A5005580584- High-pressure geophysics and materials
- earthquake and tectonic studies
- Geological and Geochemical Analysis
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Hydrocarbon exploration and reservoir analysis
- Seismic Imaging and Inversion Techniques
- Paleontology and Stratigraphy of Fossils
- Geochemistry and Geologic Mapping
- Seismology and Earthquake Studies
- Earthquake Detection and Analysis
- Geophysics and Sensor Technology
- Geological and Geophysical Studies
- Reservoir Engineering and Simulation Methods
- Geology and Paleoclimatology Research
- Advanced X-ray and CT Imaging
- Methane Hydrates and Related Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Metallurgical Processes and Thermodynamics
- Geological Modeling and Analysis
- Ionosphere and magnetosphere dynamics
- Marine and coastal ecosystems
- Space Exploration and Technology
Life Science Institute
2014-2023
Tokyo Institute of Technology
2016-2023
Earth-Life Science Institute
2014-2018
University of California, Santa Cruz
2007-2010
University of California, San Diego
2008
We present a new technique for the efficient measurement of traveltimes long period body wave phases. The is based on fact that all arrivals particular seismic phase are remarkably similar in shape single event. This allows application cross-correlation techniques usually used regional context to measure precise global differential times. analysis enhanced by inclusion clustering algorithm automatically clusters waveforms their degree similarity. discriminate against unusual or distorted and...
Global mapping of 410 and 660 km discontinuity topography transition zone thickness has proven to be a powerful tool for constraining mantle chemistry, dynamics mineralogy. Numerous seismic mineral physics studies suggest that the results from phase change olivine wadsleyite ringwoodite perovskite magnesiowustite. Underside reflections discontinuities arrive as precursors SS. With recent development semi-automated method determining SS arrivals, we have more than tripled Flanagan Shearer...
The two most abundant minerals in the Earth's lower mantle are bridgmanite and ferropericlase. bulk modulus of ferropericlase (Fp) softens as iron d-electrons transition from a high-spin to low-spin state, affecting seismic compressional velocity but not shear velocity. Here, we identify seismological expression spin crossover fast regions associated with cold Fp-rich subducted oceanic lithosphere: relative abundance velocities P- S-wave tomography models diverges ~1,400-2,000 km depth...
The iron spin crossover in ferropericlase introduces anomalies its thermodynamics and thermoelastic properties. Here we investigate how these can affect the lower mantle geotherm. effect is examined aggregates consisting of mixtures bridgmanite, ferropericlase, CaSiO$_3$ perovskite, with different Mg/Si ratios varying from harzburgitic to perovskitic (Mg/Si$\sim$1.5 0.8). We find that introduced by increase isentropic gradient thus geotherm proportionally amount ferropericlase. geotherms be...
Earth's mantle nitrogen (N) content is comparable to that found in its N-rich atmosphere. Mantle N has been proposed be primordial or sourced by later subduction, yet origin not elucidated. Here we model partitioning during the magma ocean stage following planet formation and subsequent cycling between surface over Earth history using argon (Ar) isotopes as tracers. The model, constrained Ar, shows only about 10% of total can trapped solidified due N's low solubility coefficients minerals...
Many large-scale structures in the mantle have been proposed to explain seismic observations and constrain geodynamic models. While geophysical community cannot agree on morphology nature(s) of large low shear velocity provinces (LLSVPs) due difference approaches, decorrelated P S anomaly (dVP no longer proportional dVS), inherently associated with changes composition and/or phase, can help examine models imply thermal/chemical evolution mantle. To further apply inference finer...
SUMMARY Seismic tomography models reveal differences in the geographic distribution and magnitude of P- S-wave velocity variations (VP VS, respectively) below ∼2200 km depth Earth’s mantle. In particular, large low shear provinces (LLSVPs) beneath Pacific Africa exhibit a distinct population VS that does not stand out VP models, carrying important implications for origin these features. However, it is possible absence feature an artefact having lower resolution compared to owing coverage....
The two most abundant minerals on Earth which together make up over 90% of the Earth’s lower mantle are (Mg,Fe)O-ferropericlase (Fp) and (Mg,Fe)SiO3-bridgmanite (Bm). Iron in Fp undergoes a high-spin to low-spin (HS-LS) crossover that influences density, viscosity, elasticity, thermal conductivity, elemental partitioning, however, predicted effects this transition not apparent global 1D seismic velocity profiles. This discrepancy suggests predictions inaccurate, resolution is insufficient...