Earthquakes – Page 83 – Iceland geology

November 4, 2016

All quiet in Iceland at the moment

Over the past three weeks things have been mostly quiet in Iceland. With no major activity taking place. There have been few magnitude 3,0 and above earthquakes. Over the past three weeks the average number of earthquakes over 24 hour period is just 10 earthquakes. This is based on my automatic counter and it has slightly lower number than manually checked earthquakes. Icelandic Met Office says there are around 300 – 400 earthquakes taking place in Iceland during the week (1200 earthquakes at month).

The earthquake activity in Iceland at the moment. All quiet at the moment. Copyright of this image belongs to Icelandic Met Office.

It is not possible to know for how long this quiet period is going to last. Its already been three and almost four weeks already into this quiet period. All that can be done now is to wait and relax a little.

Donations

Please remember to support my work. I spend a lot of time writing to this website and its a lot of work. There is always something going on in Iceland, even during the quiet periods. Thanks for the support. 🙂

October 30, 2016November 1, 2016

Special report: The Italy major earthquake swarm

This is a special report on the earthquake swarm in Italy. Due this being a different country I only have limited information about what is going on in Italy and I don’t have complete knowledge of the area in question. News sources with detailed images of the affected earthquake area can be found here (English) and here (Italian). Those news articles also contains images of the affected areas and aftershock areas (I can only use the image from USGS on the English website).

The earthquake swarm in Central Italy

On 26-October-2016 an earthquake swarm started in Italy, it started with a magnitude 5,5 earthquake (EMSC Information). It was followed by a magnitude 6,1 earthquake (EMSC Information). The magnitude 5,5 earthquake is a foreshock (Wikipedia information) to the magnitude 6,1 earthquake and that is the main event in that earthquake swarm. The magnitude 6,5 earthquake (EMSC Information) today (30-October-2016) is a new earthquake swarm in the same area. It has been followed by a heavy aftershock activity, with more than 300 earthquakes/h taking place in the main earthquake area. It is my view, based on the aftershock pattern that one or more magnitude 6,0 or stronger earthquakes are going to happen in this area in the next few days to months (it’s impossible to know when they happen). It does not help that this area of Italy is crossed with fault lines and they are all active (in the sense they can and do make earthquakes every few decades to hundreds of years).

The magnitude 6,1 earthquake in Central Italy on 26-October-2016. This image is under Creative Commons Licence, please see CC Licence website for details.

The magnitude 6,5 earthquake in Italy on all axes (Z, N-S, E-W). According to the measurement that I saw on my geophone in Denmark, the movement was N-S rather than E-W. There appears to have been some vertical displacement in this earthquake. This image is under Creative Commons Licence, please see CC Licence website for details.

High resolution of the vertical component (Z) in my geophone. It clearly shows how the earthquake happened in central Italy. This image is under Creative Commons Licence, please see CC Licence website for details.

It is unclear how this is going to progress over the next few days, weeks and months. I don’t know enough about this area to make any type of guess. The area in question is a subduction zone (just not under a ocean) and that makes predicting this activity even more complicated and difficult.

Basic tectonic layout of Italy with earthquake activity on top. Image is from USGS.

There is also a factor that I don’t know about. How often does this happens over the century in Italy. There is only a small clue (and it’s not even clear) of the earthquake list for Italy on Wikipedia (best that I was able to find). In Iceland (for comparison), the SISZ has an earthquake swarm activity (major) every 13 – 90 years (I wrote a list about known earthquakes here). I don’t know how often this happens in Italy, but I suspect that it is at least every few hundred years. How often this happens is mostly controlled by how fast the faults move each year and I don’t have that information.

If anything more happens in Italy I’m going to update this article.

Update on 01-November-2016 at 23:50 UTC

This morning (1-November-2016) a magnitude 4,9 earthquake (EMSC Information) took place in Central Italy. Aftershock activity continues to be heavy in Central Italy. While this earthquake doesn’t look big, it is enough to create more damage into the effected areas. Aftershock activity continues to be heavy in Central Italy.

Donations

Please remember to support my work with donations. I also want to point out that due to unusual bill situation I’m going to be rather broke in November at best, at worst I’m going to be completely broke (that might mean empty fridge). Thanks for the support. 🙂

Article updated at 23:19 UTC. Word fixes.
Article updated on 1-November-2016 at 23:52 UTC.

October 27, 2016

Earthquake activity in Bárðarbunga volcano (Week 43)

On 27-Oktober-2016 at 02:08 & 02:09 UTC an magnitude 3,5 and 3,3 took place in Bárðarbunga volcano. During the day several smaller earthquakes happened in the same place in the Bárðarbunga volcano (close to North-East of the caldera).

The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

Currently Bárðarbunga volcano is inflating with fresh magma from deep mantle. This process started in September-2015 and is going to continue until a new eruption starts from Bárðarbunga volcano (or in Bárðarbunga volcano).

Italy earthquakes

Since I’m living in Denmark I did record the earthquakes in Italy. I did record the magnitude 5,5 earthquake (poorly) and the magnitude 6,1 earthquake (clearly).

The earthquake in Italy, this is the magnitude 6,1 earthquake. This image is under Creative Commons licence, please see CC Licence for more details.

I can record those earthquakes in Denmark since the distance is only ~1500 km. The minimum magnitude for my hardware to record earthquakes at this distance is around magnitude 5,4. Due to high background noise where I live.

Laptop and other hardware issues

Since I never got the laptop I was promised (It never showed up in the mail) I might not have any computer in December when I go to Iceland. I might resort to buying a new laptop with a loan from a store I know of. If I do that, I’ll go for a cheap laptop (that is also best, since I only use them when I travel). I also did not get a used hard drive that I promised and other hardware, the persons that told me that they wanted to donate that hardware to me just vanished and have not contacted me again over that. I have gotten hardware donations in the past and that is not a issue to get them if they are sent with the mail from within the EU.

Donations

Please remember to donate. I have to pay a high electric bill next month due to problem they had for the past six months. At least they gave me a discount (I think) since it was entirely their fault. Yet that is going to leave me rather broke in November. Thanks for the support. 🙂

October 17, 2016October 17, 2016

Fresh earthquake activity in Katla volcano for the past 48 hours

Today (17-October-2016) and yesterday (16-October-2016) small earthquake swarms have happened in Katla volcano. Most of the earthquakes that happened where small, with magnitude 1,0 or less. Three earthquakes had magnitude above 2,0.

The earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

In the news in Iceland today it was mentioned that this earthquake activity was due to heavy rain last week in south Iceland. I don’t agree with that assessment, since I recorded the strongest earthquakes and they show a clear sign of being volcano earthquake. I’m not able to record glacier quake activity at distance of 56 km (Heklubyggð geophone). The problem with volcano like Katla is the constant earthquake activity, over time there is a risk that geoscientists start to look at it as the normal pattern of the volcano and there is nothing to worry about. Current earthquake activity is of this nature and in my view its highly dangerous activity, while it has yet not resulted in a eruption there is nothing saying it is not going to do so soon. I remind people that is not possible to know when a eruption starts and it’s not known how an eruption in Katla volcano starts, besides what is know for historical recordings after the eruption has started (magma pushing towards the surface).

October 15, 2016October 16, 2016

Few earthquakes in Hofsjökull volcano

Today (15-October-2016) few earthquakes took place in Hofsjökull volcano. This where just few earthquakes with the largest earthquake having the magnitude of 1,4. Slight to the east a magnitude 2,3 earthquake happened, that however was a intra-plate earthquake and is not connected to any volcano.

Earthquake activity in Hofsjökull volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity in Hofsjökull volcano appears to be a response to a stress change in the area, even if sits on its own rift zone (Skagafjörður rift zone, science paper). It is my guess that the source of this stress changes can be found in Bárðarbunga volcano and the movement of the eastern rift zone that is currently happening. I’m not expecting any eruption from Hofsjökull volcano, it’s not known when last eruption took place in Hofsjökull volcano. More earthquakes might happen in the future due to stress changes in the upper crust close to Hofsjökull volcano or in Hofsjökull volcano.

Update on 16-October-2016

The Icelandic Met Office has updated the earthquakes location. Now they are all in Hofsjökull volcano. Six earthquakes happened and the largest one had the magnitude of 2,3. No intra-plate earthquake happened, that was just a wrong manual location.

Updated locations of the earthquakes in Hofsjökull volcano. Copyright of this image belongs to Icelandic Met Office.

Donations

Please remember to support my work. The failure with the hard drives did cost me and that is leaving me a little short at the moment. Thanks for the support. 🙂

Article updated on 16-October-2016 at 16:23 UTC. Updated earthquake map added.

October 15, 2016

Minor earthquake swarm in Katla volcano

This morning (15-October-2016) a minor earthquake swarm took place in Katla volcano (east part of the caldera). This was a minor earthquake swarm, with the largest earthquake having a magnitude of 2,7.

The earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

All of the earthquakes that took place where small. With the second largest earthquake only having a magnitude 2,3. After the main earthquake swarm was over the activity quieted down and has remained quiet. The main earthquake activity ended at 08:58 UTC this morning. With only few earthquakes taking place after that.

October 15, 2016October 15, 2016

Earthquake swarm in Bárðarbunga volcano

Earthquake swarm with around 30 earthquakes took place during the night in Bárðarbunga volcano. The largest earthquakes had magnitude of 3,5. Yesterday (14-October-2016) a magnitude 3,3 earthquake took place in Bárðarbunga volcano.

The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

Other earthquakes in this earthquake swarm where smaller in magnitude. This earthquake swarm is also interesting for the fact that it seems to change the stress levels around Bárðarbunga volcano started earthquakes in nearby volcanoes. I don’t know for sure what is happening, what has been confirmed by GPS measurements is that Bárðarbunga volcano is currently inflating and that is pushing the plug that collapsed down in the eruption 2014 – 2015 up again and that is creating current earthquake activity in Bárðarbunga volcano.

Article updated at 20:11 UTC. Word fixes.

October 6, 2016

Katla volcano update at 20:10 UTC

Here goes Katla volcano again.

Earthquake activity in Katla volcano has been slowly increasing today (06-October-2016). It is not yet at the levels as it was week ago, but as Katla showed last week this change can happen rapidly and without much warning. Largest earthquake since this morning had the magnitude of 2,4 at 14:11 UTC. Other earthquakes so far have been smaller in magnitude. Other earthquakes have been smaller in magnitude.

The earthquake activity in Katla volcano at 18:55 UTC. Copyright of this image belongs to Icelandic Met Office.

The fact that current earthquake swarm is in a really tight location suggests that a dyke intrusion is possibly trying to drill its way out up through the crust at this location. I did see something similar before Bárðarbunga volcano erupted. It is not possible to know how long this process takes, since the crust is different between volcanoes. Then there is always the question if this process stops, at this moment I find that doubtful due how long its been going already. I’m expecting the earthquake activity in Katla volcano to increase until a new peak is reached or an eruption starts. Currently no eruption has started.

This article is going to be updated as needed.

Off-line warning

Due to hurricane Matthews there is a risk of this website going off-line from tomorrow as the hurricane hits Florida and Orlando, where this website is hosted. I will take a backup of it later today just in case. At worst some comments might be lost and even some articles (if I update the website after I take my backup).

October 6, 2016

Increase in earthquake activity in Katla volcano

Today (6-October-2016) a magnitude 3,2 earthquake took place in Katla volcano. This earthquake had smaller earthquake activity before it happened and after it took place. Currently bad weather in the Katla volcano area is preventing detection of the smallest earthquakes. That bad weather is going to last at least until tomorrow and then a new storm might arrive few hours later.

The earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

Heavy rain in south Iceland has prevented a good reading on conductivity in Múlakvísl glacier river. Since freshwater mixing into the glacier water results in drop of conductivity with increase amount of water. This has also resulted in some glacier quake activity in Mýrdalsjökull glacier.

Off-line warning

October 5, 2016

Earthquake activity in Bárðarbunga volcano (Week 40)

Today (5-October-2016) a minor earthquake swarm took place in Bárðarbunga volcano. Largest earthquake in this swarm had the magnitude of 3,8 and the second largest earthquake had the magnitude of 3,0. Other earthquakes where smaller in magnitude.

The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

The reason for this earthquake activity is inflation in Bárðarbunga volcano. This is pushing the crust that fell down in the eruption of 2014 – 2015 in Bárðarbunga volcano (Holuhraun area) up again and that friction creates earthquakes. New magma is flowing into shallower magma chamber (at depth of ~10 km) from more depth under the volcano (20+ km depth). This started in September-2015 and is going to continue for many more months, maybe until next eruption in Bárðarbunga volcano.

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