reply to post by angelchemuel
My apologies, I missed this post.
Perhaps you could point me in the right direction of an Irish BGS equivalent please?
Regrettably there is no Irish equivalent. Actually pretty much all the earthquakes in Ireland - you can count them on one had for the last 10 years -
are picked up by the BGS so on the rare occasion we get one it should turn up there.
I believe I am right when I say that Ireland is the least earthquake prone area in the world when the traces from the leprechauns beating the bejesus
out of one another with their shillelagh's are removed.
Some say Antarctica is the least earthquake prone, but I don't believe that is true and it also has volcanoes and is a touch on the cold side (-89
deg F a couple of days ago)
Slightly off topic, can you explain if seismo's are set at different sensitivities, how then do they ratify the readings accross the world so
that a 5.0 means the same thing everywhere? I am probably being dense at this juncture! Lol!
Not at all. I hope this will explain it.
Let us say you have a seismo in an area where you never get very large quakes. You would want to turn the sensitivity of the display up so that the
smaller ones show. In an area where larger quakes occur normally you might want to turn the sensitivity down to compensate. These are only computer
There is nothing showing on the siesmos which I can see on IRIS (by the way the BGS site still seems to be down) so I have picked this one for
Graefenburg in Germany.
Take a look at the
time between 09:00 and 14:00 and you can see a few small quakes. By changing the sensitivity of the display we can see the earthquakes better, but all
the microseisms make it look messy.
Basically I have made the display so that more shows.
This goes the other way and shows less, but if there was a BIG quake there it would prevent it from saturating the display.
Whilst this is not exactly what is happening on the BGS displays since I am playing around with the IRIS recorders, the principles are the same.
The mV basically are voltages generated by the instrument being moved by a quake or disturbance. On the LMK instrument the display shows one vertical
line for each movement caused by 200 mV generated. FOEL is set at 781.25 mV so it would take a movement almost 4 times as strong to show the same
amount on the seismogram. At Yellowstone where the seismograms are often at 1600mV it would take 8 times the amount of movement to get the same size
squiggle as at LMK.
These are however ONLY screen representations and have no effect on the underlying data whereby the characteristics of the earthquake are determined.
It would be different if we were looking at paper traces but these are just generated for the computer screens and are not actually the exact data
anyway. The seismologists do not use these to determine the quakes.
This post about quakes at Yellowstone
what they see and what we see. They are not exactly the same since in that instance the drop outs are replaced with continuous flat line on the
seismogram we see.
By the way the fact that I can get some of the UK seismograms from IRIS means that the UK data is still being collected and analysed. It just is not
available on the web site.