On shaky ground?
STOP PRESS – a further quake of 0.3ml (5 times stronger than the strongest one yesterday – a 0.2 ml ) has occurred this afternoon
The regulations require fracking to proceed with caution when induced seismicity reaches 0.0-0.5 magnitude (amber) and stop immediately (red) if it reaches 0.5.
We are already in Amber territory!
AND ANOTHER ONE!!
So yesterday, a few days into Cuadrilla’s fracking operation began we have started to see a resurgence in seismic activity in the locality.
These quakes are clustered approximately 1.5 km from the site. The lateral well that is being fracked is 782m in length according to Cuadrilla’s Hydraulic Fracture Plan but extends further away from the site due to the initial curvature of the vertical well. In the image below the red pin is the centre of the site, the red line represents the assumed approximate length and trajectory of the well based on an image provided to the BBC by Cuadrilla, and the yellow flags are the locations of the three quakes monitored yesterday. This may of course mean that there is no link between the fracking and the quakes, but the coincidence is remarkable.
Professor David Smythe commented on Drill or Drop that
Seismic expert Stephen Hicks from the University of Southampton dismissed these quakes as simply what we might expect from fracking
However it is not immediately clear why the quakes are dislocated in terms of time from the actual fracking activity.
Fracking must have stopped at 6pm at latest, so between 4 and 6 hours after any fracking was happening. It is also interesting to note that there was no seismic activity at all recorded by the BGS during or immediately after the frac jobs on 28th March 2011 or 9th April 2011.
So what is the significance of these new earthquakes. Clearly we don’t actually know yet, but what is clear is that seismic activity in the locality is relatively rare. The graphic below shows all of the earthquakes recorded by the BGS in a circle 25Km around the fracking site at Preston New Road before this recent cluster. There are 60 of them and 51 of these were recorded as a result of fracking at Preese Hall in 2011 (these are highlighted with a red background.)
So what we can see here is that 5% of the earthquakes ever recorded in the vicinity of the pad have occurred in the last 24 hours, and that the weakest of these 3 quakes was stronger than 21 of the 51 quakes associated with fracking at Preese Hall. The strongest was stronger than more than half of those quakes.
To put the quakes into context they would have to be at least 10 times stronger in terms of energy release to trigger the 0.5ml threshold to stop fracking, and it has to be said that there is nothing to prove beyond doubt that fracking caused these quakes.
Having said this research by the University of Stanford in the USA suggests that microseismic activity may be precursors of more significant activity to come.
These small earthquakes may act like canaries in a coalmine,” said study co-author William Ellsworth, a professor (research) of geophysics at Stanford’s School of Earth, Energy & Environmental Sciences. “When they happen, they should be viewed as cautionary indicators of underground conditions that could lead to larger earthquakes.
If all we see is a recurrence of quakes at this magnitude we may, of course have nothing to be worried about. However, it is concerning that this seismic activity does not seem to be associated with every frack – if it were then it might simply be the inevitable accompaniment to the hydraulic fracturing activity, but this doesn’t seem to be the case.
We will be keeping a close eye on the BGS data here https://earthquakes.bgs.ac.uk/earthquakes/recent_uk_events.html
Needless to say The Rev Roberts posting as Backing Fracking is spinning like a demented top and is trying to discredit anyone who raises valid concerns
I wonder how he will explain the latest quake today?