Earthquake discussion

doctormog
Advanced Member Topic Starter

09 October 2016 13:50:46

This thread is for general earthquake discussion.

Not that I think it is significant but what prompted me was the magnitude 4.8 quake off the west coast of Norway http://earthquake.usgs.gov/earthquakes/eventpage/us20007cxs#executive

The reason it made me stop and ink is becaus it is in a very similar location to that of the massive historical underwater land slip known as the Storegga Slide (and not I don't expect a repeat). https://en.m.wikipedia.org/wiki/Storegga_Slide

Anyway as mentioned, this thread is for any general earthquake-related discussion and will be kept "sticky".

Aberdeen

Current conditions (personal WS)

ozone_aurora
Advanced Member

09 October 2016 17:58:00

#2

The BGS downgraded it to 3.8 magnitude.

This area is seismically quite an active area; there was a 4.8 M event in January 2007, and the strongest quake in the last 100 years was a 5.7 M event in 1927. Oil and gas installations have to be designed to cope with potentially damaging earthquakes in this area.

This area has been unusually quiet in the last few years compared to more active periods in 1980's and 1990's.

Edited by user 09 October 2016 18:05:22 | Reason: Not specified

doctormog
Advanced Member Topic Starter

09 October 2016 18:40:41

#3

http://static3.emsc.eu/Images/EVID/53/536/536076/536076.regional.seismicity.mag.jpg )

Not massively unusual, just with a mention.

Aberdeen

Current conditions (personal WS)

ozone_aurora
Advanced Member

09 October 2016 19:05:32

#4

Yes, thanks for mentioning it. I find earthquakes in North Sea & Norwegian Sea interesting, prompting me to reply.

I am surprised by BGS downgrade (and perhaps little disappointed, although I don't wish any damage to installations-and glad there hasn't been any).

lizsecurro
Guest

16 October 2016 10:53:43

#5

We haven't been convincing enough with the rest of the world regarding 'climate change', so you know the liberals will blame this on the US as usual. why do earthquakes happen

doctormog
Advanced Member Topic Starter

16 October 2016 11:51:34

#6

Welcome to the forum - can you do me a favour and elaborate on what you mean by the above post (to prove it is not spam).

Elsewhere I notice there was quite a sizeable moderate quake swarm in Greece overnight

http://earthquake.usgs.gov/earthquakes/map/#%7B%22autoUpdate%22%3A%5B%22autoUpdate%22%5D%2C%22basemap%22%3A%22grayscale%22%2C%22feed%22%3A%221day_m25%22%2C%22listFormat%22%3A%22default%22%2C%22mapposition%22%3A%5B%5B39.500861822379136%2C20.29998779296875%5D%2C%5B40.15683567591309%2C21.26678466796875%5D%5D%2C%22overlays%22%3A%5B%22plates%22%5D%2C%22restrictListToMap%22%3A%5B%22restrictListToMap%22%5D%2C%22search%22%3Anull%2C%22sort%22%3A%22newest%22%2C%22timezone%22%3A%22utc%22%2C%22viewModes%22%3A%5B%22list%22%2C%22map%22%5D%2C%22event%22%3Anull%7D

Aberdeen

Current conditions (personal WS)

lizsecurro
Guest

17 October 2016 10:27:13

#7

On September 3, 2016, a magnitude 5.6 earthquake that occurred in Pawnee, Oklahoma, was recorded by Weston Observatory (see seismogram below). This earthquake is tied with another magnitude 5.6 earthquake in Prague, OK (November 6, 2011) as the two largest known earthquakes in Oklahoma.

Edited by moderator 17 October 2016 10:32:30 | Reason: URL removed spamming suspected

doctormog
Advanced Member Topic Starter

17 October 2016 10:33:13

#8

Second request. Please reply to this message to confirm you are not spamming or both your messages will be removed and your account locked. Thanks.

Aberdeen

Current conditions (personal WS)

DEW
Advanced Member

26 October 2016 21:07:09

#9

http://www.dw.com/en/strong-earthquake-strikes-central-italy-shaking-historic-buildings-in-rome/a-36165190

Some reports say two separate earthquakes

https://www.rt.com/news/364216-italy-quake-hits-perugia/

"Quick zephyrs blow, vexing daft Jim" - another weather pangram

doctormog
Advanced Member Topic Starter

26 October 2016 21:16:04

#10

Originally Posted by: DEW

http://www.dw.com/en/strong-earthquake-strikes-central-italy-shaking-historic-buildings-in-rome/a-36165190
Some reports say two separate earthquakes
https://www.rt.com/news/364216-italy-quake-hits-perugia/

Yes, there were two quakes - one at 17:10UTC (M5.5) and a stronger one at 19:18UTC (M6.1).

Aberdeen

Current conditions (personal WS)

doctormog
Advanced Member Topic Starter

28 October 2016 20:39:22

#11

And another quake in the Tyrrhenian Sea this evening, magnitude 5.9. It certainly continues to be very active in that whole region in recent days and weeks.

Aberdeen

Current conditions (personal WS)

doctormog
Advanced Member Topic Starter

30 October 2016 07:40:49

#12

...and another very large quake in the region this morning at magnitude 6.6. Not good.

Aberdeen

Current conditions (personal WS)

DEW
Advanced Member

30 October 2016 10:24:39

#13

Is there precedent for a string of near-major earthquakes in this or any other region? (I concede that a 6.6 feels major if you're in the middle of it, but with the logarithmic scale used, it's a long. long way off a 7.5, say). And if so, what happened thereafter? With Italy being a volcanic region, often a fact overlooked since it's been quiet for a generation (Vesuvius in 1944), should we expect some magma movement and eruptions which are now overdue?

"Quick zephyrs blow, vexing daft Jim" - another weather pangram

doctormog
Advanced Member Topic Starter

30 October 2016 12:57:04

#14

Originally Posted by: DEW

Is there precedent for a string of near-major earthquakes in this or any other region? (I concede that a 6.6 feels major if you're in the middle of it, but with the logarithmic scale used, it's a long. long way off a 7.5, say). And if so, what happened thereafter? With Italy being a volcanic region, often a fact overlooked since it's been quiet for a generation (Vesuvius in 1944), should we expect some magma movement and eruptions which are now overdue?

It's a good question and I'm not sure if anyone would have a definitive answer. You could say that in some cases the quakes have been releasing tension that had built up but in this case the suggestion has been more of a case of one quake leading to instability in another part of the fault region in turn leading to further quakes.

I did wonder about the potential link to volcanic activity but have a hunch it would be a tenuous one. However I would be very surprised if the experts are not checking...just in case.

In the immediate future I would expect to see the aftershocks continue for a few days but whether there are more quakes in this area of magnitude - I've no idea. It's what makes the situation so fascinating but equally so potentially deadly.

Aberdeen

Current conditions (personal WS)

Patrick01
Advanced Member

31 October 2016 05:48:41

#15

Good post over on Volcano Cafe about this:

http://www.volcanocafe.org/the-apennine-fault/

Looks as though there is a history of faults 'unzipping' in that area and it looks to be purely tectonic, though it may not be fully over which must be concerning for people living in the region.

I'm no expert, but from what I've read the connections between tectonic events and volcanic activity tend to be tenuous at best, and difficult to prove. A famous example of a potential connection between the two would be the 62 AD Pompeii earthquake, which was of course followed 17 years later by the 79 AD eruption of Vesuvius.