Rockbursts are serious worldwide problems in deep underground mines. These rockburst problems usually involve violent failures and ejection of large quantities of rock, ranging from a fraction of a cubic meter to thousands of cubic meters. The seismic energy associated with the rock ejection process can reach the equivalent of a magnitude five earthquake as designated on the Richter scale. Catastrophic rockbursts can lead to fatalities, injuries, damage to mine facilities, premature mine closures with abandonment of large reserves, and loss of production. Rehabilitation cost of rockburst damage often amounts to tens of thousands of dollars. Although systematic observation and research have improved the understanding of rockburst mechanism(s) over the years, they still occur and remain a serious problem in the mining industry.
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Maybe it's the "because" is where we may differ....

& your definition of a quake ... hmmm.

$.02