title: Irregular topography at the Earth's inner core boundary.
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.
authors.affiliation: School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Zhiyang
authors.initials: Z
authors.lastname: Dai
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Lianxing
authors.initials: L
authors.lastname: Wen
mesh_terms: D018534:Earth, Planet; D055866:Earthquakes; D055593:Geological Phenomena; D005844:Geology / Q000379:methods*; D007214:Indonesia; D007564:Japan; D009792:Oceans and Seas; D013696:Temperature