| MadSci Network: Earth Sciences |
Chris - A good question! In fact, fluid pressures probably do effect seismic shifts of the ground. Extremely high fluid (water or brines usually) pressures can create enough stress to allow seismic shifts to occur. Although, there may also be instances where larger fluid pressures act more like a lubricant and allow the the ground to move, but without the seismic effects of an earthquake, more of a smooth shift. There were instances several decades ago where large amounts of waste fluid were being pumped at pressure to great depth near Denver. During the time of this pumping there was a noticeable increase in small earthquakes (around magnitude 3-3.5 if I remember correctly) in this usually quiet area. So, human activity can have a small effect on local earthquakes. As for the oil question, I am not so sure. I am not aware of any evidence that oil extraction has been associated with significant seismic activity (maybe the pressures at which the oil resides are too low to be significant, or maybe there just isn't enough of it relative to water). In addition, the earthquakes in Turkey and Taiwan are in areas historically known to have a significant seismic hazard. It is extremely unlikely that any of the major earthquakes in these areas are related to human influence. Steve
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