WAVEFORM CROSS CORRELATION ANALYSIS FOR AFTERSHOCK DECAY MONITORING IN MINING REGION

• Main Author: Amalia, Rizka
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/61773
• Institution: Institut Teknologi Bandung

Production processes in underground mining provoke stress changes, rock failure, and seismicity. Large seismic event followed by its aftershocks causes damage to production area. Re-entry protocol restricts access to the affected areas during this time of elevated seismic activity in order to distance mine workers from the disaster. In this research, the author evaluates the decay rate of seismicity whereby the aftershocks are sequenced by waveform similarity. Cross correlation is applied to the recorded waveform following large seismic event. Secondly, curve fitting is assigned to the decay rate, and re-entry time is determined afterwards. Aftershock sequences are investigated from 20 distinct significant events resulting in 2 classes in which each feature differs. The result shows that the cross-correlation method is robustly able to detect aftershock sequence by ???????????????? 1.956 30th October 2019 event, located around the source up to 500 meters apart with the re-entry time of 19.145 hours where it is interpreted as shearing on the lithological contact and so the seismicity propagated anisotropically to the cave front which has acted as a weak zone. On the other hand, the second class depicts ???????????????? 2.2 11th April 2019 event yielding the re-entry time of 0.801 hours as well as detecting its aftershock sequence with the distance ranging from 400-1000 meters apart. This pattern of seismicity which has shown the existence of seismic gap is interpreted as crack opening mechanism resulted by stress migration from the cave to weak zone inducing seismic cluster 600 meters apart from the major event.