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分析了1985～1988年期间一条从奥斯陆(NORESS)经赫尔辛基至列宁格勒(OHL剖面)的东西向剖面用NORESS台阵记录的147次工业爆破的波形。事件离NORESS台阵的距离为250～1300km,且近震震级在2.0～3.5范围内。由赫尔辛基大学的区域地震台网提供的震源位置和发震时刻为NORESS台阵走时估计提供了可靠的基础。我们也应用了1979年在FENNOLORA南北向长距离地震剖面上由NORSAR台阵记录的3个爆破点的资料,该剖面紧邻OHL剖面。对爆破得到的地幔P波信号的分析表明:初至波可以连续追踪到750～800km的距离,该处在走时曲线上有2.0～2.5s的错动,且平均视速度增加。对剖面上观测的走时和波形的分析表明,大约在105～135km深度处存在一个低速区。对地震资料和布格重力图的联合解释得出上地幔中存在一个高速度的高密度体,它的范围大约从离NORESS以东的200～300km线性延伸到500～600km。我们假设这个岩体是古代火山系的根源,其内部更轻的硅石成分在喷发期间从上地幔中衰竭。
The waveforms of 147 industrial explosions recorded from the NORESS array from east to west from Horsinki to Leningrad (from the NORESS to the Leningrad) from 1985 to 1988 were analyzed. The distance from the NORESS array is 250 ~ 1300km, and the magnitude of the near-earthquakes is in the range of 2.0 ~ 3.5. The location of hypocenters and seismogenic times provided by the regional seismological network of the University of Helsinki provide a reliable basis for estimating the travel time of the NORESS array. We also applied the data from the three blasting points recorded by the NORSAR array on the FENNOLORA long-range north-south long-range seismic profile in 1979, which is close to the OHL profile. The analysis of the mantle P wave signal obtained by blasting shows that the first arrival wave can continuously track the distance of 750 ~ 800km, there is a 2.0 ~ 2.5s misalignment in the travel time curve, and the average apparent velocity increases. An analysis of the travel time and waveforms observed on the profile shows that there is a low velocity zone at a depth of about 105-135 km. The joint interpretation of seismic data and Bouguer gravity maps shows that there is a high-velocity, high-density body in the upper mantle extending linearly from about 200 to 300 km east of the NORESS to 500 to 600 km. We hypothesize that this rock mass is the source of ancient volcanic systems, and the lighter components of the interior are depleted from the upper mantle during eruptions.