Dr. Lise Retailleau, Postdoctoral Research Fellow at Stanford U., presents "Ambient field analysis: from source tracking to deep earth imaging" at the MIT Earth Resources Laboratory.

"Correlations of the ambient seismic field have been used successfully to study the Earth on a wide range of scales.
I will first show that body waves can be extracted from correlation functions even at teleseismic distances and be used for deep earth imaging. For this purpose, I use P and PcP waves from the secondary microseism period band (2-10 s) that are propagating between Europe and Eastern US to image the Core-Mantle Boundary (CMB) and D” structure beneath North Atlantic and present the first raw 3D image of the lower mantle obtain from ocean generated microseism data.

An important issue for the correct reconstruction of the propagation between stations is the understanding of ambient field sources. I will present a backprojection method to retrieve the seismic sources associated with typhoon Ioke (2006) with an unprecedented 3-hour resolution,  in the entire secondary microseism period band and during the all life cycle of the event. I also assess the link between the generation of the long period (6-9 s) seismic signals and the increase of the typhoon propagation speed.
Finally, one effect of the non-homogeneous nois

e source distribution is the generation of artifacts on the correlation functions that do not correspond to the propagation between the stations. While these are usually considered as a hindrance to common ambient noise correlation analyses, I will show they can be used to study the sources at their origin and characterize structural variations."