MANtle transition zone topography from ss precursors
SS precursors are the underside reflections at 410 and 660 km discontinuities. They are sensitive to the structure beneath the bounce points. We use SS precursors to map out the topography of transition zone discontinuity topography so we can study the thermal and chemical heterogeneity in the mantle.
The topography maps of 410 and 660 km discontinuities are mapped out using SS precursors. The transition zone thickness are the difference between 410 depth and 660 depth. The transition zone is thicker in most suduction zones (e.g. South America, Sumatra and Japan) and thinner beneath mantle plumes (e.g. Hawaii, Greenland and NW America). Here is a bounce point map of our SS precursor data set. This up-to-date data set has good global coverage and also azimuthal coverage in several locations.
Seismic anisotropy in The mantle transition zone
Wadsleyite has relatively strong single crystal anisotropy at the pressure and temperature conditions of mantle transition zone. Seismic anisotropy can be produced in the transition zone if the minerals are aligned by mantle flows like subducting slabs or mantle plumes. We use SS precursors to detect and quantify the magnitude and orientations of seismic anisotropy in the transition zone and upper mantle.
The geometry of central Pacific bin is plotted on top of the MTZ topography map. It is located above the Hawaii hotspot. The black lines are the SS bounce points and their orientations represent the azimuths of bounce points. The arrows and numbers on the edge of globe denotes the azimuths of different directions. The pink circles are earthquakes and green triangles are stations. The MTZ thickness is plotted as background color: red denotes a thinned MTZ and blue denotes a thickened MTZ.
Insight mission to mars
The InSight Mission landed on Mars in Dec 2018 and deployed the first seismometer (SEIS) on the surface of Mars. Hundreds of Marsquakes have been detected by SEIS which provide a unique opportunity to study the interior structures of Mars. As a student collaborator, my projects aim to detect the olivine-to-wadsleyite phase transition in Martian mantle. I'm also involved in the Martian core and impact detection projects.