欧洲上地幔顶部Pn速度结构

利用首波Pn的走时资料成像是研究上地幔顶部Moho面的速度结构及各向异性的有利手段。本文收集了ISC(1964年—2001年)欧洲南部554个台站及2831个地震事件的90000多条Pn射线的走时资料,利用地震层析成像方法反演了欧洲南部上地幔顶部Pn波速度结构。结果表明,欧洲南部地区的平均Pn速度为8.0km/s,横向速度变化为-0.3km/s到0.3km/s。Pn波低速异常主要集中在迪纳里德山脉至爱琴海北部;在意大利亚平宁山脉部分、利古里亚海至撒丁岛也表现出明显的低速异常。在亚德里亚海地区,Pn波速度表现出明显的高速异常。

The Pn wave velocities structures of uppermost mantle beneath southern Europe

Pn travel times are useful for studying crustal and uppermost mantle structure and regional tectonics because they are affected by crustal velocity and thickness as well as uppermost mantle velocity and anisotropy.We obtained more than 90000 Pn travel time picks from 2831 earthquakes and 554 stations from the International Seismological Center bulletins to invert for Pn velocity in European area.The main results indicate the average Pn velocity is about 8.0km/s in this region and transverse velocity changes from-0.3km/s to 0.3km/s.The Pn velocities show low anomalies from Dinaride and Hellenide arcs to Aegean Sea.What is more,these arcs show considerable amount of arc-parallel anisotropy.The Tyrrhenian and Sardinia regions also show low velocities but less anisotropy.The Pn velocities in Adriatic Sea regions show high anomalies.