Offshore MT sites collect during Nov 2008-January
2009. Deep-towed CSEM data were also acquired along the
entire offshore profile. Dots on land show the extensive
MT data acquired by GFZ-Potsdam duing 2005-2008.
This research project
aims to study the deep structure of the offshore
section of the Pacific-North American plate boundary
using controlled source EM and magnetotelluric
soundings. It is an international collaboration between
the Marine EM Laboratory at Scripps Institution of Oceanography,
the magnetotelluric group at GFZ, Potzdam (Michael Becken,
Oliver Ritter and Ute Weckmann) and
the US Geological Survey (Paul Bedrosian). Our colleagues
have been carrying out land MT measurements over the San
Andreas Fault from 2005 to the present day, but ran up
against an obstacle called the coastline. Modeling shows
that important parts of the San Andreas Fault structure
can only be fully imaged by extending the MT array offshore,
and so we are going to do this in the latter half of 2008.
The data will form the main part of Brent Wheelock's Ph.D.
thesis. We are funding the project from a combination of
UCSD/Scripps Institutional Shiptime and discretionaly funds
associated with our industry activities.
Update: ( January 10, 2009):
The deployment cruise (November 2008) and recovery cruise (January 2009)
have been a success. We deployed 38 sites across the continental shelf,
slope and deep ocean and towed CSEM across the entire line. After two
months' deployment, all 38 instruments were sucessfully recovered this
week. Here's a video showing the action on deck during the recovery
cruise (click on the video to access the larger version at youtube.com):