Icelandic Tsunami: unexpected danger
It might surprise you to learn that Iceland experiences flood waves, or tsunami fairly regularly. Icelandic Met office tsunami hazard assessment The government is as aware of the eventuality of another tsunami as it is of the potential for volcanic eruptions. Iceland actually has two causes of tsunami to fear. Both the immense power of a sea-borne tsunami that any nation with a coastline (particularly an island) faces, as well as inland tsunami, caused by rapid flooding. A sea-borne tsunami is much less likely, although still a very real possibility. The only recorded tsunami wave to reach Iceland's shores happened in 1755, and was caused by an earthquake near Lisbon, Portugal. While this earthquake and tsunami caused significant damage along European coasts, even as far as Ireland, Iceland is quite far away and the wave had lost most of it's power before striking the island. Tsunami risk-appraisal for Iceland. Tsunami are most often caused by earthquakes at subduction faults. Iceland's location atop a divergent fault, and it's distance from any subduction zones, means there is less chance for one of these devastating waves coming from the sea.
Hi, Brendan!
ReplyDeleteAnother very informative entry from you! I was actually not surprised that Iceland experiences tsunamis since it is surrounded by the Greenland Sea and the Atlantic Ocean, so I was actually expecting it. Due to the nature of its glacial volcanos, it looks that Iceland is very susceptible to tsunamis originating from volcanic eruptions under a glacier. I was so taken with the pictures showing the volcanic eruption under a glacier, if that's what they show. Please correct me if I'm wrong, which I very well may be... Quite a spectacular view!
hi Camelia! You are correct! The pictures and video from this week all show the same event: the glacial melt from the 2010 eruption of Eyefjallajokull bursting free in a massive flood wave. To be honest, I was most surprised this week to learn how LITTLE danger Iceland faces from sea borne waves. It was a learning experience to find that earthquakes at subduction zones are almost exclusively responsible for tsunami (barring massive landslides of course). It does make sense though due to the way the shape of a subduction fault matches a wave profile. Always good to hear from you, thank you for your interest! :)
ReplyDeleteI was thinking about the famous Storegga underwater Slide (off Norway, 6000 BC or sth like that). It provoked a megatsunami off the North Atlantic. I know it was a HUGE event and I guess it had to have affected Iceland...do you know if there is evidence on the island of this event?
ReplyDeleteThank you for the challenge Ana! I was not aware of these events, and they were quite significant! While the tsunami created by the most recent of these slides certainly impacted Iceland with a large force, information as to whether or not evidence exists on the island is conflicting. I have a very vague reference from " http://www.ecomare.nl/en/encyclopedia/natural-environment/water/water-currents/tsunamis/ " which merely states that "it's influence is apparent in Iceland." An excellent paper however, " http://home.hisf.no/steinbo/Marine%20geohazards/article.pdf " investigates the event in great detail and reported that "no field observations from Iceland" existed. Whether this is due to a lack of evidence or a lack of discovery I can't say, because their computer model does show a very large impact on the island. In any case it has been great fun to research, thanks again :)
ReplyDeletemmm...now we have to do a field trip and get samples.....(:
ReplyDeletein general, when you try to find 'tsunami layers' in the record, it is very useful is you have a 'muddy environment', like our coast in some places, so you look for a higher energy deposit like sand. That has been found in Crescent city and others. I think maybe I should try to find out if the Elkhorn Slough has any record of that (although it is pretty inland...)..maybe for a future project