The other day there there was an Earthquake which could be felt through Oxfordshire (see the source here). I have actually been unwittingly forced into some geological studies through my new degree. My brother is a geologist at Manchester University and I often tell him the study isn’t exactly my cup of tea, so to be sat there with a hand lens on a Saturday looking at a lump of peridotite reeks of hypocrisy. Anyhow; as seemingly half the population say these days “it is what it is”.
The little earthquake in the UK got me thinking, naturally about the frequency of such events. I know that when you are in a country like Japan little rumbles in the Earth aren’t anything to get excited about. Well when doing my research I found a wonderful and fairly complete resource from the British Geological Society, that lists all of the UK events here. As you can see from this, the UK is no shorter of seismic activity than a lot of the regions that suffer from quakes – it’s just the magnitude that is far less. For those that are interested, there is a world listing here.
Of course the important thing with earthquake magnitude, measured on the Richter scale is that it is a power of 10 measure. There is no special mathematical reason why this should be so, it is simply a logistical reason. If you want to capture earthquakes which occur in Oxfordshire, along with earthquakes which ruin entire cities you need a pretty enormous scale. It does of course mean that an earthquake of magnitude 4.00 is 100 times larger than an earthquake of magnitude 2.00 – not double.
For the mathematically minded, the Richter scale is actually just the logarithms of the waves (base 10) recorded by a seismograph. The only complication is of course the seismograph readings need to be adjusted to take into account the distance from the epicentre (which is NOT where the quake happened, this is the focus – it is the place on the ground directly above the focus).
The only thing I have to finish up with is this neat little infographic, which nicely ties together Richters and energy. Remember an earthquake is nothing more than a release of seismic energy.
That’s all from me now – I am trying to write less but more often, to keep up the posting.