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Iceland (Ísland, ˈistlant) is a Nordic island country between the North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is linked culturally and politically with Europe, and is the region's most sparsely populated country. Its capital and largest city is Reykjavík, which is home to about 36% of the country's roughly 380,000 residents. Located on a rift between tectonic plates, Iceland's geologic activity includes geysers and frequent volcanic eruptions. The interior consists of a volcanic plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a latitude just south of the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate. According to the ancient manuscript Landnámabók, the settlement of Iceland began in 874 AD when the Nor

Dike emplacement at Bardarbunga, Iceland, induces unusual stress changes, caldera deformation, and earthquakes

Nahid Mohajeri Pour Rayeni

A 45-km-long regional dike was emplaced over a period of 2 weeks in August 2014 at the boundary between the East and North Volcanic Zones in Iceland. This is the first regional dike emplacement in Iceland monitored with modern geophysical networks, the importance of which relates to regional dikes feeding most of the large fissure (e.g., Eldgja 934 and Laki 1783) and lava shield (e.g. early Holocene Skjaldbreidur and Trolladyngja) eruptions. During this time, the dike generated some 17,000 earthquakes, more than produced in Iceland as a whole over a normal year. The dike initiated close to the Bardarbunga Volcano but gradually extended to the northeast until it crossed the boundary between the East Volcanic Zone (EVZ) and the North Volcanic Zone (NVZ). We infer that the strike of the dike changes abruptly at a point, from about N45 degrees E (coinciding with the trend of the EVZ) to N15 degrees E (coinciding with the trend of the NVZ). This change in strike occurs at latitude 64.7 degrees, exactly the same latitude at which about 10 Ma dikes in East Iceland change strike in a similar way. This suggests that the change in the regional stress field from the southern to the northern part of Iceland has been maintained at this latitude for 10 million years. Analytical and numerical models indicate that the dike-induced stress field results in stress concentration around faults and particularly shallow magma chambers and calderas in its vicinity, such as Tungnafellsjokull, Kverkfjoll, and Askja. In particular, the dike has induced high compressive, shear, and tensile stresses at the location of the Bardarbunga shallow chamber and (caldera) ring-fault where numerous earthquakes occurred during the dike emplacement, many of which have exceeded M5 (the largest M5.7). The first segment of the dike induced high tensile stresses in the nearby part of the Bardarbunga magma chamber/ring-fault resulting in radially outward injection of a dike from the chamber at a high angle to the strike of the regional dike. The location of maximum stress at Bardarbunga fluctuates along the chamber/ring-fault boundary in harmony with dike size and/or pressure changes and encourages ring-dike formation and associated magma flow within the chamber. Caldera collapse and/or eruption in some of these volcanoes is possible, most likely in Bardarbunga, but depends largely on the future development of the regional dike.

Springer Verlag2014

Dike emplacement at Bardarbunga, Iceland, induces unusual stress changes, caldera deformation, and earthquakes

Nahid Mohajeri Pour Rayeni

Springer Verlag2014