ENAM: A community seismic experiment targeting rifting processes and post-rift evolution of the Mid Atlantic US margin
Harm J Van Avendonk, University of Texas at Austin, Institute for Geophysics, Austin, TX, United States, Maria Beatrice Magnani, Southern Methodist University, Earth Sciences, Dallas, TX, United States, Donna J Shillington, Northern Arizona University, School of Earth and Sustainability, Flagstaff, AZ, United States, James B Gaherty, Lamont Doherty Earth Observatory, Palisades, NY, United States, Matthew J Hornbach, US Naval Research Laboratory, Ocean Sciences Division, Stennis Space Center, United States, Brandon Dugan, Colorado School of Mines, Department of Geophysics, Golden, CO, United States, Maureen D Long, Yale University, Department of Earth & Planetary Sciences, New Haven, CT, United States, Daniel Lizarralde, Woods Hole Oceanographic Institution, Geology and Geophysics, Woods Hole, United States, Anne Becel, Lamont-Doherty Earth Observatory, Palisades, NY, United States, Margaret H Benoit, College of New Jersey, Ewing, NJ, United States, Steven H Harder, University of Texas at El Paso, El Paso, TX, United States, Lara S Wagner, Carnegie Institution for Science, Earth and Planets Laboratory, Washington, United States and Gail Lynn Christeson, UTIG, Austin, United States
Abstract:
The continental margins of the eastern United States formed in the Early Jurassic after the breakup of supercontinent Pangea. The relationship between the timing of this rift episode and the occurrence of offshore magmatism, which is expressed in the East Coast Magnetic Anomaly, is still unknown. The possible influence of magmatism and existing lithospheric structure on the rifting processes along margin of the eastern U.S. was one of the motivations to conduct a large-scale community seismic experiment in the Eastern North America (ENAM) GeoPRISMS focus site. In addition, there is also a clear need for better high-resolution seismic data with shallow penetration on this margin to better understand the geological setting of submarine landslides.
The ENAM community seismic experiment is a project in which a team of scientists will gather both active-source and earthquake seismic data in the vicinity of Cape Hatteras on a 500 km wide section of the margin offshore North Carolina and Virginia. The timing of data acquisition in 2014 and 2015 facilitates leveraging of other geophysical data acquisition programs such as Earthscope’s Transportable Array and the USGS marine seismic investigation of the continental shelf. In April of 2014, 30 broadband ocean-bottom seismometers were deployed on the shelf, slope and abyssal plain of the study site. These instruments will record earthquakes for one year, which will help future seismic imaging of the deeper lithosphere beneath the margin. In September and October of 2014, regional marine seismic reflection and refraction data will be gathered with the seismic vessel R/V Marcus Langseth, and airgun shots will also be recorded on land to provide data coverage across the shoreline. Last, in the summer of 2015, a land explosion seismic refraction study will provide constraints on the crustal structure in the adjacent coastal plain of North Carolina and Virginia. All seismic data will be distributed to the community through IRIS/DMC and the LDEO/UTIG Seismic data center. Two workshops are planned for 2015, where new users get an opportunity to engage in basic processing and analysis of the new data set.
