Five people killed by eruption on Mount Mayon, the Philippines.

Five people are reported to have been killed in an eruption on Mount Mayon, an active stratovolcano (cone shaped volcano) on Luzon Island in the Philippines. The five, who have been described as four German tourists and a local guide, were part of a group of 20 people who were approaching the summit  of the volcano, when they were caught by a small phreatic explosion (an explosion caused by liquid water encountering hot magma and vaporizing instantly), which though a column of ash 500 m into the air and showered them with rock fragments. Another seven people were injured in the blast, which took place at about 8.00 am on 7 May 2013, local time (midnight between 6 and 7 May, GMT).

Ash column above Mount Mayon. Reuters.

Mount Mayon is located on Luzon Island, about 330 km southeast of Manila. It is a popular tourist location, with frequent tours visiting the summit, bringing important tourism revenue into the area, but it is also a very active volcano, frequently undergoing several small eruptions in a year, with occasional larger and more devastating eruptions; an eruption in 1814 is thought to have killed over a thousand people, more recently 77 deaths were attributed to an eruption in 1984. Lahars are also a frequent problem on Mayon; these are volcanic mudflows, that do not necessarily occur at the same time as eruptions. Ashfalls can block parts of seasonal watercourses during eruptions. These ashfalls act like small damns with the arrival of the monsoon rains in April/May, blocking the flow of water temporarily, till it builds up sufficiently for the damn to burst, unleashing a torrent of thick muddy water down the sides of the volcano.

The location of Mount Mayon. Google Maps.

See also Earthquake off Mindanao Island in the Philippines, Massive Earthquake to the east of the Philippines, Massive Earthquake shakes Cebu & Negros Islands in the Philippines, Earthquake in the Babuyan Islands of the Northern Philippines and Manila shaken by mild earthquake.

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Eruption on San Cristobal, Nicaragua.

San Cristobal is an active stratovolcano (cone-shaped volcano made up of successive layers of ash and lava) in the northwest of Nicarugua. The peak 1745 m high, and has been active more-or-less continuously since about 1520 AD. The current volcano lies at the northwest end of a chain of older volcanoes known as the San Christobal Complex.

Map showing the volcanoes of Nicaragua; San Cristobal being the northwesternmost. United States Geological Survey.

On Saturday 8 September 2012 San Cristobal began to rumble and emit an increased level of ash and gas in the morning. This was followed by a series of explosions and the eruption of a 4 km high column of ash, estimated by the Nicaraguan Institute of Territorial Studies to contain about 3221 tonnes of ash. The Nicaraguan Army has evacuated nearby villages, and the volcano is being monitored closely.

Column of ash over San Cristobal on Saturday 8 September, seen from Chinandega. AFP/La Presna/Eddy Lopez.

Nicaragua, and neighbouring Central American nations, are located on the southern margin of the Caribbean Plate, close to the margin with the Cocos Plate, which underlies part of the eastern Pacific Ocean. The Cocos Plate is being subducted along the Middle American Trench, to the south of the Nicaraguan coast, and passes under Central America as it sinks into the Earth. As the plate is subducted it is partially melted by the friction and the heat of the planet's interior, giving rise to liquid magma which rises through the Caribbean Plate to fuel the volcanoes of Central America.

Map showing the margin of the Cocos and Caribbean Plates and the volcanoes of Central America. Scripps Institution of Oceanography.

See also Large Earthquake off the south coast of El Salvador, Eruption on Rincón de la Vieja, Costa Rica, Oaxaca region of Mexico struck by second major Earthquake in two weeks, Understanding the subduction zone beneath Mexico and Volcanoes on Sciency Thoughts YouTube.

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Eruption on Mount Bezymianny.

Mount Bezymianny is an extremely active stratovolcano on the central part of the Kamchatka Peninsula in the Russian Far East. The volcano was thought to be extinct until 1955, when it began a volcanic cycle that ended in 1956 with an explosive eruption caused the summit to collapse and created a large horseshoe-shaped crater. This has subsequently been filled in by further eruptive episodes on Bezymianny. The current summit is 2882 m high, but it is overshadowed by the nearby Kamen and Kluchevskaya volcanoes at 4579 m and 4750 m respectively.

Mount Bezymianny in 1957 (top) and the late 1980s (bottom) showing the growth of a new summit within the 1956 crater. Top image G.Y. Bogoyavlenskaya/Oregon State University. Bottom image Yuri Doubik/Institute of Volcanology, Petropavlovsk/Oregon State University.

Bezymianny is thought to have formed about 4700 years ago, on the remains on an older, Pleistocene, volcano active between 11 000 and 7000 years ago. It has undergone three periods of intense activity since its formation, but was apparently inactive for about a thousand years prior to its 1955 reactivation.

Bezymianny last erupted in 2011, but underwent a period of seismic activity (earthquakes) in February-March 2012. On 24 August 2012 the  Kamchatka Volcanic Eruption Response Team detected a resumption in seismic activity, followed by the onset of fumarole activity (gas emissions) on 25 August. An explosive eruption occurred on 2 September, causing to an ash cloud rising to a height of 10-12 km, which then drifted 1500 km to the northeast. This was followed on 3 September by lava flows and ash avalanches.

Ash cloud from Mount Bezymianny. Kamchatka Volcanic Eruption Response Team.

See also Seismic activity on Little Sitkin, Eruption on Ivan Grozny, Massive deep Earthquake beneath the Sea of Okhotsk, Earthquake shakes the Kamchatka Peninsula and Volcanoes on Sciency Thoughts YouTube.

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Seismic activity beneath Mount Sotará, Columbia.

The Observatorio Vulcanológico and Sismológico de Popayán reported a sharp rise in seismic activity under Mount Sotará in southeast Columbia this month, with 110 Earth tremors of magnitudes between 0.2 and 1.6 at depths of 2-6 km, within 5 km of the summit between the 8th and 14th of August 2012. Such quakes can be the result of magma moving into chambers beneath a volcano, which in turn may be a prelude to an eruption. 

Areal photograph of Mount Sotará taken in December 2007. The 'smoke' around the crater is probably just low cloud. Observatorio Vulcanológico and Sismológico de Popayán.

Mount Sotará is a stratovolcano (cone-shaped volcano made up of layers of ash and lava) slightly over 4400 m high. It has not erupted in recorded history, although it has produced fumaroles (gas emissions), and a complex of hot springs to the southeast is thought to be associated with the volcano.

Like other volcanoes along the west coast of South America, Mount Sotará is fueled by the subduction of the Nazca Plate (which underlies the southeastern Pacific Ocean) beneath the South American Plate. As the Nazca Plate passes under South America it is partially melted by the friction and the heat of the planet's interior. Some of this melted material then rises through the South American Plate, feeding the volcanoes of the Andes.

See also Seismic activity on Mount Cumbal, Colombia, Earthquake off the coast of Chiloé Island, Chile, Earthquake in eastern Chile, Strong Earthquake to the south of Panama and Volcanoes on Sciency Thoughts YouTube.

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Increased activity on Mount Yasur, Vanuatu.

Mount Yasur is located on the southeast of Tanna Island in the Republic of Vanuatu, close to the volcanically named Sulphur Bay. It is one of the world's most active volcanoes, having been erupting more-or-less continuously for 800 years, though these eruptions are seldom very large, which has enabled the island to develop a thriving tourist industry based around the volcano. Yasur is a stratovolcano (cone-shaped volcano made up of layers of ash and lava), rising 631 m above sea-level, with a summit crater nearly 400 m across. It is sacred to worshipers of John Frum.

An ash-cloud over Mount Yasur. Air Taxi-Vanuatu.

The regular eruptions on Mount Yasur are considered to be 'Strombolian' by geologists. Such eruptions consist of regular explosions throwing lava bombs, incandescent cinders and small stones and ash a few hundred meters in the air; Stombolian eruptions get their name from Mount Stromboli in Italy, which behaves in a similar way. Eruptions of this kind are spectacular, but seldom dangerous as long as a safe distance is kept.

The emptying of the postbox on top of Mount Yasur, with a Strombolian eruption in the crater to the right. The postbox is publicized as the only postbox on top of an active volcano in the world, and caters for tourists who visit the summit. Vanuatu Post.

Over the period 7-12 July 2012, the level of activity on Mount Yasur increased sharply, with lava bombs falling onto the tourist trail and car park, making the summit inaccessible. On 13 July the Vanuatu Geohazards Observatory concluded that the volcano was moving from a Strombolian phase to a sub-Plinian one, and officially closed off the area around the summit.

Plinian eruptions get their name from the eruption on Mount Vesuvius that destroyed Pompeii in AD 79. They are named after either (depending on source) the Roman author Pliny the Younger, who was the first person to describe an eruption of this sort, or his uncle Pliny the Elder, who is recorded to have been the first person killed while trying to investigate such an eruption, and is consequently regarded as the father of volcanology. 

Eruptions of this kind produce clouds of gas and ash that climb many kilometers into the stratosphere, and can prove extremely dangerous, with widespread ashfalls and pyroclastic flows (avalanches of hot ash and gas). Such eruptions can happen several times in a decade on Mount Yasur, though this frequency makes the volcano less hazardous; Vesuvius erupts infrequently, leading to the building of the cities of Pompeii and Herculanium on what appeared to be safe areas of the volcanoes flanks (modern Naples also lies on the flanks of Vesuvius). Because such eruptions are a certainty on Mount Yasur, no similar cities have been built on its flanks, and those settlements that are nearby are prepared for evacuation if this becomes necessary. Consequently major loss of life on Yasur is far less likely.

Mount Yasur, and Vanuatu in general, lies on the margin between the Pacific and Australian Plates. This is a convergent margin, with the Australian Plate being subducted beneath the Pacific. As is sinks into the Earth's interior the Australian Plate is partially melted by a combination of heat from the friction with the overlying Pacific Plate, and that from the Earth's interior. Some of the melted material then rises up through the overlying Pacific Plate as liquid magma, fueling the volcanoes of Vanuatu.

See also Earthquake in Vanuatu, Series of Earthquakes shakes Vanuatu, Earthquake in Vanuatu, 21 August 2011 and Volcanoes on Sciency Thoughts YouTube.

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Eruption on Pagan Island.

Pagan Island is located in the Northern Mariana Islands (a US territory in the west Pacific), roughly 500 km north of Guam. It is made up of the exposed tips of two submarine stratovolcanoes (cone-shaped volcanoes made up of layers of ash and lava), connected by a narrow isthmus of land. The northern of these two volcanoes is the largest and most active, reaching 570 m above sea-level; almost all recorded eruptions on the island have come from this peak. The southern cone is smaller, at 548 m, and has only been recorded to erupt twice, in 1864 and 1929. This southerly volcano has a more complex structure than the northern, with five craters strung out in a line from northeast to southwest.

Simple map of Pagan Island. Smithsonian Global Volcanism Program.

On 10 July 2012 the Washington Volcanic Ash Advisory Center reported a cloud of volcanic ash rising 1.5 km above Pagan Island, which drifted roughly 50 km to the northwest. Some ashfall was also reported on the island. Plumes of gas and steam are extremely frequent on Pagan, and small ash eruptions once or twice a year, though this is the largest such event since August 2010.

The largest eruption recorded on the island happened in 1981, when a mushroom cloud reached 13.5 km above sea-level and 53 people had to be evacuated from the island. The island was evacuated again in 1993.

Terra Satellite image of a steam plume from North Pagan on 7 May 2012. NASA/GSFC.

The volcanic Mariana Islands are located on the eastern margin of the Philippine Plate, close to its margin with the Pacific Plate. The Pacific Plate is being subducted beneath the Philippine Plate along the Mariana Trench. As it sinks into the Earth it is heated by a combination of the heat of the planet's interior and friction with the overlying Philippine Plate. This causes it to partially melt, producing liquid magma which then rises up to fuel the volcanoes of the Mariana Arc.

Simplified diagram of the subduction of the Pacific Plate beneath the Philippine plate, and how this fuels the volcanos of the Mariana Islands. NOAA Ocean Explorer.

See also Earthquake in eastern Taiwan, Earthquake shakes south Taiwan, Mapping the subductioin zone beneath Taiwan, Massive Earthquake shakes Cebu & Negros Islands in the Philippines and Volcanoes on Sciency Thoughts YouTube.

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Seismic activity on Mount Cumbal, Colombia.

Cumbal is the most southerly active volcano in Columbia; it is a stratovolcano (conventional cone-shaped volcano made up of layers of lava and ash) elongated along a northeast-southwest axis, giving it an oval shape. It has undergone two major eruptions in recorded history; one in 1877 and one in 1926. There is a lava-dome within the 250 m wide central crater (i.e. a dome formed by the injection of magma beneath the surface which has never erupted, but has caused uplift), which produces fumaroles (gas emissions) and steam plumes from time to time. There are also hot springs on the southeastern flanks.

Mount Cumbal, Colombia. Land of Winds.

On 10 July 2012, the Instituto Colombiano de Geología y Minería reported that it had recorded a steady rise in seismic activity (Earth tremors) over recent months. Such movements beneath volcanoes can be significant, as they are often caused by the arrival of fresh magma, which may indicate that a volcano is about to undergo an eruptive episode. The most recent period of seismic unrest on Mount Cumbal occurred in 1988, which led to an increase in fumarole activity, but not to an eruption. However this was accompanied by a similar increase in seismic activity on the nearby Mount Gaelras, which did develop into a full eruptive episode, culminating in the deaths of six volcanologists and three tourists visiting the volcano in 1993.

Cumbal itself is more infamous for the fatalities caused by a man-made disaster; in January 2002 a commercial airliner flew into the side of the volcano in heavy fog, killing all 94 passengers and crew onboard. 

Debris on Mount Cumbal following the 2002 air-crash. AirDisaster.com.

Cumbal is located in the Andes Mountains, which run along the entire west coast of South America from Columbia to southern Chile. These owe their origin to the subduction of the Nazca Plate which underlies the southeast Pacific beneath the South American Plate. The Nazca Plate is being subducted beneath the South American Plate along almost the entire of South America's west coast. As this happens it causes crumpling in the South American Plate, leading to uplift in the Andes. At the same time the underlying Nazca Plate is being heated by a combination of friction with the overlying South American Plate and the heat of the Earth's interior, causing it to partially melt. Some of the melted material then rises through the overlying South American Plate, fueling volcanoes scattered throughout the Andes Mountains.

Simple diagram showing the passage of the Nazca Plate beneath the South American Plate, and the formation of magma which fuels the Volcanoes of the Andes. PlateTectonics.com.

See also Earthquake off the coast of Chiloé Island, Chile, Earthquake in eastern Chile, Chile struck by large Earthquake, Eruption on Nevado del Ruiz, Columbia and Volcanoes on Sciency Thoughts YouTube.

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Eruption on Manam Motu.

Manam Motu is a volcanic island 13 km off the north coast of Papua New Guinea; it is essentially a submarine stratovolcano (cone-shaped volcano) with its tip sticking above the sea, forming a 10 km diameter circular island with the summit of the volcano at the centre. The island is remarkably symmetrical, with four valleys at 90° angles leading from the summit to the sea, which carry ejecta from the frequent eruptions.

Satellite image of water vapor emerging from Manam Motu, taken by NASA's Earth Observing-1 Satellite on 28 June 2009. Earth Observatory. 

The Rabaul Volcano Observatory in Papua New Guinea reported the appearance of a vapor cloud above Manam Motu on 5-6 May 2012, followed by an ash cloud on 6-7 May, combined with incandescence (glowing) over the summit. On the 10-11 another ash cloud was observed, accompanied by further incandescence. Incandescence resumed on 13-14 May, with further ash eruptions on the 13th. On 16 May a darker grey/black ash cloud was produced, accompanied by an increase in ejected incandescent tephra (tephra is any material ejected from a volcano, it can be ash, rock fragments or lava; this is a particularly useful term when volcanologists don't want to get close enough to inspect the ejected material). Another ash cloud was produced on 26 May, followed by a Strombolian eruption (eruption of incandescent tephra and lava bombs) on the 27th. This was followed by more further ash clouds on the 28th and 29th, and another Strombolian eruption on the 30th.

Manam Motu is one of Papua New Guinea's most active volcanoes; it underwent four eruptive cycles in 2011. The island was inhabited until 2004, when the island's population of ~9000 was evacuated after an eruption killed five people. The Papuan government allowed re-settlement to begin in March 2007, but three people were killed on the island within a month; the island's inhabitance status is currently unclear. Prior to 2004 the most recent fatalities had been in 1996, when a pyroclastic flow (avalanche of hot ash and poisonous gas) hit the village of Budua, killing 13.

Despite its small size and inhospitable nature Manam Motu was apparently settled for a long time, having developed its own distinctive language (Manam). 

Manam Motu is located on the southern margin of the South Bismarck Plate, close to its boundary with the Australian Plate, which underlies the Papuan mainland. The Australian Plate is being subducted beneath the South Bismarck, and as it does so it is partially melted by the friction and the heat of the planet's interior. Some of the melted material then rises up through the overlying South Bismarck Plate as magma, fueling the volcanoes of the north Papuan margin.

See also Earthquake in the Loyalty Islands, Eruption on Mount Sirung, Eruption on Mount Pago, Eruptions on Batu Tara and Volcanoes on Sciency Thoughts YouTube.

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Eruption on Mount Kanaga.

On Saturday 18 February 2012 a network of seismic sensors on Mount Kanaga, on Kanaga Island in the Aleutian Island Chain, Alaska, detected an outburst of Earthquake activity that lasted about an hour, according to the Alaska Volcano Observatory. Subsequently a small plume was detected drifting northeast of the island by the NOAA-15 weather satellite.

Satellite image of Mount Katanga, taken in 2002. Taken from the International Space Station with the E4 Kodak DCS760C Electronic Still Camera. NASA/Earth Observatory.

Mount Kanaga is a 1307 m high stratovolcano (cone shaped volcano) located at the northern tip of Kanaga Island in the Central Aleutians. It sits inside the older Kanaton Caldera, and has erupted a number of times since it was discovered by Europeans in 1763, the most recent significant eruptive cycle having lasted from December 1993 to August 1995, and produced a number of volcanic plumes, some of which reached 4500 m in height. Much of northern Kanaga Island is covered by layers of ash and pumice up to 7 m thick, with soil layers trapped in between, but it is not certain if all this material was produced by Mount Kanaga or whether volcanoes in neighboring islands contributed.

The Aleutian Islands are located on the boundary between the Pacific and North American Plates. The Pacific Plate is being subducted beneath the North American Plate in the Aleutiam Trench to the south of the Islands. As it sinks into the Earth's interior it is partially melted by the heat from the planet's core, the some of the melted material then rises up through the overlying North American Plate as magma, forming the volcanoes of the Aleutian Island Arc.

See also Is Mount Cleveland, Alaska, about to erupt? and Volcanoes on Sciency Thoughts YouTube

New eruptions on Mount Tungurahua, Ecuador. November 2011.

Mount Tungurahua is a stratovolcano (a 'conventional' cone-shaped volcano, the sort you see in Hollywood movies) located in the Sangay National Park in Ecuador, overlooking the town of Baños de Agua Santa. The town's major industry is tourism, attracting visitors to visit the volcano, the hot springs associated with the volcano, and the Amazon Rainforest.

Tungurahua has been intermittently active since 1999 (prior to which it had been inactive for about 75 years), with major eruptions in August 2006, February 2008, May 2010, December 2010 and April 2011. The 2006 eruption killed seven people; two volcanologists and a local family.

The August 2006 eruption on Mount Tungurahua.

On 27 November 2011 a number of earthquakes were felt in the area, followed by pyroclastic flows (flows of heavy superheated gas containing large amounts of hot ash, rocks and debris) were observed on the northern and northwestern flanks of the volcano. Later in the afternoon a series of explosions were heard near the summit of the volcano, and pyroclastic flows were observed on the southern and southwestern flanks. The following day there were further explosions, and pyroclastic flows on the south flank. A plume of ash and hot gas rose 3 km above the volcano, several local towns reported ash-falls, and nearby villages were evacuated with the help of the National Secretariat for Risk Management.

By the beginning of December the Geophysical Institute of Ecuador reported that the amount of gas being produced by the volcano had dropped dramatically, with no further pyroclastic flows. The volcano is still undergoing frequent earthquakes, but these do not necessarily imply an eruption is immanent. The situation is being monitored by the Tungurahua Volcanological Observatory in Guadelupe, 14 km to the north.

The current Tungurahua volcano is the third on the site, referred to by volcanologists as Tungurahua III. The first volcano on the site, Tungurahua I, built up and then collapsed some time in the Mid-Pleistocene. This was followed by Tungurahua II, which started to grow about 14 000 years ago, then collapsed about 3000 years ago. The current volcano has been growning since this time, and lies within the caldera of Tungurahua II.

Like all South American volcanoes Tungurahua owes its existence to the subduction of the Nazca Plate (which underlies the southeast Pacific) beneath South America. The Nazca Plate is being pushed from the east and forced down into the Earth's interior beneath South America. As it sinks rocks in the crust melt, and the lighter portions of it rise up through the overlying South American Plate to form volcanoes at the surface. These are dotted throughout the Andes Mountains; a range of mountains that is formed by a mixture of volcanism and crumpling of the South American Plate where is is forced against the Nazca Plate.

The subduction of the Nazca Plate beneath South America creates the Andes Mountains.

See also Earthquake in Jujuy Province, The Puyehue Eruption, The Puyehue-Cordón Caulle Volcanic Complex and Volcanoes on Sciency Thoughts YouTube.

The Open University run a course in Volcanoes, earthquakes and tsunamis by distance learning. This can be counted towards a degree, but does not need to be taken as part of a degree course. The course costs £170 for UK residents and £405 for overseas residents, though financial support may be available for UK and European residents.