Multiple discontinuities near 660 km beneath Tonga area
نویسندگان
چکیده
منابع مشابه
SH velocity and compositional models near the 660-km discontinuity beneath South America and northeast Asia
[1] We constrain SH wave velocity structures near the 660-km discontinuity beneath South America and northeast Asia, using triplicated phases near the discontinuity recorded in the epicentral distance range of 10 –35 for three deep events. We then explore mineralogical and compositional models appropriate for explaining the inferred seismic structures between the two regions. SH velocity struct...
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[1] High-pressure assemblages of subducted oceanic crust are denser than the normal upper mantle but less dense than the uppermost lower mantle. Thus subducted oceanic crust may accumulate at the base of the upper mantle. Direct observational evidence for this hypothesis, however, remains elusive. We present an analysis of a negativepolarity shear wave converted from compressional wave at a sei...
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a r t i c l e i n f o Keywords: mantle plumes phase transitions temperature dependent viscosity thermal expansivity lattice thermal conductivity Recent high-resolution seismic imaging of the transition zone topography beneath the Hawaiian archipelago shows strong evidence for a 1000 to 2000 km wide hot thermal anomaly ponding beneath the 660 km boundary west of Hawaii islands [Q. Cao et al. Sei...
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[1] Seismic velocity discontinuities within the top 1000 km of the Earth beneath southern Africa are imaged by stacking about 1300 source-normalized broadband seismograms recorded by the Southern African Seismic Experiment. The Moho, 410, and 660 kilometer discontinuities are clearly detected. The mean mantle transition zone thickness is 245 km, essentially the same as the global average, sugge...
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ژورنال
عنوان ژورنال: Geophysical Research Letters
سال: 2006
ISSN: 0094-8276
DOI: 10.1029/2006gl027262