SISZ – Page 2 – Iceland geology

September 29, 2016September 29, 2016

Overview of micro-earthquake activity in Iceland 28-September-2016

This is a short overview of the micro-earthquake activity in Iceland on 28-September-2016. Please note that some of this earthquake activity may have started some days ago and only got really busy on 28th September 2016.

Kolbeinsey Island / Ridge

Late on the 28-September-2016 an earthquake swarm took place in Kolbeinsey Island / Ridge. This is the largest earthquake swarm in this article. With the largest earthquakes having the magnitude above 3,0. Due to distance from the SIL network exact calculation of the magnitude and depth doesn’t appear to be possible. Last eruption taking place in Kolbeinsey Island / Ridge took place in the year 1755. No other eruptions have been documented since, but they might regardless have happened. The area is far from land and difficult to observe.

East of Grímsey Island (Tjörnes Fracture Zone)

Minor earthquake swarm has been taking place earth of Grímsey Island in a area that many suspect is a volcano (it is marked as such in the GVP database). The earthquake swarm in question does not appear to be a volcanic in origin. This appear to be a tectonic activity taking place, as the movement of TFZ is 20mm lateral movement/year (they fault slide each other 20mm/year) the rift movement is only 5mm/year (eastern part only). Image showing the movements can be found here (vedur.is).

Earthquake activity in Kolbeinsey Island and Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Met Office.

South Seismic Zone (SISZ)

A small swarm of earthquakes has been taking place in SISZ this week. The largest earthquake in this swarm has only had the magnitude of 2,1. The activity is only minor and does not suggest a large earthquake is about to happen. This might be aftershocks of the earthquakes in 2000 or 2008.

The earthquake activity in SISZ. It’s only minor and west of Selfoss (red dot). Copyright of this image belongs to Icelandic Met Office.

Reykjanes peninsula

Earthquake swarm started on 28-September-2016 on the Reykjanes peninsula. This earthquake swarm was not strong and the largest earthquake in this swarm only had the magnitude of 2,1 and all other earthquakes where smaller in magnitude. Total of 60 earthquake happened when the swarm was active.

The earthquake swarm on the Reykjanes peninsula. It was not big in magnitude, but had a total of 60 earthquakes. Copyright of this image belongs to Icelandic Met Office.

Few earthquake have also been taking place around Iceland without any other activity. This type of one-off earthquake activity is common in Iceland. Why it happens is unclear.

Article updated at 02:03 UTC on 29-September-2016. Word corrections.

October 23, 2015

Rare earthquakes in Hreppar micro-plate and other activity in Iceland

Due to family obligations I won’t be able to write a long post until Sunday (I hope). So here is a short overview of activity.

Hreppar micro-plate

A rare swarm of earthquakes took place on the Hreppar micro-plate today. All of the earthquakes had less magnitude than 1,0.

Hreppar micro-plate earthquake activity on its edge with the American plate. Copyright of this image belongs to Iceland Met Office.

South Icelandic Seismic Zone

A swarm of earthquakes took place in SISZ this week. Largest earthquake had the magnitude of 2,5 and was felt in nearby populated areas.

Earthquake swarm on SISZ. Copyright of this image belongs to Iceland Met Office.

Bárðarbunga volcano

Last week a magnitude 3,2 earthquake took place in Bárðarbunga volcano. This don’t appear to be deflation earthquakes, they rather look like inflation earthquakes. I don’t have time to write about it now, so details have to wait for now.

The magnitude 3,2 earthquake in Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

I hope to write more on Sunday if I have time.

October 11, 2015

Overview of week 41 activity in Iceland

Week 41 in Iceland was rather quiet, compared to last two weeks in Iceland. Here is a overview over the highlight in the earthquake activity in Iceland.

South Iceland Seismic Zone (SISZ)

Constant earthquake activity has been in SISZ over the week and it has been ongoing for the past weeks, none of the earthquakes have been large, with almost all of them being less then magnitude 1,0. Largest earthquake in this swarm had the magnitude of 2,5.

The earthquake activity on SISZ. Copyright of this image belongs to Iceland Met Office.

Bárðarbunga volcano

For most part earthquake activity in Bárðarbunga volcano was normal this week, with regular earthquake swarms taking place in the usual places. The most interesting earthquake this week took place under Trölladyngju, it was only magnitude 0,7, but it was on depth of 26,2 km.

Earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

Herðubreið

Earthquake swarm has been taking place all week in Herðubreið. Earthquake swarms are common in this area and often have magnitude 3,0 earthquakes or larger. The earthquake swarm is ongoing when this is written.

Earthquake activity in Herðubreið/Herðubreiðarfjöll area (north of Askja volcano). Copyright of this image belongs to Iceland Met Office.

Reykjanes ridge

A magnitude 3,4 earthquake took place deep on the Reykjanes ridge this week. The earthquake was not felt and there might have been more than one earthquake. My geophone in Heklubyggð shows more than one earthquake one hour after the magnitude 3,4 earthquake happens.

Earthquake activity on the Reykjanes ridge. Copyright of this image belongs to Iceland Met Office.

A magnitude 3,0 earthquake also took place around 200 km off the coast of Reykjanes peninsula (around 153 km south of Eldeyjarboða). That earthquake location was poor due to the distance from the SIL network.

Donations: Please remember to support my work here with donations or by using Amazon banners when you buy from Amazon. Thanks for the support.

June 12, 2015June 13, 2015

Minor earthquake swarm in SISZ (South Icelandic Seismic Zone)

During the night of 12-June-2015 a minor earthquake swarm took place on the edge of SISZ (South Iceland Seismic Zone). Around 9 earthquakes were detected, largest earthquake had the magnitude of 2,9.

Earthquake swarm on the SISZ, it appears as a group of few dots in northern part of SISZ. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake swarm did appear clearly on my geophone in Heklubyggð.

The spike in this image is the magnitude 2,9 earthquake. This image is released under Creative Commons Licence. Please see CC Licence for more details.

The reason why this magnitude 2,9 earthquake appears so strong on my geophone has normal reasons. The reason is distance, the earthquake was close to geophone and smaller earthquakes appear clearly on my geophone, even if they are small in magnitude.

Donations: Please remember to donate to support my work and prevent me from suffer from a hunger. Thanks for the support. 🙂

April 9, 2015April 10, 2015

Minor earthquake swarm on Hekla – SISZ boundary

During the night of 9-April-2015 an earthquake swarm started on Hekla volcano – SISZ boundary. This has been for most part a minor earthquake swarm so far. With largest earthquake only having the magnitude of 2,8. This earthquake activity has appeared clearly on my Heklubyggð geophone.

The earthquake swarm is located north of Mýrdalsjökull and Eyjafjallajökull. South of Hekla volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm appears to be tectonic in nature. This means there is a higher chance it might be related to stress changes in SISZ (South Icelandic Seismic Zone), rather then any activity in Hekla volcano. There is little chance in my view that this activity is going to trigger any eruption in Hekla volcano, I just can’t rule it out at the moment. Currently it appears that this earthquake swarm is ongoing. This earthquake swarm doesn’t appear to be moving quickly at the moment, that might change but I am doubtful that is going to happen while minor earthquakes are just taking place. If stronger earthquakes start to happen this minor earthquake swarm might grow into a middle sized one or a big one. Largest known earthquakes in this area have reached magnitude Mw7,0. Such earthquake has not taken place in this part of SISZ for the past 103 years. Currently there is nothing indicating that earthquake with that type of magnitude is about to take place.

Donations: Please remember to donate to support my work. It can be done with the PayPal button or by shopping truth the Amazon banners that I have here. Donations regardless of the form they are in help me to do this work and inform people what is going on in Iceland when it comes to geology. Thanks for the support. 🙂

Article updated at 00:20 UTC on 10-April-2015.

May 9, 2014May 9, 2014

Magnitude 3,9 earthquake in SISZ last night

Yesterday (8-May-2014) a magnitude 3,9 earthquake took place in SISZ (South Icelandic Seismic Zone). This earthquake was felt over all of south Iceland, no damage took place following this earthquake. This earthquake appears to have been on N-S fault in SISZ. Only few minor aftershocks took place following this earthquake. I don’t know why that is and this lack of aftershocks is interesting.

The star marks the magnitude 3,9 earthquake in SISZ. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake in SISZ as it appeared on my geophone station in Heklubyggð. This image is released under Creative Commons licence. Please see CC Licence page for more details.

It is possible to see any future earthquake activity here on my geophone station at Heklubyggð. The geophone station at Böðvarshólar is not updating due to failed 3G transmitter the area that I use to connect that geophone station to the internet. I hope it gets fixed soon. People can also used the website of Icelandic Meteorological Office to watch for any future earthquake activity in SISZ.

Update 1: According to Icelandic Meteorological Office this earthquake took place on a fault that had a magnitude 7,0 earthquake in the year 1784, on 14-August that year. More details can be found here, the text is in Icelandic.

Updated at 12:43 UTC on 9-May-2014.
Updated at 12:56 UTC on 9-May-2014.

May 9, 2014

Strong earthquake in South Iceland (SISZ)

Today (9-May-2014) at 23:15 UTC a strong earthquake took place in SISZ. Exact magnitude is not clear at this moment, but the magnitude of 4,0 is wrong in my view based on how this earthquake appeared on my geophone. This earthquake was felt in south Iceland and in the capital area. I am going to post updates on this earthquake once I have the details.

The earthquake can be seen here along with all the aftershocks that are going to take place.

October 10, 2012October 10, 2012

Earthquake swarms in Brennisteinsfjöll volcano and TFZ

Over the past few days there has been continued earthquake activity in Breinnisteinsfjöll volcano. The largest earthquake in this swarm had the magnitude of ML2.5. It is possible that this earthquake swarms have there orgin in SISZ. Rather then Breinnisteinsfjöll volcano. But at current time is hard to be sure on this detail.

Earthquake activity in Breinnisteinsfjöll volcano during the past few days. Copyright of this image belongs to Icelandic Meteorological Office.

Tjörnes Fracture Zone

Earthquake activity has also been taking place east of Grímsey Island. This earthquake activity has mostly been small. But this are earthquake swarm did not have any earthquake that was above 3.0 in magnitude.

Earthquake swarm on TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

The largest earthquake in this swarm had the magnitude of ML2.8. More earthquake activity should be expected in this area. As this is one of most active areas in Iceland when it comes to earthquake swarm.

September 3, 2012September 3, 2012

Ongoing earthquake swarm in Breinnisteinsfjöll volcano / SISZ

Since yesterday (02.09.2012) there has been ongoing earthquake swarm in Breinnisteinsfjöll volcano / SISZ (south iceland seismic zone). It is impossible to know how this earthquake swarm is going to proceed. But from what I can tell. It does not seem like it is going to be over any time soon. It is also an possibility that current earthquake swarm is part of an larger stress change in the area. But for now it is too early to know for sure what it means in the long term. Current earthquake activity is ongoing. With almost no breaks or stops. Most earthquakes have the magnitude of 0.1 and up to 2.0. But no larger earthquakes have been detected so far. The first earthquake in this earthquake swarm had the magnitude of ML4.4. Depth of this earthquakes is from 3 to 7 km (in that range).

The earthquake activity in Breinnisteinsfjöll volcano. The earthquakes align them self on an fault line that almost directly north-south direction. Copyright of this image belongs to Icelandic Meteorological Office.

It is impossible to know what is going to happen next in this earthquake swarm. But strong earthquake should not be ruled out for now. This might also activate nearby fault lines if the activity intensifies. As that sometimes happens in Iceland. Whatever happens next in this area. It is worth keeping an eye on the progress of this earthquake swarm.

Icelandic news about this earthquake swarm

Enn skelfur undir Bláfjöllum (mbl.is)
Enn skelfur í Bláfjöllum (Rúv.is)

July 31, 2012

Earthquake swarm in SISZ this morning (31.07.2012)

This morning there was an earthquake swarm in SISZ. This earthquake swarm was located just south of Hveragerði and Selfoss town. The largest earthquake in this earthquake swarm had the magnitude of ML1.3. Most of the other earthquake where less the magnitude 1.0 in size. Focal depth for this earthquake swarm was 5 to 6 km. Total of 30 or so earthquakes where recorded in this earthquake swarm. This earthquake swarm is in continued activity in this area. But SISZ often has frequent smaller earthquake swarms.

The area of earthquake activity in SISZ this morning (31.07.2012). Copyright of this image belongs to Iceland Meteorological Office.

This doesn’t mean anything special. But SISZ (South Icelandic Seismic Zone) is always at risk having large earthquakes. But based on how short it was since last one took place (May 2008). It is unlikely that is going to happen now.

Cookie acceptance