| Popis: |
In this chapter, I presented seismic data that was made available for analysis and interpretation. This data originated from four mines: El Teniente Diablo Regimento Sector (DR Sector), Northparkes Mines Lift 2 (NPM), PT Freeport Indonesia DOZ Mine (DOZ) and Palabora Mining Company (PMC). I have compared small size events that were recorded at the different mines against each other. The presented very basic data analysis leads to two important conclusions: Hydro-fracturing resulted in seismicity with lower seismic energy releases than in other mines. One of the mines was using a different and faulty version of the seismic processing software. These conclusions were only possible because the analysis involved seismic data recorded in several mines. With regard to quality control of some of the seismic databases, the facts indicate that the quality decreases when the processing task is given to external contractor who is operating outside of the mine. Most of the recorded small size seismic events are an indication of the cave propagation process. This seismicity is a natural process indicating that the cave is progressing. The space and time distribution of these seismic events along with the changes of their source parameter values over time should be associated directly with what is happening in the rock mass around the cave and the mining excavations. Unfortunately, this is not always true as in some cases these changes can also be attributed to the difference in software versions or to the reprocessing after a new version of the software was installed. |
