The British Geological Survey recorded
a Magnitude 1.1 Earthquake at a depth of 2 km, about 1 km to the south of Norwood Hill in Surrey, England,
slightly before 6.15 am GMT (slightly before 5.15 am GMT) on Monday 2 September 2019. There are no
reports
of any damage or casualties associated with this Earthquake, and nor
would they be expected with such a small event, people have reported
feeling it locally.
The approximate location of the 2 September 2019 Surrey Earthquake. Google Maps.
This is the latest in a series of shallow Earthquakes in the area, which
began with a Magnitude 2.6 event on 1 April 2018, the first recorded
Earthquake in Surrey in over 268 years, and included a Magnitude 2.4
event on 14 February, Magnitude 2.0 event on 19 February, and magnitude 3.1 event on 27 February this year. Local
residentshave raised concerns that these events may be linked to oil
and gas exploration in the region, and have formed a protest group, Frack Free Surrey, which has called for a moratorium on such
activities, a demand which has won the support of several senior British geologists, though the British Geological Survey has not been able to
establish a link between the Earthquakes and the drilling, and the companies involved UK Oil & Gas PLC, and Angus Energy, deny such a link is even possible.
Letter written to The Times newspaper in London in August 2019, by four senior British geologists, Stuart Gilfillan, Stuart Haszeldine, Bill McGuire, and Richard Selley, calling for a moratorium on explorationary oil drilling in Surrey. Drill or Drop?
Earthquakes become more common as you travel north and west in Great
Britain, with the west coast of Scotland being the most quake-prone part
of the island and the northwest of Wales being more prone to quakes
than the rest of Wales or most of England. However, while quakes in
southern England are less frequent, they are often larger than events in
the north, as tectonic pressures tend to build up for longer periods of
time between events, so that when they occur more pressure is released.
The precise cause of Earthquakes in the UK can be hard to determine; the
country is not close to any obvious single cause of such activity such
as a plate margin, but is subject to tectonic pressures from several
different sources, with most quakes probably being the result of the
interplay between these forces.
Britain is being pushed to the east by the expansion of the Atlantic
Ocean and to the north by the impact of Africa into Europe from the
south. It is also affected by lesser areas of tectonic spreading beneath
the North Sea, Rhine Valley and Bay of Biscay. Finally the country is
subject to glacial rebound; until about 10 000 years ago much of the
north of the country was covered by a thick layer of glacial ice (this
is believed to have been thickest on the west coast of Scotland),
pushing the rocks of the British lithosphere down into the underlying
mantle. This ice is now gone, and the rocks are springing (slowly) back
into their original position, causing the occasional Earthquake in the
process.
(Top) Simplified diagram showing principle of glacial rebound. Wikipedia.
(Bottom) Map showing the rate of glacial rebound in various parts of
the UK. Note that some parts of England and Wales show negative values,
these areas are being pushed down slightly by uplift in Scotland, as the
entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.
Witness accounts can help scientists to understand Earthquakes and the
geological processes that cause them. If you felt this quake (or if you
were in the area and did not, which is also useful information) then you
can report it to the British Geological Survey here.
See also...
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