through the use of finite frequency kernels or fully numerical
approaches, the Global Seismology Group continues its commitment to
applying the latest theoretical and computational advances to the study
of Earth structure.
The Global Seismology Group has pioneered the use of full-waveform tomography using finite frequency kernels (see Theory below), and we have produced a number of models of the velocity and anisotropic structure of the mantle.
We have have been a trailblazer in using tomographic techniques to map the distribution of seismic attenuation in the Earth's mantle.
Taking advantage of the unprecedented coverage of North America made available by recent PASSCAL and USARRAY deployments, we have undertaken a series of studies looking at the velocity and anisotropic structure beneath North America.
Study of D" Region
The mantle's lower thermal boundary layer, also known as D", has been the subject of waveform modeling and tomographic study by the Global Seismology Group. Our investigations have revealed strong seismic heterogeneity in D", and have provided insight into flow occurring within and the thermochemical state of this fascinating region of the Earth.
Using observations of free oscillations and higher frequency body waves, the Global Seismology Group has probed Earth's very center. Our study of this remotest part of our planet has helped constrain its dynamics and thermochemical state.
The Global Seismology Group has been actively researching the processes by which seismic waves are excited, be they earthquakes themselves or ocean-atmosphere-lithosphere interactions giving rise to Earth's evepresent "hum".
an effort to gain experience in deploying and maintaining ocean-bottom
seismometers, a three component very broadband seismometer package
recording system, as well as auxiliary differential pressure gauge
(DPG) and current meter, were installed on the seafloor, in Monterey
Bay, 40 km off-shore, at 1000m water depth.
Detection and identification of PKJKP, published in Science (2005)
Origin of the Earth's "hum", published in Nature (2004)
Radial anisotropy at the base of the mantle, published in Science (2004)
Anisotropy and thickness of the lithosphere, published in Nature (2003)
Superplumes from the core mantle boundary to the lithosphere, published in Science (2002)