Date of Award

2010

Level of Access

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Earth Sciences

Advisor

Joseph T. Kelley

Second Committee Member

Daniel F. Belknap

Third Committee Member

Walter A. Barnhardt

Abstract

Nearshore pockmarks are one the largest, most ubiquitous types of marine landforms in world, yet they are one of the least understood. These seafloor craters can be hundreds of meters in diameter, and may occur in fields of thousands. Questions persist regarding their origins, activity, how these fields evolve overtime and their potential role as geohazards. To address these uncertainties we conducted geophysical, sedimentological, spatial, geotechnical, numerical and analog investigations of the Belfast Bay, Maine pockmark field. Stratigraphic analysis suggests that the field at one time was an environment rich in organic material, which could relate to the abundance of modern shallow gas in the field. We find that the pockmarks are non-randomly clustered and correspond to irregular underlying topography. The distribution of pockmarks within the field may relate to bedrock structural controls. Within our detection limits pockmark initiation appears to be an episodic, potentially catastrophic, event. Once initiated pockmarks become scoured by nearbed currents. These currents may maintain and enlarge pockmarks.

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