Shortly after 6 p.m. of 4 August 2020, I was in my office located in the museum building (Post Hall) of the Mediterranean‐facing campus of the American University of Beirut when I felt what was like a strong but short‐duration earthquake. A couple of seconds later, a bang followed. I stood up and went to one of my windows trying to figure out what was going on, and unexpectedly I was blown away to

On 13 January 2021, at the age of 86, Edgar Kausel, a renowned Chilean seismologist, passed away after a long illness. Kausel was born on 22 June 1934, in Santiago, Chile.In the wake of the 1960 May, giant earthquake in southern Chile, he decided to specialize in seismology after earning his first degree in mining engineering at the University of Chile. He did so at Lamont–Doherty Geological (now Earth)

Strong ground‐motion records are the primary input data in earthquake engineering studies to improve understanding of seismic hazard and risk. As the overseer of the Iran Strong Motion Network (i1‐net), the Road, Housing, and Urban Development Research Center occupies the leading position in this field in the country. With more than 1260 active accelerometers and a collection of over 14,129 earthquake

On 12 July 2020, an Ms 5.1 moderate earthquake occurred on the north segment of the Tangshan fault in North China, which was the seismogenic fault of the 1976 Ms 7.8 Tangshan earthquake and numerous small‐to‐moderate earthquakes in recent decades in the Tangshan seismic zone. The Ms 5.1 event was well‐recorded by dense ground‐motion observation stations, including the national strong‐motion stations

The 18 May 2020 Ms 5.0 Qiaojia earthquake occurred in Qiaojia County, Yunnan Province, ∼25 km away from the 3 August 2014 Ms 6.5 Ludian earthquake. This earthquake was well recorded by dense local seismic stations of the Qiaojia array constructed near the Xiaojiang fault zone. The focal mechanism of the mainshock exhibited strike‐slip motion with a centroid depth of 8 km. We determined the seismogenic

The 2017 Mw 6.3 Jinghe earthquake represents one of the few large earthquakes that are well recorded by seismic instruments and Interferometric Synthetic Aperture Radar (InSAR) observations in the seismically active Tian Shan region. In this study, we use the rupture fault solution (dip, dip direction, and slip sense) from seismologic and InSAR results, along with analysis of our collected surface

The 2016 Fukushima earthquake (M 7.4) generated a moderate tsunami, which was recorded by the offshore pressure gauges of the Seafloor Observation Network for Earthquakes and Tsunamis (S‐net). We used 28 S‐net pressure gauge records for tsunami data assimilation and forecasted the tsunami waveforms at four tide gauges on the Sanriku coast. The S‐net raw records were processed using two different methods

We conducted a seismic intensity survey in Ecuador, following the 16 April 2016 Mw 7.8 Pedernales earthquake, to document the level of damage caused by the earthquake. Our modified Mercalli intensities (MMIs) reach a maximum value of VIII along the coast, where single, two, and multistory masonry and concrete designed buildings partially or completely collapsed. The contours of our MMI maps are similar

Developing new ways to observe tsunami contributes to tsunami research. Tidal and deep‐ocean gauges are typically used for coastal and offshore observations. Recently, tsunami‐induced ground tilts offer a new possibility. The ground tilt signal accompanied by 2010 Mw 8.8 Chilean earthquake were observed at a tiltmeter network in Japan. However, tiltmeter stations are usually not as widely installed

Coseismic offset is an important parameter to determine the characteristics of surface ruptures produced by large earthquakes and has significant implications for understanding fault‐zone mechanics. To date, most studies have focused on broad‐wavelength variations in coseismic offset and their related mechanisms. However, high‐frequency variations in coseismic offset have been less commonly reported

The Motuo fault (MTF) strikes along the Yarlung Zangbo suture zone on the eastern boundary of the Namche Barwa syntaxis. The movement pattern and Quaternary activity of the MTF remain unclear, which hampers efforts to undertake meaningful seismic hazard assessments near the southeastern part of the Tibetan plateau and to understand the tectonic evolution of the Namche Barwa syntaxis. In this study

In response to the dramatic increase in earthquake rates in the central United States, the U.S Geological Survey began releasing 1 yr earthquake hazard models for induced earthquakes in 2016. Although these models have been shown to accurately forecast earthquake hazard, they rely purely on earthquake statistics because there was no precedent for forecasting induced earthquakes based upon wastewater

Thanks to the new permanent seismic stations installed in the Franz Joseph Land and Severnaya Zemlya arctic archipelagoes, it has become possible at present to record earthquakes occurring in the eastern Gakkel ridge with a much lower detection threshold than that provided by the global network. At present, the lowest recorded magnitude is ML 2.4 and the magnitude of completeness is 3.4. We examined

We show that macroseismic intensities assessed in Italy in the last decade are not homogeneous with those of the previous periods. This is partly related to the recent adoption of the European Macroseismic Scale (EMS) in place of the Mercalli–Cancani–Sieberg (MCS) scale used up to about one decade ago. The underestimation of EMS with respect to MCS is about a half of a degree on average and, even more

The stability and robustness of determining earthquake magnitude are of great significance in earthquake monitoring and seismic hazard assessment. The routine workflow of determining earthquake local magnitude, such as the widely used Richter magnitude, may result in an unreliable measurement of earthquake magnitude because it relies on individual amplitude measurement of a single station, which is

The National Seismological Network (NSN) of India has a history of more than 120 yr. During the last two decades, the NSN has gone through a significant modernization process, involving installation of seismic stations equipped with a broadband seismograph (BBS) and a strong‐motion accelerograph (SMA). Each station has a very‐small‐aperture terminal connectivity for streaming data in real time to the

The accuracy of timing across a seismic network is important for locating earthquakes as well as studies that use phase‐arrival information (e.g., tomography). The Global Seismographic Network (GSN) was designed with the goal of having reported timing be better than 10 ms. In this work, we provide a brief overview of how timing is kept across the GSN and discuss how clock‐quality metrics are embedded

We present a novel physics‐guided neural network to estimate shear‐tensile focal mechanisms for microearthquakes using displacement amplitudes of direct P waves. Compared with conventional data‐driven fully connected (FC) neural networks, our physics‐guided neural network is implemented in an unsupervised fashion and avoids the use of training data, which may be incomplete or unavailable. We incorporate

Infrasound sensors record the ambient acoustic field that contains not only signals of interest but also noise and clutter. Noise is defined as atmospheric turbulence that is incoherent over the distances of meters, whereas, signals of interest and clutter are acoustic pressure waves that are coherent over 10s of meters to 100s of kilometers. There is a growing interest in monitoring sources that extend

Earthquakes are among the most devastating natural disasters in China, causing serious casualties and property losses. To effectively reduce catastrophic risk, it is important to establish an earthquake catastrophe insurance system based on the earthquake catastrophe model, of which seismic hazard analysis is a main module. Probabilistic seismic‐hazard analysis uses the potential source model, seismicity

Earthquake early warning (EEW) is becoming an increasingly attractive real‐time strategy for mitigating the threats posed by potentially devastating incoming seismic events. As efforts accelerate to develop practical EEW‐based solutions for earthquake‐prone countries in Europe, it is important to understand and quantify the level of performance that can be achieved by the underlying seismological algorithms

Declustering aims to divide earthquake catalogs into independent events (mainshocks), and dependent (clustered) events, and is an integral component of many seismicity studies, including seismic hazard assessment. We assess the effect of declustering on the frequency–magnitude distribution of mainshocks. In particular, we examine the dependence of the b‐value of declustered catalogs on the choice of

We cluster a global database of 3529 Mw>5.5 earthquakes in 1995–2018 based on a dynamic time warping distance between earthquake source time functions (STFs). The clustering exhibits different degrees of complexity of the STF shapes and suggests an association between STF complexity and earthquake source parameters. Most of the thrust events have simple STF shapes across all depths. In contrast, earthquakes

Correct identification and modeling of anthropogenic sources of ground motion are of considerable importance for many studies, including detection of small earthquakes and imaging seismic properties below the surface. To understand signals generated by common vehicle traffic, we use seismic data recorded by closely spaced geophones normal to roads at two sites on San Jacinto fault zone. To quantify

We present the first estimates of moment tensor solutions and probabilistic nonlinear hypocenter locations for the 1968 Belice earthquake sequence, which is the most relevant seismic activity occurred in western Sicily in historical times. This seismic phase, including six earthquakes with magnitude between 5 and 6.4, produced severe damages and fatalities in a sector of the Nubia–Eurasia plate margin

Risks assessment and risks comparison are basic concepts for emergency management. In the fields of earthquake engineering and engineering seismology, the operational earthquake loss forecasting (OELF) is the research frontier for the assessment of short‐term seismic risk. It combines seismicity models, continuously updated based on ground‐motion monitoring (i.e., operational earthquake forecasting)

Thunderstorms are a common atmospheric phenomenon that cause abundant acoustic disturbances, which can interact with the ground surface, creating a link between atmospheric and solid Earth processes. This article reports seismological observations of four thunderstorms through the spring and summer of 2019, as recorded by the distributed acoustic sensing fiber‐optic array (4.9 km) on the Penn State

Two events of magnitude (⁠mb⁠) 3.6–3.8 occurred in southern North Korea (NK) on 27 June 2019 and 11 May 2020. Although these events were located ∼330–400 km from the known nuclear test site, the fact that they occurred within the territory of NK, a country with a recent history of underground nuclear tests, made them events of interest for the monitoring community. We used P/Lg ratios from regional

Seismograms are convolution results between seismic sources and the media that seismic waves propagate through, and, therefore, the primary observations for studying seismic source parameters and the Earth interior. The routine earthquake location and travel‐time tomography rely on accurate seismic phase picks (e.g., P and S arrivals). As data increase, reliable automated seismic phase‐picking methods

In exploration and earthquake seismology, most sources used in subsurface structure imaging and rock property estimation are fixed in certain positions. Continuously moving seismic sources, such as vehicles and the metro, are one kind of important passive sources in ambient noise research. Commonly, seismic data acquisition and processing for moving sources are based on the assumption of simple point

The intrinsic array nature of distributed acoustic sensing (DAS) makes it suitable for applying beamforming techniques commonly used in traditional seismometer arrays for enhancing weak and coherent seismic phases from distant seismic events. We test the capacity of a dark‐fiber DAS array in the Sacramento basin, northern California, to detect small earthquakes at The Geysers geothermal field, at a

We image the shallow structure across the East Bench segment of the Wasatch fault system in Salt Lake City using ambient noise recorded by a month‐long temporary linear seismic array of 32 stations. We first extract Rayleigh‐wave signals between 0.4 and 1.1 s period using noise cross correlation. We then apply double beamforming to enhance coherent cross‐correlation signals and at the same time measure

To understand earthquake interaction and forecast time‐dependent seismic hazard, it is essential to determine which static or dynamic stress change due to a mainshock plays a major role in triggering its aftershocks and subsequent mainshocks. Using small mainshocks (⁠2≤M<3⁠) and their aftershocks, Felzer and Brodsky (2006) argued that mainshock induced dynamic stress change is responsible for earthquake

In recent years, the Delaware basin of west Texas has seen a sharp rise in earthquake occurrence, driven in large part by increases in unconventional hydrocarbon production. The advent of Texas Seismological Network in 2017 has allowed for the characterization of these events in greater detail. We exploit the recent densification in seismic station coverage to study the spectral properties of earthquakes

To estimate the hazard posed by active faults, estimates of the maximum magnitude earthquake that could occur on the fault are needed. I compare previously published scaling relationships between earthquake magnitude and rupture length with data from recent earthquakes in Indonesia. I compile a total amount of 13 literatures on investigating coseismic deformation in Indonesia, which then divided into

For observations of vertical‐component acceleration in the normal‐mode band (0.3–10 mHz), the detection sensitivity for signals from the Earth’s body can be improved to levels below the Peterson low‐noise model (PLNM). This is achieved by deterministic procedures that (at least partly) remove the accelerations originating from atmospheric mass fluctuations. The physical models used in such corrections

The rapid availability of reliable damage statistics, after the occurrence of a major earthquake, is an essential mitigation strategy to drive and support emergency intervention operations. Unfortunately, the latency in collecting and organizing actual damage information has a substantial impact on the efficiency of the initial phases of the intervention framework. To speedup preliminary management

We present a detailed analysis of the 10 June 2019 ML 4.0 Ohio earthquake sequence, which is the largest earthquake that struck Lake County, northeastern Ohio, since 1986. This sequence is well recorded by local seismic networks, which provides an unprecedented opportunity to understand the local seismotectonics. We utilize a waveform‐based cross‐correlation method to identify ∼12 times more events

A pair of small earthquakes (⁠MN 2.4 and 2.6, Earthquakes Canada) hit the city of Dartmouth, Nova Scotia, Canada, in early March 2020. The events were recorded by three seismic stations within 200 km, but only one station (HAL, <10 km⁠) is close enough to offer high‐quality broadband signals. In this study, we explore their source parameters using the nearest station through waveform modeling. A nearby

To better understand relationships among crustal anisotropy, fracture orientations, and the stress field in Oklahoma and southern Kansas, we conduct shear‐wave splitting analysis on the last 9 yr of data (2010–2019) of local earthquake observations. Rather than a predominant fast direction (⁠ϕ⁠), we find that most stations have a primary fast direction of polarization (⁠ϕpri⁠) and a secondary fast

We examine earthquake hypocenters, focal mechanisms, and the state of tectonic stress in the Lower St. Lawrence Seismic Zone (LSZ), a paleorift zone in eastern Canada. The largest earthquake recorded in the region is the 1999 Côte–Nord MN 5.1, which was followed by ∼80 aftershocks of MN>1⁠. It is not known if the region is capable of producing hazardous Mw>6 earthquakes, similar to the Charlevoix Seismic

The seismicity evolution in Oklahoma between 2010 and 2018 is analyzed systematically using an epidemic‐type aftershock sequence model. To retrieve the nonstationary seismicity component, we systematically use a moving window of 200 events, each within a radius of 20 km at grid points spaced every 0.2°. Fifty‐three areas in total are selected for our analysis. The evolution of the background seismicity

Coulomb stress change is the change in resultant force of shear stress and friction imposed on a receiver fault plane. The resulting stress change is often computed using the Coulomb 3.4 and the postseismic Green’s functions and postseismic components (PSGRN‐PSCMP) programs. Notwithstanding both preferences, both have incomplete optimally oriented failure planes (OOPs) and are inconvenient to resolve

We present an open‐source Python package, lsforce, for performing single‐force source inversions of long‐period (tens to hundreds of seconds) seismic signals. Although the software is designed primarily for landslides, it can be used for any single‐force seismic source. The package allows users to produce estimates of the three‐component time series of forces exerted on the Earth by a landslide with

In modern seismological analysis, it is not unusual to process huge amounts of data, as illustrated by two case studies exemplified in this work, both assessing the quality of several millions of segments selected for computing local and energy magnitudes. In this scenario, quality control tools to filter, discard, or rank data are of extreme importance and should ideally be simple, fast, and generalizable

We present an interactive graphical tool for extraction of group‐velocity dispersion curves of seismic traces for rapid manual picking of large amounts of data: a task commonly encountered in ambient‐noise tomography. The program can be used for group‐velocity analysis of surface waves from earthquakes and controlled source data as well as of Green’s functions from cross‐correlated ambient‐noise data

The 410‐ and 660‐km discontinuities define the top and bottom of the mantle transition zone (MTZ). The properties of these mineralogical phase transformation interfaces provide critical constraints on the dynamics, temperature, and composition of the MTZ. Triplicated body waves that bottom near these discontinuities carry rich information about them. To streamline the modeling of upper‐mantle triplications

In response to a pandemic causing the cancellation of numerous professional development programs for emerging seismologists, we successfully planned, promoted, and executed an 11 week online school for advanced graduate students worldwide during the summer of 2020. Remote Online Sessions for Emerging Seismologists included 11 distinct lessons focused on different topics in seismology. We highlight

Seismic bulletins, with trustworthy phase picks, origin times, and source locations are key for regional seismic studies, such as travel‐time (TT) tomography, attenuation tomography, and anisotropy studies. To lay the groundwork for such studies in Israel, we revised the seismic bulletin of Israel and the surrounding area and obtained a trustworthy TT data set. From the earthquake and explosion bulletins

The seismic activity in Israel and its surrounding neighbors originates mainly from the active Dead Sea fault system. The historical and archeological records suggest a recurrence interval of approximately 102 and 103 yr for earthquakes of M 6 and 7, respectively. Despite the existing hazard, local advancements on this topic have been slow and incremental, partly due to inherent challenges, such as

Horea Mircea Ioan Sandi, the most prominent Romanian researcher in Seismology and Earthquake Engineering passed away on 4 December 2020, a few weeks before his 89th birthday.He studied at the Technical University of Civil Engineering in Bucharest, during 1950–1955, and at the Faculty of Mathematics of the University of Bucharest, during 1950–1954. He received his Ph.D. with the doctoral thesis “Contributions

Observational seismology in Europe is firmly rooted in national and regional observatories in charge of managing more than 100 permanent seismic networks and more than 200 past and present temporary deployments. Primarily driven by governmental mandates to detect local seismicity and provide earthquake information to civil protection agencies and the general public, this monitoring effort also results

Although Norway has had an open data policy for seismological data for a long time, access to a good portion of the data required the use of nonstandard tools. This changed with the establishment of a dedicated European Integrated Data Archive (EIDA) node that is operated jointly by the UiB (University of Bergen)‐NORSAR. This now gives access to 139 stations and currently 12.1 Tb of data. The archive

This contribution describes the development of Norwegian Seismic Array (NORSAR), from its origin 50 yr ago as a project for installing a single seismic array in southern Norway to a seismological research institute operating a network of six arrays and 14 three‐component stations located in Norway and Antarctica. In addition, we document the different instrumentations from narrowband, mostly short‐period

The correct orientation of seismic sensors is critical for studies such as full moment tensor inversion, receiver function analysis, and shear‐wave splitting. Therefore, the orientation of horizontal components needs to be checked and verified systematically. This study relies on two different waveform‐based approaches, to assess the sensor orientations of the broadband network of the Kandilli Observatory

The complex tectonic setup of eastern Europe—resulting in strong spatial variations of the local seismic hazard—caused relevant institutions of neighboring countries to form a research cooperation to ease seismological research cooperations across borders.Here, we briefly introduce the original and new Central and Eastern Europe Earthquake Research Network (⁠CE3RN⁠) parties, with a synthesis of the

New data acquisition techniques are generating data at much finer temporal and spatial resolution, compared to traditional seismic experiments. This is a challenge for data centers and users. As the amount of data potentially flowing into data centers increases by one or two orders of magnitude, data management challenges are found throughout all stages of the data flow.The Incorporated Research Institutions

Portugal, located in the southwest region of the Eurasian plate, has been affected by several destructive earthquakes throughout its history, the most well‐known being the 1755 Great Lisbon earthquake. The seismicity of the territory, both in the mainland and in the Azores and Madeira islands, has prompted the continuous development of seismic monitoring, from the first known macroseismic inquiry,

As the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes in the region, the Kandilli Observatory and Earthquake Research Institute (KOERI) has a long history in seismic observation, which dates back to the installation of its first seismometers soon after the devastating Istanbul earthquake of 10 July 1894. For over a century, since the deployment of its first

We present an overview of the seismic networks, products, and services in Finland, northern Europe, and the challenges and opportunities associated with the unique combination of prevailing crystalline bedrock, low natural intraplate seismic background activity, and a high level of anthropogenic seismicity. We introduce national and local seismic networks, explain the databases, analysis tools, and