Analysis of Steep Angle Seismic Reflections from Earth's Inner and Outer Core

建议摘要EAR0087330(PH#17x)标题：来自地球内外核的陡角地震反射分析PI：亚利桑那大学的基思·D·科珀拟议的研究重点是全球地形变化对内核-外核边界(ICB)和核幔边界(CMB)的地震约束。陡角(S，P)KiKP-(S，P)CP差分走时的变化将被用来估计内、外核的椭圆度，寻找这些边界上的短波地形，为液态外核的均匀性提供观测界限，并寻找地球内核差异旋转的证据。陡角外核差异旅行时间的变化，主要是SCP-PCP，也将被用来量化主体声速的垂直地幔剖面的全球变化。从原型国际数据中心(PIDC)编制的地震活动目录中可以获得前所未有数量的陡角差分岩心反射数据。在向PIDC报告数据的全球分布的台站中，大约有20个由短周期垂直分量地震仪阵列组成。阵列站对陡角岩心反射的敏感度明显高于传统的三分量台站，并且阵列站的方位和慢度观测大大减少了相位误判。通过考虑这类反射的不同走时，地震错位和上地幔不均匀的影响得到了很大程度的减弱，揭示了CMB和ICB的地震结构。

Abstract for proposal EAR0087330 (PH # 17x)Title: Analysis of Steep Angle Seismic Reflections from Earth's Inner and Outer CorePI: Keith D. Koper, University of ArizonaThe proposed research focuses on seismic constraints of global variations in topography on the inner core-outer core boundary (ICB) and the core-mantle boundary (CMB). Variations in steep angle (S,P)KiKP-(S,P)cP differential travel times will be used to estimate the ellipticity of the inner and outer core, to search for short-wavelength topography on these boundaries, to provide observational bounds on the homogeneity of the liquid outer core, and to search for evidence of differential rotation of Earth's inner core. Variations in steep angle outer core differential travel times, primarily ScP-PcP, will also be used to quantify global variations in vertical mantle profiles of bulk sound velocity. An unprecedented number of steep angle differential core reflection data are available from the seismicity catalog produced by the prototype International Data Center (pIDC). Approximately 20 of the globally distributed stations that report data to the pIDC consist of arrays of short period vertical component seismometers. Array stations are markedly more sensitive to steep angle core reflections than traditional three component stations, and the azimuth and slowness observations made by array stations greatly reduce phase misidentification. By considering the differential travel times of pairs of such reflections the effects of earthquake mislocation and upper mantle heterogeneity are substantially reduced and seismic structure at the CMB and ICB is revealed.