SEKS: Side Edge of Kamchatka Subduction

9614639本研究涉及在堪察加半岛上部署PASSCAL的宽带便携式地震仪，以研究堪察加和阿留申群岛交界处太平洋/北美板块边界急剧向会聚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，这些特征可能与板片边缘周围的软流圈流动有关，例如包括板片和地幔熔体在内的异常高的弧形岩浆活动，以及科曼多尔斯卡亚盆地最近的裂谷和扩张。来自耶鲁大学和俄罗斯火山研究所的科学家将利用便携式和附近的永久观测站，利用剪切波分裂、面波散射、体波混响、衰减和绕射观测以及区域地震活动来研究地震速度、各向异性和Q的横向变化。他们将讨论太平洋板块下方是否存在海沟平行流动，以及堪察加火山活动是否受到低速、低Q的上地幔楔体的影响，该楔体与地幔物质在下降板块周围和上方拉动有关。来自阿留申交叉口以北的监测站的数据将被用来确定是否存在年轻的科曼多尔斯卡亚盆地俯冲而来的停滞的浮力板块，或者低速上地幔是否表明存在“板块窗口”。阿留申交叉口的岛弧火山活动最近才停止。日本和千岛岛弧的地震具有测量堪察加半岛地壳扩散和地壳厚度变化的理想几何形状。***

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. ***