Can coal fires cause earthquakes to happen, or possibly prevent or postpone earthquakes? Also can coal fires trigger(or prevent) volcanic eruptions by affecting flow of magma underground or by some other means?
1 Answer
I'm assuming you mean underground fires within coal seams whether they are caused naturally or through human neglect or error.
Regarding the possibility of them "triggering volcanic eruptions by affecting the flow of magma or by some other means", the answer is no.
Underground coal seam fires are mostly smoldering type fires rather than raging fires, due to the lack of oxygen underground. Most are located far away from sources of magma: either laterally or in terms of depth.
Concerning whether coal seam fires can "cause, ... prevent or postpone earthquakes", they cannot prevent or postpone earthquakes. Can they cause a seismic earthquake? Unlikely.
Coal seam fires create a void underground. If the fire is extensive and the extensive burnt out zone abuts an active geological fault the resultant void may cause a ground stress redistribution which might cause a minor earthquake. The other possibility is that the geological strata overlying the burnt out void is weak and eventually subsides, either slowing or quickly. A quick subsidence can create a minor earth tremor and could cause a hole to puncture the surface of the earth, depending on the depth of the coal seam and the void.
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1$\begingroup$ Coal fires by their nature only occur in surface sedimentary rock. If the fire goes low enough it will encounter the ground water levels or collapses that will eventuality seal off the burn. The fires can result in large scale surface subsistence but nothing that would trigger a significant earthquake or create a channel for magma to flow if it was near by. In the area I worked in the fires only occurred on ridges and only burned slowly. The biggest issue was the forest fires they would start. $\endgroup$– user824Jan 2, 2019 at 18:49