Geophysical and Petrologic Study of the Toba Magma System, Northern Sumatra

小行星9316344 这项研究是为了研究苏门答腊火山弧内100 × 30公里的多巴凹陷。 多巴洼地是世界上最大的第四纪复活破火山口。 它形成于74，000年前的一次大规模喷发，在至少400万平方公里的面积上散布了超过2800立方公里的火山灰。 鸟羽的岩浆系统大概是在一个主要喷发事件之间的休止期。 这项研究结合了地震和岩石学调查，目的是了解多巴岩浆系统的起源和演化，熔体在其中的分布，以及其与深（俯冲板）和浅（地壳）结构的关系。 岩浆分布及其与板块和地表断层的关系将通过断层摄影和构造分析多巴附近浅层地震、多巴下方俯冲板块可能裂缝中的中深层地震和火山地震的地震学数据进行评估，所有这些数据都记录在48个测站的地震仪阵列上。 这种岩石学和地球物理相结合的方法将提供有价值的限制的演变和火山/地震活动的大容量，岩浆水库，和其他收敛边缘岩浆系统。 这项研究是国家地震减灾计划的一个组成部分。 *** ??

9316344 McCaffrey This research is to study the 100 by 30 km Toba depression, within the Sumatra volcanic arc. The Toba depression is the world's largest Quaternary resurgent caldera. It formed 74,000 years ago during a massive eruption that dispersed over 2800 cubic kilometers of ash over an area of at least 4 million square km. Toba's magma system is presumably in a period of repose between major eruptive events. This study combines seismic and petrologic investigations with the goals of understanding the origin and evolution of the Toba magma system, the distribution of melt within it, and its relation to deep (subducted slab) and shallow (crustal) structures. Magma distribution and its relation to slab and surface faults will be assessed by tomographic and tectonic analyses of seismological data from shallow earthquakes near Toba, from intermediate-depth earthquakes in a possible tear in the subducted slab beneath Toba, and from teleseisms, all recorded on a 48-station seismograph array. This combined petrologic and geophysical approach will provide valuable constraints on the evolution and volcanic/seismic activity of large-volume, silicic magma reservoirs, and of other convergent-margin magma systems. This research is a component of the National Earthquake Hazard Reduction Program. *** ??