Caving activity results in an increased induced seismicity which should be monitored to avoid massive and uncontrolled rock damage. This research was conducted at the Deep Mill Level Zone (DMLZ) underground mine, the deepest underground mine in Indonesia operated by PT Freeport Indonesia. This research aims to monitor cave propagation by using 4D tomography with a catalogue of microseismic for 57 days with a total of 14,821 events recorded by 84 stations consisting of 176,265 P phases and 133,472 S phases. The data is divided into four subsets to see the velocity evolution related to cave progress. Checkerboard Resolution Test (CRT) and Derivative Weight Sum (DWS) are used to assess the resolution of the inversion. 3D initial velocity model is constructed based on geological information and coring data. We have succeeded in identifying the interpreted cave propagation of a 60 m extension to the NW at around 100 m above undercut level based on 4D changes in velocity tomogram validate by Time Domain Reflectometry data. The decrease of Vp and Vs in subset 3 is interpreted due to the fracturing processes as the cave progresses. Furthermore, we observe a stress redistribution along with the progress of the cave, which is characterized by high velocities (Vp and Vs) due to compensation for changes in low velocity values ​​in the area in front of the cave, which is starting to collapse. We suggest that a considerable change in the velocity tomogram as an indicator of impending caving.

崩落活动会导致诱发地震活动增加，应对此进行监测以避免大规模且不受控制的岩石损坏。这项研究是在 Deep Mill Level Zone (DMLZ) 地下矿山进行的，这是由 PT Freeport Indonesia 运营的印度尼西亚最深的地下矿山。这项研究旨在利用 4D 断层扫描技术以及 57 天的微震目录来监测洞穴传播，84 个台站记录了总共 14,821 个事件，其中包括 176,265 个 P 相和 133,472 个 S 相。数据分为四个子集，以查看与洞穴进展相关的速度演变。棋盘分辨率测试（CRT）和导数权重和（DWS）用于评估反演的分辨率。 3D初速度模型是根据地质信息和岩心数据构建的。根据时域反射数据验证的速度断层图的 4D 变化，我们成功地识别了在底切平面上方约 100 m 处向西北延伸 60 m 的解释洞穴传播。子集 3 中 Vp 和 Vs 的减小被解释为由于洞穴进展时的破裂过程。此外，我们观察到随着洞穴的进展，应力重新分布，其特征是高速度（Vp 和 Vs），这是由于对洞穴前面区域低速度值变化的补偿，洞穴开始坍塌。我们建议将速度断层图的显着变化作为即将崩落的指标。