Structure of the Chesapeake Bay Impact Crater from Wide-Angle Seismic Waveform Tomography

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dc.contributor.authorLester, W. Ryanen
dc.contributor.committeechairHole, John A.en
dc.contributor.committeememberImhof, Matthias G.en
dc.contributor.committeememberBurbey, Thomas J.en
dc.contributor.departmentGeosciencesen
dc.date.accessioned2014-03-14T20:45:38Zen
dc.date.adate2006-10-31en
dc.date.available2014-03-14T20:45:38Zen
dc.date.issued2006-08-24en
dc.date.rdate2009-10-31en
dc.date.sdate2006-09-17en
dc.description.abstractThe Chesapeake Bay impact structure is one of the largest and most well preserved impact structures on Earth. It has a unique morphology composed of an inner crater penetrating crystalline basement surrounded by a wider crater in the overlying sediments. In 2004, the U.S. Geological Survey conducted a seismic survey with the goals of constraining crater structure and in support of the drilling of a borehole into the deepest part of the crater. Travel-time and waveform inversion were applied to the data to produce a high-resolution velocity model of the crater. Low-fold reflection processing was also applied. Northeast of the crystalline crater, undeformed, eastward-sloping crystalline basement is ~1.5 km deep. The edge of the inner crater is at ~ 15 km radius and slopes gradually down to a depth of 1.5 - 1.8 km. A central peak of 4-5 km radius rises to a depth of ~0.8 km. Basement velocity in the crystalline crater is much lower than undeformed basement, which suggests ~10% fracturing of the crater floor, and up to 20% fracturing of the central uplift. A basement uplift and lateral change of velocity, interpreted as the edge of the transient crater, occurs at a radius of ~ 11 km. Assuming a 22 km diameter transient crater, scaling laws predict a ~30 km diameter crater and central peak diameter of 8-10 km. This indicates that post-impact collapse processes that created the ~ 30 km diameter crystalline crater were unaffected by the much weaker rheology of the overlying sediments.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-09172006-145835en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09172006-145835/en
dc.identifier.urihttp://hdl.handle.net/10919/35090en
dc.publisherVirginia Techen
dc.relation.haspartThesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectseismic refractionen
dc.subjectwaveform inversionen
dc.subjectChesapeake Bay impact structureen
dc.subjectimpact processesen
dc.titleStructure of the Chesapeake Bay Impact Crater from Wide-Angle Seismic Waveform Tomographyen
dc.typeThesisen
thesis.degree.disciplineGeosciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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