Volcanic Explosivity Index (VEI): 3
Last Eruption: 2000
Volcanic Explosivity Index (VEI): 3
Last Eruption: 2000
Since instrumental monitoring of Hekla began in the seventies, pre-eruptive signals have been detected only tens of minutes before an eruption commenced. Great efforts continue to be made to operate and expand a robust monitoring network on and around Hekla for the purpose of detecting precursory eruptive signals.
The goal is to optimize the observation and interpretation of the available signals to allow a timely warning about volcanic activity. Such a warning would be issued to major stakeholders (Iceland’s Civil Protection Department, Isavia and London VAAC) and to the public.
In addition to the extended seismic (SIL) network, the monitoring network around Hekla includes instruments that detect ground deformation (GPS and borehole strain meters), volcanic gases (DOAS and MultiGAS) and fixed sites for web-camera observations. As in 1991 and 2000, the next eruption of Hekla should be preceded by the measurable propagation of magma towards the Earth’s surface; this process should be detected initially by two nearby borehole strain meters.
Earthquakes accompanying the ascent of magma should also be detected in near-real-time. Improvements in the SIL network in recent years allow for the detection of smaller, and thus many more earthquakes, as well as enabling better constrain on earthquake location and depth. Additionally, the onset of the next eruption will be identified using nearby infrasound sensors that detect volcanic explosions and radar (for ash-cloud detection), which will further help to assess the intensity of the eruption.
During the last millennium, Hekla has erupted 23 times, making it the third most active volcano in Iceland. Hekla’s most recent eruption was in February 2000, when a 10 to 12-km-high plume of ash, gas and water vapour persisted for a couple of hours. Hekla eruption in 1947 created a volcanic plume that rose to about 30 km in the stratosphere. Hekla eruptions often result in multiple hazards, including tephra emissions, lava flows, pyroclastic flows and flooding due to snow-melt.
Depending on weather conditions at the time of the next eruption, fine-grained ash could be lofted to high elevation, with international implications for air travel. Since 1970, the volcano has erupted at roughly decadal intervals (1970, 1980-81, 1991 and 2000). This is one reason why the volcano is now considered to be ‘overdue’, as the last eruption occurred more than 19 years ago.
Before 1970, Hekla erupted less frequently, with repose intervals up to 120 years in past centuries. An overview of Hekla´s activity is available from the Catalogue of Icelandic Volcanoes .
If you are thinking about traveling to Iceland one of the most popular recommendations that you will find in the guides is the Hekla volcano. We invite you to come and visit our modern exhibition, winner of several international awards, where you will find interactive information about the Hekla and other important volcanoes in Iceland.
This spring 2019 we have built for all of you a new architectural infrastructure from which to observe up to 5 different volcanoes such as Hekla, Eyjafjallajokull, Katla, Vestmannaeyjar and Tindfjöll.
You can buy your tickets online at the following link LAVA Centre Tickets, our team will be happy to welcome you and take a look at all the rooms and information of LAVA Center.
Hekla is a stratovolcano in the south of Iceland with a height of 1,491 m (4,892 ft). Hekla is one of Iceland’s most active volcanoes; over 20 eruptions have occurred in and around the volcano since 874. During the Middle Ages, Europeans called the volcano the “Gateway to Hell”.
Hekla is part of a volcanic ridge, 40 km (25 mi) long. The most active part of this ridge, a fissure about 5.5 km (3.4 mi) long named Heklugjá, is considered to be within Hekla proper. Hekla looks rather like an overturned boat, with its keel being a series of craters, two of which are generally the most active.
The volcano’s frequent large eruptions have covered much of Iceland with tephra, and these layers can be used to date eruptions of Iceland’s other volcanoes. Approximately 10% of the tephra created in Iceland in the last thousand years has come from Hekla, amounting to 5 km3. Cumulatively, the volcano has produced one of the largest volumes of lava of any in the world in the last millennium, around 8 km3.
Hekla has a morphological type between that of a crater row and stratovolcano (built from mixed lava and tephra eruptions) sited at a rift-transform junction in the area where the south Iceland seismic zone and eastern volcanic zone meet. The unusual form of Hekla is found on very few volcanoes around the world, notably Callaqui in Chile.
Hekla is situated on a long volcanic ridge of which the 5.5 km Heklugjá fissure is considered Hekla proper. This fissure opens along its entire length during major eruptions and is fed by a magma reservoir estimated to have a top 4 km below the surface with centroid 2.5 km lower.
The tephra produced by its eruptions is high in fluorine, which is poisonous to animals. Hekla’s basaltic andesite lava generally has a SiO2 content of over 54%, compared to the 45–50% of other nearby transitional alkaline basalt eruptions (see TAS classification).It is the only Icelandic volcano to produce calc-alkaline lavas. Phenocrysts in Hekla’s lava can contain plagioclase, pyroxene, titanomagnetite, olivine, and apatite.
When not erupting Hekla is often covered with snow and small glaciers; it is also unusually aseismic with activity only starting 30–80 minutes before an eruption.Hekla is located on the mid-ocean ridge, a diverging plate boundary. Hekla is closely studied today for parameters such as strain, tilt, deformation and other movement and seismic activity.Earthquakes in the volcano’s vicinity are generally below magnitude 2 while it is dormant and magnitude 3 when erupting.
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