ABSTRACT
The German mining districts are well known for their deep longwall coal mining operations. Currently the average operating depth is below 1200 m and due to the high stresses and strong rocks/rock masses there is an abundance of seismic events with considerable local magnitudes. Coal mining activity and the occurrence of seismic events show good correlation in space and time so there is little doubt about the causes for the seismicity. There are some special features about the coal mining operations in the Germany which may be summarized as follows:
– The depth of mining today is below 1200 m. – The in situ stresses at depth are in the order of
19-44 MPa. – The rocks are very strong with a lower bound for
UCS of 50 MPa. – The strata are jointed, faulted and folded. – Typical seam height is some 2-2.5 m – The longwall excavation method is employed with-
out barrier pillars and single entry head-and tailgates.
