Mapping Seismic Attenuation in the Upper Mantle
Understanding the distribution of seismic attenuation in the mantle is important for: 1. Discriminating between chemical and thermal heterogeneity; 2. Interpreting models of elastic structure derived from data at different frequencies.
Yet, while mapping of the 3D elastic structure of the upper mantle has benefited from approximate
first-order
perturbation techniques, modeling of the 3D distribution of seismic attenuation has lagged behind due to
difficulties in accounting for purely elastic effects of scattering at sharp interfaces and (de)focusing,
which can obscure the anelastic signal.
I work on combining forward modeling using the coupled spectral element method (cSEM) with the use of
approximate finite-frequency kernels (NACT+F) in the inversion to construct a higher resolution 3D Q model
of the upper mantle.
To read more about techniques of global seismology, click here.
Frequency Dependence of Seismic Attenuation
NEW: We have devised a way of constraining the frequency dependence of attenuation using normal mode attenuation measurements (provided by Guy Masters). You can read more about it in here: http://dx.doi.org/10.1016/j.
An important aspect of the study of seismic attenuation is its frequency dependence. Most long-period seismic analyses assume that attenuation (per cycle of oscillation) is independent of frequency; however, insights from theoretical and experimental mineral physics
indicate that attenuation should decrease with increasing frequency. The strength of this dependence is important since it can affect the temperature derivatives of attenuation, as well as construction of attenuation profiles in the Earth.
Planetary Seismology - Europa
As our most powerful technique for probing the unreachable interior of planetary bodies, seismology holds great promise for answering some of the important questions of planetary science. Europa, the smallest of Jupiter, has fascinated the scientific community and general public alike, with the prospect of a deep, global ocean of water - a potential habitat for life. Evaluating the ocean's prospects for habitability requires knowing the thickness of the overlying ice-shell, as well as the state of the moon's rocky interior. Together with Michael Manga, Mark Panning, Fabio Cammarano and Barbara Romanowicz, I attempted to determine what, if any, seismological observations would be needed for constraining the thickness of Europa's ice shell and the state of its interior. You can read about our findings here and here.
