Earth Tremor

Chat and items of interest about Crete and Greece.
Jeffstclair
Posts: 1097
Joined: Thu Sep 06, 2007 10:00 pm
Location: The centre of the universe

Earth Tremor

Postby Jeffstclair » Sat Nov 11, 2017 10:00 am

Anyone else feel it ...last evening it came from the south ,I felt two waves the second a little bit stronger .The epicentre was less than 30 km south of Μακρύ Γιαλός....

Mixos
Posts: 403
Joined: Mon Aug 13, 2012 8:26 am
Location: North East Crete or S.W.England

Re: Earth Tremor

Postby Mixos » Sat Nov 11, 2017 10:24 am

Yes, we felt it in our village near Sitia, Jeff. it was magnitude 4.4, according to the EMSC website. Quite lively for about 5 to 10 seconds with a noise like a sudden rush of wind. Didn't feel a second shock though.

altohb
Posts: 810
Joined: Sun Aug 05, 2007 2:51 pm
Location: Sitia

Re: Earth Tremor

Postby altohb » Sat Nov 11, 2017 10:36 am

Yes, felt it here as well, though as Mixos said, only one tremor in this area.

Jeffstclair
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Joined: Thu Sep 06, 2007 10:00 pm
Location: The centre of the universe

Re: Earth Tremor

Postby Jeffstclair » Sat Nov 11, 2017 10:37 am

Yeah I'm about 20 mins from Μακρύ Γιαλός so must be near you ...it wasn't so much a second tremor but one event with a ripple if that makes sense .. I felt it come and go ...

Kilkis
Posts: 9516
Joined: Sat Apr 21, 2007 3:58 pm
Location: Near Chania

Re: Earth Tremor

Postby Kilkis » Sat Nov 11, 2017 10:57 am

Each earthquake event simultaneously generates both P-waves and S-waves but they travel at different speeds so may reach you displaced in time. P- waves are longitudinal, i.e. like sound waves, while S-waves are transverse, i.e. like waves on a string. I guess it is possible that is why you felt two events slightly separated in time. I am not certain because I understand the principle but I don't know the details such as the relative speeds and how it is affected by the rock formation it is passing through.

Warwick

Jeffstclair
Posts: 1097
Joined: Thu Sep 06, 2007 10:00 pm
Location: The centre of the universe

Re: Earth Tremor

Postby Jeffstclair » Sat Nov 11, 2017 12:04 pm

Brilliant ,Warwick ...did you feel it down your end of Crete?

Kilkis
Posts: 9516
Joined: Sat Apr 21, 2007 3:58 pm
Location: Near Chania

Re: Earth Tremor

Postby Kilkis » Sat Nov 11, 2017 12:26 pm

No, but I only notice them if they are big and nearby. 4.4 at the opposite end of the island wouldn't register with me.

Warwick

PS Incidentally the P- and S- waves are how Earth scientists get measurements of the structure of the Earth. P-waves can pass through both solids and liquids while S-waves can only pass through solids. Both suffer refraction. So, if you observe them at a range of stations on the opposite side of the Earth, by examining the zones where different waves reach and don't reach plus some propagation theory you can build up a picture of the Earth's structure.

BST
Posts: 362
Joined: Wed Jul 10, 2013 3:29 pm

Re: Earth Tremor

Postby BST » Sun Nov 12, 2017 5:17 pm

There are also L waves which cause rippling of the earth's surface eg roads and railway lines. They are the slowest but are often responsible for toppling buildings and major damage.


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