Geophysics and Seismology Commons^™

Alaska Earthquake Center Quarterly Review October-December 2025, Heather Mcfarland, Beth Grassi, Austin Holland, Nate Murphy, Elisabeth Nadin, Carolyn Parcheta, Michael West

Alaska Earthquake Center Reports

This series of technical quarterly reports from the Alaska Earthquake Center (AEC) includes detailed summaries and updates on Alaska seismicity, the AEC seismic network and stations, fieldwork, our online presence, public outreach, and lists publications and presentations by AEC staff. Multiple AEC staff members contributed to this report.

Microbial Diversity And Biogeochemical Interactions In The Seismically Active And Co2-Rich Eger Rift Ecosystem, Daniel Lipus, Zeyu Jia, Megan Sondermann, Robert Bussert, Alexander Bartholomäus, Sizhong Yang, Dirk Wagner, Jens Kallmeyer

College of Life Sciences Faculty Papers

The Eger Rift subsurface is characterized by frequent seismic activity and consistently high CO2 concentrations, making it a unique deep biosphere ecosystem and a suitable site to study the interactions between volcanism, tectonics, and microbiological activity. Pulses of geogenic H2 during earthquakes may provide substrates for methanogenic and chemolithoautotrophic processes, but very little is currently known about the role of subsurface microorganisms and their cellular processes in this type of environment. To assess the impact of geologic activity on microbial life, we analyzed the geological, geochemical, and microbiological composition of rock and sediment samples from a 238 m deep drill …

Local Seismic Investigations In Arizona: Analysis Of A Low-To-Moderate-Magnitude Aftershock Sequence And A Pilot Study Of Monsoon-Driven Flash Floods, Kathryn Margo Dorn

USF Tampa Graduate Theses and Dissertations

Arizona encompasses a strikingly diverse array of geological terranes and physiographic terrain and consequently experiences a wide range of tectonic and meteorological phenomena, many of which generate distinctive seismic signals. For much of the past century, however, the state has largely lacked the style of dense seismic networks now prevalent in some regions of neighboring California, allowing myriad low-magnitude earthquakes and other subtle seismic sources to elude detection and characterization. In this dissertation, I utilize the high-resolution data of two temporary local seismic networks to investigate two such sources – the primarily low-magnitude but prolific aftershock sequence of the 29 …

Mapping Of Microseismic Aftershock Sequences Following The 2017 Lincoln, Montana M 5.8 Earthquake, Reyer M. Fenoff

Undergraduate Theses, Professional Papers, and Capstone Artifacts

The Rocky Mountains of western Montana have long been experiencing tectonic compression and extension that has shaped much of western North America. This activity consistently produces seismic events, like the 6 July 2017 M 5.8 earthquake 11 km southeast of Lincoln, MT, which can be used to advance understanding of crust and mantle dynamics and structure. Seismic mapping is vital to understanding structure and tectonic activity in western Montana as well as in analogous locations across the world. Recently deployed seismometers from the University of Montana as well as the Montana Regional Seismic Network (MRSN) from the Montana Bureau of …

Dynamic Relationship Study Between The Observed Seismicity And Spatiotemporal Pattern Of Lineament Changes In Palghar, North Maharashtra (India), Biswajit Nath, Ramesh P. Singh, Vineet K. Gahalaut, Ajay P. Singh

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

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 …

Understanding The Multiple Small Magnitude Induced Seismic Soil Fatigue Potential On Hazard Assessments, Merissa L. Zuzulock, Oliver Denzil S. Taylor, Norbert H. Maerz

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Soils under spacio-temporally clustered events loading are susceptible to soil fatigue as pore pressure dissipates and the soil is unable to recover. This potential for damage from soil fatigue is identified through an induced seismic fatigue equation provided in this paper. The objective of this paper is to present an induced seimic equation for soils under spacio-temporally clustered impulse loading to identify potential hazards to the subsurface that supports critical infrastructure. It further illustrates the use of the equation as determined from a comparison of three varying soil profiles with resulting data that shows a need to establish new critieria …

Seismicity And Pn Velocity Structure Of Central West Antarctica, Erica M. Lucas, Andrew A. Nyblade, Andrew J. Lloyd, Richard C. Aster, Douglas A. Wiens, John Paul O'Donnell, Graham W. Stuart, Terry J. Wilson, Ian W. D. Dalziel, J. Paul Winberry, Audrey D. Huerta

Geological Sciences Faculty Scholarship

We have located 117 previously undetected seismic events mainly occurring between 2015 and 2017 that originated from glacial, tectonic, and volcanic processes in central West Antarctica using data recorded on Polar Earth Observing Network (POLENET/ANET) and UK Antarctic Network (UKANET) seismic stations. The seismic events, with local magnitudes (M_L) ranging from 1.1 to 3.5, are predominantly clustered in four geographic regions; the Ellsworth Mountains, Thwaites Glacier, Pine Island Glacier, and Mount Takahe. Eighteen of the events are in the Ellsworth Mountains and can be attributed to a mixture of glacial and tectonic processes. The largest event noted …

The Geophysical Kitchen Sink Approach To Improving Our Understanding Of Volcano-Tectonic Interactions, Ophelia Ann George

USF Tampa Graduate Theses and Dissertations

A multi-prong approach was taken in this dissertation to understand volcanic processes from both a long-term and more immediate hazard perspective. In the long-term, magma sources within the crust may produce measurable surficial response and long-wavelength gravity anomalies that provide information about the extent and depth of this magma. Long-term volcanic hazard forecasting is also improved by developing as complete a record as possible of past events. In the short-term, a long-standing question has been on the casting of precursory volcanic activity in terms of future volcanic hazards. Three studies are presented in this dissertation to address these issues. Inversion …

Crustal And Upper-Mantle Structure Beneath Ice-Covered Regions In Antarctica From S-Wave Receiver Functions And Implications For Heat Flow, C. Ramirez, Andrew A. Nyblade, S. E. Hansen, Douglas A. Wiens, Sridhar Anandakrishnan, Richard C. Aster, Audrey D. Huerta, Partick Shore, Terry Wilson

Geological Sciences Faculty Scholarship

S-wave receiver functions (SRFs) are used to investigate crustal and upper-mantle structure beneath several ice-covered areas of Antarctica. Moho S-to-P (Sp) arrivals are observed at ~6–8 s in SRF stacks for stations in the Gamburtsev Mountains (GAM) and Vostok Highlands (VHIG), ~5–6 s for stations in the Transantarctic Mountains (TAM) and the Wilkes Basin (WILK), and ~3–4 s for stations in the West Antarctic Rift System (WARS) and the Marie Byrd Land Dome (MBLD). A grid search is used to model the Moho Sp conversion time with Rayleigh wave phase velocities from 18 to 30 s period to estimate crustal …

Science And Public Policy Of Earthquake Hazard Mitigation In The New Madrid Seismic Zone, Alice M. Orton

Theses and Dissertations--Earth and Environmental Sciences

In the central United States, undefined earthquake sources, long earthquake recurrence intervals and uncertain ground motion attenuation models have contributed to an overstatement of regional seismic hazard for the New Madrid Seismic Zone on the National Seismic Hazard Maps. This study examined concerns regarding scientific uncertainties, overly stringent seismic mitigation policies and depressed local economy in western Kentucky through a series of informal interviews with local businessmen, public officials, and other professionals in occupations associated with seismic mitigation. Scientific and relative economic analyses were then performed using scenario earthquake models developed with FEMA’s Hazus-MH software. Effects of the 2008 Wenchuan …

Instrument Correction And Dynamic Site Profile Validation At The Central United States Seismic Observatory, New Madrid Seismic Zone, Clayton M.J. Brengman

Theses and Dissertations--Earth and Environmental Sciences

The Central United States Seismic Observatory (CUSSO), is a fifteen-element array of three-component accelerometers and seismometers in the New Madrid seismic zone, within the upper Mississippi embayment. Its location within the thick (up to 1 km) sequences of unlithified sediment comprising the embayment, make CUSSO a unique array in its ability to directly measure seismic wave propagation, including ground motion site effect; however, before the observational data can be used for analysis, the orientation and instrument response of the CUSSO array must be defined. This study used cross-correlation and direct comparisons to filter out the instrument response and determine the …

Glacier Slip And Seismicity Induced By Surface Melt, Peter L. Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Miriam Jackson, Mark E. Mathison, Denis Cohen

All Faculty Scholarship for the College of the Sciences

Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed …

San Miguel Volcanic Seismicity And Structure In Central America: Insight Into The Physical Processes Of Volcanoes, Ezer Patlan

Open Access Theses & Dissertations

San Miguel volcano lies near the city of San Miguel, El Salvador (13.43°N, 88.26°W). An active stratovolcano, it presents a significant natural hazard for the city of San Miguel. In general, the internal state and activity of volcanoes like San Miguel remains an important component to understanding volcanic hazards. The main technology for addressing volcanic hazards and associated processes is through the analysis of data collected from the deployment of seismic sensors that record ground motion. Six seismic stations were deployed by UTEP around San Miguel volcano during the 2007-2008 the time period to define internal structure or magmatic plumbing …

Relation Of Recent Seismicity (1988-Present) To The 1958 Huslia, Alaska Earthquake Sequence, Abigail Monreal^, Diane I. Doser*

COURI Symposium Abstracts, Spring 2011

We have examined how recent seismicity in the Huslia region of central Alaska is related to active faults and the 1958 earthquake sequence (with at least 3 events of magnitude >6). Most of this region is swampy lowland dominated by alluvial material deposited by the Koyukuk River, making surficial identification of active faults difficult.  This portion of Alaska is also of interest because it appears to be a region in transition between the strike-slip faulting of the Salcha-Fairbanks-Minto Flats seismic zone and normal faulting of western Alaska (Norton Sound/Seward Peninsula). Researchers have suggested this change in the nature of faulting …

Studies Of Seismicity Near The Active Volcano Mt. Spurr, Sarah J. Olivas^, Diane I. Doser*

COURI Symposium Abstracts, Spring 2011

Seismicity patterns and fault orientations can indicate local stress fields related to volcanic eruptions. There have been many moderate magnitude, shallow earthquakes occurring in the Strandline Lake region about 100km from Anchorage, Alaska near the active volcano, Mt. Spurr. Previous researchers have found that the local stress under Mt. Spurr, before and after its 1992 eruption (1992-1997), differed from the regional stresses, which are related to subduction of the Pacific Plate and Yakutat micro plate. We are analyzing location and patterns of earthquakes occurring since 1998 to determine if more recent seismicity is similar to that occurring before or after …

Surface Wave Inversion Of The Upper Mantle Velocity Structure In The Ross Sea Region, Western Antarctica, James D. Rinke

All Master's Theses

The Ross Sea in Western Antarctica is the locale of several extensional basins formed during Cretaceous to Paleogene rifting. Several seismic studies along the Transantarctic Mountains and Victoria Land Basin’s Terror Rift have shown a general pattern of fast seismic velocities in East Antarctica and slow seismic velocities in West Antarctica. This study focuses on the mantle seismic velocity structure of the West Antarctic Rift System in the Ross Embayment and adjacent craton and Transantarctic Mountains to further refine details of the velocity structure.

Teleseismic events were selected to satisfy the two-station great-circle-path method between 5 Polar Earth Observing Network …

Fluid Budget Of Metasedimentary Rocks From A Tertiary Accretionary Prism And Connections To Seismicity, Olympic Peninsula, Northwest Washington State, Holly Makena Macfadden Rotman

All Master's Theses

Metamorphic dehydration reactions and fluid movement in accretionary prisms have been linked to the recently discovered episodic tremor and slip (ETS) earthquake events along subduction zones, but prior studies lack the detail to effectively test the hypothesis that fluid flow triggers ETS events. I conducted field work along a 52.5 km transect on the Olympic Peninsula metasedimentary accretionary prism of the Cascadia subduction zone, and collected approximately 40 representative samples of sandstone and mudrock that were buried to 6–15 km. This depth range intersects the 10–50 km depth range of ETS events. My objectives are to quantify the water flow …

Analysis Of Shallow Seismicity And Stress Fields In Southeastern Alaska, Hugo Rodriguez

Open Access Theses & Dissertations

Southeastern Alaska is dominated by strike-slip motion along the Queen Charlotte-southern Fairweather fault system (QCFS) in the south and transitions to oblique convergent motion partitioned between strike-slip motion along the Denali and northern Fairweather fault systems and thrusting along faults of the St. Elias region. Geologic complications are further increased by the subduction of the Yakutat microplate beneath North America and glacial processes. By studying regional background seismicity we intend to better determine the current state of stress of southeastern Alaska from the Dixon Entrance to Yakutat Bay. Phase data was gathered for over 4000 earthquakes of depths <20 km and magnitude <5 that occurred from 1973-2005 from Alaskan and Canadian databases. We relocated these earthquakes using the Double-Difference joint hypocenter method. Two areas of interest were identified with high concentrations of seismicity after relocation calculations for the entire southeast Alaska region; Glacier Bay through Yakutat (GBY) and the area surrounding Mt. Ogden (MOG). Earthquake locations in GBY are diffuse with some isolated clusters. The MOG subregion is dominated by a large northeast to southwest trending cluster that trends along the Speel River. We used these relocations and first motion data to estimate the stress fields for earthquake clusters that formed. Only a few of the calculated stress tensors were successful in representing the region's overall tectonic signature. We combined the calculated stress information with GPS, magnetic and gravity data in order determine how plate motion is partitioned in this region and to identify other potentially active faults.

The 2004 And 1861 Tsunami Deposits On Simeulue Island, Western Sumatra, Katherine Frances Whitlow

All Master's Theses

Megathrust earthquakes and associated tsunamis along the subduction zone along western Sumatra represent a significant seismic hazard that is not well understood. I present the results of mapping, paleoseimologic, and geochronologic studies of tsunami deposits exposed on Simeulue Island, western Sumatra, to document the timing of past tsunamis. Three field sites were targeted to conduct these studies: Inor, Busong Bay, and Langi Bay. Stratigraphic relationships, geochronologic data, and grain size analyses from these field sites show evidence of a tsunami that occurred in 1861 following a Mw ~8.5 earthquake. A wood fragment collected from an excavation at Inor yielded an …

Energy Budget Analysis Of Slow-Slip Tremor Events Along The Cascadia Subduction Zone Using Continuous Gps Array Data, James Steven Chapman

All Master's Theses

Seismic hazards poised to cities by subduction zones are strongly controlled by fault slip along the deeper extent of the two plate interaction closest to population densities. In Cascadia, where Mw=9 size events are known to occur from a variety of sources, modeling of leveling data has suggested that the region of maximum slip lies well offshore and diminishes rapidly inland. However, over two dozen slow slip distributions have been imaged using Global Positioning System (GPS) along the lower reaches of the northern Cascadia locked zone between 30 and 40 km in depth. Averaged over many episodic tremor and slip …

Seismic Constraints On Slow Slip Events Within The Cascadia Subduction Zone, Ana Cristina Aguiar

All Master's Theses

Reanalysis of geodetic GPS time series from the Cascadia subduction zone have revealed at least 30 resolvable slow slip events along the megathrust, ranging from northern California to southern British Columbia, since 1997. Many of the smaller and more recent events are barely resolvable with GPS, but stand out clearly as tremor sequences. Since tremor bursts lasting less than 10-seconds are often visible across multiple stations, they offer the highest resolution for studying moment release through time. To test the hypothesis that tremor and transient deformation are two manifestations of the same faulting process, and to quantify the relative contribution …