Michael Brudzinski

Miami University | MU

The clustering of earthquake magnitudes is poorly understood compared to spatial and temporal clustering. Better understanding of correlations between earthquake magnitudes could provide insight into the mechanisms of earthquake rupture and fault interactions, and improve earthquake forecasting models. In this study we present a novel method of exa...

As the carbon sequestration community prepares to scale up the number and size of commercial operations, the need for tools and methods to assess and mitigate risks associated with these operations becomes increasingly important. One outstanding question is whether aftershocks of induced events decay quickly after injection operations cease or if a...

The clustering phenomenon in seismology draws significant attention from geophysicists as well as the public at large. The reason for this is rooted in the fundamental interest of reliable earthquake prediction; or otherwise, if earthquake prediction is possible. The investigations of earthquake spatial-magnitude clustering, especially if earthquak...

Clustering of earthquake magnitudes is still actively debated, compared to well-established spatial and temporal clustering. Magnitude clustering is not currently implemented in earthquake forecasting but would be important if larger magnitude events are more likely to be followed by similar sized events. Here we show statistically significant magn...

A recent study found ∼90% of earthquakes in the Eagle Ford shale in Texas from 2014 to 2018 were spatiotemporally related to hydraulic fracturing (HF) wells. Since then, earthquakes have remained prevalent, including a new region of seismicity in Live Oak county. We sought to perform a deeper exploration of how HF has contributed to recent seismici...

Public engagement through outreach is a key mechanism for learning about science and to communicate societal impacts of government-funded science. However, outreach effectiveness could be limited if approaches are not evidenced based. Partnerships with cognitive scientists who study fundamental learning processes suggest helping people learn how ea...

The recent Indios, Puerto Rico earthquake sequence has drawn attention, as the increased seismicity rate in this area was unprecedented. The sequence began on 28 December 2019, caused a 6.4 magnitude earthquake on 7 January 2020, and remained active over a year later. This sequence fits the nominal definition of an earthquake swarm in that it had a...

Plain Language Summary Increases in subsurface fluid pressure following years of deep disposal of oilfield wastewater are widely accepted to have caused earthquakes from 2008 through 2020 in the Fort Worth Basin (FWB) of north‐central Texas, underlying the population centers of the Dallas‐Fort Worth metropolitan area, were caused by increases in su...

The COVID-19 pandemic led to the suspension of many summer research opportunities for science, technology, engineering and mathematics students. In response, the Incorporated Research Institutions for Seismology Education and Outreach program, in collaboration with Miami University, offered a free online Seismology Skill Building Workshop to increa...

On March 26, 2020, a M 5.0 earthquake occurred in the Delaware Basin, Texas, near the border between Reeves and Culberson Counties. This was the third largest earthquake recorded in Texas and the largest earthquake in the Central and Eastern United States since the three M 5.0–5.8 induced events in Oklahoma during 2016. Using multistation waveform...

The La Crucecita earthquake ruptured on the megathrust, generating strong shaking and a modest but long-lived tsunami. This is a significant earthquake that illuminates important aspects of the behavior of the megathrust as well as the potential related hazards. The rupture is contained within 15–30 km depth, ground motions are elevated, and the en...

Over the past decade, Oklahoma became the most seismically active region of the mid-Continental USA as a result of industry operations. However, seismic network limitations and completeness of earthquake catalogs have restricted the types of analyses that can be performed. By applying multi-station template matching on the 23,889 cataloged earthqua...

Hydraulic fracturing (HF) is a technique that is used for extracting petroleum resources from impermeable host rocks. In this process, fluid injected under high pressure causes fractures to propagate. This technique has been transformative for the hydrocarbon industry, unlocking otherwise stranded resources; however, environmental concerns make HF...

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 near...

The La Crucecita earthquake ruptured on the megathrust generating strong shaking and a modest, long-lived tsunami. This is a significant earthquake that illuminates important aspects of the behavior of the megathrust as well as the potential related hazards. The rupture is contained within 15-30km depth, ground motions are elevated and the energy t...

The seismicity rate in the Delaware Basin, located in western Texas and southeastern New Mexico, has increased by orders of magnitude within the past ~5 years. While no seismicity was reported in the southern Delaware Basin during 1980–2014, 37 earthquakes with M > 3 occurred in this area during 2015–2018. We generated an improved catalog of ~37,00...

Plain Language Summary We investigated the recent increase in seismicity rate in the Eagle Ford oil and gas field of south Texas in 2018 that grew to 33 times higher than previous years and how hydraulic fracturing (HF) contributed. We compared times and locations of HF wells with a catalog of seismicity we enhanced through seismogram similarity de...

Significance We provide an interpretation for the interaction of crustal faults, clusters of earthquakes (swarms), and slow slip (a slower form of fault rupture) in southern Mexico. Our observations indicate that swarms and slow slip are occurring on a sliver fault in the overriding plate that allows the oblique plate convergence to be separated in...

Eastern Ohio is an area of North America where a significant increase in seismicity rate was noted in the early 2010s. This increase has been associated with intensification of unconventional gas extraction performed in the Appalachian Basin and has been directly linked to two processes: hydraulic fracturing and disposal of the associated wastewate...

We combine multi-array relative back-projection of high-frequency P waves and finite-fault modeling of low-frequency P waves from the 8 September 2017 Mw 8.2 Chiapas, Mexico earthquake to image unilateral rupture on a southeast-northwest striking subvertical fault plane over depths of 10–70 km. Improved multi-array relative back-projection estimate...

Eastern Ohio is an area of North America where a significant increase in seismicity rate was noted in the early 2010s. This increase has been associated with intensification of unconventional gas extraction performed in the Appalachian Basin and has been directly linked to two processes: hydraulic fracturing and disposal of the associated wastewate...

Wastewater disposal is generally accepted to be the primary cause of the increased seismicity rate in Oklahoma within the past decade, but no statewide analysis has investigated the contribution of hydraulic fracturing (HF) to the observed seismicity or the seismic hazard. Utilizing an enhanced seismicity catalog generated with multistation templat...

The Mexican Subduction Zone is an ideal location for studying subduction processes due to the short trench-to-coast distances that bring broad portions of the seismogenic and transition zones of the plate interface inland. Using a recently generated seismicity catalog from a local network in Oaxaca, we identified 20 swarms of earthquakes (M<5) from...

Observing the full seismic wavefield by deploying large numbers of seismometers (also known as large-N deployments) and analyzing the resultant large datasets is now more feasible than ever before as a result of advances in instrumentation, computational power, and data analysis techniques. In 2015, the Incorporated Research Institutions for Seismo...

A dramatic seismicity rate increase in the central and eastern United States (CEUS) over the past decade has been largely associated with the increase in enhanced oil and gas recovery operations and change in industry practices. However, certain areas of the CEUS that have experienced large increases in oil and gas operations, such as the Bakken an...

Recent seismicity in Washington County, Ohio has been suggested to be induced by wastewater disposal operations despite injection ~2 km above the Precambrian basement. We investigated the relationships between disposal-well locations and operational histories, spatio-temporal patterns of seismicity enhanced by waveform correlation, and mapped subsu...

Significance Recent studies have focused on how wastewater disposal wells have caused dramatic increases in eastern US earthquakes. We focused instead on less common cases where hydraulic fracturing alone has caused earthquakes and found seismicity separated into two depth zones: a shallow zone on younger faults, with more small-magnitude earthquak...

The states of Jalisco, Colima, and Michoacán in western Mexico overlie the boundary of the subducting Rivera and Cocos plates, presenting an ideal target for seismological inquiry to better understand the resulting mantle flow and regional volcanism. The different dips between the two subducting plates are thought to provide a mantle conduit that h...

The recent emphasis in higher education on both student engagement and online learning encouraged the authors to develop an active e-learning environment for an introductory geohazards course, which enrolls 70+ undergraduate students per semester. Instructors focused on replicating the achievements and addressing the challenges within an already es...

The Youngstown earthquake sequence of 2011 is one of the clearest examples of inadvertently induced seismicity for which detailed documentation is available. In this paper, we investigate (i) likely stress states in the vicinity of the injection well, (ii) a range of likely permeability scenarios, and (iii) relatively simple methods by which induce...

The March 20, 2012 7.4 Ometepec earthquake in the Oaxaca region of Southern Mexico provides a unique opportunity to examine whether subtle changes in seismicity, tectonic tremor, or slow slip can be observed prior to a large earthquake that may illuminate changes in stress or background slip rate. Continuous Global Positioning System (cGPS) data re...

Repetitive earthquake swarms have been recognized as key signatures in fluid injection induced seismicity. We investigate earthquake swarms by developing a Repeating Signal Detector (RSD), a computationally efficient algorithm utilizing agglomerative clustering to identify similar waveforms buried in years of seismic recordings. Instead of relying...

Repetitive earthquake swarms have been recognized as key signatures in fluid injection induced seismicity, precursors to volcanic eruptions, and slow slip events preceding megathrust earthquakes. We investigate earthquake swarms by developing a Repeating Signal Detector (RSD), a computationally efficient algorithm utilizing agglomerative clustering...

We examine the along-strike transition from flat to steeper subduction in Oaxaca, Mexico to provide a better understanding of what controls the slab morphology. Prior studies have suggested the slab tends to tear along the transitions in dip as the slab rolls back. We determine the slab geometry based on local seismicity, nonvolcanic tremor (NVT),...

North Texas has seen an increase in seismic activity around the Dallas/Fort Worth area since the early 2000’s, with activity in Johnson County in particular culminating in magnitude 3 and 4 events in 2011 and 2015 respectively. Previous analysis of the Johnson County sequence between 2009 and 2011 concluded that many of the events were induced by w...

We have constructed an automated routine to identify prominent bursts of tectonic tremor and locate their source region during time periods of raised amplitude in the tremor passband. This approach characterizes 62 episodes of tectonic tremor between 2005 and 2011, with tremor epicenters forming a narrow band spanning the entire length of the Casca...

Increased rates of seismicity in tectonically quiescent regions like the midcontinent region of the United States have been hypothesized to be related to human activities such as oil and gas production and wastewater injection. It can be difficult to establish how human activities relate to earthquakes, particularly when local seismic networks are...

Online Material: Description and figure representing the stratigraphy and construction of the two wastewater disposal wells. As oil and gas well completions utilizing multistage hydraulic fracturing have become more commonplace, the potential for seismicity induced by the deep disposal of frac‐related wastewater and the hydraulic fracturing proces...

This study investigated the utility of multistation waveform cross correlation to help discern induced seismicity. Template matching was applied to all Ohio earthquakes cataloged since the arrival of nearby EarthScope TA stations in late 2010. Earthquakes that were within 5 km of fluid injection activities in regions that lacked previously document...

This study characterizes subduction related seismicity with local deployments along the northwestern section of the Mexico Subduction Zone where 4 portions of the plate interface have ruptured in 1973, 1985, 1995, and 2003. It has been proposed that the subducted boundary between the Cocos and Rivera plates occurs beneath this region, as indicated...

Tectonic tremor has previously been observed along two major transform faults: the San Andreas fault (SAF) and the Alpine fault (AF); and we extend the search for tectonic tremor to another transform fault, the North Anatolian fault (NAF). We investigate a two-year-long temporary broadband seismic deployment on an ∼400 km long NAF segment in centra...

Slow slip events (SSEs) observed in subduction zones around the world exhibit a wide range of recurrence intervals, durations, and propagation speeds. To illuminate possible mechanisms responsible for the observed variability and guide future modeling efforts, we employ the earthquake simulator RSQSim to explore the effects of variations in the con...

Felt seismicity induced by hydraulic fracturing is very rare, with only a handful of reported cases worldwide. Using an optimized multistation cross-correlation template-matching routine, 77 earthquakes were identified in Poland Township, Mahoning County, Ohio, that were closely related spatially and temporally to active hydraulic fracturing operat...

A series of earthquakes in 2011 near Youngstown, OH, has been a focal point for discussions of seismicity induced by a nearby wastewater disposal well. Utilizing an efficient waveform template matching procedure, the optimal correlation template to study the Youngstown sequence was identified by varying parameters such as the stations utilized, fre...

We use continuous GPS measurements from 31 stations in southern Mexico to model coseismic slip and post-seismic deformation from the 2012 March 20 Mw = 7.5 Ometepec earthquake, the first large thrust earthquake to occur below central Mexico during the modern GPS era. Coseismic offsets ranging from ∼280 mm near the epicentre to 5 mm or less at sites...

We model measurements from 19 continuous GPS stations to determine the location and magnitude of a slow slip event (SSE) below southern Mexico that began in late 2011 and remained active up to the 2012 March 20 Mw = 7.4 Ometepec earthquake. Modelling of the space–time evolution of the SSE indicates that it initiated in 2011 November, migrated westw...

Using a recently constructed catalog of megathrust earthquake swarms, we present results that illustrate how fault slip for Mw⩾8.5Mw⩾8.5 earthquakes with a publicly available finite fault rupture model is delimited along-strike by swarm regions. We further investigate this relationship for all Mw>7.5Mw>7.5 subduction zone megathrust earthquakes tha...

The discovery of episodic tremor and slip (ETS) spurred increased instrumentation and investigation of the Cascadia margin, which is now typified by the seismic phenomena. We utilize established detection and location techniques already present in the region to guide the development of a new single station detection method. While detailed network-w...

While the surface of Tibet is undergoing pervasive pure shear, stable terranes, straddling subsurface sutures, remain in the sub-continental lithospheric mantle (SCLM), attesting to its strength. Furthermore, sub-horizontal, cohesive remnant of Indian SCLM is traced northward from the Himalayan deformation front for about 600km, exemplifying the lo...

Non-volcanic tremor is a subtle ground vibration thought to be composed of a swarm of low-frequency earthquakes that represent fault slip on the interface between plates. By knowing when and where tremor is triggered, as well as when it is not triggered, we hope to grasp a better understanding of what conditions are necessary to induce fault slip....

The discoveries of tectonic tremor along with slow slip provide exciting new insights into fault deformation at major tectonic boundaries. Tremor and slip were first recorded in Cascadia, but have now been observed in a variety of other subduction zones. Recent studies in Oaxaca, Mexico reveal both slow slip and tectonic tremor, but analysis of the...

Tectonic (non-volcanic) tremor is difficult to locate due to its emergent nature, but critical to assess what impact it has on the plate interface slip budget. Tectonic tremor has been observed in Jalisco, Colima, and Michoacán regions of southern Mexico using the MARS seismic network. A semi-automated approach in which analyst-refined relative arr...

For each Mw≥8.5 earthquake with a publicly available finite fault rupture model, we find slip is closely bounded along-strike by earthquake swarms, either prior or subsequent. These earthquake swarms tend to have much larger spatial extents than their cumulative moment would suggest, arguing against a static stress triggering mechanism. In Japan, C...

The Middle America Trench along southwestern Mexico marks the subduction of both Cocos and Rivera plates. A wide range of seismic activity is seen all along this trench including great earthquakes with short (50-100 y) cycles, abundant microseismicity, prominent earthquake afterslip, recurring interseismic slow slip, and bands of non-volcanic tremo...

In order to fully attain the benefits of inquiry-based learning, instructors who typically employ the traditional lecture format need to make many adjustments to their approach. This change in styles can be intimidating and logistically difficult to overcome, both for instructors and students, such that a stepwise approach to this transformation is...

Along strike variation in the characteristics of subduction zone processes has been observed throughout the Cascadia Subduction Zone through magmas analysis of arc magmas and the distribution of seismicity. We investigate links between these observations and subduction zone structure by imaging three-dimensional lithospheric scale shear velocity wi...

We systematically and manually search through clusters of earthquakes along circum-Pacific subduction zones to identify potential earthquake swarms. In total, we find 266 potential earthquake swarms: 180 we classify as megathrust and 68 we classify as volcanic due to their proximity to the megathrust or to volcanoes. We focus on the megathrust swar...

In subduction zones, megathrust events occur within the locked zone due to the abrupt release of accumulated shear strain. Geodetic evidence has led to the identification of slow slip events (SSE) in several subduction zones, which are a more gradual (months to years) release of shear strain downdip of the seismogenic zone. SSE are often spatially...

We conduct an investigation of slow slip processes in Cascadia and focus on three aspects that have been less well constrained in previous studies: plate interface coupling between major slow slip episodes (inter-ETS coupling), slow slip during broad non-volcanic tremor events across central and southern Cascadia, and a discrepancy between the sour...