Gail M. Atkinson

Gail M. Atkinson
Western University | UWO · Department of Earth Sciences

PhD Geophysics

About

311
Publications
129,598
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Introduction
Engineering seismologist researching: (i) engineering ground motion; (ii) earthquake source and attenuation processes; (iii) seismic hazard analysis; (iv) seismological processes in eastern North America; induced seismicity. Active on Canadian code committees responsible for developing seismic design regulations. President, Seismological Society of America (2001-2003).Chair (SCEC Advisory Council), 2014-2016. President, Canadian Geophysical Union, 2011-2013.
Additional affiliations
September 2007 - present
Western University
Position
  • Professor (Full)

Publications

Publications (311)
Conference Paper
Full-text available
A probabilistic earthquake and tsunami risk assessment was conducted for Tofino and neighboring Tla-o qui-aht First Nation (TFN) communities on Vancouver Island, British Columbia. It aims to provide guidance on disaster risk reduction planning at a local scale. The project is funded by the National Disaster Mitigation Program of Canada. The primary...
Article
We develop ground-motion models (GMMs) to characterize the Fourier amplitude spectrum (FAS) for earthquakes in British Columbia (B.C.), Canada. GMMs developed for FAS are useful for understanding the underlying seismological parameters and can be transformed into GMMs for response spectral values for other applications (e.g., probabilistic seismic...
Article
Kappa (the high-frequency spectral decay slope at near-source distances; often referred to as κ0) is determined at 25 seismograph stations in Eastern Canada using broadband ground-motion modeling approaches. The database comprises Fourier spectra (effective amplitude spectrum for the horizontal component and the vertical component, 0.8–40 Hz) compu...
Article
The amplitudes and decay rate of ground motions from small to moderate earthquakes are important to the assessment of induced seismicity hazards and useful as input components to finite-fault models of larger events. The decay rate of mining events (M < 3) recorded on hard rock is consistent with a geometric spreading rate of R−1.3, with no apparen...
Conference Paper
Full-text available
The New Zealand National Seismic Hazard Model (NSHM) has undergone its first significant revision in 10 years. An expectation of the model was to provide epistemic uncertainty to Building Code decisions and to model appropriately the complexity in both the source and ground motion modelling. An update of all major components was done, including asp...
Article
In this article, ground-motion models (GMMs) for subduction earthquakes recently developed as part of the Next Generation Attenuation-Subduction (NGA-Sub) project are compared. The four models presented in this comparison study are documented in their respective articles submitted along with this article. Each of these four models is based on the a...
Article
This article summarizes the Next Generation Attenuation (NGA) Subduction (NGA-Sub) project, a major research program to develop a database and ground motion models (GMMs) for subduction regions. A comprehensive database of subduction earthquakes recorded worldwide was developed. The database includes a total of 214,020 individual records from 1,880...
Article
We develop semi-empirical ground motion models (GMMs) for peak ground acceleration, peak ground velocity, and 5%-damped pseudo-spectral accelerations for periods from 0.01 to 10 s, for the median orientation-independent horizontal component of subduction earthquake ground motion. The GMMs are applicable to interface and intraslab subduction earthqu...
Article
In this article, we present an overview of the research project NGA-East, Next Generation Attenuation for Central and Eastern North America (CENA), and summarize the key methodology and products. The project was tasked with developing a new ground motion characterization (GMC) model for CENA. The final NGA-East GMC model includes a set of 17 median...
Article
As a companion article to Goulet et al., we describe implementation of the NGA-East ground motion characterization (GMC) model in probabilistic seismic hazard analysis (PSHA) for sites in the Central and Eastern United States (CEUS). We present extensions to the EPRI/DOE/NRC seismic source characterization (SSC) model for the CEUS needed for full i...
Article
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 develo...
Article
Full-text available
In western Canada, there has been an increase in seismic activity linked to anthropogenic energy‐related operations including conventional hydrocarbon production, wastewater fluid injection, and, more recently, hydraulic fracturing (HF). Statistical modeling and characterization of the space, time, and magnitude distributions of the seismicity are...
Preprint
Full-text available
In western Canada, there has been an increase in seismic activity linked to anthropogenic energy‐related operations including conventional hydrocarbon production, wastewater fluid injection, and, more recently, hydraulic fracturing (HF). Statistical modeling and characterization of the space, time, and magnitude distributions of the seismicity are...
Article
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...
Article
As recently as 2015, it was common in the scientific literature to find assertions that the risk of triggering a damaging earthquake by hydraulic fracturing (HF) — an industrial process where pressurized fluids are used to create or open fractures within rock layers — could be treated as negligible. However, that viewpoint has changed dramatically....
Article
Full-text available
Ground-motion models (GMMs) are a key driver for the results of probabilistic seismic hazard analyses and their uncertainty. GMMs that bridge seismological and empirical approaches are an effective tool to represent the distribution of ground motion and its uncertainty in seismic hazard assessment. A methodology is presented that uses ground-motion...
Article
A regional ground-motion prediction equation (GMPE) is defined for earthquakes in the western Canada sedimentary basin. The stress parameter model that is input to the GMPE, which controls high-frequency amplitudes, is developed based on an empirical Green’s function (EGF) study in the same region (Holmgren et al., 2019). The GMPE is developed usin...
Article
The damage potential of induced earthquakes is compared to that of natural tectonic events, considering recent instrumental data and felt records from events of M 3.5–5.8 (in which M is the moment magnitude). Ground motions are mutually consistent at close distances (<30 km) for natural earthquakes in California, induced earthquakes in Oklahoma, an...
Article
Spectral decay of ground-motion amplitudes at high frequencies is primarily influenced by two parameters: site-related kappa (κ0) and regional Q (quality factor, inversely proportional to anelastic attenuation). We examine kappa and apparent Q-values (Qa) for M≥3.5 earthquakes recorded at seismograph stations on rock sites in eastern and western Ca...
Article
The U.S. Geological Survey national seismic hazard maps have historically been produced for a reference site condition of V S30 760 m/sec. For other site conditions, site factors are used, which heretofore have been developed using ground motion data and simulations for shallow earthquakes in active tectonic regions. Research results from the NGA-E...
Article
This paper evaluates linear simulation-based and empirical site amplification models including site natural period dependency parameters to account for the distinctive amplification behavior near site fundamental frequencies resulting from the sharp impedance contrast between soil and underlying hard bedrock in Central and Eastern North America (CE...
Article
Full-text available
The Western Canada sedimentary basin (WCSB) has experienced an increase in seismicity during the last decade due primarily to hydraulic fracturing. Understanding the ground motions of these induced earthquakes is critical to characterize the increase in hazard. Stress drop is considered an important parameter in this context because it is a measure...
Article
Full-text available
On 30 November 2018, three felt earthquakes occurred in the Septimus region of northeast British Columbia in an area where hydraulic fracturing was in progress. The proximity of oil and gas activities to populated areas and to critical infrastructure including major dams raises significant concern regarding the seismic hazard posed by moderate indu...
Conference Paper
Full-text available
It is often assumed that hard rock sites should exhibit no earthquake ground motion amplification, but in reality, some amplification occurs typically at higher frequencies due to weathered and fractured layers near the surface. According to seismic provisions in the National Building Code of Canada (NBCC), the subsurface ground conditions at a sit...
Article
Full-text available
We compile and process an electronic database of ground motions recorded on accelerometers and broadband seismographic instruments for induced earthquakes of M ≥ 4 at distances <50 km in central and eastern North America. Most of the data are from Oklahoma, with some records from Alberta. Our focus is on the subset of available records that are of...
Presentation
Kappa results for Eastern and Western Canada
Article
Full-text available
We produce year-by-year probabilistic seismic hazard maps based on the seismicity from 2011 to 2018 for the western Canada sedimentary basin (WCSB) and compare them with corresponding maps of the baseline historical hazard levels through 2010. Rates of earthquakes across the WCSB, of moment magnitude (M) ≥ 3:0, have increased in the past decade bec...
Article
An important predictive variable for site amplification is the site dominant frequency (fd). At seismic monitoring stations, fd can be calculated from the peak of the horizontal-to-vertical spectral ratios (HVSRs) obtained from earthquake recordings (eHVSR). For other sites, fd can be estimated from microseismic (mHVSR) observations. We compare the...
Article
Full-text available
Any process that causes a sudden brittle failure of material has the potential to cause earthquake-like seismic events. Cryoseisms represent an underreported class of seismic event due to their (often) small magnitudes. In this paper, we document the phenomenon of some of the largest magnitude lake-associated icequakes (ML 2.0) yet reported. These...
Article
A region-specific ground-motion prediction equation (GMPE) is developed using a selected and compiled database of 7278 ground-motion observations in Oklahoma, including 188 events of magnitude 3.5-5.8, recorded over the hypocentral distance range from 2 to 500 km; most events are considered to be induced by wastewater injection. A generalized inver...
Article
Characterizing the ground-motion signature of various event types is important for event discrimination and for the development of reliable earthquake catalogues. Small-magnitude seismic events are often enigmatic and determining their cause can be challenging. This is because there are various sources of energy (e.g., rock bursts, construction bla...
Article
Full-text available
We analyze a comprehensive database of ∼63,000 geocoded community intensity observations from > 400 earthquakes of moment magnitude M ≥ 3.5 in Oklahoma from 2010 to 2016 to define the intensity signature of induced events. We show that natural and induced events have similar average intensities within 10 km of the epicenter. At greater distances, i...
Article
We modified the simulation-based generic ground-motion prediction equation (GMPE) model proposed by Yenier and Atkinson (2015b) to enable adjustments for the near-surface attenuation parameter commonly referred to as kappa (κ0). This enhances the usefulness of the model in applications over a broad range of site conditions from hard rock to soil. T...
Article
An important issue in ground motion and hazard analysis for induced earthquakes is the variability of ground-motion amplitudes (sigma). We investigate the contributions of uncertainty in source parameters to sigma using ground-motion recordings from 38 earthquakes in central United States (CUS) having moment magnitudes from 3.0 to 4.3.We optimize t...
Article
Full-text available
Seismicity curbed by lowering volume Determining why hydraulic fracturing (also known as fracking) triggered earthquakes in the Duvernay Formation in Canada is important for future hazard mitigation. Schultz et al. found that injection volume was the key operational parameter correlated with induced earthquakes in the Duvernay. However, geological...
Article
We collected site-specific geophysical data at 28 seismic stations on various soils in Alberta, Canada. Noninvasive seismic procedures are combined with the earthquake database and other available regional data sets to improve current understanding of earthquake site effects at the stations. Such an understanding allows the separation of site effec...
Article
A marked increase in seismic activity related to oil and gas development in Alberta, Canada, over the past decade has highlighted interest in quantifying earthquake ground-shaking hazard in the province. In this study, we use station-average horizontal-to-vertical spectral ratios (HVSRs) calculated from earthquake and microtremor recordings to esta...
Article
We develop an empirical site-amplification model for central and eastern North America (CENA) that is parameterized using two site variables: (1) the peak site frequency (fpeak) and (2) the time-averaged shear-wave velocity in the upper 30 m (VS30). The model is developed by first deriving empirical site-amplification terms for seismographic sites...
Article
In this study, we explore the applicability of fpeak (the peak frequency of the site-response transfer function) as a site-effect parameter for sites in California. The study is motivated by the results of our companion paper (Hassani and Atkinson, 2017), in which we show that peak frequency is a primary site variable for central and eastern North...
Article
Several recent clusters of earthquakes of moment magnitude M ≥3 in Alberta have been identified as potentially induced seismicity, triggered by hydraulic fracturing, oil and gas production, and wastewater disposal. We characterize ground motions from these events, recorded within 100 km, focusing on the empirical definition of response spectral sha...
Article
Full-text available
In this study we investigate how hazard is impacted according to whether a specified rate of seismicity is random versus clustered, in time and space. This issue is explored using a case study of seismicity induced by hydraulic fracturing operations near Fox Creek, Alber-ta. The observed earthquake catalogue for the area within ~25 km of Fox Creek...
Article
In southern Ontario, Canada, site amplification plays a major role in the interpretation of ground motions and felt shaking during earthquakes. Sediments in the region vary from soft to stiff and overlie very hard glaciated bedrock, providing a strong impedance contrast that results in pronounced amplification of horizontal-component motions. Gener...
Article
Full-text available
Ground motions for earthquakes of M7.5 to 9.0 on the Cascadia subduction interface are simulated based on a stochastic finite-fault model and used to estimate average response spectra for reference firm soil conditions. The simulations are first validated by modeling the wealth of ground-motion data from the 2011 M9.0 Tohoku earthquake of Japan. Ad...
Article
The December 2015 moment magnitude (M) 4.7 Vancouver Island earthquake is one of the largest recorded inslab earthquakes within Georgia Strait, British Columbia, Canada. Ground motions from all seismic stations within 500 km from the epicenter are examined. Peak ground acceleration reached a maximum of 4.65%g in Greater Victoria. We compare the obs...
Article
We use ShakeMap ground-motion parameters from small seismic events in the western Alberta region to develop a reliable seismic discriminant that can be used in an automated procedure to distinguish blasts from earthquakes. In comparison with earthquakes, quarry blasts have higher vertical-to-horizontal (V/H) ratio of ground-motion parameters at hig...
Article
Full-text available
There has been a significant increase in the rate of felt earthquakes in western Alberta and eastern British Columbia, which has been associated with hydraulic fracturing and wastewater disposal. The increased rate of seismicity and the potential for localized strong ground motions from very shallow events poses an increased hazard to critical infr...
Article
Full-text available
Site amplification effects in southern Ontario are highly variable and strongly influence felt effects and damage potential. Site parameters such as shear-wave velocity in the top 30 metres of soil (VS30), traditionally used to estimate site amplification, are not well known in this region. Thus, regional maps of shaking potential and seismic hazar...
Article
Full-text available
Natural earthquakes in western North America can be reasonable proxies for induced earthquakes in central and eastern North America because of the opposing effects that source depth and tectonic setting have on the stress parameter that scales high-frequency ground-motion amplitudes. It is critical that ground-motion prediction equations selected a...
Article
Full-text available
We examine ground motions for a sequence of earthquakes in Oklahoma, where assessment of hazard contributions from induced seismicity is of particular interest. We aim to empirically-calibrate a model-driven equation that was derived for central and eastern North America (CENA), so that it will match the observed ground motions of the 2011 Prague,...
Article
Full-text available
This paper summarizes the current state of understanding regarding the induced seismicity in connection with hydraulic fracturing operations targeting the Duvernay Formation in central Alberta, near the town of Fox Creek. We demonstrate that earthquakes in this region cluster into distinct sequences in time, space, and focal mechanism using (i) cro...
Conference Paper
High-damping spectral amplitudes and corresponding damping reduction factors (ƞ) are key parameters for seismic design and analysis of structures equipped with seismic protection systems, as well as for displacement-based design methodologies. In addition, spectral amplitudes at damping levels lower than 5% are important for design and safety evalu...
Conference Paper
Full-text available
Earthquake recording stations, seismographs and/or strong-motion instruments, located on underlying soils are generally installed without comprehensive knowledge or testing of the underlying geologic material in Canada and Chile. To remedy this issue, various in situ geophysical methods are applied to evaluate the underlying ground conditions at ea...
Article
We develop a regional site-effects model for central and eastern North America based on an analysis of the residuals of observed ground-motion parameters relative to two regional ground-motion prediction equations: one model has a hardrock (site class A) reference site condition, whereas the other is referenced to a B/C boundary site condition (sit...
Article
We characterize the statistical relationship between hydraulic fracturing and seismicity in western Canada using the concept of cellular seismicity. We determine the regionally-averaged probability that hydraulic fracture operations will be associated with M>=3 seismicity within a 10 km-grid cell. This rate is 0.01 to 0.026 at the 95th percentile c...
Technical Report
Full-text available
A technical meeting was held on October 6, 2015, at the downtown campus of the University of Calgary to discuss the effectiveness of the traffic light protocol (TLP) approach for management of risks from induced seismicity. The meeting was attended by 64 participants from industry (55%), various government agencies (25%), academia (10%), and profes...
Article
Full-text available
The accurate modeling of ground motion for induced-seismicity hazard estimation is critically dependent on how amplitudes scale with distance near the hypocenter. A rich database of ground motions from small events recorded at close distances in the Geysers region of California has been used to constrain the near-distance saturation effects that co...
Article
A critical component in the interpretation of earthquake ground motions is the role that site effects play. In eastern Canada, the sediment layers which overlie glaciated bedrock produce strong and highly variable site responses. We use horizontal-to-vertical (H/V) response spectral ratios as the indicator variable by which to characterize the sali...
Article
We employ a network-based method to map the spatiotemporal variations of the magnitude of completeness (Mc) in the Composite Alberta Seismicity Catalog (CASC; see Data and Resources) from 1985 to 2015 across a grid of sites. The underlying principle is that we expect events to be located and cataloged if they are detected on four or more seismic st...
Article
Full-text available
The development of most unconventional oil and gas resources relies upon subsurface injection of very large volumes of fluids, which can induce earthquakes by activating slip on a nearby fault. During the last 5 years, accelerated oilfield fluid injection has led to a sharp increase in the rate of earthquakes in some parts of North America. In the...
Article
Full-text available
We present ground motion prediction equations (GMPEs) for computing natural log means and standard deviations of vertical-component intensity measures (IMs) for shallow crustal earthquakes in active tectonic regions. The equations were derived from a global database with M 3.0–7.9 events. The functions are similar to those for our horizontal GMPEs....
Poster
Full-text available
The moment magnitude (M)4.7 Vancouver Island earthquake of December 30, 2015 (48.62, -123.3) was a normal-faulting in-slab event located approximately 21 km NNE of Victoria, BC, at a depth of 60 km. The moderate earthquake was felt roughly 150 kilometers in all directions across much of B.C.’s South Coast and parts of Washington State. Ground motio...
Article
We examine the applicability of the Next Generation Attenuation-West2 (NGA-West2) site-effects model (Seyhan and Stewart, 2014), which is a V S30-based (time-averaged shear-wave velocity in the upper 30 m) model, to sites in central and eastern North America (CENA), using the NGA-East ground-motion database. We determine residual site terms by comp...
Article
High-damping displacement spectra and corresponding damping reduction factors (η ) are important ingredients for seismic design and analysis of structures equipped with seismic protection systems, as well as for displacement-based design methodologies. In this paper, we investigate η factors for three types of earthquakes characterizing seismic haz...
Conference Paper
We examine the distance attenuation of peak Wood-Anderson (WA) amplitudes obtained from earthquakes in western Alberta, to develop a regionally-calibrated local magnitude (ML) equation. A comparison of WA amplitudes from earthquakes and mining/quarry blasts in the region show that both event types decay at similar rates with distance and demonstrat...
Article
We introduce a new proxy measure for VS30 (time-averaged shear-wave velocity in the upper 30 m) for central and eastern North America (CENA). The new proxy is the site fundamental frequency (fpeak), measured from the horizontal-tovertical (H/V) spectral ratios of recorded ground motion (or ambient noise). In this study, H/V spectral ratios are obta...
Article
Full-text available
An earthquake with a reported magnitude of 4.4 (ML) was detected on 13 June 2015 in western central Alberta, Canada. This event was the third felt earthquake this year near Fox Creek, a shale gas exploration region. Our results from full moment tensor inversions of regional broadband data show a strong strike-slip mechanism with near-vertical fault...
Article
We thank John Ebel for his interest and his comment (Ebel, 2016) on our paper that presented our statistical analysis of aftershock activities in the St. Lawrence Valley, including the sequence from the 1663 Charlevoix earthquake. The main disagreement he had with our paper is that he found it difficult to understand how the data points plotted on...
Article
We describe an efficient method to determine moment magnitude and stress parameter in near real time, in the immediate aftermath of a small-to-moderate earthquake (M∼ 3–6), from ShakeMap ground-motion parameters (5% damped pseudospectral acceleration) at 1 Hz, 0.33 Hz, 10 Hz and/or peak ground acceleration. The methodology is based on relating Shak...
Article
This study compares the nonlinear response potential of generic inelastic single-degree-of-freedom systems subjected to three sets of ground motion records for the 2011 Tohoku mainshock. The compared record sets, all for the same sites, are: (i) observed accelerograms at 48 KiK-net strong motion stations; (ii) time-histories simulated from the empi...
Article
Full-text available
We develop a generic ground-motion prediction equation (GMPE) that can be adjusted for use in any region by modifying a few key model parameters. The basis of the GMPE is an equivalent point-source simulation model whose parameters have been calibrated to empirical data in California, in such a way as to determine the decoupled effects of basic sou...