Shield volcano?

The volcanic eruption on the Reykjanes peninsula continues to surprise geoscientists. Elemental analyzes of the magma are now available and it has been found that it consists of olivine toluide, which is derived from the upper layers of the mantle and not from the earth’s crust as is most common. This magma is therefore getting very deep without touching a magma chamber or a magma chamber. It can be said that there is an open channel all the way from the mantle to the eruption site.

The biggest crata in Geldingardal
Photo Tómas Guðbjartsson

In fact, it soon became apparent that the eruption was not a traditional eruption. It started very slowly but not by force as eruptions often do.  It slowed down a bit the first night, but for the last three days it has continued to grow and not slow down. Volcanic eruptions usually start with great force but then slowly diminish until they burn out. This is because a specific compartment or development is being emptied. In this case, it is not, it is just a direct connection to the mantle! Very deep earthquakes indicated that magma was reaching deep. The shape of the lava is also special, very thin liquid lava.

The bloom season of the Shields volcano eruptions in Iceland was around the time when the ice age glacier began to recede, and great pressure was lifted from the land mass. This opened an easy path for the magma to the surface. At this time, i.e., 10-14,000 years ago, many geyser-sized mounts formed, e.g., Skjaldbreiður and Þráinsskjöldur. The latter shield volcano is right next to the current eruption sites. Shield volcano eruption now is therefore taken lightly unexpectedly.

Gos í Geldingardal
Photo Tómas Guðbjartsson

More than 20 mounts are known on the Reykjanes peninsula, but none younger than about 3-4000 years. The largest known lava flows on the peninsula are all from Shield volcano eruption.

The eruption in Geldingardalur would have to continue for decades to form a large shield volcano. There is little indication that it will threaten settlements in the coming years unless the flow changes. A volcanologist says that this could be suitable for tourists if the eruption continues. The flow from the crater has remained stable, with a flow of 5 to 10 cubic meters per second since it began on Friday night. Like a basic bowl upside down

Scientists now believe it is possible that the volcano in Geldingadalur is, or will be, a Shield volcano. Shield volcano are broad, sloping, and conical volcanoes that form in a prolonged eruption on a circular eruption (Vísindavefurinn). Shield volcano resembles a bowl or shield upside down and Skjaldbreiður and Trölladyngja are probably the best known in this country.


Skjaldbreið shield volcano
© Skjaldbreið Photo Guðmundur E.Jóelsson

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