Raving Ravens

Earthquakes in Iceland

This morning many inhabitants in Reykjavik were woken up by an earthquake that measured around 4 on Richter. It was the biggest one in a series of earthquakes that started in the Krýsuvík area south of Hafnarfjordur around 3 am. Since then 4 other earthquakes over 3.0 on Richter have been detected in the area, the biggest one being 4.1 on Richter.

I live only a few kilometers from the epicenter and it is not uncommon to feel earthquakes here. Not that it is daily events, but happens maybe like once a year. None of them is dangerous though with the biggest ones just over 4 on Richter and today's earthquakes do not worry us in any way.

The last 24 hrs have been unusually active though with over 400 earthquakes detected, 76 of them over 2 on Richter. The surface of the earth has been rising in the area of a few centimeters which might point to increased magma pressure. We are surrounded by volcanoes but the last eruption was more than 700 years ago so theoretically, yes, it is possible, but it is still extremely unlikely to happen any time soon. 

Once every 100 years a rather big earthquake strikes southern Iceland and it struck May 29th 2008, measuring 6.3 on Richter. It didn't cause any serious injuries and only caused some damage around the epicenter. All houses are built to withstand much stronger earthquakes than that without collapsing. Larger earthquakes than that are extremely unlikely to happen. The reason is simple. The strongest earthquakes happen where the tectonic plates are being thrust towards each other but here in Iceland they are moving away from each other, making the tension and the pressure less in the earth.

There is therefore no reason be frightened if you ever feel an earthquake in Reykjavik. Some may experience it as unpleasant, others as exciting, but it should never become life threatening. 

Hjörtur
Reykjavik, shaken but not stirred.  

Flooding from Grímsvötn Volcano in Vatnajökull Glacier

More seismic activity has been registered in the last few days with several earthquakes between 3 and 4 Richter scale. Most of them have been around Blönduvirkjun north of Langjökull and Hofsjökull (on Kjölur highland road). There was one earthquake registered 3.0 on Richter in Grimsvötn in Vatnajökull Glacier today suggesting that some flooding might be expected, and it just started few minutes ago. 

Grímsvötn is a subglacial lake in Vatnajökull located on top of a magma chamber. Melting water from the glacier builds up in the lake until it bursts down in a big flood to the sea. The last big flooding from Vatnajökull was in 2004. There's is little danger from the flooding as the whole area is uninhabited (because of regular floodings) but it can damage roads and bridges though. 

This map shows seismic activity in Iceland in the last 48 hrs. The green stars are earthquakes larger than 3.0 on Richter scale. As you can see there are several in the same spot in north of Langjökull and Hofsjökull glaciers (the second and third largest white spots) and there is one in the large white spot which is in Grímsvötn in Vatnajökull. The flooding comes from beneath the ice south of the green star heading to the sea. 

Scientests are monitoring the flooding closely. It has usually gone down the Skeidara river but this time it seems to be going down Gígjuá river. As the glaciers have been shrinking the edge of the glacier where the water surfaces is further inland than last time. This results in the water taking a different path. 

The flooding is expected to reach up to 3.000 square meters per second, severely bigger than the flooding in Markarfljot river during the eruption in Eyjafjallajökull. When the pressure from the water is released from the top of the magma chamber it can lead to an eruption. Scientists have already predicted that the next eruption will be coming from Grímsvötn, one of Iceland's most active volcanoes, and this increases the probability. 

Hjörtur Smárason

ps. I'll be posting news, pictures and videos about earthquakes and volcanic eruptions in Iceland here as they happen, so make sure you subscribe to us through RSS, Facebook or follow me on twitter where you get the most frequent updates and can ask questions about the situation (my twitter is not a feed, it's me in person). 

Volcanic Activity in Iceland - The Next Eruption?

Gjálp eruption 1996. Notice the plane for scale! Photo by Oddur Sigurðsson

  Bárðarbunga Volcano - Iceland's largest volcano
Last night two rather powerful earthquakes (3.5 and 3.7) were in Bárðarbunga, a large stratovolcano in Vatnajökull glacier. Bardarbunga is probably Iceland's largest volcano, 2009 meter high and the crater being 10 km wide. 8.500 years ago Earth's largest lava flow came from that crater covering some 950 squarekilometers. The volcano is a part of Iceland's largest volcanic system stretching 200 km and being up to 25 km wide. There has been seismic activity recorded in the volcano in the last years so these earthquakes are not unique and do not mean there is anything that indicates an eruption in the coming days or months. But it is a reminder that the volcano is alive and a possible threat. In 1996 the Gjálp eruption in Vatnajökull started with a 5.6 earthquake on Richter scale in Bárðarbunga. The earthquake make a regular circle around the volcano. You can read more about the earthquakes in Bárðarbunga volcano here. The last two eruptions in Bárðarbunga took place in the year 870 and 1477. If that's an indication on how far it is between eruptions there, we should see another one this century.

 

Is Katla Volcano about to erupt?
Katla volcano has been discussed a lot following the eruption in Eyjafjallajokull in March 2010. History shows us that an eruption in Katla often follows an eruption in Eyjafjallajokull (meaning within two years). On the other hand, the eruption in Eyjafjallajokull started in Fimmvorduhals, a passage between the two volcanoes which could have released the pressure of Katla and made it more unlikely to erupt soon. I have earlier discussed how likely Katla is to erupt.

 

The Infamous Hekla Volcano
One of Iceland's most famous volcanoes is probably Hekla Volcano, and it is also one of the most active ones. In the last 100 years it has erupted 6 times, in 1913, 1948, 1970, 1980, 1981, 1991 and 2000. The one in 1948 was the most powerful one with the one in the year 2000 only being a minor one. After a very destructive eruption in 1104 it was believed to be the gateway to Hell! In the last 40 years it has erupted every 10 years, and it's been 10 years since the last one. Thus many are expecting an eruption soon, but this has not been a pattern for long and therefor no reason this pattern will continue. There are no other indications that Hekla is about to erupt. 

There are hundreds of active volcanoes in Iceland and an eruption occurs on average every 5 years in Iceland. Where and when the next one will take place is hard to say but they are all well monitored and do not pose any significant security risks to tourists. You can read more about how safe it is to travel to Iceland here. 

The best indicators of an eruption are earthquakes and the rise of mountains. The Icelandic Met Office monitors earthquakes and has GPS monitors on the volcanoes to measure the rise. Below you'll see a video made by Datamarket that shows the seismic activity leading up to the Eyjafjallajokull eruption in the spring of 2010:

 

Hjörtur

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