摘要
本文的研究工作,得到了埃特纳火山下面的一组新的三维速度模型。作者们用1980年以来地方性地震在永久和临时地震台网在4个或更多台记录到的1249次地震的P和S波,被选来作走时反演。选择了几种判别标志与参数化办法以显示其类似的基本特征。表明在火山的东南象限在浅层,有P波的高速分怖,它同布格重力高异常有密切关系。在该区存在低的Vp/Vs比值;沿着中央火山管道,分布有高速P波和高的Vp/Vs比值;建议该处存在有稠密的侵入的岩浆体,延伸到20千米左右的深度,该区附近有低速的P波速度。对震源的重新定位也显示出向外倾斜的易碎区,与中央火山管道延伸出一段P波高速异常区,位于中央火山口的附近。沿着中央火山口附近,有P波的低速区,它同次生的火山锥的分布有关,与部份熔融的深部岩浆库有联系。
A new set of three dimensional velocity models beneath Etna volcano is derived in the present work. We have used P and S wave arrivals from local earthquakes recorded at permanent and temporary seismic networks installed since 1980.A set of 1,249 earthquakes recorded at more than 4 seismic stations was selected for travel time inversion. The velocity models obtained by using different data selection criteria and parametrization display similar basic features,showing a high P wave velocity at shallow depth in the SE quadrant, in close connection with a high gravimetric Bouguer anomaly. This area share a low Vp/Vs ratio.High P wave velocities and high Vp/Vs ratios are obtained along the central conduits,suggesting the presence of dense,intrusive magmatic bodies extending to a depth of about 20 km.This region is surrounded by lower P wave velocities.The relocated earthquake hypocenters also display the presence of outward dipping brittle region,away from the central conduite, surrounding a ductile zone spatially related to the high P wave velocity anomalies located in the proximity of central craters.The distribution of parasitic cones, suggesting the location of partial meltlinked to deep magmatic reservoirs.
出处
《CT理论与应用研究(中英文)》
1998年第1期43-51,共9页
Computerized Tomography Theory and Applications
关键词
火山
三维速度结构
岩浆体
岩浆库
地震活动性
Volcano, Three dimensional velocity structure, Intrusive magmatic bodies, Magmatic reservoirs