881—recorded in Martínez‐Solares and Mezcua’s Catálogo sísmico de la Península Ibérica (Martínez‐Solares and Mezcua, 2002) are reviewed. Their evolution is traced through references to them in the works of Spanish and Portuguese historians and authors published between the sixteenth and nineteenth centuries, and

Nine major earthquakes that affected the islands of Corfu, Paxoi, Lefkada, Kephalonia, Ithaca, and Zakynthos in the Ionian Sea offshore western Greece at the time of British Protectorate of the United States of the Ionian Islands (1815–1864) have been reappraised by means of a systematic investigation of contemporary, locally produced documents of diverse typologies. With an in‐depth study of the earthquakes

The historic Lāna‘i earthquake of 1871 is reappraised based on new science. This 1871 event occurred between O‘ahu and Maui, where currently 80% of the State of Hawai‘i population resides. I focus on expanding the considered modified Mercalli intensities (MMIs) applied in prior seismic hazard analyses and the application of an earthquake MMI–magnitude, duration–magnitude, and fault‐scaling relations

The 2019 Ridgecrest, California, earthquake sequence included Mw 6.4 and 7.1 earthquakes that occurred on successive days beginning on 4 July 2019. These two largest earthquakes of the sequence occurred on orthogonal faults that ruptured the Earth’s surface. To better evaluate the 3D subsurface fault structure, (P‐ and S‐wave) velocity, 3D and temporal variations in seismicity, and other important

Cast your vote today for the 2021 SSA Board of Directors at seismosoc.org. The Board serves as the governing body for SSA. Its members set broad policy and direction for the organization. They ensure that the Society meets your evolving needs and also keeps pace with rapid changes in technology, publishing, and government policy.The 2021 board members will serve for a three‐year term in April 2021

Earthquakes and viral epidemics spread are totally different events, but under rare circumstances they could strike at the same time. At midnight on 3 February 2020, a magnitude 5.1 earthquake occurred near Chengdu, the capital of Sichuan Province in China. This event was unique because it occurred during the outbreak of a new coronavirus known as the severe acute respiratory syndrome coronavirus 2

The topic of earthquake prediction has a long history, littered with failed attempts. Part of the challenge is that possible precursory signals are usually reported after the event, and the systematic relationships between potential precursors and main events, should they exist, are unclear. Several recent studies have shown the potential of new approaches to simultaneously detect earthquake foreshocks

Accurate monitoring of volcanic activity demands expertise in fields including geophysics, geology, and geochemistry. Data obtained from the most recent technical advances are particularly vital in pre‐eruptive phases. In particular, seismic monitoring in near real time is essential to locating and discriminating early signs among different sources of seismic waves, especially those related to movement

The accuracy of preinstrumental earthquake data, which cover longer time periods than instrumental recordings, and a more widespread assessment of macroseismic intensity data have significantly improved the knowledge of the seismic behavior of many regions of the world. The importance of these data is now widely recognized, and such an awareness stemmed from the realization that even though instrumental

Archives and libraries were visited to find previously unknown documents testifying to the Lurøy, Norway, earthquake of 31 August 1819 in northernmost continental Europe. The focus here is on Sweden, Finland, and Russia, which are important for determining the area of perceptibility east of Norway. The new written sources include 12 notes or entries in original archived documents, six contemporary

The continental part of west‐central Mexico is characterized by the active extensional tectonic regimes of the Trans‐Mexican volcanic belt and the adjacent southern Basin and Range Province. The deformation of the latter is distributed over several topographically very pronounced grabens and half‐grabens (width 10–20 km, length ≤200 km⁠; throw 1–2 km), including the Aguascalientes, Juchipila, Tlaltenango

Information about historical earthquakes in the Iberian Peninsula going back to Antiquity (Roman times) can be found in different types of documents, such as unpublished contemporary manuscripts preserved in archives, general, and regional histories in Spain and Portugal, published documents and reports on the damage of specific earthquakes, and reports in newspapers and magazines. The 1755 Lisbon

In 4 August 1885, 06:30 local time, a strong earthquake (reported intensities up to VI–VII modified Mercalli intensity [MMI]) was felt in the French Guiana, causing slight damage. Recently discovered newspaper records show that this event was also felt as far as Georgetown (British Guyana), Belém, and several other localities along the Amazon River toward Manaus (Brazil). The distribution of intensities

The 1703 Mw 6.9 seismic sequence (⁠I0 11 Mercalli–Cancani–Sieberg scale) was one of the most important crises ever occurred in Italy and has left a deep mark on the seismic history of cities and towns of central Italy. Abundant documents testify the damage suffered by the city of Rome during this sequence; however, the descriptions are mainly referred to monumental buildings. For the recent macroseismic