Field and Laboratory Investigations on Seismic Properties of Unconsolidated Saline Permafrost

• Main Author: Dou, Shan
• Other Authors: Dreger, Douglas
• Format: Other/Unknown Material
• Language: English
• Published: eScholarship, University of California 2015
• Subjects: Geophysics; effective medium theory; full-wavefield inversion; multichannel surface wave; permafrost; rock physics; saline permafrost; Barrow; Ice; Alaska
• Online Access: https://escholarship.org/uc/item/9td240s4

Saline permafrost is mechanically weak and very sensitive to temperature disturbances, which makes its degradation particularly worrisome in a warming climate. For the purposes of hazard mitigation and prevention, it is crucial to gain knowledge about the properties and distributions of saline permafrost. However, one major challenge is that saline permafrost is hard to access, as it often is covered with a surficial layer of non-saline permafrost. Seismic methods are cost-effective methods for detecting and delineating saline permafrost, but research on seismic properties of unconsolidated saline permafrost is lacking.The body of work comprising this dissertation is the first systematic study to investigate seismic properties of unconsolidated saline permafrost. Encompassing field and laboratory components, the study reveals pervasive presence of saline permafrost across the Barrow Environmental Observatory (BEO) in Alaska, and illustrates saline permafrost’s striking vulnerability to temperature disturbances. Besides these findings regarding the distributions and properties of saline permafrost, other key deliverables of this dissertation include 1) rich seismic datasets for field and laboratory investigations of unconsolidated saline permafrost, 2) full-wavefield-based workflow for delineating irregularly dispersive media, and 3) improved microstructural realization regarding pore-scale distributions of ice in saturated frozen sediments. Through this work we hope to call attention to the possibly ubiquitous presence of saline permafrost along the polar coasts. Considering the potentially large impact of saline permafrost degradation in a warming climate, we advocate future research needs in regional-scale mapping of saline permafrost and assessing its influences in climate modeling.