Opportunities for Onshore/Offshore Geophysical and Environmental Protection Monitoring Experiments in the Great Lakes

The Illinois State Geological Survey (ISGS) contributed to the USArray and EarthScope plans for obtaining broadband seismic and magnetotelluric data using ocean bottom and lake bottom seismometers and magnetotelluric stations as a complement to the USArray as it approaches the Great Lakes. The planned arrival of the EarthScope's seismic array (USArray) to the Midwest offers a unique opportunity for scientists to learn more about the crustal and mantle structure of the Illinois region. Simultaneous deployment of the lake-bottom broadband seismometers and magnetotelluric stations in Lake Michigan will complement the land-based transportable array and possible flexible array campaigns in the area and provide an unprecedented dataset to study the Earth structure in this region. Because a significant part of the midcontinent rift is located beneath the Great Lakes, dense instrument coverage in and around Lake Michigan will enable a detailed study of its structure and should advance our understanding of its origin. It is very important for the ISGS to participate in the Earthscope Great Lakes initiative.

The Earthscope Great Lakes initiative discussion was organized primarily by Bob Woodward, director of USArray on May 12, 2009, during the EarthScope National Meeting in Boise, Idaho. The discussion was intended to give both a general and broad overview of bottom geophysical stations and data quality and to give the user specific capabilities to determine when and where data quality issues arise. During the meeting, the ISGS contributed to the Earthscope Great Lakes initiative by developing a conception of the Great Lakes Geophysical Observation System based on using offshore underwater cables that can support a set of geophysical equipment. Such a system would be a step toward development of the Great Lakes bottom cable geophysical observatories, which would allow automatic or semiautomatic data collection and measurements and would be coordinated in time with all stages of development from exploration through construction, operation, and liquidation. Integration of the system in the offshore underwater cables infrastructure will be an important in providing a tool for Great Lakes environmental protection.

In recognition of the ISGS contribution to the planning process with the presentation entitled "Illinois-Lake Michigan EarthScope Seismic Experiment" during the national meeting, ISGS was invited to participate in the Workshop for an EarthScope Science Plan (WESP), which was held on October 7 to 9, 2009, at Snowbird, Utah, to discuss the USArray and EarthScope Science plan for the next 5 to 10 years. The final science plan document is due to the National Science Foundation no later than January 31, 2010.