基于近震W震相的中国大陆强震震源破裂过程快速反演方法研究

The seismologists in China and international countries are trying to solve the essential problem that how to make full use of regional waveforms to quickly retrieve the rupture history of strong earthquakes for mitigating earthquake hazard. The W-phase has a very long period, and it is less effected by the complex velocity structure of the Crust. Therefore, the W-phase has been widely used to determine point-source parameters of strong earthquakes. However, the study on the rapid finite-fault modeling using regional W-phase waveforms is rarely involved because of the W-phase with a long-period range and the limit of the real-time data access . We thus plan to focus on the following research: .（1）With the use of time-domain method, we extract unbiased W-phase waves from the high-quality real-time broadband waves recorded by the Chinese seismic networks. Sometime these regional waves possibly include several clipped records. .（2）We carefully confirm the suitable frequency band for filtering in order to enhance the ability of the W-phase to effectively resolve the detail of the rupture history..（3）We apply the wavelet-domain method to invert the rupture history of strong earthquake based on the simplified one-dimensional velocity model, using the regional（3°～15°）W-phase waves，which are less affected by the complex velocity structure. In this study, we try to make full of the characteristics of the regional W-phase waves with the help of the real-time seismic waveforms observed by the Chinese seismic networks, and extend the research method for the source process inversion. .With this method, We retrieve an image of the coseismic slip within 10—15 minutes after we collect enough data, and deal with the importance problem that the real-time finite fault modeling for strong earthquakes is not well solved recently.

如何充分利用近震波形快速反演强震破裂过程，为抗震救灾服务，成为国内外地震学家亟待解决的重要课题。W震相周期长, 能有效避免复杂地壳结构干扰，广泛应用于强震点源模型的震源参数测定。但使用近震W震相波形反演破裂过程方法研究还很少, 主要由于资料未能实时获取及传统W震相频率低等原因。因此本项目拟开展以下研究： (1) 采用高质量实时中国地震台网记录的近震波形（含限幅记录），利用时间域反卷积技术无失真地提取W震相；（2）确定合适的滤波频段，以提高W震相有效分辨震源过程细节的能力；(3) 采用近震（3°～15°）W震相波形，有效避免复杂速度异常体的影响，通过小波域反演法快速求解强震破裂过程。本研究将充分利用近震W震相的特性，结合中国地震台网实时记录资料，拓展了震源破裂过程研究方法。有望在获得数据后10～15分钟内重建我国强震震源滑动分布图像，以解决现阶段我国强震破裂过程尚不能近实时获知之难题。

如何充分利用近震波形快速反演强震破裂过程，为抗震救灾服务，成为国内外地震学家亟待解决的重要课题。W震相周期长, 能有效避免复杂地壳结构干扰，广泛应用于强震点源模型的震源参数测定。但使用近震W震相波形反演破裂过程方法研究还很少，主要由于资料未能实时获取及传统W震相频率低等原因。因此本项目开展以下研究：（1）采用高质量实时中国地震台网记录的近震波形（含限幅记录），利用时间域反卷积技术无失真地提取W震相；（2）确定合适的滤波频段，以提高W震相有效分辨震源过程细节的能力；（3）采用W震相波形，有效避免复杂速度异常体的影响，通过小波域反演法快速求解强震破裂过程。通过本项目研究，取得如下进展和成果：（1）发展了W震相波形快速反演地震矩张量方法，研制了地震震源参数快速测定系统，发布国内外地震矩张量结果约198次，在地震应急中发挥实效；（2）研究了基于W震相的中国大陆强震震源破裂过程快速反演方法。2013年芦山Ms7.0地震等实例测试结果表明方法的有效性；（3）在国内外权威地球物理学期刊上发表SCI论文5篇。本项目研究不仅能增进人们对我国强震震源复杂性的了解，而且对地震海啸预警、强地面运动评估等研究有着重要意义。