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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Sismologie
 Iceland - Húsavík whaling port in Skjálfandi Bay - photo Gentle Giants Husavik

Iceland - Húsavík whaling port in Skjálfandi Bay - photo Gentle Giants Husavik

The Tjörnes Fracture Zone (TFZ) is home to a seismic swarm that began on February 14, 2018.

The earthquakes occur off northern Iceland, about 10-12 km northeast of Grimsey Island.

Since noon February 16, more than 1,000 earthquakes have been detected, of which 10 of magnitude greater than 3, the largest of magnitude 4.1 is dated 15.02 to 19:27. A slight decrease in the swarm was recorded yesterday.

Iceland, Grimsey Island - photo M.Schüler / vulkane islands

Iceland, Grimsey Island - photo M.Schüler / vulkane islands

The small population of Grimsey, 40 km from Iceland felt a few.

According to Professor Sigurjón Jónsson, one of the leading experts in the Tjörnes area, this seismic swarm, the most intense in this area since 2013, could be a sign of a larger earthquake yet to come. It is difficult to predict with certainty.

This seismic swarm follows that started on January 28, 2018, the most important shocks were recorded at magnitude 4.1 and 3.4.

Location of earthquakes and magnitude on 16.02.2018 / 15h55 and 17.02.2018 / 08h10 - doc.IMO
Location of earthquakes and magnitude on 16.02.2018 / 15h55 and 17.02.2018 / 08h10 - doc.IMO
Location of earthquakes and magnitude on 16.02.2018 / 15h55 and 17.02.2018 / 08h10 - doc.IMO

Location of earthquakes and magnitude on 16.02.2018 / 15h55 and 17.02.2018 / 08h10 - doc.IMO

GPS measurements show no detectable deformation associated with this seismic swarm; the activity therefore seems purely tectonic, although the local geothermal activity could have been a triggering factor.

No magmatic activity, the last eruption goes back according to the Global Volcanism Program in December 1867-January 1868.

TFZ - Earthquakes since the beginning of 2018 are seen as red dots. Earthquakes with a magnitude between 3-4 are indicated as black stars and earthquakes with a magnitude over 4 as white stars. Grey dots show earthquake activity in 1994-2017. Black triangles show the location of seismic stations and the black arrows show the movement across the Húsavík Flatey fault. 

TFZ - Earthquakes since the beginning of 2018 are seen as red dots. Earthquakes with a magnitude between 3-4 are indicated as black stars and earthquakes with a magnitude over 4 as white stars. Grey dots show earthquake activity in 1994-2017. Black triangles show the location of seismic stations and the black arrows show the movement across the Húsavík Flatey fault. 

Northern Iceland - volcanic formations of the NVZ and Kolbeinsey ridge, with location of the Tjörnes fracture zone and fault Húsavík - Flatey

Northern Iceland - volcanic formations of the NVZ and Kolbeinsey ridge, with location of the Tjörnes fracture zone and fault Húsavík - Flatey

Sources: IMO, RÚV, Iceland review, Th. Augustdottir.

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