Tsunamis

Steve Fifield · Post by **Steve Fifield** » Fri Dec 31, 2004 11:20 am

We feel similarly shocked and helpless about the current situation in Asia, and have donated to [Editor: broken link removed]. I suppose that every little will help.

Regarding activity in the Caribbean, I certainly wouldn't want to put anyone off travelling, as disaster could strike anywhere, but it is quite an interesting area. Two years ago, I remember that people in Tobago were concerned about the possibility of a Tsunami there. I found this article, no longer accessible on the web:

RECENT TSUNAMIS OF VOLCANIC ORIGIN IN THE LESSER ANTILLES REGION

In recent times, Soufriere Hills on Montserrat, Kick'em Jenny near Grenada, Soufriere of St. Vincent, and Mt. Pelée on Martinique, are volcanoes in the Lesser Antilles region that have generated local tsunamis by renewed volcanic activity and associated flank failures and landslides (Lander et al 2002). Given the degree of violent volcanic activity and the flank instabilities of stratovolcanoes in the region, it is believed that the occurrences of tsunami waves have been under-reported in historical records, probably because the effects of such sea level disturbances were either localized or were overshadowed by greater catastrophes caused by violent volcanic eruptions The following is a brief overview of some of the reported historical tsunami events. .....

Kick'em Jenny is an active and growing submarine volcano about 8 km off the North side of the island of Grenada, which erupted frequently during the 20th Century (Smithsonian Institution, 1999). There have been several local tsunamis generated by these eruptions. The volcano's first recorded eruption reportedly occurred in 1939, but undoubtedly there were many unreported occurrences before that date. Since 1939 there have been at least ten more eruptions. The better known are those that occurred in 1943, 1953, 1965, 1966, 1972 and 1974. The 1974 eruption was major.

The pattern (if there can be one?) looks like a 10 year cycle, but with nothing happening in the last 30 years.

The recent disaster seems to have woken up CDERA as reported in the Jamaica Observer:

- Wednesday, December 29, 2004

Caribbean in talks to establish tsunami warning system

The Caribbean Disaster Emergency Response Agency (CDERA) yesterday said that there was no formal tsunami early warning system in the region, but the agency was in discussions with at least four institutions with the aim of setting up one....
http://www.jamaicaobserver.com/news/htm ... SYSTEM.asp

Also see CDERA's official press release: http://www.cdera.org Sobering stuff, however really no more likely today than yesterday, and the official report says that "They can therefore occur in the Caribbean however, the probability is low".

Should we eat, drink and be merry? We arrive in Tobago tomorrow, and I'm sure that the locals will insist that we do.

Steve F.

Paul Tallet · Post by **Paul Tallet** » Fri Dec 31, 2004 8:00 pm

Hi Steve

Interesting ...

I think that every country in the world with a coastline is at risk of being affected by a Tsunami, simply because Tsunami devastation can occur over such a wide area and not necessarily be restricted to an Earthquake risk zone (i.e.; the cause of the Tsunami could be half way around the globe).

The good news for Tobago is that the Caribbean's seismicity is influenced mainly by tectonic activity from volcanoes and the actual faultlines around the Caribbean do not appear to have any 'subduction' zones similar to the trench off western Indonesia where last week's catastrophe manifested itself.

On this basis, any local seismicity is unlikely in the extreme to be as severe as the Asia event and consequently any locally generated Tsunami activity is unlikely to be anywhere near as destructive.

Even the Mid-Atlantic trough is unlikely to cause considerable Tsunami due to the type of faultline it is (i.e.; the plates are moving apart) ... although I acknowledge that there is a risk of a substantial land slip in the Canaries that could potentially cause problems all around the Atlantic one day.

The Asia event was 9 on the scale and only 3 other events of this magnitude are recorded in living memory ... 2 just off Alaska and 1 off the Chilean coast ... even these events happen only once every 2 or 3 decades.

Indonesia has a history of 'subduction' quakes where 2 plates suddenly slip but none of these on the scale of last week ...

What happened last week was quite awesome ... the changes underwater have yet to be seen, however it is estimated that a line, 1,200 kms long, of subduction occurred between 2 plates ... the overriding plate moved upwards aboyut 100 feet (just imagine a 100 foot cliff being formed in 0.5 seconds !!) ... the upwards motion pushed billions of tonnes of waters skywards and caused the Earth's cycle to wobble ... so you need to adjust your watch backwards by 0.3 seconds !!!

The rest is history and the affects of this disaster will get worse before they get better ... my thoughts are mainly with the Indonesians because the whole thing is quite incomprehensible and I am still struggling to take stock of this tragedy.

But, please be assured that a disaster of this type and scale can only happen in a few parts of the world and not in the Caribbean.

I hope this is of some assurance.

Regards

Brian Taylor · Post by **Brian Taylor** » Sat Jan 01, 2005 12:39 pm

thanks for making us feel a bit safer already!!! living at a coastline it gives you even more goosebumps, when you see the traqgic pictures!
would be glad if you keep us informed, the local news are as everything here...a bit slow.... relaxed... laid back....

to steve: yea. we INSIST on you enjoying yourself as much as possible, especially since not doing so would not help anyone... guess the only help can be financial...

you all take care and have a great (better) 2005...

Paul Tallet · Post by **Paul Tallet** » Sat Jan 01, 2005 2:55 pm

Hi Brian

For those of you that need to know ...

There have been 104 aftershocks since the big one. Many of these exceeded 6 on the scale and 2 shocks exceeded 7. the last one this morning was 6.6.

The quake was a 'mega-thrust' event so it will be a long time before we can know if it released years of pressure and this event will not happen again in 200 years ... or ... if the thrust event is causing pressures in other areas and further major quakes could occur in the short term around the Pacific.

Tsunami have also been recorded along the north and south American coasts and New Zealand.

Officially 150,000 dead so far, many more missing ... Indonesia got to 80,000 and stopped counting ... judging by the population in the affected areas of Indonesia where damage was 'total' one could speculate that there were 100's of thousands that perished plus the bodycount in other areas.

Probably not know the real scale of this tragedy for years to come.

With Regret

Brian Taylor · Post by **Brian Taylor** » Sat Jan 01, 2005 10:56 pm

yeah, it is unbelievable. it makes the damage that ivan did to grenada look small, altough devastating for the people and the island....

Paul Tallet · Post by **Paul Tallet** » Mon Jan 03, 2005 3:50 am

Here is an excellent site from Puerto Rico that assesses the risks of Tsunami in the Caribbean.

http://poseidon.uprm.edu/

There is also a link on the site to another excellent report from the New York Times about the Asia Tsunami.

Hope this is of assistance to those who need to know.

Regards