Basins with thick sediments can amplify and prolong the incoming seismic waves, which may cause serious damage to surface facilities. The amplification of seismic energy depends on the shear‐wave velocity of the uppermost layers, which is generally estimated through surface wave analysis. Surface waves may propagate in different modes, and the mechanism of the mode development is not well understood

We present a new method to discriminate between earthquakes and buried explosions using observed seismic data. The method is different from previous seismic discrimination algorithms in two main ways. First, we use seismic spatial gradients, as well as the wave attributes estimated from them (referred to as gradiometric attributes), rather than the conventional three‐component seismograms recorded

To explore the ability to indirectly detect and attribute various operations conducted at a nuclear reactor using waveform data, we investigated the seismic signals recorded near the High Flux Isotope Reactor (HFIR) located at Oak Ridge National Laboratory in Oak Ridge, Tennessee. Specifically, we processed seismic data collected from a single seismoacoustic station, WACO, near the HFIR facility, and

We report tremor or local earthquake signals that occurred during the propagation of Love and Rayleigh waves from the 2012 Mw 8.6 Sumatra earthquake in three intraplate regions: Yellowstone, central Utah, and Raton basin (Colorado). These surface waves likely also dynamically triggered seismic activity along the western boundary of the North American plate, and did not trigger seismic activity in the

The use of numerical simulations in probabilistic seismic hazard analysis (PSHA) has achieved a promising level of reliability in recent years. One example is the CyberShake project, which incorporates physics‐based 3D ground‐motion simulations within seismic hazard calculations. Nonetheless, considerable computational time and resources are required due to the significant processing requirements imposed

Employing extrapolation models to estimate the time‐averaged shear‐wave velocity to 30 m (⁠VS30⁠) from a shallow borehole profile is an effective way to expand the VS30 data volume and a necessary initial step for developing VS30 proxy models. Past extrapolation model studies have relied only on shallow borehole shear‐wave velocity (⁠VS⁠) profiles to estimate VS30⁠. In this study, we enhance the model

We use converted body‐wave phases from local earthquakes to constrain depth to basement and average attenuation relations for the Seattle basin in Washington and the Tualatin basin in Oregon. P‐, P‐to‐S‐(Ps), S‐to‐P‐(Sp), and S‐wave arrivals are present in three‐component recordings of magnitude 2.5–4.0 earthquakes at seismic stations located in these basins. Based on their relative travel times, these

Double differencing of body‐wave arrival times has proved to be a useful technique for increasing the resolution of earthquake locations and elastic wavespeed images, primarily because (1) differences in arrival times often can be determined with much greater precision than absolute onset times and (2) differencing reduces the effects of unknown, unmodeled, or otherwise unconstrained variables on the

We have developed a global earthquake deformation monitoring system based on subsecond‐latency measurements from ∼2000 existing Global Navigational Satellite System (GNSS) receivers to rapidly characterize large earthquakes and tsunami. The first of its kind, this system complements traditional seismic monitoring by enabling earthquake moment release and, where station density permits, fault‐slip distribution

An earthquake early warning (EEW) system rapidly analyzes seismic data to report the occurrence of an earthquake before strong shaking is felt at a site. In Japan, the integrated particle filter (IPF) method, a new source‐estimation algorithm, was recently incorporated into the EEW system to improve the source‐estimation accuracy during active seismicity. The problem of the current IPF method is that

The Global Seismographic Network (GSN) is a multiuse, globally distributed seismic network used by seismologists, to both characterize earthquakes and study the Earth’s interior. Most stations in the network have two collocated broadband seismometers, which enable network operators to identify potential metadata and sensor issues. In this study, we investigate the accuracy with which surface waves

A theoretical model of the seismometer self‐noise can be used to predict the self‐noise. Its inputs are mechanical and electrical parameters of the seismometer. In this article, we studied the theoretical model of the self‐noise of the velocity‐broadband seismometer, using the CS60 seismometer as an example. Velocity‐broadband seismometer is a type of feedback seismometer. The previous theoretical

We used teleseismic P and S waves recorded in the course of the 2016 Incorporated Research Institutions for Seismology (IRIS) community‐planned experiment in northern Oklahoma, to estimate amplitude correction factors (ACFs) and orientation correction factors (OCFs) for the gradiometer’s three‐component Fairfield nodal sensors and two other gradiometer‐styled subarray nodal sensors. These subarrays

Dynamic strains have never played a role in determining local earthquake magnitudes, which are routinely set by displacement waveforms from seismic instrumentation (e.g., ML⁠). We present a magnitude scale for local earthquakes based on broadband dynamic strain waveforms. This scale is derived from the peak root‐mean‐squared strains (⁠A⁠) in 4589 records of dynamic strain associated with 365 crustal

Recent efforts to characterize small (⁠Mw<3⁠) seismic events at local distances have become more important because of the increased observation of human‐triggered and induced seismicity and the need to advance nuclear explosion monitoring capabilities. The signals generated by low‐magnitude seismic sources necessitate the use of nearby short‐period observations, which are sensitive to local geological

The Mw 4.6 earthquake that occurred on 17 August 2015 northwest of Fort St. John, British Columbia, is considered the largest hydraulic‐fracturing‐induced event in Canada, based on its spatiotemporal relationship with respect to nearby injection operations. There is a ∼5 day delay of this Mw 4.6 mainshock from the onset of fluid injection at the closest well pad (W1). In contrast, other two nearby

Earthquakes in the Fort Worth basin (FWB) have been induced by the disposal of recovered wastewater associated with extraction of unconventional gas since 2008. Four of the larger felt earthquakes, each on different faults, prompted deployment of local distance seismic stations and recordings from these four sequences are used to estimate the kinematic source characteristics. Source spectra and the

This study presents the coupling of the spectral decomposition results for anelastic attenuation, stress drop, and site effects with the Graves‐Pitarka (GP) hybrid ground‐motion simulation methodology, as implemented on the Southern California Earthquake Center (SCEC) broadband platform (BBP). It is targeted to applications in the Upper Rhine graben (URG), which is among the seismically active areas

Induced seismicity predominantly occurs along faults that are optimally oriented to the local principal compressive stress direction, and the characterization of these stress orientations is an important component of understanding seismic hazards. The seismicity rate in southern Kansas rapidly increased in 2013 primarily due to the disposal of large volumes of wastewater into the Arbuckle Group. Previously

The epidemic‐type aftershock sequence (ETAS) model is widely used in seismic forecasting. However, most studies of ETAS use point estimates for the model parameters, which ignores the inherent uncertainty that arises from estimating these from historical earthquake catalogs, resulting in misleadingly optimistic forecasts. In contrast, Bayesian statistics allows parameter uncertainty to be explicitly

This study addresses questions about the productivity of Cascadia mainshock–aftershock sequences using earthquake catalogs produced by the Geological Survey of Canada and the Pacific Northwest Seismic Network. Questions concern the likelihood that future moderate to large intermediate depth intraslab earthquakes in Cascadia would have as few detectable aftershocks as those documented since 1949. More

Probabilistic seismic hazard assessment relies on long‐term earthquake forecasts and ground‐motion models. Our aim is to improve earthquake forecasts by including information derived from geodetic measurements, with an application to the Colombia–Ecuador megathrust. The annual rate of moment deficit accumulation at the interface is quantified from geodetically based interseismic coupling models. We

The NGA‐Sub (subduction zone earthquake) database developed by the Pacific Earthquake Engineering Research center is used to derive new correlation coefficients for a number of ground‐motion intensity measure (IM) parameters from ground motions in subduction zone earthquakes, considering both interface and intraslab tectonic settings. The IMs include peak ground acceleration, pseudospectral accelerations

In this article, we address the question of how observed ground‐motion data can most effectively be modeled for engineering seismological purposes. Toward this goal, we use a data‐driven method, based on a deep‐learning autoencoder with a variable number of nodes in the bottleneck layer, to determine how many parameters are needed to reconstruct synthetic and observed ground‐motion data in terms of

Traditional, empirical ground‐motion models (GMMs) are developed by prescribing a functional form between predictive parameters and ground‐motion intensity measures. Machine‐learning techniques may serve as a fully data‐driven alternative to widely used regression techniques, as they do not require explicitly defining these relationships. Although, machine‐learning methods offer a nonparametric alternative

The structural complexity of active faults and the stress release history along the fault system may exert control on the locus and extent of individual earthquake ruptures. Fault bends, in particular, are often invoked as a possible mechanism for terminating earthquake ruptures. However, there are few records available to examine how these factors may influence the along‐fault recurrence of earthquakes

Numerical models of rupture dynamics provide great insights into the physics of fault failure. However, resolving stress interactions among multiple faults remains challenging numerically. Here, we derive the elastostatic Green’s functions for stress and displacement caused by arbitrary slip distributions along multiple parallel faults. The equations are derived in the Fourier domain, providing an

In mountainous terrain, large earthquakes often cause widespread coseismic landsliding as well as hydrological and hydrogeological disturbances. A subsequent transient phase with high landslide rates has also been reported for several earthquakes. Separately, subsurface seismic velocities are frequently observed to drop coseismically and subsequently recover. Consistent with various laboratory work

Ambient seismic noise (ASN) is becoming of interest for geophysical exploration and engineering seismology, because it is possible to exploit its potential for imaging. Theory asserts that the Green’s function can be retrieved from correlations within a diffuse field. Surface waves are the most conspicuous part of Green’s function in layered media. Thus, the velocities of surface waves can be obtained

Heidari (2016) studied the B−Δ methodology to rapidly estimate epicentral distance and earthquake magnitude employing 17 large earthquakes that occurred between 2002 and 2013 in Iran for use in an earthquake early warning system around the Tehran region. In the B−Δ approach, the epicentral distance (⁠Δ⁠, as unknown and dependent parameter) is estimated from the initial slope (coefficient B⁠, as known

Recently, a comment named “Comments on “Quick Estimation of the Magnitude and Epicentral Distance Using the P Wave for Earthquake in Iran by R. Heidari,” was submitted to BSSA by Nazeri et al. (2021). The authors have commented on the validity and accuracy of the developed empirical relationships for an earthquake early warning system (EEWS), using B−Δ approach by Heidari (2016). After carefully reading

Based on the diffuse field concept for a horizontal‐to‐vertical spectral ratio of earthquakes (eHVSR), the effectiveness of eHVSRs to invert P‐ and S‐wave velocity structures down to the seismological bedrock (with the S‐wave velocity of 3 km/s or higher) has been shown in several published works. An empirical method to correct the difference between eHVSR and a horizontal‐to‐vertical ratio of microtremors

Ambient noise cross‐correlations, used to obtain fundamental‐mode Rayleigh‐wave group velocity estimates, and teleseismic P‐wave receiver functions are jointly modeled to obtain a 3D shear‐wave velocity model for the crust and upper mantle of Oklahoma. Broadband data from 82 stations of EarthScope Transportable Array, the U.S. National Seismic Network, and the Oklahoma Geological Survey are used. The

Site response, sedimentary basin amplification, and earthquake stress drops for the Portland, Oregon area were determined using accelerometer recordings at 16 sites of 10 local earthquakes with MD 2.6–4.0. A nonlinear inversion was applied to calculate site response (0.5–10 Hz), corner frequencies, and seismic moments from the Fourier spectra of the earthquakes. Site amplifications at lower frequencies

Pulse‐like ground motions cause severe damage in structures at certain periods. Hence, pulse effects need to be considered during probabilistic seismic hazard analysis and seismic design in the near‐fault region. Traditional ground‐motion models used to quantify the hazard posed by pulse‐like ground motions may underestimate them, but they are relatively suitable for describing the residual ground

Ground‐motion records are critical for seismic hazard assessment and seismic design of buildings and infrastructures. Large (⁠>1g⁠), asymmetric vertical accelerations (AsVAs) have been observed at strong‐motion stations during recent earthquakes. However, it is not clear whether all of the observed AsVAs reflect actual ground shaking or the interaction of a building structure and underlying ground

In the widely used stochastic finite‐fault method, the scaling of subsource spectra effectively eliminates the dependence of the synthetics on the subsource size but makes the subsource corner frequency lose its function. For this issue, we propose the concept and determination procedure of slip‐correlated corner frequency (SCF) for stochastic finite‐fault modeling of ground motion. The proposed corner

We introduce double‐corner‐frequency (DCF) source spectral models JA19 and JA19_2S, which, in conjunction with a stochastic ground‐motion model, can reproduce the mean peak ground acceleration (PGA) and mean peak ground velocity (PGV) of the Next Generation Attenuation‐West 2 database for magnitudes 3.3–7.3. Their displacement amplitude spectrum remains constant for frequencies less than fc1⁠, decays

The magnitude–frequency distribution (MFD) of many earthquake catalogs is well described by the Gutenberg–Richter (GR) law or its tapered version (TGR). This distribution is usually extrapolated to any subsets of the space–time window covered by the catalog. However, some empirical observations and logical thoughts may raise doubts about the validity of this extrapolation. For example, according to

Seismic waveform data are generally contaminated by noise from various sources. Suppressing this noise effectively so that the remaining signal of interest can be successfully exploited remains a fundamental problem for the seismological community. To date, the most common noise suppression methods have been based on frequency filtering. These methods, however, are less effective when the signal of

We derive a theoretical parameter for three seismic scattering regimes where seismic wavelengths are either much shorter, similar, or much longer than the correlation length of small‐scale Earth heterogeneities. We focus our analysis on the power spectral density (PSD) of the von Karman autocorrelation function (ACF), used to characterize the spatial heterogeneity of small‐scale variations of elastic

A series of classical absorbing boundary conditions (ABCs), including paraxial‐approximation ABCs, Liao’s multi‐transmitting formula (MTF), Higdon ABCs, and some other related techniques, have the common feature that the motion of an arbitrary artificial boundary node at each timestep is directly predicted from the motions of some adjacent nodes at several previous timesteps. They are expressed in

Regional ground‐motion simulation is important for postearthquake seismic damage assessment. Herein, a ground‐motion simulation method using recorded ground motions is proposed. Inverse‐distance‐weighted interpolation of the response spectra is performed to obtain the response spectrum at the target location. Then the ground‐motion time history for the target location is obtained by correcting the

A probabilistic model of the time–frequency power spectral density (TFPSD) is presented. The model is developed, based on the time–frequency representation of records from strike‐slip earthquakes, in which the time–frequency representation is obtained by applying the S‐transform (ST). The model for the TFPSD implicitly considers the amplitude modulation and frequency modulation for the nonstationary

Using a recently completed database of uniformly processed strong‐motion data recorded in Greece, we derive a ground‐motion prediction model (GMPM) for horizontal‐component peak ground velocity, peak ground acceleration, and 5% damped pseudoacceleration response spectra, at 105 periods ranging from 0.01 to 10 s. The equations were developed by modifying a global GMPM, to account for more rapid attenuation

Hydraulic fracturing of the first shale gas well at Preston New Road (PNR), Blackpool, United Kingdom, in late 2018, marked the end of a 7 yr United Kingdom‐wide moratorium on fracking. Despite a strict traffic‐light system being in place, seismic events up to ML 2.9 were induced. The ML 2.9 event was accompanied by reports of damage and was assigned European Macroseismic Scale 1998 (EMS‐98) intensity

We present a nonergodic framework for probabilistic seismic‐hazard analysis (PSHA) that is constructed entirely of deterministic, physical models. The use of deterministic ground‐motion simulations in PSHA calculations is not new (e.g., CyberShake), but prior studies relied on kinematic rupture generators to extend empirical earthquake rupture forecasts. Fully dynamic models, which simulate rupture

This study evaluated the source, path, and site effects of the vertical ground motions from the western and the southwestern parts of China (referred to as SWC hereafter) using 2403 records from 449 earthquakes, including the records from the 2008 Mw 7.9 Wenchuan earthquake and its aftershocks. Only 677 records are from 73 mainshocks, and 259 events do not have a known focal mechanism. There is a large

In this study, a ground‐motion model (GMM) for deep intraslab subduction zone earthquakes in northeastern India (NEI) and adjacent regions, including portions of Bangladesh, Bhutan, China, Myanmar, and Nepal, is developed. Strong‐motion data for deep intraslab earthquakes in NEI are very sparse, so it is not possible to develop a robust empirical GMM; hence, we used the stochastic point‐source model

We use an equivalent point‐source ground‐motion model (GMM) to characterize subduction earthquakes (interface and in‐slab) in Japan. The model, which is calibrated using the newly published Next Generation Attenuation (NGA) Subduction database (Bozorgnia et al., 2020), provides a useful complement to the more traditional empirical NGA models developed from the same database. The utility of the point‐source

We estimated the areas exhibiting high‐frequency (⁠1∼10 Hz⁠) wave radiation on the fault plane of the 2008 Wenchuan earthquake, by applying envelope inversion to strong‐motion acceleration records. The corrected records of two small earthquakes are adopted as the empirical Green’s functions. Considering the change in the rupture pattern of the Wenchuan earthquake from southwest to northeast, the records

A multidimension source model for generating broadband ground motions with deterministic 3D numerical simulations is proposed in this article. In this model, the source is composed of several superimposed layers, and the total seismic moment is assigned to these layers in different proportions. Each layer exactly fills up the seismic fault and is uniformly divided into subsources with size decreased

The 2019 Mw 7.1 mainshock of the Ridgecrest earthquake sequence, which was the first event exceeding Mw 7.0 in California since the 1999 Hector Mine earthquake, caused near‐fault ground motions exceeding 0.5g and 70 cm/s⁠. In this study, the rupture process and the generation mechanism of strong ground motions of the mainshock were investigated through waveform inversions of strong‐motion data in the

The Mw 7.5 earthquake that struck central Papua New Guinea in 2018 was the largest event ever recorded in the region with modern seismic instruments. The ground motions associated with this event also triggered widespread landslides and affected more than 500,000 people. However, due to the absence of a local seismic and Global Positioning System network in the vicinity, the fault location, system

In this article, we examine the 24 April 2014 Mw 6.4 earthquake offshore Vancouver Island using a surface‐wave empirical Green’s function (EGF) deconvolution method and compare the results with SeaJade II double‐difference aftershock locations. The 24 April event was well recorded and provides the first opportunity to evaluate the suitability of surface‐wave EGF deconvolution to constrain rupture details

A new reference attenuation model for calculating local magnitude (⁠ML⁠) for New Zealand earthquakes is derived. An earlier reference model, denoted NZ16, was developed in 2016 as a possible alternative to the classical reference model used by GeoNet for earthquakes located by the SeisComP processing system since January 2012. It aimed to provide a logA0 attenuation relation of the amplitude with the

Seismic rays traveling just below the Moho provide insights into the thermal and compositional properties of the upper mantle and can be detected as Pn phases from regional earthquakes. Such phases are routinely identified in the continents, but in the oceans, detection of Pn phases is limited by a lack of long‐term instrument deployments. We present estimates of upper‐mantle velocity in the equatorial

On 1900‐10‐09 a large (⁠Mw 7.6–8.0) earthquake occurred in the Gulf of Alaska and strongly shook the port town of Kodiak. Some damage occurred to buildings and the wharf, and dozens of aftershocks were felt over the next several hours and days. Global seismic stations recorded the earthquake from as close as Victoria, western Canada, to as far as Capetown, South Africa. Here we collect an expanded

New paleoseismic trenching indicates late Quaternary oblique right‐lateral slip on the Leech River fault, southern Vancouver Island, Canada, and constrains permanent forearc deformation in northern Cascadia. A south‐to‐north reduction in northward Global Navigation Satellite System velocities and seismicity across the Olympic Mountains, Strait of Juan de Fuca (JDF), and the southern Strait of Georgia

Both earthquake displacement and rupture length correlate with magnitude, and, therefore, observations of each from past earthquakes can be used to estimate the magnitude of those earthquakes in the absence of instrumental records. We extend the Bayesian inversion method of Biasi and Weldon (2006), which estimates paleoearthquake magnitude from displacement observations, to incorporate both rupture