Research
I have diverse research interests reflected by ongoing projects ranging from crustal fault studies in the Cascadia forearc to back arc, Portland Basin, the northern San Andreas fault system, and intraplate faulting in Oklahoma. Below are descriptions some representative research projects.
Pacific Northwest:
I am currently interested in mapping and understanding crustal deformation and slip history of active faults here in the Pacific Northwest (PNW). I seek to understand broad patterns of crustal deformation by evaluating distributed Quaternary active faults in a transect across the Cascadia convergent margin of the PNW region of the United States. Our group is doing this through targeted tectonic-geomorphic and paleoseismic investigations in the central Pacific Northwest where the rates and timing of faulting during the past 30,000 years remain unconstrained. Data in this time range is beginning to bridge the observational gap between geodetic (short-term) and bedrock (long-term) observations of clockwise rotation (e.g. Wells and McCaffrey, 2013) . I have also worked on geothermal storage in the Portland Basin, a fun project that allowed us to think about Portland Basin structure and stratigraphy (Scanlon et al, 2021; Horst et al., 2021).
Multiple Holocene Earthquakes on the Gales Creek Fault, Northwest Oregon Fore-Arc (Horst et al., 2021). Our recent paleoseismic studies of the Gales Creek fault (GCF) have yielded new earthquake-timing constraints for the 73-km-long, northwest-trending fault which has youthful geomorphic expression (Horst et al., 2021).
Earthquake and slip history on the recently identified Strawberry Mountains Fault, near John Day Oregon. The Strawberry Mountain Fault is within the Blue Mountains region in Eastern Oregon. We constrained Quaternary vertical slip rates on the SBF with 3He surface exposure age dating of glacial features and find a slip rate of ~0.18 ± 0.02 mm/yr. since late Pleistocene time (Dunning, Streig et al., in review).
Earthquake Recurrence & Slip Rate Studies of the Previously Unmapped Mt. Hood Fault Zone, new paleoseismic results from the Twin Lakes fault.
A morphotectonic evaluation of the Rocky Ledge Fault, Shasta County, CA. Poster.
Portland Deep Direct-Use Thermal Energy Storage (DDU-TES) Feasibility Study, Lead Organization: Portland State University; Other Team Members (alphabetically): AltaRock Energy, Inc.; City of Portland, OR; Oregon Health and Science University; and U.S. Geological Survey.
Intraplate setting - Oklahoma:
I am also interested in the recurrence of intraplate earthquakes. These regions are fascinating because intraplate faults occur in regions where traditional explanations of fault movement are not sufficient to explain the hazard. Characterizing the frequency of large earthquakes and rupture behavior (single versus multi-section rupture) for intraplate faults is critical to improve seismic hazard models for the Central and Eastern United States region.
What do Paleoseismic histories tell us about active intraplate faults? Reevaluating a Holocene cluster of large earthquakes on the Meers Fault, Oklahoma (in preparation).
Neotectonic and Paleoseismic Analysis of the Northwest Extent of Holocene Surface Deformation along the Meers Fault, Oklahoma (Hornsby et al., 2020).
Paleoseismic Investigation of the Meers Fault, Oklahoma; Extending the Paleoseismic Earthquake Record and Refining Holocene Fault Length. Poster.
San Andreas fault system:
In the Santa Cruz Mountains, CA, my colleagues and I have found evidence of three post-European settlement earthquakes in 1838, 1865, and culminating in the 1906 rupture (Streig et al., 2014). My colleagues and I continued to work with these data to evaluate organic materials from forested settings that are commonly used for radiocarbon dating. We ultimately used this unique age dataset to better constrain the timing of large earthquakes in the region and understand uncertainties associated with different sample materials (Streig et al., 2020).
New Insights on Inputs to Paleoseismic Age Determination Models: Updated Earthquake Ages and Earthquake Correlations on the Northern San Andreas Fault, CA (Streig et al., 2020). Research Poster here. Poster.
Determining slip per event on the southern San Andreas Fault from fold deformation at Frazier Mountain, CA (Streig et al., 2014). Poster.
Paleoseismic Record of Earthquakes on the Santa Cruz Mountains Section of the San Andreas Fault – Testing the Influence of the Northern Transition Zone using Earthquake Chronologies and Implications for Seismic Hazards on the SAF. Poster.
I am involved in the recent NSF funded Cascadia Region Earthquake Science Center (CRESCENT, cascadiaquakes.org). I am part of the Community Fault Model (CFM) working group leadership. Our primary goal is to develop a 3D model of the best representation of active fault geometries ranging from the plate interface to upper plate faults, with regular input by the broader community. See the CRESCENT CFM website for more details, https://cascadiaquakes.org/cfm/
Asia:
Cross border Collaboration - Paleoseismic investigations of the Mae Chan Fault, northern Thailand, paired with Paleoseismic Training Course (Winter 2017), Researchers from Geological Surveys of Cambodia, Lao-PDR, Myanmar, Thailand, Vietnam, Malyasia, China, and the U.S. This course was funded by the Thai Department of Mineral Resources (DMR) and Earth Observatory Singapore (EOS). Two week field course. Instructors from UO, PSU, OSU, the California Geological Survey, and Earth Observatory Singapore.
Evidence for prehistoric coseismic folding along the Tsaotun segment of the Chelungpu fault near Nan-Tou, Taiwan (Streig et al., 2007).
I am also interested in research investigating whether faults fail in the months and years immediately following a megathrust subduction zone earthquake as a result of local stress changes in the crust. This occurred in Japan following the 2011 Tohoku earthquake, which I documented as part of a Geotechnical Extreme Event Reconnaissance (GEER) field response (EERI Special Report 2011).
