Feasibility of Detecting Submerged Landforms and Archaeological Resources Using Controlled Source Electromagnetic Methods
Geophysics Joint Doctoral Candidate
UCSD / SDSU
Sponsored by Dr. Jillian Maloney
Wednesday, April 10th at 1pm
Sea-level rise following the last glacial maximum (~20 kya) has resulted in the submergence of paleochannels, tar seeps, and archeological sites on continental shelves. The distribution of these sites is important for archeological research, offshore infrastructure development, and environmental hazard assessment. Modification of controlled source electromagnetic (CSEM) equipment has led to a new surface-towed CSEM system, Porpoise. The Porpoise system has proven useful in obtaining resistivity data of the marine subsurface in water depths as shallow as 5 meters. The surface-towed electric dipole-dipole CSEM system has been shown to detect paleochannels offshore from Del Mar and San Diego, California using Archie’s law to relate resistivity data to inferred or known porosities of geological features. We aim to test the limitations and viability of the Porpoise system for the exploration of tar seeps, paleochannels, and archaeological shell middens offshore from the Northern Channel Islands, California. The study is dependent on the results of forward and inverse models created using the MARE2DEM software developed by Kerry Key and from preliminary results from surveying offshore Isla Vista and the Northern Channel Islands. We demonstrate that CSEM methods may provide a useful tool in areas where other geophysical data (e.g., high-resolution sub-bottom data) does not adequately image features of interest.
Roslynn King is a second-year Joint Doctoral Program (JDP) student studying the applications and limitations of controlled-source electromagnetic methods. She is advised by Dr. Jillian Maloney at the SDSU Department of Geological Sciences and Dr. Steve Constable at the Institute of Geophysics and Planetary Physics at UCSD. She holds a B.S. in Geological Engineering from Colorado School of Mines and has held positions as a physical scientist at the USGS, an exploration geologist at Nyrstar Mining, and a geotechnical engineer at G3SoilWorks before joining JDP. She aims to aid in archeological exploration, hazard management, and resource identification in a marine setting by combining CSEM methods with other geophysical data.