Earth structure and earthquakes in Indonesia and Russia

在俄罗斯的南萨哈林斯克和印度尼西亚苏门答腊岛北部的帕拉帕特，数字宽带地震记录或多或少是连续的。帕拉帕特站的特点是夜间噪声低，但白天会出现几个小时的大振幅噪声。虽然将噪声出现的时间与Parapat测量的日温度进行比较确实得出了一个确定的结论，但噪声谱的1/f依赖性强烈表明，噪声是由太阳光线的辐射热引起的温度波动引起的。俄日双方同意，俄日宽带合作地震观测的第二个地点应设在堪察加半岛北部的卡门斯科耶。俄罗斯和日本科学家成功地交换了有关1993年日本海地震海啸和余震的宝贵数据。在我们获得的三维地震速度结构的基础上，对Parapat不同传播路径的宽带数字地震图进行了检验。Halmahere事件的地震记录显示出强烈的衰减，这与三维结构显示的摩鹿加海峡非常低的地震波速度一致。数字宽带波形分析表明，1993年kushiroo - oki地震具有高应力降的特征，1993年日本海地震具有初始破裂过程与整体破裂过程明显不同的特征。

Digital broadband seismograms are more or less continuously recorded at Yuzhno-Sakhalinsk in Russia and at Parapat, northern Sumatra, Indonesia. Parapat station is characterized by low noise at night, but large-amplitude noises appear for several hours in day time. Although the comparison between time of the day when the noises appear and daily temperature measured at Parapat did lead to a firm conclusion, the 1/f dependence of noise spectrum strongly suggests that the noises are due to temperature fluctuations caused by the radiative heat of the sun light.The Russian and Japanese sides agree on that the second site for cooperative broadband seismic observation between Russia and Japan should be Kamenskoye in northern Kamchatka. The valuable data concerning the tsunami and aftershocks of the 1993 Japan Sea earthquake were successfully exchanged between Russian and Japanese scientists.On the basis of the three-dimensional seismic velocity structure obtained by us, broadband digital seismograms at Parapat for various propagation paths are examined. The seismograms of Halmahere events show strong attenuation, which is consistent with very low seismic wave velocity in the Straits of Molucca shown in the three-dimensional structure.Waveform analyses of digital broadband seimograms indicate that the 1993 Kushiro-Oki earthquake is characterized by high stress drop and that the 1993 Japan Sea earthquake is characterized by a marked differecne between the initial and overall rupture processes.