Relationship between stress fi eld and apparent velocity and Poisson ratio fi elds  

应力场与视波速比场和视泊松比场的关系

作　　者：Li Shou-Yong Song Xiu-Qing 李守勇;宋秀青(邯郸地震监测中心站,邯郸056001;上海市地震局,上海200062)

机构地区：[1]Handan Central Seismic Station,Handan Hebei 056001,China [2]Shanghai Earthquake Agency,Shanghai 200062,China

出　　处：《Applied Geophysics》2025年第1期110-118,234,共10页应用地球物理(英文版)

摘　　要：Earthquakes are caused directly by the motion of the stress fi eld,therefore,observing the stress fi eld is signifi cant.Experiments on the relationships among wave velocity,stress factors,and faults show that the wave velocity of rock media under stable stress fi elds corresponds one-to-one with stress factors.Therefore,the wave velocity gradient can indicate the direction of stress vector,and the gradient divergence can indicate the strength of the stress fi eld.To verify the results,considering the limitations of wave velocity measurement in solid crustal media,two quantities,namely the apparent wave velocity and Poisson ratios relating to wave velocity,were used to refl ect the stress fi eld state.The seismic data of the Tangshan and Luzhou regions were studied separately.The calculated apparent wave velocity and Poisson ratios were interpolated to achieve regional data gridding.The gradients and the gradient divergences of the apparent wave velocity and Poisson ratio fi elds in the two regions were analyzed,and it was found that their spatial distribution in the same region was the same.They are believed to refl ect the vertical projection of the stress direction vector and strength on the surface in the stress fi eld,consistent with the experimental results.Whether it can eff ectively refl ect the stress fi eld requires further analysis of the specifi c situation of the local medium and the movement mode of the stress fi eld.应力场是地震发生的直接原因,因此应力场的观测有重要的意义,由波速与应力因素和断层的关系实验可知在应力场稳定的情况下,岩石介质的波速与应力因素是一一对应的关系,于是波速的梯度可以表示应力的失量方向,而梯度的散度可以表示应力场的强弱。为了验证该结果,考虑到固体地壳介质内波速测量的局限性,采用了与波速相关的视波速比和视泊松比两个不同量的梯度及梯度的散度来反映应力场状态,分别研究了唐山与泸州两个地区的地震数据,对计算的视波速比和视泊松比进行插值实现区域的数据网格化,分析了两个地区的视波速比场与视泊松比场的梯度的散度,发现同一地区它们的空间分布是相同的,视波速比场和视泊松比场都可以反映应力场的方向和强度在地表的垂直面投影,与实验的结果是一致的,至于其能否有效的反映出应力场情况,需要进一步对当地的介质的具体情况和应力场的运动方式进行分析。

关 键 词：stress field apparent wave velocity ratio field apparent Poisson’s ratio field divergence of gradients 

分 类 号：P31[天文地球—固体地球物理学]