Research

One of my long-standing interests concerns the mid-ocean ridges. Using various geophysical techniques, I document their changing geometry and investigate possible driving mechanisms [see article]. Another aspect of this work concerns the actual geological events that contribute to crustal accretion, and in particular, the frequency, recurrence, magnitude, and spatial distributions of volcanic eruptions [see article]. I used an AUV to produce microbathymetric maps of the ridge axis that highlight individual eruptive vents, lava flow boundaries, fissures, and minor faults [see summary figure]. Combined with detailed maps of the magnetic field and photomosaics of sub-areas, this approach reveals lava pathways in the shallow subsurface and at the seafloor [see article]. I also collaborated on a project to assess the timing of eruptions by measuring the magnetic paleointensity of basaltic glasses [see article]. And recently, I co-led a project to deploy an array of pressure sensors along a section of the East Pacific Rise, with the goal to monitor any vertical motion related to magmatic intrusion. That 3-year field experiment is coupled with a numerical modeling of seafloor deformations [see slide] [RIDGE2000 experiment coordination].

Another focus for my research concerns the neotectonics of coastal areas. I recently coordinated a project to evaluate the seismic hazards associated with the North Anatolian Fault beneath the Marmara Sea (Turkey) [see recent workshop site]. We developed a methodology for underwater paleoseismology and the characterization of Holocene fault behavior using marine geophysical methods and carefully sited sediment cores [see article]. We determined the likely termination of the ground rupture from the 1999 Mw=7.2 earthquake, evaluated Holocene horizontal and vertical slips along the main fault branch [see articles: Cormier et al., 2006 & Seeber et al. 2006 and Polonia et al., 2004], and recognized historical earthquakes in the sediment stratigraphy [see article]. As an extension of that effort, we are now initiating a study of the Tan-LU fault system beneath the shallow Bohai Sea, offshore China [see MU PIRE site and figure].

I also apply emerging marine geophysical methodologies to the investigation of offshore gas seeps. In a 2004 expedition offshore Virginia-North Carolina, we carried out a detailed near-bottom survey of giant "pockmarks" at the shelf break. We collected a series of water samples and gravity cores and used an autonomous underwater vehicle (AUV) to produce photomosaics of the seafloor and measure dissolved methane concentration [see article and project workshop site].

Finally, I am involved with the study of western Long Island Sound [project site], just offshore New York City. The objectives are to investigate the interplay between climate change, rising sea level, sediment transport, oceanic circulation, and anthropogenic activity, while providing NYC students with hands-on experience with oceanographic research.

marie-helene cormier | department of geological sciences | college of arts & science | university of missouri

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