SEKS: Side Edge of Kamchatka Subduction

本研究包括在堪察加半岛部署来自pascal的宽带便携式地震仪，以研究在堪察加半岛和阿留申群岛交汇处太平洋/北美板块边界的急剧转换-收敛转变周围的上地幔流动的影响。堪察加地区的地质具有不同寻常的特征，可能与板块边缘的软流圈流动有关，如异常高的弧岩浆活动速率，包括板块和地幔的融化，以及最近Komandorskaya盆地的裂谷和扩张。耶鲁大学和俄罗斯火山学研究所的科学家将利用便携式和附近的永久站点，利用剪切波分裂、表面波散射、体波混响、衰减和衍射观测以及区域地震活动性，研究地震速度、各向异性和Q的横向变化。他们将研究太平洋板块下方是否存在与海沟平行的流动，以及堪察加火山活动是否由一个低速、低q的上地幔楔体所支撑，该上地幔楔体与被拉绕在下降板块上方的地幔物质有关。来自阿留申交汇处北部的站点的数据，岛弧火山活动最近才停止，将用于确定是否存在来自年轻的科曼多尔斯卡亚盆地俯冲而来的停滞浮力板块，或者低速上地幔是否表明存在“板块窗口”。日本和千岛岛弧的地震具有测量地壳弥散的理想几何形状，因此沿着堪察加半岛测量地壳厚度变化。＊＊＊

9614639 Lees This research involves the deployment of broadband portable seismometers from PASSCAL on the Kamchatka Peninsula to study the effect of upper mantle flow around the sharp transform-to- convergent transition in the Pacific/North-American plate boundary at the intersection of Kamchatka and the Aleutian Islands. The geology of the Kamchatka region has unusual features which may be related to asthenospheric flow around the slab edge, such as exceptionally high rates of arc magmatism involving both slab and mantle melts, and recent rifting and spreading of the Komandorskaya Basin. Using portable and nearby permanent stations, scientists from Yale University and the Russian Institute of Volcanology will investigate lateral variations in seismic velocity, anisotropy and Q using shear-wave splitting, surface-wave scattering, body wave reverberation, attenuation and diffraction observations, and regional seismicity. They will address whether trench-parallel flow exists below the Pacific plate, and whether Kamchatka volcanism is underlain by a low-velocity, low-Q upper-mantle wedge associated with mantle material pulled around and above the descending slab. Data from stations north of the Aleutian intersection, where island-arc volcanism has only recently ceased, will be used to determine whether a stalled, buoyant slab from the subduction of the young Komandorskaya Basin exists, or whether low-velocity upper mantle suggests the presence of a "slab window." Earthquakes in Japan and the Kurile arc have ideal geometry for measuring crustal dispersion, and hence crustal thickness variations, along the Kamchatka Peninsula. ***