Estuarine Pockmark Field Dynamics and Evolution

• Main Author: Brothers, Laura
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2011
• Subjects: Methane hydrate; permafrost
• Online Access: https://scholars.unh.edu/ccom_seminars/46; https://scholars.unh.edu/context/ccom_seminars/article/1045/type/native/viewcontent/47.jpg_AWSAccessKeyId_AKIAYVUS7KB2IXSYB4XB_Signature_5Zb26mM9N1A8EXqyel8jd1KKflc_3D_Expires_1725029609

Pockmarks are one the largest, most ubiquitous types of marine landforms in world. Common in areas with gas hydrates or underlying thermogenic fluids, pockmarks are not well understood in nearshore settings lacking such extensive subsurface fluid sources. Questions persist regarding their origins, activity, how pockmark fields evolve overtime and their potential role as geohazards. To address these uncertainties we conducted repeat-swath bathymetry surveys, seismic, sedimentological, spatial, geotechnical, numerical and analog investigations of the Belfast Bay, Maine pockmark field. The pockmarks are non-randomly clustered and correspond to irregular underlying topography, which likely created the fluid-focusing gradients necessary for sea floor alteration. This finding coupled with a review of global pockmark field distribution suggests that irregular underlying topography may ultimately control nearshore pockmark field occurrence. Over 100 years of bathymetric observations and shallow sediment characterization indicate that pockmark initiation is an episodic, potentially catastrophic, event. Numerical simulations and flume tank experiments suggest roughness-induced turbulence creates a feedback loop responsible for pockmark maintenance and evolution. Presenter Bio Laura Brothers is the National Energy Technology Laboratory (NETL)/ National Research Council Methane Hydrate Fellow. Working at the Woods Hole USGS Coastal & Marine Science Center she currently maps Arctic subsea permafrost. Laura received her Ph.D. in 2010 from the University of Maine in Earth Sciences where she studied seafloor pockmarks. Also at the University of Maine, she completed a dual Masters’ program in Oceanography and Marine Policy. Laura holds undergraduate degrees from Bryn Mawr College and West Virginia University.