Article from the February 2007 issue of
Earthquake of magnitude 3.4
hits Basel, Switzerland
Earthquakes in Switzerland are a regular occurrence, firstly as a result of Africa moving north and helping to form the Alps and secondly with Basel itself sitting at the southern end of the Rhinegraben, a seismically-active area of SW Germany. For the most part, these tremors are barely discernible but every so often, earthquakes of mag. 3.5 plus are registered. In 1356 an earthquake in Basel with an estimated magnitude of 6.2-6.9 caused extensive damage in the city and many castles in the surroundings that were popular retreats of the European gentry were completely destroyed. Recent research on the earthquake potential of the area argues that a large earthquake is again due.
On Friday 8 December around 17.45hrs, the earth trembled again. A loud bang heralded a quake of magnitude 3.4, shaking buildings and causing cracks to appear in walls, but this time the event was not natural but man-made. Within a geothermal project named 'Deep Heat Mining', that aims to provide heat and electricity from a deep earth source, a borehole with a depth of ca. 5km has been sunk and water under high pressure was being pumped in to increase permeability of the rock. Since the pumping started, many small tremors have been registered, the result of fracturing of the rocks surrounding the borehole, the effect that is required, but the mag. 3.4 event was completely unexpected. Work was stopped immediately and will not be resumed until further scientific analyses have been made, and the people responsible for the project are to be prosecuted, firstly because of the damage caused and secondly for scaring the local population.
From a report in '"20minutes' on-line news to be found at: http://www.20min.ch/news/basel/story/27421234, 9 December 2006
Annette
Annette
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Last modified on Friday, February 09, 2007 at 17:46
