Regional Studies of Surface Wave Dispersion and Anisotrophy in the Pacific Basin

本研究旨在研究地震面波在太平洋海盆中的传播。首先，将研究一些“无地震”海脊和高原上的面波频散，包括纳斯卡海脊、科科斯海脊和夏威夷海脊；目标是获得地壳-地幔界面以及地链下方低速带范围的精确测绘。这将对岛屿形成过程中移动的大洋板块和固定的羽流之间的热-机械相互作用造成很大的限制，就夏威夷链而言，还将限制热点下游板块的“愈合”过程。第二项研究将是上地幔各向异性，特别是目的是确定最近的面波观测所要求的地震软流层的各向异性是偏振型还是方位型。这直接关系到软流圈的组成和晶体布局，以及地震岩石圈底部冷却时的吸积过程。

This research is to study seismic surface wave propagation in the Pacific Ocean Basin. First, surface-wave dispersion will be investigated over a number of "aseismic" ridges and plateaus, including the Nazca, Cocos and Hawaiian Ridges; the goal will be to obtain precise mapping of the crust-mantle interface, as well as of the extent of the low-velocity zone under the chains. This will put substantial constraints on the thermo-mechanical interaction between the moving oceanic plate and the fixed plume during the formation of the island, and, in the case of the Hawaiian chain, on the process of "healing" of the plate downstream from the hotspot. The second investigation will be of upper mantle anisotropy, in particular with the goal of determining whether the anisotropy required in the seismic asthenosphere by recent surface wave observations is of the polarization or azimuthal type. This bears directly on the composition and crystalline layout of the asthenosphere and on the processes of accretion upon cooling at the base of the seismic lithosphere.