Irregular topography at the Earth's inner core boundary |
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Authors: | Dai Zhiyang Wang Wei Wen Lianxing |
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Institution: | School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China. |
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Abstract: | Compressional seismic wave reflected off the Earth’s inner core boundary (ICB) from earthquakes occurring in the Banda Sea and recorded at the Hi-net stations in Japan exhibits significant variations in travel time (from -2 to 2.5 s) and amplitude (with a factor of more than 4) across the seismic array. Such variations indicate that Earth’s ICB is irregular, with a combination of at least two scales of topography: a height variation of 14 km changing within a lateral distance of no more than 6 km, and a height variation of 4–8 km with a lateral length scale of 2–4 km. The characteristics of the ICB topography indicate that small-scale variations of temperature and/or core composition exist near the ICB, and/or the ICB topographic surface is being deformed by small-scale forces out of its thermocompositional equilibrium position and is metastable. |
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Keywords: | inner core growth geodynamo outer core convection |
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