216 Seismology

61 Route 9W - PO Box 1000

Palisades

NY

10964-8000

US

Phone: 

(845) 365-8351

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One of my long-standing interests concerns the study of mid-ocean ridges. Using multibeam bathymetry, side-scan sonars, magnetic and gravity data, I document their changing geometry and investigate possible driving mechanisms. Another aspect of my work concerns the actual geological events that contribute to crustal accretion, exploring various geophysical methods to address fundamental questions regarding the frequency, recurrence, magnitude, and spatial distributions of volcanic eruptions. I used an AUV to produce microbathymetric maps of the ridge axis that highlight individual eruptive vents, lava flow boundaries, fissures, and minor faults. 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. I also collaborated on a project to assess the timing of eruptions by measuring the magnetic paleointensity of basaltic glasses. In fall 2006, we will deploy an array of pressure sensors along a section of the East Pacific Rise to monitor any vertical motion related to magmatic intrusion, a field experiment that will be coupled with numerical modeling of seafloor deformations.

Another focus for my research concerns the neotectonics of coastal areas. Since 2000, I have been coordinating an international project to evaluate the seismic hazards associated with the North Anatolian Fault beneath the Marmara Sea (Turkey). We developed a methodology for underwater paleoseismology and the characterization of Holocene fault behavior using marine geophysical methods and carefully sited sediment cores. 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, and recognized historical earthquakes in the sediment stratigraphy. More recently, I applied emerging marine geophysical methodologies to the investigation of gas seepages. In July 2004, we investigated some enigmatic crack-like features off Virginia-North Carolina that are thought to be large-scale excavations resulting from the expulsion of gas through the seafloor. 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. Our results indicate active venting of methane, although we cannot determine their precise location.

I was funded by NSF for a collaborative project with Queens College (CUNY) to provide hands-on research experience to undergraduate students. This project involved taking 10 undergraduate students to sea in western Long Island Sound for one week in June 2006 and collect a complete suite of oceanographic data. The resulting database highlights the interplay between climate change, rising sea level, sediment transport, oceanic circulation, and anthropogenic activity. We paired each student with a mentor scientist to help him/her analyze and interpret a subset of the data over the ensuing two years. The objectives are to attract and retain undergraduate students from traditionally under-represented groups in the geosciences, and to provide interested scientists with a mechanism for educational outreach. An indirect benefit will be to spearhead investigations in a little studied area of Long Island Sound.

Some of my projects include:

• Collaborative project: Submarine earthquake geology in the Marmara seismic gap
• Collaborative Research: an AUV investigation of fluid expulsion (past and present) in the large-scale elongated gas blowouts, offshore Virginia / North Carolina
• Testing models of magma movement along the East Pacific Rise using combined geodetic and numerical experiments
• Collaborative research: Track 1: Partnership to enhance diversity in marine geosciences: Holocene climate and anthropogenic changes from Long Island Sound, NY ( details )
• LDEO participation in R/V Natsushima cruise to site of the great thrust earthquake which triggered the disastrous Indian Ocean tsunami on December 26, 2004