Town of Grindavik evacuated again as new eruption begins on the Reykjanes Peninsula, Iceland.

Eruptive activity on the Reykjanes Peninsula, Iceland began again on 29 May 2024, according to the Icelandic Met Office, the first such eruption since activity on a fissure which opened in March petered out three weeks ago. The activity is thought to have started when magma flowing from the magma reservoir beneath Svartsengi into the area beneath the Sundhnúkur crater row. At about 4.00 pm on 29 May the magma encountered groundwater penetrating through a fissure from a previous eruption, leading to a phreatic explosion as a large volume of the water was turned into steam instantly. This led to the formation of a new fissure running southwest to northeast (parallel to previous fissures on the peninsula) for about 2.4 km. This fissure has produced lava fountains up to 50 m high, and is extruding lava at a rate of about 1500-2000 m³ per second. The eruption has prompted the evacuation of the town of Grindavik, and the nearby Blue Lagoon Geothermal Spa. The fissure is further from the town than the eruption in January which saw lava entering the streets of the settlement and several buildings destroyed, but is also significantly larger, and is evolving significant amounts of toxic gasses.

A volcanic fssure on the Reykjanes Peninsula, Iceland, which opened on 29 May 2024. Marco Di Marco/AP.

Although dramatic, lava flows are not usually considered particularly dangerous, as their advancing fronts are quite slow and can quickly be outpaced by an able-bodied Human being. The more deadly volcanic events are pyroclastic flows, such as the one which engulphed the Roman town of Pompeii, in which clouds of superheated gas and ash move downhill at high speeds in an avalanche-like motion, and phreatic explosions, caused by bodies of lava encountering bodies of water, which evaporate almost instantly, causing huge explosions.

The size and position of the new fissure on the Reykjanes Peninsula, Iceland. Icelandic Met Office/BBC.

Iceland lies directly upon the Mid-Atlantic Ridge, a chain of (mostly) submerged volcanoes running the length of the Atlantic Ocean along which the ocean is splitting apart, with new material forming at the fringes of the North American and European Plates beneath the sea (or, in Iceland, above it). The Atlantic is spreading at an average rate of 25 mm per year, with new seafloor being produced along the rift volcanically, i.e. by basaltic magma erupting from below. The ridge itself takes the form of a chain of volcanic mountains running the length of the ocean, fed by the upwelling of magma beneath the diverging plates. In places this produces volcanic activity above the waves, in the Azores, on Iceland and on Jan Mayen Island. All of this results in considerable Earth-movement beneath Iceland, where Earthquakes are a frequent event.

The passage of the Mid-Atlantic Ridge beneath Iceland. NOAA National Geophysical Data Center.

See also...

Volcanic eruption on the Reykjanes Peninsula, Iceland.

On 11 November 2023 residents of the town of Grindavík on the Reykjanes Peninsula, Iceland, were evacuated from their homes following a major increase in seismic activity beneath the nearby Fagradalsfjall Volcano. The evacuations were triggered by the discovery of a magma tunnel running directly beneath the town at a depth of about 1.5 km. This is about 12 km long, originating near Stóra-Skógfell hill, and running beneath the town and some way out to sea. Seismic activity in the area has remained high in the area in the intervening weeks, although some people had begun to return to their homes. 

Slightly after 10.15 pm on Monday 18 December 2023, a new volcanic fissure opened on the peninsula, spewing vast amounts of lava and prompting a new series of evacuations. The fissure is about 3.5 km in length, and about 3 km from the town of Grindavík. It is currently producing 100-200 m³ of lava per second, although this is not flowing towards the town, and is not thought to present a threat to Human life.

Lava spewing from a new volcanic fissure on the Reykjanes Peninsula, Iceland, which opened on Monday 18 December 2023. BBC.

Although dramatic, lava flows are not usually considered particularly dangerous, as their advancing fronts are quite slow and can quickly be outpaced by an able-bodied Human being. The more deadly volcanic events are pyroclastic flows, such as the one which engulphed the Roman town of Pompeii, in which clouds of superheated gas and ash move downhill at high speeds in an avalanche-like motion, and phreatic explosions, caused by bodies of lava encountering bodies of water, which evaporate almost instantly, causing huge explosions.

People watching a lava flow on the Reykjanes Peninsula, Iceland, this week. Kristin Elisabet Gunnarsdottir/AFP/Getty Images.

Iceland lies directly upon the Mid-Atlantic Ridge, a chain of (mostly) submerged volcanoes running the length of the Atlantic Ocean along which the ocean is splitting apart, with new material forming at the fringes of the North American and European Plates beneath the sea (or, in Iceland, above it). The Atlantic is spreading at an average rate of 25 mm per year, with new seafloor being produced along the rift volcanically, i.e. by basaltic magma erupting from below. The ridge itself takes the form of a chain of volcanic mountains running the length of the ocean, fed by the upwelling of magma beneath the diverging plates. In places this produces volcanic activity above the waves, in the Azores, on Iceland and on Jan Mayen Island. All of this results in considerable Earth-movement beneath Iceland, where Earthquakes are a frequent event.

The passage of the Mid-Atlantic Ridge beneath Iceland. NOAA National Geophysical Data Center.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.

Eruptions on La Palma, Canary Islands.

Following a marked increase in seismic activity beneath La Palma volcano, on the Canary Island of the same name, authorities on the island began to make plans to evacuate residents from the area in the event of an eruption on 17 September 2021. Two days later, on Sunday 19 September, the volcano began to erupt at about 3.10 pm, with two fissures roughly 200 m long and 200 m apart opening on the flank of the volcano, producing columns of gas and ash that rose to 1.5 and 3.0 km above sealevel respectively, and lava fountains that set fire to nearby forests. Lava began to descend the sides of the volcano at a rate of about 700 m per hour (slow enough to evade at a walking pace), prompting evacuations and causing extensive damage to properties in its path. The volcano produced a vast plume of sulphur dioxide, which reached the coast of Morocco on 20 September, by which time lava flows had reached up to 3 km from the vents and destroyed 166 buildings. Over the next few days, the volcano produced further ash columns, which rose to heights as great as 4.6 km, while the lava spread to cover about 1.54 km², destroying over 350 homes and prompting the evacuation of over 5000 people.

 

Spanish police officers evacuating people from the course of a lava flow on La Palma. Emilio Morenatti/AP.

The eruptions continued through the remainder of September, producing ash columns that rose up to 5 km above sealevel and lava flows that reached the west coast of the island at Playa de los Guirres, destroying over 650 buildings and 18.9 km of roads, and sulphur dioxide emissions of up to 25 000 tons per day. 

 

Lava engulphing a residential building on La Palma. AP.

On Friday 1 October 2021 a third vent was discovered to have opened on the side of the volcano, producing two new lava flows, one of which flowed rapidly towards the town of Los Llanos de Aridane, which has been partly evacuated in response. A total of over 6000 people have now been evacuated from their homes on the island, with over 7 km² covered by lava flows and over a thousand homes and other buildings destroyed.

 

Satellite image of a lava flow running through a settlement on the west coast of La Palma. Copernicus Sentinel/European Space Agency/Reuters.

The Canary Islands are a group of volcanic islands fuelled by a mantle plume rising through the African Plate, on which they are situated. The plume is rising from deep within the Earth, and is independent of the movement of the tectonic plates at the Earth's surface. As the plate moves relative to the hotspot new volcanic islands form on its surface, each over the hotspot when it forms, with the oldest islands of the chain in the east (the African Plate is being pushed east by the expansion of the Atlantic Ocean, but the hotspot is relatively motionless).

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.

 

Hawai'ian man dies after falling into sinkhole.

A Hawai'ian man has been found dead after apparently falling into a sinkhole on his property. Police were called to the home of 71-year-old Robert Hisashi Nishimoto of Hilo on Big Island, on Monday 4 November 2019, after neighbours failed to see him for several days. a search of the property revealed a hole approximately 60 cm wide and eight metres deep, into which Mr Nishimoto had apparently fallen while trimming branches in his garden.

The approximate location of the Hilo sinkhole. Google Maps.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.

On this occasion the sinkhole is believed to have been caused by the collapse of the roof of a lava tube beneath the surface. A lava tube is a form of cave formed not by erosion, as in the case of most limestone caves, but by the way in which the lava from which the rock is formed cools and solidifies. As lava flows on the surface its outermost layers, which are in contact with the atmosphere, cool and harden more rapidly than layers lower down. This means that a solid crust can form over the lava flow, slowly solidifying from the outside, while the lave beneath is still flowing. Eventually a cavern is formed through which lava is flowing surrounded by solid rock. If the supply of lava is then cut off (by an eruption ending or the lava finding a different course) before the route through which the lava is draining is blocked, then a void (cave) will be left running through the rock, which we call a lava tube.

The formation of a lava tube. Caves of Lanzarote.

See also...

Follow Sciency Thoughts on Facebook.

Mount Etna enters new eruptive phase.

The Etna Observatory of the Istituto Nazionale di Geofisica e Vulcanologia has reported a new eruption on Mount Etna, Sicily. The volcano began to erupt overnight between Wednesday 29 and Friday 30 May, producing a dense column of ash that persisted till the afternoon of Thursday 30 May. Following which three new fissures opened up around the New Southeast Crater (a feature which itself appeared in December 2018), two to the southeast and one to the northeast, which produced lava fountains and flows which ran down into the Valle del Bove, the longest reaching about 3 km from the northeast fissure.

The eruptive scene at dawn on 31 May 2019, as recorded by the high-resolution surveillance camera installed at Monte Cagliato, on the eastern slope of Etna, at the lower end of the Valle del Bove. Istituto Nazionale di Geofisica e Vulcanologia.

Etna first erupted about half a million years ago, beneath the sea off the east coast of Sicily, and has been going strong ever since. It now stands 3330 m above sea level, and covers 1200 km³. It is responsible for fertile soils across eastern Sicily. Records of eruptions on Etna go back to 1500 BC. It is Europe's second largest volcano, after Teide in the Canary Islands, and is one of the most active volcanoes in the world.

 Lava fountains and flows on Mount Etna this week. BBC.

Despite all this Etna has only ever caused 77 recorded deaths (the most recent being two tourists caught in a summit explosion in 1987) and relatively little destruction. In 1928 it destroyed the village of Mascali on its northeastern flank, though there were no reported casualties, the village being slowly overrun by a lava flow. In 1669 a much larger lava flow destroyed at least 10 villages, reaching the walls of the city of Catania, 40 km to the south, but again without loss of life. In 122 BC a heavy ash fall covered much of the region, causing several buildings to collapse in Catania. The destruction was deemed so severe by the Roman authorities that they granted the city a 10 year tax holiday. In about 6000 BC a landslide on the eastern flank of the volcano is thought to have caused a tsunami that caused destruction around much of the eastern Mediterranean. 

 The location of Mount Etna. Google Maps.

 
Etna is located on the border of the African and European Plates, specifically where Africa is being subducted beneath the European Plate. As it is drawn into the Earth's interior material from the African Plate melts, and the lighter portions rise up through the overlying European Plate, causing a number of volcanoes including Etna and Vesuvius.

 Map showing the tectonic plates underlying Italy and southern Europe, and the location of the l'Aquila Earthquake. Napoli Unplugged.

See also...

Follow Sciency Thoughts on Facebook.

Eruptions from new fissure on Mount Ambrym, Vanuatu.

The Vanuatu Geohazards Observatory has reported an eruption from a new fissure on Mount Ambrym, a basaltic island volcano in the New Hebrides Island Arc. The activity began with a series of small earthquakes, leading up to the onset of eruptive activity at about 6.00 am local time on Saturday 15 December 2018, from a fissure to the southeast of the Lewolembwi  Crater, which produced lava fountains about 40 m high and a lava flow which ran to the east and filled much of the Lewlembwi Crater. Activity on the volcano persisted for another two days, with the lava fountains slowly being replaced with ash emissions.

Lava fountaining from a new fissure on Mount Ambrym, Vanuatu, on 15 December 2018. John Tasso/Vanuatu Island Experience.

Mount Ambrym comprises a complex of basaltic structures overlying an older shield volcano, which was initially formed in a massive eruption in about 50 AD, since when it has continued to grow. It has a 12 km widr caldera, which contains two smaller cones (Marum and Benbow) as well as seven smaller craters, Lewolembwi, Marumliglar, Mbwelesu, Minnei, Niri Mbwelesu, Niri Mbwelesu Taten, and Niri Mbwelesu Taten, and four cinder cones, Dalahum, Tuvio, Vetlam, and  Woosantapaliplip.

Vanuatu is located on the southwestern fringe of the Pacific Plate, close to its boundary with the Australian Plate, which is being subducted along the New Hebrides Trench, to the west of the islands. The subducting Australian Plate passes under the islands of Vanuatu as it sinks into the Earth, causing Earthquakes as the plates stick together then break apart as the pressure builds up. As the plate sinks further it is partially melted by the heat of the Earth's interior. Some of the melted material then rises through the overlying Pacific Plate, fuelling the volcanoes of Vanuatu.

See also...

Follow Sciency Thoughts on Facebook.