【摘要】 利用泰安台YRY-2型钻孔差应变仪的观测资料,研究了两次印尼苏门答腊地震的环型振荡的剪应变方向。首先对差应变仪观测数据进行实地标定,然后用标定后的数据检测2004年12月26日和2005年3月28日印尼苏门答腊两次大地震激发的环型振荡,发现基频环型振荡0T11~0T18最明显,且两次地震的振幅变化趋势基本一致。两次地震得到的0T11~0T18型环型振荡的最大剪应变方向随时间变化比较小。通过与理论预期的对比,发现实测值的平均值与理论值之差仅为2°。这不仅证实了理论模型的正确性,同时也证实了该观测的可靠性。更多还原

【Abstract】 Using observations of the YRY-2 borehole shear strainmeter,we studied maximum shear strain orientation of the earth’s torsional oscillation excited by two Sumatra earthquake occurred on December 26,2004 and March 28,2005.Firstly,we did in-situ calibration for the data of borehole shear strainmeter and then detected the torsional oscillations.It is found that fundamental torsional modes-0T-11～-0T-18 were very obvious and variation trend of the two earthquakes’ amplitude were in agreement with each others,and variations of maximum shear strain orientations with time of fundamental torsional modes-0T-11～-0T-18 of the two Sumatra earthquakes are small.Through the comparison,we found that the D-value of the mean measured value with theoretical anticipation value was only 2°.On the one hand,it comfirmed the theoretical model,on the other hand it also comfirmed that this observation was reliable.更多还原