Toward a Better Understanding of Spatiotemporal Rupture Evolution Through a Concrete Accounting of Site Effects: The Iwate–Miyagi 2008 Case

• DOI: 10.1785/0120240151
• Publication Date: 2025-03-17T17:45:46Z
• Authors: Ioannis Fountoulakis; Olga-Joan Ktenidou; Pierre-Yves Bard; Christos P. Evang...; Efthimios Sokos

ABSTRACT Local soil conditions significantly influence the characteristics of observed seismic waves, often obscuring or distorting original source signature and modifying recorded waveforms. backprojection (BP) imaging, a common technique for identifying spatiotemporal high-frequency energy release during ruptures, typically relies on strong motion data that is frequently not installed bedrock. We evaluate impact effects local BP images by analyzing obtained from 2008 Iwate–Miyagi Nairiku earthquake recordings both surface downhole stations Kiban–Kyoshin network. Initially, we conducted detailed study sites near source. Surface station were corrected site using horizontal-to-vertical spectral ratios established correction methods account nonlinearity effects, providing accurate estimations horizontal amplification, which then eliminate signals. Extensive comparisons between records, uncorrected borehole records reveal can distort coherence, leading to inaccurate results. However, applying effect corrections enhances image quality, aligning outcomes more closely with those records. In addition, examine independence concerning effects. This highlights importance incorporating in analyses improve accuracy. Finally, propose comprehensive workflow integrating these into future studies.