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本文根据青藏高原东部地区的4条射线上5次地震的记录资料,利用两台间测定面波介质品质因数的方法,测得了瑞利波的Q_R值。 结果表明:此区是大陆地壳中一个十分突出的低Q值区域。在7～51秒周期范围,Q_R值为31—376;在短周期范围(T≤15秒),Q_R值约为140—380,其离散度大;在长周期范围(T≥40秒),Q_R值约为30—40。实测Q_R值与MM8模型的理论值比较接近。 这种低Q值的分布特点,反映了地震面波在青藏高原东部地区衰减强烈,这不仅在于地壳上部构造中差异显著,引起了较强的散射作用;还在于地壳内及至岩石层底部可能存在局部熔融区域,吸收了弹性波的能量。上述各种现象与板块间的碰撞可能有关系。
Based on the recorded data of 4 earthquakes on 4 rays in the eastern Qinghai-Tibet Plateau, the Q_R values of Rayleigh waves were measured using the method of measuring the quality factor of surface wave media between the two stations. The results show that this area is a prominent low-Q region in the continental crust. In the range of 7 ~ 51 seconds, the value of Q_R is 31-376; in the short period (T≤15 seconds), the value of Q_R is about 140-380, the dispersion is large; in the long period (T≥40 seconds) The Q_R value is about 30-40. The measured Q_R value is close to the theoretical value of the MM8 model. The distribution of low Q values reflects the strong attenuation of seismic surface waves in the eastern Qinghai-Xizang Plateau, not only because of the significant difference in the upper crustal structure, but also in the strong scattering from the crust to the bottom of the lithosphere Local melting area, absorbing the energy of the elastic wave. The above phenomena may be related to the collision between plates.