Reservoir Characterization    Gashydrate    Tomography    Near Surface    Casadia Subduction Zone

I am developing research projects focused on   imaging   subsurface   structures using  seismic refraction and reflection tomography (controlled source and earthquake data). This  involves research and development in the areas of   reflection seismic data processing and interpretation, and integration with other complementary geophysical methods.

 Seismic Tomography and Reflection Seismology: Imaging Complex Structures

 Seismic reflection imaging of complex subsurface structures involves design and development of an acquisition and processing sequence that is planned for a specific target. This can be achieved by  good  seismic field acquisition design and data processing strategies for improving spatial and temporal resolution of complex structures. Such an approach  can be successfully applied to map  targets for hydrocarbon and mineral exploration, near surface environmental investigations, and deep seismic studies to map crust/mantle structure .

Quantitative interpretation of geophysical data through inverse methods

Quantitative interpretation of gravity and magnetic data, together with seismic data by inversion/modeling is of direct application in  oil exploration for target size and depth delineation.  I am  keen on integrating gravity and magnetic modeling/inverse methods with seismic tomography to  constrain the velocity models.

Mapping lithospheric structure

Controlled source reflection and refraction seismic experiments enable imaging of the continental and oceanic lithosphere in two and three dimensions. Gravity, magnetic and heat flow studies offer additional constraints to synthesize an integrated structural interpretation. Results from laboratory measurements of physical properties of rocks at different temperature/pressure conditions offer additional constraints in interpreting their composition.  Comparative study of regions with similar geology brings out the subtle differences in the lithospheric structure and helps differentiate the processes responsible for such differences.  For example, warm and cold subducting slabs produce different Wadati-Benioff zone seismicity pattern. Continuous geodetic observations help to identify compression and extension stress regimes. Integrated modeling/interpretation enables mapping the structural elements and understanding of the tectonic forces in action.   For example, at the Cascadia margin in British Columbia and Washington, the compressive regime is N-trending. Oblique subduction of the Juan de Fuca plate northeastward beneath North America has been shown to produce arc-parallel migration of the forearc creating an additional seismic hazard from the relative motions of the forearc blocks. Motions of the order of 7 to 9 mm/yr of the Cascadia forearc has been proposed, leading to large upper-plate earthquakes in the forearc over historically significant time.

Seismic tomography of reflection and refraction data of controlled source and earthquakes relocate the position of earthquakes within the 3-D velocity structure, simultaneously solving for P wave and possibly S wave velocity structure. Continued tomographic studies will improve the quality, resolution and coverage of the velocity model. Tomographic modeling can be targeted to specific zones in the subsurface to address a particular research aspect, like structure of a sedimentary basin, mapping a possible fault and computing V_p/V_s ratio for a target zone. Mapping the structural elements in subduction zones from reflection/refraction seismology, earthquake studies, and constraining the interpretation with gravity and magnetic data is one of my research interests. The results of such a study will delineate the structural elements and related earthquake hazards in subduction zones.