Earthquake Swarm Research Articles

Prospective evaluation of multiplicative hybrid earthquake forecasting models in California

SUMMARYThe Regional Earthquake Likelihood Models (RELM) experiment, conducted within the Collaboratory for the Study of Earthquake Predictability (CSEP), showed that the smoothed seismicity (HKJ) model by Helmstetter et al. was the most informative time-independent earthquake model in California during the 2006–2010 evaluation period. The diversity of competing forecast hypotheses and geophysical data sets used in RELM was suitable for combining multiple models that could provide more informative earthquake forecasts than HKJ. Thus, Rhoades et al. created multiplicative hybrid models that involve the HKJ model as a baseline and one or more conjugate models. In retrospective evaluations, some hybrid models showed significant information gains over the HKJ forecast. Here, we prospectively assess the predictive skills of 16 hybrids and 6 original RELM forecasts at a 0.05 significance level, using a suite of traditional and new CSEP tests that rely on a Poisson and a binary likelihood function. In addition, we include consistency test results at a Bonferroni-adjusted significance level of 0.025 to address the problem of multiple tests. Furthermore, we compare the performance of each forecast to that of HKJ. The evaluation data set contains 40 target events recorded within the CSEP California testing region from 2011 January 1 to 2020 December 31, including the 2016 Hawthorne earthquake swarm in southwestern Nevada and the 2019 Ridgecrest sequence. Consistency test results show that most forecasting models overestimate the number of earthquakes and struggle to explain the spatial distribution of epicenters, especially in the case of seismicity clusters. The binary likelihood function significantly reduces the sensitivity of spatial log-likelihood scores to clustering, however; most models still fail to adequately describe spatial earthquake patterns. Contrary to retrospective analyses, our prospective test results show that none of the models are significantly more informative than the HKJ benchmark forecast, which we interpret to be due to temporal instabilities in the fit that forms hybrids. These results suggest that smoothing high-resolution, small earthquake data remains a robust method for forecasting moderate-to-large earthquakes over a period of 5–15 yr in California.

Quantitative Assessment of Temporal Changes in Subaqueous Hydrothermal Activity in Active Crater Lakes During Unrest Based on a Time-Series of Lake Water Chemistry

Regular sampling of lake water has been performed at many volcanoes to assess the state of volcanic activity. However, it is not clear whether the absolute concentrations or, instead, rate of changes in concentrations are more suitable for such assessments. In this study, we show that temporal changes in concentrations of an element in lake water are described by a simple differential equation, assuming changes in lake volume and chemical processes are negligible. The time constants (63% response time for changes in the chemical concentration in lake water) have a wide range varying between 20 and 1,000 days for the studied volcanoes in Japan, meaning it takes a long time to assess volcanic activity based on the absolute concentration of an element. In order to assess the volcanic activity in a shorter time period, based on a time-series of lake element concentration data, we developed a numerical model to calculate temporal changes in the steady-state concentration, which is proportional to the elemental concentrations of the bulk hydrothermal fluid injected from subaqueous fumaroles and hot springs. We applied our method to Yugama crater lake at Kusatsu–Shirane volcano, Japan, and quantitatively evaluated temporal changes in the hydrothermal input from 1964 to 2020. As a result, we detected changes in the Cl concentrations of the bulk hydrothermal input that were associated with unrest including the phreatic eruption in 1976 and earthquake swarms in 1989–1992 and 2014–2020. The future concentration in the lake water can be predicted from the most recent steady-state concentrations. Comparing the predicted concentration curve with the concentration obtained from lake water samples, it is possible to quickly assess whether the concentration of the bulk hydrothermal input has increased/decreased or remained constant.

Geologic aspects (faults, landslides and volcanic dikes) of the Nateekin River shallow earthquake swarm of 15 June 2020 near Makushin Volcano, Unalaska Island, Alaska, U.S.A.-siftdesk

Starting 15 June 2020, a shallow earthquake swarm occurred in the Nateekin River valley just east of Makushin Volcano of Unalaska Island, Alaska, U.S.A. Focal mechanism determinations were made on the larger earthquake events. These correlated with four known fault groups originally recognized during 1980-85 field work in this region. These are (a) numerous N 54° W ± striking normal faults, (b) prominent N 74° W ± striking normal faults, (c) N 50° E ± strike-slip faults, and (d) a N 36° E ± striking reverse faults. These fault groups correlate with known dikes for the region, which suggest magmatic intrusions are associated with this earthquake swarm. These faults reflect a predictable fault structure for a regional maximum horizontal tectonic stress direction of N 54° W ± with a localized spreading rift zone associated with Makushin Volcano that is striking N 74° W ±. This rift zone has a reactivated landslide and numerous nearby small landslides caused by this June/July earthquake swarm. This swarm sheds insight into the faulting, volcanic and geothermal processes of the region. Key words: Shallow earthquake swarm in a volcanic rift zone; four different seismic focal (fault) mechanisms recognized; associated active faults and landslides observed; related Holocene dikes and volcanic activity; regional maximum horizontal tectonic stress and magmatic processes; extensive geothermal resources.

Cryptoexplosive breccia: A genetic mark of the paleoearthquakes

全球到处发育的隐爆角砾岩表明隐爆作用的普遍性，并标志着古地震的一种形成机制。隐爆角砾岩具有特殊的角砾形状和构造。地震地质资料表明大地震产生的地表破裂带没有肉眼可观测到的断层位移。材料聚集应变能估算值表明岩石聚集的应变能不足以产生大地震。携带高能量的地核-地幔流体不仅为自己逸散提供了能量，而且为产生地震提供了充足的能量。深部流体以运移-聚集-爆炸-运移-聚集-爆炸的循环方式向地表逃逸，在地球内部不同深度产生了不同震级的地震。因此，超高压流体隐爆应该是地震形成的主要机制。地震隐爆成因机制不仅能够更好地解释各种天然地震（中深源地震、震群、慢地震和非双力偶性地震等）以及全球地震、火山和地热带的空间吻合，而且能够解释隐爆角砾岩及其伴生矿的形成。;The cryptoexplosive breccias found all over the world indicated that cryptoexplosion was pervasive in the geological history. Cryptoexplosive breccias are characterized by the special structure, which indicates a genetic mark of paleoearthquakes. The seismic-geological data indicated that the great earthquakes produced the ruptures with evident surface displacement, but on visible fault displacement. Estimation of strain energy accumulated in the materials demonstrates that rocks in the crust and mantle cannot accumulate huge strain energy to produce great earthquake. High energy density fluids derived from the core and mantle can provide energy for their migration, as well as enough energy for producing great earthquakes. The deep fluids migrate upward in the way of migration-accumulation-explosion-migration-accumulation-explosion, producing earthquakes with the different magnitudes at different depths. Therefore, the crypto-explosion can be considered as the predominant mechanism of earthquake generation. The proposed genetic mechanism not only can be used to much better explain the generation of different kinds of earthquakes, such as the moderate and deep focus earthquakes, earthquake swarm, slow earthquakes and no-dipole-couple earthquakes, as well as special overlap of the seismic, volcanic and geothermal zones in the world, but also to explain the formation of ore deposits companied with cryptoexplosive breccias.

Seismic Swarms as Intermittent Quasi-Static Ruptures Driven by Pore Pressure Variations Due to the Water Reservoir Impoundment

Seismic Swarms as Intermittent Quasi-Static Ruptures Driven by Pore Pressure Variations Due to the Water Reservoir Impoundment

Understanding swarm earthquakes in Southeast Aceh, Sumatra

The cause of the swarm earthquakes occurring from September until November 2020 remains unclear. The swarm activities are close to the Tripa active fault but also close to Mt. Bendahara. This study offers the analysis of seismic P and S wave arrivals and relocate the hypocenter of the swarm. We analysed the hypocentre distribution that recorded by Badan Meteorologi Klimatologi dan Geofisika (BMKG) from July 2020 to January 2021. The arrival of P and S-wave from 103 events was used obtain 1-D seismic velocity model. The earthquake used for this study consisted of at least 6 phases of seismic arrivals with the azimuthal gap angle less than 180 degree. The different velocities occurred in the upper and lower of the crustal thickness of 0 – 40 km. The Vp values are about 5.0 – 7.0 km/s and 3.0 – 5.0 km/s for Vs value while the Vp/Vs ratio are ranging from 1.5 to 1.7. Our preliminary results indicate that the potential swarm activities near to Mt. Bandahara maybe triggered by an unknown fault activity as no volcanic activity was reported.

Evidence for Deeply Subducted Lower‐Plate Seamounts at the Hikurangi Subduction Margin: Implications for Seismic and Aseismic Behavior

AbstractSeamounts are found at many subduction zones and act as seafloor heterogeneities that affect slip behavior on megathrusts. At the Hikurangi subduction zone offshore the North Island, New Zealand, seamounts have been identified on the incoming Pacific plate and below the accretionary prism, but there is little concrete evidence for seamounts subducted beyond the present‐day coastline. Using a high‐resolution, adjoint tomography‐derived velocity model of the North Island, we identify two high‐velocity anomalies below the East Coast and an intraslab low‐velocity zone up‐dip of one of these anomalies. We interpret the high‐velocity anomalies as previously unidentified, deeply subducted seamounts, and the low‐velocity zone as fluid in the subducting slab. The seamounts are inferred to be 10–30 km wide and on the plate interface at 12–15 km depth. Resolution analysis using point spread functions confirms that these are well‐resolved features. The locations of the two seamounts coincide with bathymetric features whose geometries are consistent with those predicted from analog experiments and numerical simulations of seamount subduction. The spatial characteristics of seismicity and slow slip events near the inferred seamounts agree well with previous numerical modeling predictions of the effects of seamount subduction on megathrust stress and slip. Anomalous geophysical signatures, magnetic anomalies, and swarm seismicity have also been observed previously at one or both seamount locations. We propose that permanent fracturing of the northern Hikurangi upper plate by repeated seamount subduction may be responsible for the dichotomous slow slip behavior observed geodetically, and partly responsible for along‐strike variations in plate coupling on the Hikurangi subduction interface.

Attention-Based Fully Convolutional DenseNet for Earthquake Detection

We propose a novel deep learning method using an attention-based fully convolutional dense network (FCDNet) for automatic earthquake detection. The FCDNet consists of encoder-decoder parts with skip connections, where each encode-decoder block contains a block of densely connected layers to enhance the feature learning capability. The spatial attention mechanism is added within the FCDNet to assign greater attention to useful features and hence improve the accuracy of earthquake detection. The time-frequency representations of three-component seismograms produced by the Stockwell transform are used for better extracting the hidden data features. The attention-based FCDNet extracts the time-frequency features needed for distinguishing the seismic signal from the background noise. We evaluate the performance of the proposed method using a Mediterranean dataset. The attention-based FCDNet is trained using 90% of the Mediterranean dataset and tested using the remaining 10%. Accordingly, the training and testing accuracies are 97.71% and 97.02%, respectively. The intersection over union (IoU), precision, recall, and F1-score of the attention-based FCDNet are 93.80%, 99.72%, 99.55%, and 99.64%, respectively. Moreover, to evaluate the generalization ability of the trained model, we utilize 100,000 seismic waveforms recorded in different seismic regions from the global STanford EArthquake Dataset (STEAD) dataset for testing, which shows robust performance. We also apply the attention-based FCDNet to the Japanese seismic data and compare the performance to the CRED and SCALODEEP methods. The attention-based FCDNet outperforms the benchmark methods and achieves a higher detection accuracy of 99.46%. The attention-based FCDNet is additionally evaluated using one-day continuous seismic data recording a seismic swarm that occurred in the Helike region. As a result, the attention-based FCDNet recognizes 135 earthquakes and raises 15 false alarms with a detection accuracy of 90.06%.

Short-time Seismic Swarm Activity in the Wakamiko Caldera in August, 2020

Short-time Seismic Swarm Activity in the Wakamiko Caldera in August, 2020

A 20 year-long GNSS solution across South-America with focus in Chile

Over the last 3 decades, GPS measurements have been instrumental in quantifying tectonic plates current motion and deformation. Complex patterns of deformation along the plate boundaries revealed heterogeneous coupling on the plates interface and imaged seismic segments at different stages of their seismic cycle. Along the South-American trench in Chile, where large earthquakes occur frequently, continuous GPS observations (cGPS) captured both the long-term plate motion and the transient deformations associated with the seismic cycle. Over the years, a network of hundreds of cGPS stations has been deployed all across the South-American continent by many different institutions for many different sorts of purposes ranging from geographic reference to tsunami early warning. We report here on the processing of 20 years (2000–2020) worth of data over a selection of cGPS stations, devoted to the quantification and analysis of the deformation along the Chilean subduction zone between 18°S and 40°S. We use all available data near the trench in Chile and a less dense network inside the continent where the gradient of deformation is lesser. Our database, namedSOAM_GNSS_solENS, provides time series of precise daily station position, obtained from double difference (DD) processing and expressed in the International Terrestrial Reference Frame 2014 (ITRF14). These time series allow to quantify, with sub-millimetric precision, any kind of ongoing deformation process, either from tectonic origin such as interseismic deformation, co- and post-seismic displacements associated with earthquakes, transient deformation associated to seismic swarms and/or a-seismic slow-slip events, or of other origin such as hydrological loading (for ex., the Amazonian basin load) or any other type of loading affecting the surface of the Earth (tides, atmosphere, etc.). We also provide a database of coseismic displacements associated with close to 60 earthquakes of Mw larger than 6.5 that occurred over the last 20 years within the observation area. All time series are directly accessible through a deposit and we plan to make them available through a web interface that will allow any user to perform elementary operations like estimating offsets, detecting outliers, detrending, filtering and stacking. That database will evolve with time, aggregating more data. In the future, we also plan to complement that database with a rapid solution in quasi real time processed in Precise Point Positioning (PPP), and with hourly atmospheric delays associated with water vapor content of the lower layer of the atmosphere.

New eruption at Fagradalsfjall Volcano follows days of seismic swarms

After a weekend of intense earthquakes, a spectacular new eruption at Fagradalsfjall volcano in Iceland began Wednesday afternoon. Volcano scientists are keeping a close eye on this eruption, but only time will tell what will happen.

Volcanic Origin of a Long‐Lived Swarm in the Central Bransfield Basin, Antarctica

AbstractUnderstanding the extensional processes in tectonic context at the transition from continental to oceanic spreading is fundamental to obtain new insights about formations of new oceans. To that scope, we study a large and long‐lived earthquake swarm occurring in 2020–2021 in a back‐arc rift (the Bransfield Basin) south of the South Shetland Islands, Antarctica. We make use of one local seismological station to detect more than 36,000 small earthquakes, occurring from August 2020 to June 2021. Together with the occurrence of earthquakes, we observe a significant, geodetic deformation at a nearby GPS station. By joint interpretation of b‐value, spatiotemporal evolution of seismicity and geodetic deformation, we infer a volcanic origin for this swarm that takes place close to the ridge axis. Our study suggests that beyond the 7 mm/yr deformation reported at the Bransfield Basin ridge, transient deformation episodes localized at the ridge axial volcanic structure also modulate the extension.

Dynamic Relationship Study between the Observed Seismicity and Spatiotemporal Pattern of Lineament Changes in Palghar, North Maharashtra (India)

The Palghar region (north Maharashtra, India), located in the northwestern part of the stable continental region of India, experienced a low magnitude earthquake swarm, which was initiated in September 2018 and is continuing to date (as of October 2021). From December 2018 to December 2020, ~5000 earthquakes with magnitudes from M1.2 to M3.8 occurred in a small region of 20 × 10 km2. These earthquakes were probably triggered by fluid migration during seasonal rainfall. In this study, we have used multi-temporal Landsat satellite data of the year 2000, 2015, 2018, 2019, and 2020, extracted lineaments, and studied the changes in frequency and pattern of lineaments before and after the initiation of the swarm in the Palghar region. An increase in the lineament density and amount of rainfall are found to be associated with the increasing frequency of earthquakes.

Information Preference and Information Supply Efficiency Evaluation before, during, and after an Earthquake: Evidence from Songyuan, China.

Efficient risk communication is aimed at improving the supply of risk information to meet the information needs of individuals, thus reducing their vulnerability when facing the risk of emergency. There is little information available in the literature regarding information preference from an individual’s need perspective, and there is a lack of differentiation in evaluation between information need and supply. Under the guidance of the crisis stage analysis theory, using multiple response analysis and weighted analysis methods, this study explores earthquake disaster information content and communication channel preferences, and develops an information deviation index (IDI) to evaluate the efficiency of risk communication before, during, and after an earthquake. A questionnaire-based survey of 918 valid respondents in Songyuan, China, which had been hit by a small earthquake swarm, was conducted to provide practical evidence for this study. The results indicated the following. Firstly, the information needs of individuals are highly differentiated in the different stages of an earthquake. From pre-disaster to post-disaster, individuals show a shift in information need from “preparedness and response knowledge” to “disaster information”, then to “disaster information and disaster relief information” in parallel, to “reconstruction and reflection information”. Based on the above analysis, a composition of the main earthquake disaster information is proposed for different stages. Secondly, by measuring the values of the IDI, we found that most individuals’ information needs were met for the earthquake. Thirdly, the TV and the internet were the two preferred commutation channels for acquiring disaster information from among all the effective channels in all the stages.

Groundwater Interacting at Depth With Hot Plastic Magma Triggers Phreatic Eruptions at Yugama Crater Lake of Kusatsu-Shirane Volcano (Japan)

Interpreting the triggering mechanisms for phreatic eruptions is a key to improving the hazard assessment of crater lakes. Yugama Crater Lake at Kusatsu-Shirane volcano, Japan, is the site of frequent phreatic eruptions with the recent eruptions in 1982–83, 1989, and 1996, as well as volcanic unrest, including earthquake swarms in 2014 and 2018. To understand the magma–hydrothermal interaction beneath Yugama Crater Lake, we analyzed lake waters from November 2005 to May 2021. From 2005 to 2012, Cl and SO4 concentrations decreased slowly, suggesting the development of a self-sealing zone surrounding the crystallizing magma. We focused on Ca, Al, and Si concentrations as representatives of the breach and dissolution of minerals comprising the self-sealing zone and the Mg/Cl ratio as an indicator for enhanced interaction between groundwater and hot plastic rock within the self-sealing zone. In 2006–2007, the Ca, Al, Si concentrations and the Mg/Cl ratio increased. No Cl and SO4 increase during this period suggests the self-sealing zone was leached by deep circulating groundwater rather than by magmatic fluids injection. After the 2014 earthquakes, Ca, Al, and Si increased again but were associated with a significant Cl increase and a pH decrease. We believe that the HCl-rich magmatic fluids breached the self-sealing zone, leading to fluids injection from the crystallizing magma to the Yugama crater. During this period, the Mg/Cl ratio did not increase, meaning that magmatic fluids ascending from the breached area of the self-sealing zone inhibited deep intrusion of groundwater into the hot plastic rock region. In 2018, magmatic fluids ascended through the self-sealing zone again with less intensity than in 2014. All eruptions since 1982 have been accompanied by a Mg/Cl ratio increase and a Cl decrease, whereas, when a significant HCl input occurs, as in 2014, no eruptions and no Mg/Cl ratio increase occurred. This demonstrates that the groundwater–hot plastic rock interaction, rather than the magmatic fluids input, played an essential role in triggering phreatic eruptions; i.e., phreatic eruptions can potentially occur without clear signs of fresh magma intrusions.

Relationship Between Dike Injection and b‐Value for Volcanic Earthquake Swarms

AbstractDike swarms are the fossil remains of regions of the crust that have undergone repeated magma injections. Volcanic earthquake swarms and geodetic measurements are, at least in part, a record of active injection of fluids (water, gas, or magma) into fractures. Here, we link these two ways of observing magmatic systems by noting that dike thicknesses and earthquake magnitudes share similar scaling parameters. In the Jurassic Independence dike swarm of eastern California median dike thickness is ∼1 m, similar to other swarms worldwide, but glacially polished exposures reveal that a typical dike comprises a number of dikelets that are lognormally distributed in thickness with a mean of ∼0.1 m. Assuming that dikes fill penny‐shaped cracks of a given aspect ratio, the geodetic moment and earthquake magnitude of a diking event can be estimated. A Monte Carlo simulation of dike‐induced earthquakes based on observed dike thickness variations yields a frequency‐magnitude distribution remarkably like observed volcanic earthquake swarms, with a b‐value of ∼1.7. We suggest that swarms of dikes composed of dikelets, as well as plutons built incrementally by sheet intrusions, are physical complements to volcanic seismic swarms, and that at least some earthquake swarms are a palpable expression of incremental magma emplacement.

Hydrogeochemical changes before and during the 2019 Benevento seismic swarm in central-southern Italy

Insights into seismic precursors have been obtained in the last decades. However, a detailed understanding of hydrogeochemical anomalies prior to earthquakes still remains the aim of many research teams worldwide. In order to investigate the earthquake-groundwater relationship, between 2018 and 2020, we performed sampling surveys coupled with continuous multiparametric monitoring in Grassano spring fed by the Matese aquifer (central-southern Apennines, Italy). Hydrogeochemical changes were observed before the onset and during the 2019 Benevento seismic sequence, including dissolved CO2 increase, pH lowering, and anomalies in major ions (i.e., Ca2+, Na+, HCO3–) that later recovered to their typical concentrations. We suggest that variations in groundwater geochemistry were induced by dilatative preparatory phases of earthquakes, typical of the extensional setting. This condition allowed the deep CO2 upwelling along tectonic discontinuities, as testified by the Cext (carbon from external sources) behaviour detected in Grassano groundwater during the 2019 year. Despite the small-intermediate magnitude of the mainshock, results highlight and confirm the occurrence of a potential pre-seismic geochemical process in the fractured carbonate aquifers, similar to the one proposed in literature for the stronger 2016–2017 Amatrice-Norcia seismic sequence.

Geomorphological evidence of tectonic activity of the Marianske Lazne Fault (Czech Republic) and its influence to stream network evolution

The Mariánské Lázně Fault (western Bohemia, CZE) is a morphologically, geologically and tectonically prominent structure with that is 150 km long with an NNW-SSE orientation. Its tectonic activity, especially in the NW part and in the neighbouring Cheb basin, is well known and has been proven by present-day earthquake swarms, mantle-derived CO2 emanations, geophysical and paleoseismological research. It seems that other parts of the MLF (especially segments of NNW-SSE and N-S orientation) might also have been active during the Pleistocene, possible even in the Holocene. This study provides a robust set of morphometric analyses – mountain-front sinuosity, basin asymmetry, longitudinal stream profiles, SL-index, which assesses the possibility of recent tectonic activity. The results suggest that the activity of the central and southern part of the MLF could have been very young. A reconstruction of the evolution of the stream network of the Mže River, as a result of different timing of the activity of particular segments of the MLF, is also put forward. The first ideas about the evolution of terrain morphology and the stream network are proposed by this study, however subsequent field research (geophysics, paleoseismology) could prove and date the tectonic activity. The delineation of segments with young activity may also have a great implication for seismic hazard assessment.

Fast and Robust Earthquake Source Spectra and Moment Magnitudes from Envelope Inversion

ABSTRACTWith the present study, we introduce a fast and robust method to calculate the source displacement spectra of small earthquakes on a local to regional scale. The work is based on the publicly available Qopen method of full envelope inversion, which is further tuned for the given purpose. Important source parameters—seismic moment, moment magnitude, corner frequency, and high-frequency fall off—are determined from the source spectra by fitting a simple earthquake source model. The method is demonstrated by means of a data set comprising the 2018 West Bohemia earthquake swarm. We report moment magnitudes, corner frequencies, and centroid moment tensors inverted from short-period body waves with the Grond package for all earthquakes with a local magnitude larger than 1.8. Moment magnitudes calculated by envelope inversion show a very good agreement to moment magnitudes resulting from the probabilisitc moment tensor inversion. Furthermore, source displacement spectra from envelope inversion show a good agreement with spectra obtained by multiple taper analysis of the direct onsets of body waves but are not affected by the large scatter of the second. The seismic moments obtained with the envelope inversion scale with corner frequencies according to M0∝fc−4.7. Earthquakes of the present data set result in a smaller stress drop for smaller magnitudes. Self-similarity of earthquake rupture is not observed. In addition, we report frequency-dependent site amplification at the used stations.

Earthquakes Induced by Wastewater Disposal near Musreau Lake, Alberta, 2018–2020

Abstract Although hydraulic fracturing-induced earthquakes have been widely reported in Alberta, Canada, only one seismic cluster (the Cordel Field) has thus far been linked to wastewater disposal (WD). In this study, we report a statistically significant spatiotemporal correlation between recent earthquakes and nearby WD wells near Musreau Lake—the second disposal-induced earthquake swarm in Alberta. This newly occurred swarm contains five events with local magnitudes ML>3 from January 2018 to March 2020, forming into three tightly spaced clusters. The refined locations and focal mechanisms suggest a ∼10 km long northwest–southeast-trending rupture along the northern Rocky Mountains that developed over time, during which both poroelastic effects and static stress transfer played key roles. Through a statistical analysis of all reported induced earthquake clusters in the western Canada sedimentary basin (WCSB), we propose a linear predictive relationship (i.e., the “Interpolated Strike Orientation” model) between fault rupture direction and fault distance to the Rocky Mountains. This observation-based model, which is supported by both the focal mechanisms of the natural earthquakes and the nearby northwest-striking geological faults, is a new and useful reference for future assessments of seismic hazard in the WCSB.