Detection and analysis of small magnitude events is valuable for better characterization and understanding of reservoirs in addition to developing strategies for mitigating induced seismicity. Three‐component (3C) receivers, which are now widely used, are commonly deployed in boreholes to provide continuous seismic data amenable to novel and powerful analysis. Using multicomponent continuous records

We present a set of revised ground‐motion models (GMMs) for shallow events at Mt. Etna Volcano. The recent occurrence of damaging events, in particular two of the strongest earthquakes ever instrumentally recorded in the area, has required revising previous GMMs, as these failed to match the observations made for events with local magnitude ML>4.3⁠, above all for sites situated close to the epicenter

The geodynamic features of the north–south seismic zone (NSSZ) and the formation of the Emeishan large igneous province (ELIP) in China remain controversial. In this study, we conducted detailed P‐wave teleseismic tomography studies in the NSSZ and adjacent regions. The results revealed large high‐velocity anomalies beneath the Songpan–Ganzi Block and the South China Block, possibly representing large‐scale

We explore the detectability of M2 tidal tilt in the western part of the United States, using seismic velocity data from 40 stations in the EarthScope Transportable Array (TA) network. We augment these data with data from two additional stations both collocated at the Piñon Flats Observatory (PFO) in southern California (networks TA and Incorporated Research Institutions for Seismology [IRIS] International

The Longmen Shan fault zone (FZ), which consists of the back‐range, the central, and the front‐range faults, acts as the boundary between the Sichuan basin and eastern Tibet. In this study, local and teleseismic waveforms recorded by a 2D small aperture seismic array (176 temporary short‐period seismometers) deployed by China University of Geosciences (Beijing) from 22 October to 20 November 2017 and

Multivariate normality of logarithmic intensity measures (IMs) is conventionally assumed in earthquake engineering applications. This article introduces a vine copula approach as a useful tool for multivariate modeling of IMs. This approach provides a flexible way to decompose a joint distribution into individual marginal distributions and multiple dependences characterized by a cascade of bivariate

Idealization of acceleration response spectra is the basis for construction of target spectra for seismic design and assessment of structures. The adequacy of current methods to reasonably idealize (or smooth) the acceleration spectra of pulse‐like and nonpulse‐like ground motions is examined in this study. The influence of separated pulses on different regions of acceleration response spectrum is

Permanent ground offsets, constituting a prime dataset for constraining final fault‐slip distributions, may not be recovered straightforwardly by double integration of near‐field accelerograms due to tilt and other distorting effects. Clearly, if a way could be found to recover permanent ground offsets from acceleration records, then static datasets would be enlarged, and thus the resolution of fault‐slip

The calculation of earthquake hypocenters requires careful treatment, particularly when prior knowledge of the study area is limited. The prior knowledge, such as wave velocity and data noise, is often assumed to be known in earthquake location algorithms. Such assumptions can greatly simplify the inverse problem but are less general than nonlinear approaches. A nonlinear treatment is of particular

The velocity pulse in near‐fault ground motions has been used as a key characteristic of damaging ground motions. Characterization of the velocity pulse involves three parameters: presence of the pulse, period of the pulse, and amplitude of the pulse. The basic concept behind the velocity pulse is that a large amount of seismic energy is packed into a short time, leading to larger demands on the structure

Earthquake records in the historical literature provide valuable information on the seismic hazard potentials for long recurrence times. The Seoul metropolitan area is the center of the economy and infrastructure in South Korea. Six major earthquakes that occurred around the Seoul metropolitan area during the Joseon dynasty in 1392–1910 are analyzed using a probabilistic joint inversion method based

The steady increase of ground‐motion data not only allows new possibilities but also comes with new challenges in the development of ground‐motion models (GMMs). Data classification techniques (e.g., cluster analysis) do not only produce deterministic classifications but also probabilistic classifications (e.g., probabilities for each datum to belong to a given class or cluster). One challenge is the

Surface ruptures from the 18 April 1906 M∼7.9 San Francisco earthquake were distributed over an ∼35‐meter‐wide zone at San Andreas Lake on the San Francisco Peninsula in California (Schussler, 1906). Since ∼1906⁠, the surface ruptures have been largely covered by water, but with water levels at near‐historic low levels in 2008–2011, we observed that the 1906 surface ruptures were no longer visible

During an earthquake, site effects can play an important role in triggering landslides. To document the seismic response of steep hillslopes, we deployed broadband seismometers across a mountain ridge in Taiwan, in an area with a high earthquake‐induced landslide hazard. The ridge has a simple, representative shape, and landslides have previously occurred there. Our seismometer array has recorded continuously

The main purpose of the site classification or velocity determination at a target site is to obtain or estimate the horizontal site amplification factor (HSAF) at that site during future earthquakes because HSAF would have significant effects on the strong‐motion characteristics. We have been investigating various kinds of methods to delineate the S‐wave velocity structures and the subsequent HSAF

This study examines analog seismograms that were generated when most seismic stations had their own clock for timing, making precise comparison of time between different stations difficult. Availability of accurate relative timing facilitates differential travel‐time analyses, such as seismic tomography and local earthquake relocations, to be performed using data originally recorded on paper or other

The autocorrelation of ambient noise is used to capture reflected waves for crustal and sedimentary structures. We applied autocorrelation to strong‐motion records to capture the reflected waves from sedimentary layers and used them for tuning the S‐wave velocity structure of these layers. Because a sedimentary‐layered structure is complicated and generates many reflected waves, it is important to

We apply a spectral decomposition approach to isolate the source spectra from propagation and site effects and, in turn, to estimate the source parameters of small‐to‐moderate earthquakes that occurred in central Italy. The data set is composed of about 400,000 waveforms relevant to 4111 earthquakes in the moment magnitude range 1.5–6.5, recorded by a high‐density network of stations installed in the

We present the first parametric catalog of historical earthquakes in Mexico from 1469 to 1912 composed of 323 historical earthquakes. The historical earthquakes were assigned to specific seismotectonic provinces, and attenuation relations of seismic intensity versus distance were calculated using instrumental earthquakes. The intensity data were inverted using a linear regression for the best‐fitting

A small earthquake with strong rupture directivity is inappropriate to use as a point source when estimating ground motion. A source spectrum model is proposed to remove the effects of rupture directivity and finite fault size from observed earthquakes. This model is developed by using a kinematic source model of a rectangular fault with bilateral‐bidirectional rupture propagation. Its amplitude spectrum

We present a regional short‐period Sn magnitude scale mb(Sn) for small earthquakes along the northern Mid‐Atlantic Ridge. Surface‐wave magnitudes, teleseismic body‐wave magnitudes, and seismic moments cannot be reliably determined for small earthquakes along this and other midocean ridges. Local magnitudes that rely on Lg waves are likewise not generally useful due to the substantial oceanic paths

Large earthquake ground‐motion simulations in 3D Earth models provide constraints on site‐specific shaking intensities but have suffered from limited frequency resolution and ignored site response in soft soils. We report new regional‐scale 3D simulations for moment magnitude 7.0 scenario earthquakes on the Hayward Fault, northern California with SW4. Simulations resolved significantly broader band

Thrust‐fault earthquakes are particularly hazardous in that they produce stronger ground motion than normal or strike‐slip events of the same magnitude due to a combination of hanging‐wall effects, vertical asymmetry, and higher stress drop due to compression. In addition, vertical surface displacement occurs in both blind‐thrust and emergent thrust ruptures, and can potentially damage lifelines and

In recent years, energy‐based seismic design methodology has received increasing attention because it takes into account not only the force and displacement behavior of a structure but also the cumulative damage effect caused by seismic loading. Specifically, as a fundamental parameter, input energy parameters (both absolute and relative measures) are directly related to the cumulative damage potential;

In this study, changes in atmospheric pressure recorded by absolute microbarometers operating in the Longitudinal Valley (Taiwan) during the passing seismic waves from strong earthquakes (⁠Mw≥6⁠) are systematically analyzed during the 2007–2019 period. Using a continuous wavelet transform analysis, local infrasound signals are detected for 23% of the events (21 events out of 89), with Mw ranging from

The 2016 Mw 7.0 Kumamoto earthquake resulted in exceptional datasets of Global Navigation Satellite Systems (GNSS) and seismic data. We explore the spatial similarity of the signals and investigate procedures for combining collocated sensor data. GNSS enables the direct observation of the long‐period ground displacements, limited by noise levels in regimes of millimeters to several centimeters. Strong‐motion

Capturing the center, the body, and the range of ground‐motion predictions is an indispensable element of site‐specific probabilistic seismic hazard analyses (PSHAs), for which the logic tree is the ubiquitous tool in current practice. The criteria for selecting the ground‐motion models (GMMs) used in such studies have generally been focused on their potential applicability to the region and site for

In the Koyna–Warna region, western India, an enormous number of microearthquakes was detected automatically on borehole records. Most of these events could not be identified on the surface network by a routine approach based on visual inspection primarily due to signal attenuation and the presence of noise. In this work, we implemented an automatic detection workflow to analyze the time series of an

Three alternative site‐response models are developed, using two complementing predictors, accounting for both stiffness and depth effects. The analysis is based on a large database of velocity profiles and their associated calculated amplifications with respect to the local generic rock profile. The frequency of peak amplification—fpeak—is chosen to supplement VS30⁠, after considering the predictability

We develop a new dynamic earthquake simulator to numerically simulate both spontaneous rupture and aseismic slip over earthquake cycles on geometrically complex fault systems governed by rate‐ and state‐dependent friction. The method is based on the dynamic finite‐element method (FEM) EQdyna, which is directly used in the simulator for modeling 3D spontaneous rupture. We apply an adaptive dynamic relaxation

Strong‐motion observations of recent interface earthquakes along the Chilean subduction zone are evaluated with two ground‐motion models (GMM). One GMM was developed with Chilean data and the other with global data. The GMM developed with local Chilean data is found to have an overall better prediction performance than the GMM developed using a global data set. Using residual analysis with the Chilean

A new equation for predicting Japanese instrumental seismic intensities at arbitrary surface sites in Japan for Mw 5.4–8.7 and distances ranging from 10 to 1000 km was derived from approximately 30,000 observed intensities for various types of earthquakes. The equation incorporates the differences in the subsurface characteristics immediately beneath each site using VS30⁠. The equation can also predict

In this study, we conducted a series of microtremor surveys to understand the contribution of soil amplifications to the heavy structural damage of wooden houses in downtown Mashiki, Kumamoto, Japan, during the 2016 Kumamoto earthquake. We analyzed the microtremor horizontal‐to‐vertical spectral ratios (MHVRs) of each observation site. A few previous studies have demonstrated the applicability of the

The west part of Java sits at the transition from oblique subduction of the Australian plate under the Sunda block of the Eurasian plate along Sumatra to orthogonal convergence along central and eastern Java. This region has experienced several destructive earthquakes, the 17 July 2006 Mw 7.7 earthquake and tsunami off the coast of Pangandaran and the 2 September 2009 Mw 7 earthquake, located off the

Cornell’s, Esteva’s, and classical formulations for seismic hazard analysis are theoretically described and mathematically unified by a suitable treatment of the random ground‐motion variable. Differences and connections among the schemes are discussed, allowing for a better understanding of the underpinning principles of probabilistic seismic hazard analysis. The classical formulation is equivalent

The high‐frequency decay term of the acceleration spectrum κ is a commonly used parameter in engineering seismology. In recent years, the assumption of a linearly decaying spectrum in log–linear space has been recognized to not always be valid as the value of κ depends on the analyzed frequency band. We present an alternative model for the spectral falloff in which the frequency dependence is explicitly

Peak ground velocity (PGV) is a commonly used parameter in earthquake ground‐motion models (GMMs) and hazard analyses, because it is closely related to structural damage and felt ground shaking, and is typically measured on broadband seismometers. Here, we demonstrate that strainmeters, which directly measure in situ strain in the bulk rock, can easily be related to ground velocity by a factor of bulk

The horizontal orientation estimation of an ocean‐bottom seismometer (OBS) is critical for providing reliable data for seismological studies. In this article, we applied three independent polarization analysis methods to estimate the absolute horizontal orientation of a pilot shallow‐water OBS array in Bohai Sea, China. The OBS array was deployed in the autumn of 2018 and comprised 32 broadband seismometers

The 2018 Mw 6.4 Hualien earthquake generated a large peak‐to‐peak velocity of over 2 m/s⁠, with a period of 3 s at the south end of the Milun fault, which resulted in the collapse of five buildings. To investigate the shallow subsurface soil structure and evaluate possible effects on the ground motion and building damage, we performed microtremor measurements in the Hualien basin. Based on the velocity

We would like to correct some typographical errors in Figure 15 and its caption in Oshima and Takenaka (2020). Here we present a list of errors, the corrected figure, and its revised caption. None of the conclusions of the study are changed due to these typographical errors. We would like to express our sincere apology for these errors to all those who helped us with this article and to our readers

The increasing rate and magnitude of induced seismicity over the past decade has generated public interest and spurred research across a broad range of geoscientists and stakeholders. Here, induced seismicity is broadly defined to include earthquakes associated with geothermal exploration, hydrocarbon production, wastewater disposal, carbon sequestration, and gas storage. Innovations in energy technologies

The clustering behavior of injection‐induced earthquakes is examined using one month of data recorded by the LArge‐n Seismic Survey in Oklahoma (LASSO) array. The 1829‐node seismic array was deployed in a 25 km×32 km area of active saltwater disposal in northern Oklahoma between 14 April and 10 May 2016. Injection rates in the study area are nearly constant around the time of the deployment. We develop

The development of organic‐rich, low‐permeability formations for hydrocarbon production requires the use of unconventional techniques such as multiwell pad drilling of horizontal wells and massive multistage hydraulic‐fracturing stimulations. However, proliferation of these unconventional development methods has been linked to localized cases of fault reactivation during or shortly after hydraulic

The sequence of foreshocks, mainshock, and aftershocks associated with a fault rupture is the result of interactions of complex fault systems, the tectonic stress field, and fluid movement. Analysis of shock sequences can aid our understanding of the spatial distribution and magnitude of these factors, as well as provide seismic hazard assessment. The 2017 Mw 5.5 Pohang earthquake sequence occurred

Two M 5 earthquakes struck the southeastern Korean Peninsula in September 2016 and November 2017, causing damage near the epicentral areas. We analyze the stress‐drop scaling of these two earthquake sequences using coda‐based methods and Bayesian inversion. The 2016 Gyeongju earthquake sequence is a typical earthquake sequence generated by tectonic processes. In contrast, the 2017 Pohang earthquake

A generalized inversion technique (GIT) is applied to local seismic data from 90 induced earthquakes (⁠ML 2.0–3.9) in the Fort Worth Basin (FWB) of north Texas to separate path, site, and source characteristics and to improve local seismic hazard assessment. Seismograms from three earthquake sequences on spatially separated basement faults are recorded on 66 temporary stations. Because of the lack

Production‐induced earthquakes in the Groningen gas field caused damage to buildings and concerns for the population, the gas‐field owner, and the local and national authorities and institutions. The largest event (⁠ML=3.6⁠) occurred in 2012 near Huizinge, and, despite the subsequent decision of the Dutch government to reduce the gas production in the following years, similar magnitude events occurred

Since 1991, induced earthquakes have been observed and linked to gas production in the Groningen field. Recorded waveforms are complex, resulting partly from a Zechstein salt layer overlying the reservoir and partly from free‐surface reverberations, internal multiples, interface conversions, guided waves, and waves diving below the reservoir. Therefore, picking of polarities or amplitudes for use in

Recent developments in the densification of the seismic network covering the Groningen gas field allow a more detailed study of the connection between induced seismicity and reactivated faults around the gas reservoir at 3 km depth. With the reduction of the average station distance from 20 km to 4–5 km, a probabilistic full‐waveform moment tensor inversion procedure could be applied, resulting in

In underground mines, episodes of sudden inelastic deformation in the rockmass are often induced by mining and are therefore localized near the excavations. The seismic radiation associated with such deformation can be described by a point seismic source using a volume integral of the stress‐free strain (or incremental plastic strain)—expression (1) in the Theory section. This conventional description

On 17 June 2019, an ML 6.0 earthquake struck the Changning county in Sichuan Province of China, causing substantial casualties and property losses. The earthquake is the largest and the most damaging event in the Changning area and close to shale gas and salt mining production region. To investigate the possibility of the earthquake being induced, we resolve its rupture dimension and hypocentral depth

Using seismic data recorded on permanent and temporary stations around the Changning area in the Sichuan basin, the high‐resolution 3D crustal VP⁠, VS⁠, VP/VS models and earthquake locations in the Changning–Xingwen area are obtained using the VP/VS model consistency‐constrained double‐difference seismic tomography method. The results show that crustal structures in the source area of the 2019 Ms 6

The three‐year CO2 injection period at the Illinois Basin ‐ Decatur Project site (Decatur, Illinois, United States) produced a number of microseismic events distributed in very distinct spatiotemporal clusters with different orientations. Further characterization of the microseismicity encompasses the determination of the event source mechanisms. Initially, the microseismic monitoring network consisted

The results of monitoring of carbon dioxide (⁠CO2⁠) injection at the Illinois Basin—Decatur Project (IBDP) and the companion Illinois Industrial Carbon Capture and Sequestration Sources (IL‐ICCS) project—have shown that reservoir response to fluid pressure changes can vary significantly at different injection locations within the same reservoir. Predrill reservoir characterization is important to identify

Seismic swarms are defined as an increase in seismicity that does not show a clear mainshock–aftershock sequence. Typically, swarms are primarily associated with either fluid migration or slow earthquakes (aseismic slip). In this study, we analyze a swarm induced by hydraulic fracturing (HF) that persisted for an unusually long duration of more than 10 months. Swarms ascribed to fluid injection are

Using geodetic methods, significant static ground deformation has been observed for many large natural earthquakes. Some of the largest earthquakes induced by hydraulic‐fracturing operations have been observed in the Western Canada Sedimentary Basin; however, because of the size and depths of these events, the associated static ground deformations have not yet been observed using traditional geodetic

Most current seismicity in the southern U.S. midcontinent is related to oil and gas operations (O&G Ops). In Texas, although recorded earthquakes are of low‐to‐moderate magnitude, the rate of seismicity has been increasing since 2009. Because of the newly developed Texas Seismological Network, in most parts of Texas, recent seismicity is reported on a daily basis with a magnitude of completeness of

We have analyzed shear‐wave splitting (SWS) data from local earthquakes in the Permian basin in west Texas to understand crustal stress change and induced seismicity. Two SWS parameters, the fast polarization direction and the delay time, are computed using a semiautomatic algorithm. Most measurements are determined in the Delaware basin and the Snyder area. In both regions, SWS fast directions are

The rate of M≥3 earthquakes associated with hydraulic fracturing (HF) in horizontal wells (HF wells) in the Western Canada Sedimentary Basin is estimated for the period from 2009 to 2019. The estimates are based on a statistical discrimination algorithm that uses an objective scoring function deduced from the observed spatiotemporal correlations between wells and earthquakes. A Monte Carlo simulation

Injection‐induced seismicity became an important issue over the past decade, and although much of the rise in seismicity is attributed to wastewater disposal, a growing number of cases have identified hydraulic fracturing (HF) as the cause. A recent study identified regions in Oklahoma where ≥75% of seismicity from 2010 to 2016 correlated with nearly 300 HF wells. To identify factors associated with