RESEARCH PROGRAM

(Ronald Bruhn, Geology and Geophysics, University of Utah)

Tectonics and Structural Geology

Research in regional tectonics and structural geology is being carried out in Alaska as part of the Saint Elias Erosion and Tectonics Project, which is supported by the Continental Dynamics Program of the National Science Foundation. Structural research focuses on the geometry and kinematics of folding and faulting where the Yakutat microplate is colliding into and being subducted beneath southern Alaska. We are also studying how deformation associated with collision and low-angle subduction of the microplate has propagated far in the interior of Alaska several hundred kilometers from the plate boundary. Additional information on this research is included under the earthquake geology and dynamics section below. This photo is from the Calico Bluffs located along the upper reach of the Yukon River near Eagle, Alaska.

Earthquake Geology & Dynamics

Earthquake geology is a fascinating blend of techniques and skills extracted from structural geology and tectonics, Quaternary geology and geomorphology, and paleoseismology. My research group is carrying out studies of active faulting both in Alaska and Utah. Research in Alaska includes studies of strike-slip and thrust faults, as well as normal fault-like scarps that may be caused by gravitational collapse of mountain blocks caused by strong ground motion during earthquakes, or in some cases are associated with flexural-slip or bending moments in active folds. Localities include the Alaska Range, the Susitna Basin and Cook Inlet region, and the Saint Elias Mountains. In Utah I am working with my colleague Jerry Schuster and his students on applications of high-resolution seismic tomography and reflection methods to image deposits beneath normal fault scarps. Our goal is to define the faults and sedimentary structure of Quaternary deposits at depths greater than those normally obtained by trenching. The seismic data is used to locate subsurface targets for drilling into and coring the sedimentary deposits so that we can constrain earthquake rupture histories for periods up to several hundred thousand years. We are also creating numerical mechanical models of faulting as an aid to better understanding how thrust and normal fault scarps evolve over time as displacement accumulates from multiple earthquakes. As part of this work we also map Quaternary deposits and make detailed topographic profiles of fault scarps both for determining earthquake displacements and estimating fault slip rates based on models of scarp degradation by weathering. The photo shows the Susitna Glacier thrust fault scarp which formed in November, 2002 on the southern flank of the Alaska Range.

Radio-Controlled Aerial Vehicles & Environmental Sensing (RAVENS)

The RAVENS program uses radio-controlled airplanes (UAV) to obtain aerial photographs of geological and environmental features. The images are used to create image pairs for stereo-viewing, very high resolution digital models of topography, 3D – photo-realistic models of outcrops and structures, and to measure ground displacement over time. Applications include landslide monitoring, outcrop studies of rock fracturing, mapping of geological structures, and temporal monitoring of changes in the landscape caused by deposition and erosion. We are also pursuing environmental monitoring by radio-controlled aircraft. (Learn More?) The photo is a collage of aerial and ground images obtained while imaging the Navajo Sandstone at Lake Powell, Utah.