强衰减条件下能量比法的修正及其应用

A modified energy ratio method in strong attenuation condition

吸收衰减是引起地震波能量损失的一个重要因素,尤其是在近地表强衰减条件下。常规的能量比法是利用地震波能量的线性衰减速率定量估测品质因子Q,不适用于近地表的强衰减(Q小于30)情况;修正的能量比法利用地震波能量的指数衰减速率估算Q值,减小了常规方法的理论误差,适用于近地表条件。仿真模型和实际资料处理结果表明,在非固有衰减(主要为几何扩散)得到较好补偿的前提下,修正能量比法估算的近地表Q值合理、可靠,具有实用性。

Attenuation is one of the important factors that weakens seismic wave energy,especially under the condition of near-surface strong attenuation.Energy ratio method(ERM),which estimates quality factors based on the linear decay rate of seismic wave energy,is unsuitable for this condition(e.g.,Qless than 30).Modified energy ratio method(MERM),which estimates quality factors based on the exponential decay rate of seismic wave energy,reduces the theoretical error of ERM,and is suitable for this condition.Model tests and data applications show that Qvalue estimated by MERM is reliable when intrinsic attenuation is properly compensated.So MERM provides an applicable tool in the practice.