A quarry failure along the slopes of the Wai Khar open-pit jade mine in Hpakant, Myanmar has led to the deaths of at least 172 jade miners on 2 July 2020. This paper conducts a systematic investigation of the incident by integrating data from multiple sensors, including high-resolution optical imagery, Sentinel-1 synthetic aperture radar (SAR) images, unmanned aerial system (UAS) footage, SRTM and ALOS digital elevation models (DEMs), soil moisture product from multi-spectral Landsat-8 satellite and precipitation records from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS). Optical imagery, UAS footage and DEMs allow us to build a comprehensive mapping of tailing areas and quarry scarps from 2010 and reconstruct the 2D pit geometry prior to failure. Deformation signals from multi-temporal SAR interferometry (MTInSAR), soil moisture variations and precipitation trends further allow us to identify possible failure causes. To evaluate the quality of deformation obtained from different distributed-scatterer phase estimators, we develop an empirical mapping function based on areal fraction values to facilitate the comparison of temporal coherence values that are differently formulated in each phase estimator. The comparison shows that phase linking algorithm outperforms the small baseline subset method in terms of signal recovery and phase reliability. Our investigation points out that the mining site is under aggressive mining cycles that are exacerbated by frequent, uncontrolled landslides. Seepage failure, which involves the expulsion of water from rapidly compacting tailings, may be a critical factor in the 2020 incident. Instead of extreme weather, the failure had occurred under normal to drier conditions. This means that the sliding planes were already in a critical state, which is evident from the accelerated deformation around the collapse area since the beginning of 2020. Based on these findings, we provide recommendations to improve mining site regulations and management practices for safer open-pit mining in Myanmar and probably in similar contexts outside Myanmar.

2020 年 7 月 2 日，缅甸帕干 Wai Khar 露天玉矿斜坡沿线的采石场故障导致至少 172 名玉石矿工死亡。 本文通过整合多个传感器的数据对事件进行系统调查，包括高分辨率光学图像、Sentinel-1 合成孔径雷达 (SAR) 图像、无人机系统 (UAS) 镜头、SRTM 和 ALOS 数字高程模型 (DEM)、多光谱 Landsat-8 卫星的土壤水分产品和降水来自气候危害组红外降水与站点数据 (CHIRPS) 的记录。光学图像、UAS 镜头和 DEM 使我们能够构建 2010 年以来的尾矿区和采石场陡坡的综合地图，并在故障前重建 2D 坑几何结构。来自多时相 SAR 干涉测量 (MTInSAR) 的变形信号，土壤水分变化和降水趋势进一步使我们能够确定可能的失败原因。为了评估从不同分布散射体相位估计器获得的变形质量，我们开发了一个基于面积分数的经验映射函数，以方便比较每个相位估计器中不同公式化的时间相干值。比较表明，相位链接算法在信号恢复和相位可靠性方面优于小基线子集方法。我们的调查指出，该矿场正处于激烈的采矿周期中，频繁、不受控制的山体滑坡加剧了这种情况。渗漏故障（涉及从快速压实的尾矿中排出水）可能是 2020 年事故的关键因素。而不是极端天气，故障发生在正常至干燥的条件下。这意味着滑动平面已经处于临界状态，从 2020 年初以来坍塌区域周围的加速变形可以明显看出这一点。基于这些发现，我们提供建议以改进矿区法规和管理实践，以实现更安全的开放。缅甸的矿坑开采，可能还有缅甸以外的类似情况。