发表机构
Kyoto University; National Institute for Earth Physics; Tohoku University; University of Tsukuba; University of Shizuoka; Kyoto Institute of Technology（京都大学; 罗马尼亚地球物理研究所; 东北大学; 筑波大学; 静冈大学; 京都工艺纤维大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用监控视频，通过金字塔光流和归一化互相关模板匹配法，首次（继2025年缅甸地震后）直接获取2026年熊本地震同震地表断层的时间分辨位移，揭示其核心位移在约0.9秒内完成及表观超调现象。
AI 中文摘要
视频记录能为同震地表断层位移的时间演化提供异常直接的约束，但当相机运动和记录伪影污染表观图像运动时，定量分析会变得复杂。我们分析了一段捕捉到2026年7月28日熊本地震期间地表位移的监控（CCTV）二次录像。据我们所知，这是继2025年缅甸Mw7.7级地震之后，仅有的第二次由监控直接捕捉到同震地表断层运动的地震报告。我们将金字塔光流和归一化互相关模板匹配两种独立方法应用于可用的视频帧，从空间分离的参考区域估计共同的记录运动。图像位移根据实地测量的永久偏移矢量进行校准：1.05米右旋、0.90米东侧上盘、总位移1.383米。两种方法得出的位移历史高度一致，永久位移的20%-80%核心部分在0.87-0.91秒内完成，对应平均位移速率约0.9-1.0米/秒，这些估计在合理的处理选择和目标区域扰动下保持稳定。两种方法还分辨出一个短暂的位移峰值，比后续稳定水平高出约5%-7%，随后向最终平台发生反向运动。这种表观超调在视频衍生的位移历史中是稳健的，但由于两项分析都依赖同一段二次录像，无法排除存在相干残留伪影的可能。
英文摘要
Video recordings can reveal how rapidly fault displacement develops at the Earth's surface, but camera motion and recording artifacts can obscure the ground signal. We analyze a secondary copy of security-camera footage that captured surface displacement during the 28 July 2026 Kumamoto earthquake; the native recording was unavailable and could not be recovered. Two independent image-tracking methods were used. Optical flow follows identifiable image features, whereas normalized cross-correlation (NCC) template matching follows fixed image patches by their similarity. Both measured target-region motion relative to spatially separated reference regions while correcting motion shared by the recording. Image displacement was calibrated to the magnitude of the field-measured offset vector: 1.05 m right-lateral and 0.90 m east-side-up, or 1.383 m in total. We characterize the principal rise by the time required for displacement to progress from 20% to 80% of the selected final level. Across prespecified endpoint choices, optical flow gives 0.866-0.901 s and NCC gives 0.910-0.928 s. These durations correspond to average rates of 0.920-0.958 and 0.895-0.912 m/s, respectively. Checks using independently published tracking windows reproduce the displacement scale, although exact timing is more sensitive in spatially restricted tests. The record also shows an early apparent peak and decline followed by renewed apparent horizontal displacement. Because that later motion may represent either continued ground displacement or the geometry of the secondary recording, neither the permanent endpoint nor physical overshoot can be determined. The most robust conclusion is that the central part of the surface displacement developed in approximately 0.9 s at an average rate near 0.9 m/s.
CommentsVersion 3: Revised and expanded manuscript submitted to Earth, Planets and Space. The author list, regional and site geometry, methodological validation, recording-artifact diagnostics, and data availability information have been updated. The principal approximately 0.9 s surface-displacement timescale result is unchanged
