Shangqin Hao

Shangqin Hao

He/Him

Seismologist, Mineral Physicist

Posts by Collection

research

Elasticity of akimotoite under the mantle conditions: Implications for multiple discontinuities and seismic anisotropies at the depth of ~600–750 km in subduction zones

Updated:

Comparison of velocities and densty of mantle minerals

  • Calculated the elasticity of akimotoite under the mantle conditions using first-principles calculations
  • Estimated the VP, VS, and density contrasts caused by the akimotoite-related transitions
  • Proved that the discontinuity at the depth of ~700-750 km in cold slabs could result from the decomposition of pyrope rather than the akimotoite-bridgmanite transition

Compositional and thermal state of the lower mantle from joint 3D inversion with seismic tomography and mineral elasticity

Updated:

  • Inverted for the 3D chemical composition and thermal state of the lower mantle based on seismic tomography and mineral elasticity data
  • Found that velocity heterogeneities in the upper lower mantle mainly result from thermal anomalies, whereas those in the lowermost mantle mainly result from compositional or phase variations
  • Found that LLSVPs have ~500 K higher temperature, higher bridgmanite and iron content than the ambient mantle, supporting the origin from an ancient basal magma ocean

Upper-mantle structure beneath Alaska imaged by teleseismic S-wave reverberations

Updated:

cs

  • Imaged the Moho and mantle transition zone (MTZ) discontinuities beneath Alaska by stacking long-period teleseismic SH waves
  • Observed crustal thickness is generally consistent with surface topography and gravity measurements
  • Suggested that the Pacific slab may have penetrated into the upper MTZ under central Alaska but not under the Alaska Peninsula

Thermoelasticity of phase D and implications for low-velocity anomalies and local discontinuities at the uppermost lower mantle

Updated:

Contrasts

  • Obtained elasticity and density of phase D under the lower-mantle conditions
  • Proved that the accumulation of phase D may account for seismic anisotropy rather than low-velocity anomalies in the uppermost lower mantle (ULM)
  • Suggested that the decomposition of phase D in the ULM causes a density jump, possibly explaining some discontinuities in subduction zones

Substantial global radial variations of basalt content near the 660-km discontinuity

Updated:

Radial variations of basalt fraction and Mg/Si ratio.

  • Constrained seismic velocity, density, and basalt content at and below the 660-km discontinuity (d660) by S660S waveform inversions
  • Found that slabs exhibit a smaller impedance jump across the d660 but a steeper gradient below the d660 compared to other regions
  • Suggested that basalt accumulates at the d660, especially in subduction zones, but decreases significantly below it, forming a harzburgite-enriched layer