Volcano and earthquake activity in Iceland
A geophone and seismometers record a lot more then just earthquakes, they also record noise from all types of things. Most common is the wind, but also cars, people, animals and other things.
The GeoNet in New Zealand has put together a great guide on this noise sources.
This guide can be viewed here.
Seismic Monitoring of Volcanoes (geonet.org.nz)
Following the two large earthquakes (ML3.5 and ML4.2) there was a swarm of small earthquakes in that area. The earthquakes where seen on Grímsfjall SIL station, but do not appear to have been strong enough to be recorded on other SIL stations around Vatnajökull glacier. This appears to have lasted until around 13:00 UTC on 13th of January 2011. But after that it did quiet down.
Plot is from IMO web site.
Icelandic Met Office tremor plot that shows the two large earthquakes and following minor earthquakes. This area in Grímsfjall volcano has been quiet since the two earthquakes took place few days ago.
Earlier this morning there where two earthquakes in Grímsfjall volcano. There size was ML3.5 at 09:06 UTC and ML4.2 at 09:22 UTC. I am currently unsure about the depth of this earthquakes. This earthquakes take place in a area north-east in the Grímsfjall volcano system. But according to news this area has been seeing a increased earthquake activity in recent weeks.
No aftershocks have been detected since this earthquakes took place. But currently the weather is rather bad in this area, so that might be the explanation for the absence of earthquakes that should have followed this two earthquakes. According to the news the Icelandic Met Office is monitoring the area for more earthquakes or signs that a eruption might be starting. So far nothing indicates that a eruption is about to start in Grímsfjall volcano.
The area that was active today (13th of January 2011) in Grímsfjall volcano.
Icelandic News about this. Use Google Translate at own risk.
2 jarðskjálftar við Grímsvötn (Rúv.is)
Snarpur jarðskjálfti við Grímsfjall (Vísir.is)
Fylgjast náið með Grímsfjalli (mbl.is)
Jarðskjálfti við Grímsfjall (mbl.is)
Blog post updated at 13. January 2011 at 22:51 UTC. Picture has been added to the blog post.
A magnitude ML3.8 earthquake has hit Kverkfjöll volcano. This earthquake had the depth of 14,4 km according to the automatic SIL system.
This earthquake appears to have triggered earthquakes in Grímsfjall volcano. But two earthquakes appeared imminently after the ML3.8 earthquake in Kverkfjöll volcano. – This is not the case, the earthquakes happened before (09:06 UTC) the ML3.8 earthquake in Kverkfjöll volcano.
I have been going over the reviewed data on this earthquake. The web site EMSC is reporting this to be a ML4.0 earthquake that took place at 09:22 UTC, with the depth of 10 km. While IMO is reporting this earthquake to have the size ML4.2 (depth unkown). There was a earlier earthquake that took place at 09:06 UTC, it has has the size of ML3.5 (depth unkown). Both of this earthquakes took place in Grímsfjall volcano. There is a good chance that Icelandic Met Office is underestimating the size of this earthquake, given the data from EMSC and the fact that this earthquake was recorded on remote seismometer networks in Europe.
I am going to post updates on this if anything more happens.
Text updated at 09:49 UTC on 13th January 2011.
Text updated at 10:21 UTC on 13th of January 2011.
Text updated at 12:55 UTC on 13th of January 2011.
A string of small earthquake swarms took place yesterday. It started with a small earthquake swarm at Geysir volcano. The a small earthquake swarm took place at Hengill volcano few hours later. This string of earthquake swarm ended with a earthquake swarms did end with a short but powerful earthquake swarm out on Reykjanes Ridge. Where the largest earthquake was ML4.1 in size (depth 10,4 km) according to the automatic SIL system. All of this swarms lasted from 1 hour and up to 3 hours and the total number of earthquakes was something less then few dozens of earthquakes.
Besides this it remains rather quiet earthquake wise in Iceland. But that can change without any warning at any time.
Tonight at 01:34 UTC (9th of January 2011) a earthquake swarm started at Geysir volcano. So far this earthquake swarm is slow moving, but with the largest earthquake reaching the size ML2.7 at 4.2 km depth according to automatic earthquake detection system that Icelandic Met Office has (SIL system).
So far it is hard to know how this earthquake swarm is going to develop. As this area normally does not have a lot of earthquakes.
I am going to post more updates of there are any major developments in regards to this earthquake swarm at Geysir volcano. I do expect the largest earthquake to have been felt in nearby farms in this area.
In the last two days there have been a strong winter storm going over Iceland. The wind has been coming from the north with snow and cold weather. But this has also been followed by a strong wind all over Iceland and this strong wind has been preventing the SIL network from detecting micro-earthquakes in Iceland. Because of that it appears that Iceland has been unusually quiet on Iceland Met Office maps. This might not necessary be the case in reality. But due to a lot of wind noise the SIL network is unable to detect the smallest earthquakes that happen in Iceland. Some stronger earthquakes might appear on the SIL network if they take place.
So the quiet time in Iceland is down to weather, not something else. As the weather improves we should start to see micro-earthquakes again on Icelandic Met Office maps. It is always a good idea to check the weather forecast in Iceland if there is a sudden drop in earthquakes in Iceland.
Note 1: There are sometimes times however in Iceland when there is nothing wrong with the weather and yet still no earthquakes. What is going on there is simple, there are no earthquakes taking place in Iceland. This happens sometimes. But this is a rare, but it does sometime happen.
Over the last few hours it has been getting cold. The frost has been getting down to -10C and even colder in the higher areas. This has started a interesting events that takes place in Iceland (this might happen elsewhere too). But the events that take place here are frost earthquakes. This are not real earthquakes, but a event that the frost creates and are in fact false earthquakes. Most of them are too small and too poor in terms of quality to be located by the SIL network that Icelandic Met Office has. But when there is a sudden drop in temperature the frost earthquakes can appear on the SIL network, but with a extremely low quality. The driving force behind this earthquakes is water that is freezing in the ground and in rocks (cracks).
During the next 24 hours or so there is going to be a cold snap in Iceland with temperature going down to -20C in some areas, and even lower at glacier and higher areas. So we can expect a lot of frost earthquakes (false earthquakes) in that time. So the Icelandic Met Office maps might start to look interesting and with a lot of earthquakes in the next 24 hours.
Picture: Icelandic Met Office Picture saved: 6th January 2011 at 20:39 UTC.
Frost earthquakes on Fagurholsmyri SIL station close to Öræfajökull volcano and Esjufjöll volcano. This frost earthquakes are not located by the automatic SIL system.
The weather forecast in Iceland: Temperature
Iceland news about this. Use Google translate at own risk.
Frostbrestir í Eyjafjallajökli (Vísir.is)
Text is updated at 22:46 UTC on 6th of January 2011. News link is added.
The night of the 6th of January 2011 had few earthquakes in the Eyjafjallajökull volcano. This minor earthquake activity has been reported by the Icelandic media this morning. The news on this is not a long one. But confirms that some of the earthquakes in Eyjafjallajökull volcano are real (but might be wrongly located by the automatic SIL system). In the same news it is claimed that icelandic geologist are not concerned about this minor earthquake activity in Eyjafjallajökli volcano. But none of the earthquakes that did happen tonight (on the 6th of January 2011) did get over the size of ML2.0.
The news on the earthquake activity in Eyjafjallajökli volcano. Use Google translate at own risk.
Nokkrir jarðskjálftar í Eyjafjalla- og Mýrdalsjökli (Vísir.is)
The seismometers that British Geological Survey did pay for to be installed around Eyjafjallajökull volcano and Mýrdalsjökull (Katla volcano) have been integrated into the Icelandic Met Office SIL Seismometer Network. They have at least been marked into the Icelandic Met Office earthquake web page.
Image is from Icelandic Met Office. Copyright of this picture belongs to them.
The new stations are marked with a triangles on the map. The older SIL stations can be found at Icelandic Met Office tremor web page. Currently the new SIL stations are not on Icelandic Met Office Tremor web page yet.
What this means for earthquake recording in this area is that Icelandic Met Office is now able to detect smaller earthquakes. Location of earthquakes is also going to improve a great deal, so automatic location of earthquakes is going to improve a great deal in this area. This means that more earthquakes are going to be visible on Icelandic Met Office maps then before.