Cross-correlated ambient data recorded on a distributed acoustic sensing array

Distributed acoustic sensing (DAS) is a relatively new technology used in
many geophysical applications. The versatility and high temporal-spatial
resolution make DAS ideal for rapid deployment surveys such as
earthquake-aftershock monitoring and hazard assessment. However, these
applications often rely on trenched cable installations that are time
consuming and cost prohibitive, or on existing telecom fibers that are
limited in spatial coverage. We deploy a DAS array composed of six
parallel linear subsections directly on ground surfaces with different
conditions. We apply ambient interferometry and adopt a simplified
spectral-analysis-of-surface waves (SASW) method to determine the average
shear-wave velocity of the top 30 m (VS30). Our methodology results in
robust VS30 estimates for each surface deployment subsection that are
consistent with collocated 1 m-depth trenched cables. The implications of
these findings support DAS as a viable method for non-invasive rapid
deployment surface surveys for earthquake hazard assessment.

分布式声学传感（Distributed acoustic sensing, DAS）是一项应用于诸多地球物理场景的较新型技术。其兼具多功能性与优异的时空分辨率，非常适用于余震监测、灾害评估等快速部署类勘测工作。然而，此类应用通常依赖耗时耗资且成本高昂的开槽电缆敷设方案，或是空间覆盖范围受限的现有电信光纤。本研究布设了由6组平行线性子阵列组成的DAS阵列，直接铺设于不同地表条件的地面之上。我们采用环境干涉法，并简化了面波频谱分析（Spectral Analysis of Surface Waves, SASW）方法，以测定地表以下30米深度范围内的平均剪切波速度（VS30）。本研究方法可针对每个地表布设子阵列生成稳健可靠的VS30估算结果，且与同期布设的1米深度开槽电缆所得结果保持一致。本研究结果证实，DAS可作为一种切实可行的非侵入式快速部署地表勘测手段，用于地震灾害评估工作。