|Date||March 9, 2012||Time||3:00 - 4:00 pm|
|Description|| Fire and Water – Seismic Investigations of Volcanic and Oceanic Processes|
Applications for seismic imaging techniques are expanding. Methods that were once (and still are) used to look for oil or explore mid-ocean ridge structure are now used to also investigate mixing and turbulence in the ocean. This presentation will focus on seismic investigations in two very different settings. First we will visit the Campi Flegrei caldera in southern Italy, an active volcanic system displaying some of the most dramatic short-term ground deformation in the world. As part of a project aimed at improving volcanic hazard assessment in the Naples region, a type of depth migration for converted phases was applied to three-component active and passive seismic data collected at Campi Flegrei. The converted phases migration method images interfaces where there is a contrast in impedance, making it a useful companion to tomographic images, which tend to smear impedance interfaces in depth. The images we obtained at Campi Flegrei allowed us to tighten constraints on the location and depth of the submerged caldera rim as well as the caprock for the overpressured gas-bearing formation beneath the city of Pozzuoli. In the second part of the presentation we will introduce the emergent field of Seismic Oceanography (SO) in which conventional multichannel marine seismic data is used to image and analyze reflections in the water that result from small rapid variations in temperature with depth. SO provides new information that oceanographers have not been able to obtain before: densely spaced measurements of reflectivity that can be related to temperature (and to a smaller extent salinity) variations in the water. Recent work in 3D imaging of oceanic finestructure and waveform inversion of marine seismic data to obtain temperature images of the ocean will be highlighted.
|Publisher||Department of Geosciences|
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