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The Húsavík-Flatey (HFF) transform faut and location of earthquakes in the TFZ (IMO)
The earthquake swarm has decreased in intensity. At least some scientists believe that the cause has been a magmatic intrusion in Iceland's northern rift zone that activated the Húsavík-Flatey (HFF) transform fault at the southern limit of the TFZ where the earthquakes were concentrated.
An intense earthquake swarm has been going on offshore North Iceland, 10 km NW of Gjögurtá, since 25 September. This morning, 2 earthquakes reaching magnitude 3 and 3.2 occurred at 06:14 and 07:41. In total, more than 1000 quakes have been recorded by IMO. ...more
The depths of the quakes vary from about 15 km depth (crust-mantle boundary) to near surface. The area is located on an active fault line related to rifting, and a possible cause of the earthquake swarm could be a magmatic intrusion.
A (probably tectonic) swarm of earthquakes has been occurring since yesterday in the eastern part of the TFZ, about 10-15 km north of the shore at various depths mostly below 15 km. It includes more than 100 quakes yesterday including 6 above magnitude 3 (up to 3.8 yesterday morning).
Earthquakes in the TFZ during the past 48 hours (Icelandic Met Office)
The powerful earthquake swarm that started a week ago continues, but at reduced intensity compared to 2 April when the large magnitude 5.4 quake struck. Each day, hundreds of earthquakes have been occurring (more than 200 > magnitude 2 during the past 2 days). ...more
The earthquake swarm is the result of release of tectonic stress that has accumulated in the crust and is being released at the moment. The area is one of the main so-called transform zones,- regions where the separating Eurasian and North-American tectonic plates move sideways along strike-slip faults rather than spreading apart directly as is the case in the main rift zones, where also the main volcanoes are located, because the opening movment here allows large batches of magma to rise easily. The transform zones separate the rift zones at spreading plate boundaries at regular intervals in order to accommodate differential movements that are a result of the earth's curved surface where rigid plates move apart. In the transform zones, the sideways movement can produce much more strain in the rocks and has therefore the potential of larger earthquakes.
Map of tectonic faults and rift zones in northern Iceland (Icelandic Met Office)
Depth vs time of quakes under the Tjörnes Fracture Zone
A strong earthquake swarm including a widely felt magnitude 5.4 earthquake at 15 km depth this morning and hundreds of pre- and aftershocks is occurring in the Tjörnes Fracture Zone in a N-S elongated area about 15 km east of the island of Grimsey.
Quakes during the past 7 days (red=during the past 48 hours)
The earthquake swarm in the Tjörnes Fracture Zone north off Iceland still continues at reduced intensity and there seems no end in sight. Most quakes are very small, but there are still occasional quakes at around magnitude 3, and the area remains at risk for a larger quake.
The earthquake swarm in the Tjörnes Fracture Zone north off Iceland continues into its 10th day. After a decline in intensity during 25-28 Oct, the frequency of quakes has again picked up. There are often more than 100 quakes a day including some above magnitude 3. The Icelandic Met Office maintains a warning for a possible larger quake in the area.
Seismic sequence at Eyjafjarðaráll (Iceland Met Office)
The seismic swarm in the Tjörnes Fracture Zone continues at reduced rate. According to the Icelandic Meteorological Office, there is enough stress to produce a magnitude 6.8 earthquake, but it is impossible to predict if and when such a quake might occur.
Time and magnitude of quakes in the TFZ (Iceland Met Office)
A strong seismic swarm started shortly before midnight GMT in the Tjörnes Fracture Zone (TFZ) north of Iceland. ...more
During the first 12 hours, about 300 quakes greater than magnitude 1 occurred at various depths ranging between 1 and 13 km, including 47 greater than magnitude 3. The largest was a widely felt M5.2 event in 10,8 km depth. Most quakes are located between the north coast of Iceland and the small island of Grimsey. A submarine volcano is known from a location north of Grimsey that erupted in 1372. A weaker swarm yesterday around noon preceded the current one. Earthquakes, mostly of tectonic origin, are frequent in the TFZ, but since it is also near the volcanic rift zone, a magmatic component cannot be ruled out. At present, the nature of the quakes (purely seismic or magma intrusion) is not known. [less]
A new small swarm of earthquakes started east of Grímsey Island in the Tjörnes Fracture Zone (TFZ) north of Iceland yesterday 4 Oct. So far, there have been 41 quakes during the past 48 hours, mostly of small magnitudes (1-2) at various depths mostly around 10 km. The largest quakes was a magnitude 3.1 event at 11:35 UTC. ...more
There are possibly a few active volcanoes in this area, but whether this swarm (and the recent other swarms) is tectonic in nature (likely) or related to magma movements is unclear. [less]
Earthquakes in the TFZ on 20 Sep (Icelandic Meto Office)
The seismic swarm at the Tjörnes Fracture Zone has been calming down. ...more
It included hundreds of small to medium quakes up to magnitudes around 4, the largest being a 4.2 event at 19:42 UTC on 20 Sep. This earthquake swarm was most likely felt in the towns of Siglufjöður, Dalvík town and nearby places. [less]
Ibu volcano photos: Ibu in Halmahera is one of the most active, but rarely visited volcanoes in Indonesia. A spectacular lava dome is growing inside the volcano's breached crater, with frequent explosions.
Volcano Calendar 2016: We're proud to present our new volcano calendar 2016: 13 different and attractive images of volcanoes, volcanic landscapes and phenomena taken during volcano tours over the past few years.
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