Volcano news - Archive Nr. 17

For the latest part of this report - Click here

Manaro Voui, Ambae, Vanuatu (Philippa)
The Manaro Voui crater eruption on the volcanic island of Ambae continues. Due to the heavy ash fall, conditions are now critical across much of the island. 3 people have already died: two of these were elderly inhabitants who went into shock due to the situation, whilst the third person died due to a lack of clean drinking water as a result of ash contamination.


As well as the effect on drinking water, food supplies on the island are dwindling, and illness is starting to spread as a secondary effect. The latest article on the RNZ site describes it as flu-like symptoms and a sore throat. This is an allergic reaction by the body to the volcanic ash, as well as the effects of ash inhalation.


A state of emergency has now been called on Ambae. There is talk of moving inhabitants to the one area of the island that remains unaffected, but there is still no official announcement about plans to evacuate the inhabitants off the island.

In such a situation, the short-term problem is where to evacuate people to that will take them out of immediate harm's way, and how best to provide shelter, food, and water, i.e. the basics for living. Secondary problems can occur, for example the outbreak of diseases such as cholera due to a lack of emergency sanitation, as was the case in the Democratic Republic of Congo when Nyiragongo volcano last erupted. Other secondary problems can be caused by bad weather, particularly hurricanes / typhoons or generally heavy rainfalls, which then wash volcanic ash down-slope after eruptions, creating lahars. The long-term problem then becomes a waiting game to see how the volcanic activity will evolve, if it will ever be possible for a clean-up operation to take place for people to eventually move back to their homes, or whether they will need to be permanently re-located elsewhere, requiring them also to change their entire livelihoods. As evidence has shown in other parts of the world that have had eruptions requiring long-term evacuations, such as the Eastern Caribbean island of Montserrat and the town of Chaiten in Chile, there are no simple solutions.

via Philipson Bani (@philipsonbani) / Orsbon Smith - 11th April 2018

Klyuchevskoy and Sheveluch, Kamchatka, Russia (Philippa)
Beautiful viewing conditions at the moment via the webcams of several of the volcanoes in Kamchatka, far eastern Russia.

Klyuchevskoy - via the Institute of Volcanology and Seismology (IVS / KVERT) - Kamchatka Branch

Sheveluch - via IVS / KVERT

Anak Krakatau, Sunda Strait, Indonesia (Philippa)
The images (below) were taken over the weekend using a drone. They show the steaming vents of Anak Krakatau, a volcanic island, which is the active remnant of the bigger Krakatau caldera (a volcano which has collapsed at the end of a large eruption).

Anak Krakatau last erupted in February 2017 with Strombolian-style emissions and lava flows, but the larger Krakatau caldera was the site of the famous 1883 eruption, which was so big (estimated VEI 6 on a scale of 1-8) that the eruption was heard as far away as Australia.

via Øystein L. Andersen (@OysteinLAnderse)

Mount Yasur, Tanna Island, Vanuatu (Philippa)
Here at Earthquake-Report.com we love seeing people's fieldwork photos. PhD student Benjamin Simons is lucky enough to be studying Mount Yasur, a volcano characterised by frequent, Strombolian-style eruptions. All around the active crater are pyroclasts ('hot rocks') and larger lava 'bombs' spat out from the vent. If a really big, really hot glob of lava gets spat up into the air, it is still so runny when it lands on the ground that it splays out, like in these images below. Person for scale.

via Benjamin Simons (@dread_rocks)

Rotarua, North Island, New Zealand (Philippa)
PhD student Geoff Lerner is currently on fieldwork at the Rotokawa geothermal field and Waimangu Valley in the vicinity of Taupo volcano on North Island in New Zealand. He is posting daily updates featuring not only images, but descriptions of the 'fragrant' (pungent!) smells and bubbling sounds of the hot pools.

Geoff is doing temperature profiling around the hot springs, Waimangu lake, and various volcanic lakes, which have been the sites of hydrothermal (i.e. involving water heated by the ground) eruptions, including Echo Crater within Mount Tarawera. The waters are hot enough to boil an egg, and the still-hot ground is the source of energy at a nearby geothermal power plant.

Also found here is Taupo pumice, very light rocks formed from the bubbly froth erupted first from the top of a gassy magma column in a conduit. It is not clear from either Geoff's tweets or the academic literature which eruption from the area this originates from - the geological history in this region is complicated - but is thought to have been from within the past 2,000 years.

Pumice rock is full of holes, and so as the geothermal gases permeate through these and cool, they form crystals, in this case - sulfur, within the holes.

Making lava, Syracuse University, New York, USA (Philippa)
As well as doing fieldwork, volcanology researchers also do lab experiments to try and replicate natural phenomena in order to better understand them. PhD candidate James Farrell has had a fun week making lava in a university lab. This video (sped up!) gives an example of how low viscosity (fluid) lavas, similar to the ones currently erupting from Kilauea volcano on Hawaii, flow and inflate before cooling.

via James Farrell (@breakmohrrocks)

April 17, 2018

Weekly Volcanic Activity Report: 4 to 10 April 2018
Via Smithsonian Institution - Global Volcanism Program / US Geological Survey

Ambae | Vanuatu
Vanuatu Geohazards Observatory (VGO) reported sustained ash and/or gas emissions from Ambae’s Lake Voui during March through 4 April. Satellite data showed a significant sulfur dioxide gas emission (~0.15 Tg SO2) beginning in the very early hours of 6 April, indicating that the SO2 emission was the largest since Calbuco in April 2015. No significant high-altitude ash plume accompanied the emission, though the eruption generated lightning detected by the WWLLN (World Wide Lightning Location Network). Pictures of local areas posted on social media showed the continuing and significant ashfall on the island. Within a few days, by 8 April, the sulfur dioxide plume had spread across an area from the E coast of Australia to Tahiti, a distance of about 6,000 km. The Alert Level remained at 3 (on a scale of 0-5).

Kirishimayama | Kyushu (Japan)
JMA reported that an explosive eruption at Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, occurred at 0531 on 5 April and generated an ash plume that rose 8 km above the crater rim. According to news articles lightning was detected in the ash plume. JMA noted that incandescent tephra was ejected 1.1 km from the vent, and a pyroclastic flow traveled 800 m down the SE flank. Sulfur dioxide emissions increased to 1,400 tons/day, from 300 tons/day last measured on 28 March. The eruption possibly ceased at 0715. During an overflight later that day scientists confirmed a large amount of ashfall in parts of Kobayashi City and other areas of the Miyazaki Prefecture, in part of Takahara Town, and in areas of the Kumamoto prefecture. White plumes rose 200 m during 6-9 April. The Alert Level remained at 3 (on a scale of 1-5).

Lascar | Chile
OVDAS-SERNAGEOMIN reported that, although seismicity at Láscar during March was low, characteristics of the signals were similar to patterns observed prior to previous minor phreatic explosions, particularly before events in 2013 and 2015. The Alert Level was raised to Yellow (second highest level on a four-color scale); SERNAGEOMIN recommended no entry into a restricted area within 5 km of the crater. ONEMI declared an Alert Level Yellow (the middle level on a three-color scale) for San Pedro de Atacama.

Nevados de Chillan | Chile
Servicio Nacional de Geología and Minería (SERNAGEOMIN) Observatorio Volcanológico de Los Andes del Sur (OVDAS) reported continuing activity through 5 April associated with growth of the Gil-Cruz lava dome in Nevados de Chillán’s Nicanor Crater. During 16-31 March the seismic network recorded 44 volcano-tectonic events with maximum local magnitude (ML) of 2.6. In addition, there were 3,874 earthquakes associated with fluid movement; of those 2,645 earthquakes were long-period events. A total of 1,229 tremor events were also detected. Explosive events totaled 765, mainly accompanying magmatic gas emissions and/or acoustic signals recorded by microphones on the flanks. Acoustic pressure from explosions increased on 24 March, and culminated with two major explosions on 30 and 31 March exceeding pressures much higher than previously recorded since the emergence of the dome. Webcam images showed mainly gas emission from explosions, rising no higher than 2 km above the crater rim. Incandescence associated with some explosions was sporadically visible at night.
During an overflight on 3 April scientists observed intermittent whitish-to-grayish emissions rising from the SE-NW-trending fissure on the lava dome’s surface. They also noted lapilli deposits as far as 1 km. Even though subsidence in the central part of the dome was visible, the dome had grown compared to the last observation on 11 March. The dome had extended E to the edge of Nicanor Crater and rose higher than the crater rim, although was mostly circular. The maximum temperature of the dome surface was 670 degrees Celsius. The report noted that a decrease in daily seismic events (suggesting pressurization), two significant explosions, and the dome growing higher than the crater rim prompted OVDAS- SERNAGEOMIN to raise the Alert Level to Orange, the second highest level on a four-color scale. ONEMI maintained an Alert Level Yellow (the middle level on a three-color scale) for the communities of Pinto, Coihueco, and San Fabián.

Sinabung | Indonesia
PVMBG and BNPB reported that an eruption at Sinabung at 1607 on 6 April generated a dark gray ash plume that rose 5 km above the crater, and a pyroclastic flow that descended the SE and SW flanks 3.5 km. The Alert Level remained at 4 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions of 7 km on the SSE sector, 6 km in the ESE sector, and 4 km in the NNE sector. According to news articles, ashfall affected hundreds of hectares of agricultural land in the district of Karo, North Sumatra, and the Alas Leuser airport was closed on 7 April due to ash. The Alert Level remained at 4 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions of 7 km on the SSE sector, 6 km in the ESE sector, and 4 km in the NNE sector.

Manaro Voui, Ambae, Vanuatu 

April 12, 201

Manaro Voui, Ambae, Vanuatu (Philippa)
Increasing activity continues from Manaro Voui crater within the volcanic island of Ambae.

The latest bulletin from the Vanuatu Meteorology and Geo-Hazards Department (VMGHD) indicated that the Alert Level had been raised again to Level 3 (following the lowering to Alert Level 2 in December 2017). There is a 3 km exclusion zone around the crater, and the yellow zone on the latest volcano hazard map for the island shows the areas which VMGHD have warned could be vulnerable to further ash fall, lahars / flooding, and/or landslides if there is heavy rainfall.

via Vanuatu Meteorology and Geo-Hazards Department

According to Simon Carn (@simoncarn), who uses satellite data and other remote sensing techniques to monitor volcanoes globally, Ambae had its highest emissions of (volcanic gas) sulphur dioxide (SO2) so far during an eruption on the afternoon of 5th April (estimated loading ~ 0.1-0.15 Tg), and this was the greatest amount of SO2 emitted by a volcano globally since the eruption of Calbuco in Chile in 2015. Increasing SO2 emissions are indicative of new / younger batches of magma rising beneath a volcano.

Simon's satellite data and clusters of (volcanic) lightning** strikes that have been detected via the Worldwide Lightning Location Network (@WWLLN) would indicate that eruption columns from Manaro Voui crater have increasingly been reaching altitudes of the upper troposphere. The Troposphere is the layer of the atmosphere between the ground and the stratosphere. This in turn would indicate that the eruptions are becoming more sustained again, and there are considerations for re-evacuating the inhabitants of the island.

** Lightning can be generated by volcanic eruptions, as well as meteorologically. The upward rush from the convection of hot volcanic gases and the turbulent flow of ash particles bumping into each other within an eruption column causes the particles to become electrically charged. The difference between positive and negative charges within the column cause a discharge, i.e. lightning.

The images (below) show the heavy ash fall on the traditional houses on the island of Ambae.

via Philipson Bani (@philipsonbani) / Ghevin Banga

Such conditions can cause major problems for local inhabitants, including: contamination of drinking water; crop failure; building collapse from the weight of the ash fall; long-term respiratory problems, fluorosis (damage to teeth), eye irritation, and other health problems; death of livestock. For local government, the biggest considerations will be the cost of being able to maintain life on these parts of the  Ambae versus the cost of temporary re-evacuation or permanent re-settlement. Even once the Manaro Voui crater eventually stops erupting, the clean up operation of volcanic ash can take years.

This image (below), taken from a different part of the island, shows an eruption column from Manaro Voui crater and the volcanic ash falling out as the plume is blown by trade winds.

via Sherine (@SherineFrance) / John Siba & Wilfred Woodrow (https://www.facebook.com/groups/558036627684741/permalink/974980079323725/https://www.facebook.com/john.siba.3/posts/1768721766521765)

Nevados de Chillan, Chile (Philippa)
Preparedness activities continue around Nevados de Chillan, which is currently on Orange alert due to a growing lava dome. (Monitoring agency) SERNAGEOMIN have been working closely with (Chilean civil defense) ONEMI, emergency response units, including the military, and municipal officials (local decision makers and community leaders). Special press releases have been issued and media interviews done to inform the public to be vigilant around the volcano, which is a popular location for outdoor pursuits and spas.

via Szabolcs Harangi (@szharangi) /  SERNAGEOMIN (@sernageomin)

In their social media output, ONEMI have issued a volcano hazard map produced for Nevados de Chillan by SERNAGEOMIN, asking local inhabitants, tourists and other visitors to the area to be aware of the situation, to learn about communal evacuation plans, and to read the preparedness and response recommendations

via SERNAGEOMIN (@sernageomin) / ONEMI (@onemichile)

In the event of an eruption, the volcanic hazard map (above) indicates the most likely possible scenarios based on geological mapping of volcanic deposits and features from previous eruptions. Red indicates the areas that would be most susceptible to ash fall, pyroclastic density currents (avalanches of hot volcanic gases, ash, and rocks), and lahars; stripy purple indicates the areas that would additionally be susceptible to ash fall; the arrows indicate the direction of flow along valleys which would additionally be susceptible to lahars and flooding.

A volcanic hazard map is NOT a forecast of what will definitely happen should a volcano erupt. Nor is it necessarily an indication of which areas potentially would be 'safe' should an eruption happen. There are many different variables which can affect both an eruption itself and people's response to an eruption, in particular factors such as: style of eruption (explosive versus effusive), size of eruption, time of eruption (day versus night), duration of eruption, and not least, meteorological (weather) factors, particularly wind direction and rainfall during and after eruption.

Two of the biggest problems with hazard maps, other than the uncertainty of what exactly a future eruption could do, are: 1) people understanding their own location relative to the hazard map, and 2) updating a hazard map in real-time once an eruption begins. The latter is important for emergency responders, particularly, for example, if access roads becomes cut off by lahars or other eruption products. Volcanology researchers and IT innovators are working hard to find additional solutions to such problems.

Here is a link to the general volcano eruption preparedness and response recommendations (in Spanish, English, and French)


Webcam shots, World (Philippa)
It has been a little while since we have done a round-up of the best volcano webcam shots, particularly from Kamchatka in the far east of Russia, as a lot of our favourite volcanoes have been shrouded by low cloud and generally poor weather conditions for viewing. But here are a selection from the past week (and a few fieldwork shots too):

Avachinsky | Kamchatka, Russia - via the Institute of Volcanology & Seismology, Kamchatka branch

Merapi | Java, Indonesia - via BPPTKG (@BPPTKG) / PVMBG

Fuego | Guatemala - via INSIVUMEH (@insivumehgt)

Sakurajima | Kagoshima Prefecture, Kyushu, Japan - via James Hickey (@jameshickey77)

Vesuvius (with the city of Naples in the foreground) | Italy - via www.campanialive.it

Mt. Nakadake / Mt. Aso | Kyushu, Japan - via Fumihiko Ikegami (@fikgm)

Mount Nakadake, which is part of the larger Mount Aso caldera complex in southern Japan, was the first active volcano that I ever visited way back in 2001. Fumihiko Ikegami's image from 2012 shows it as pretty much the same as when I first saw it, with these fantastic phreato-magmatic (explosive water-magma interaction) eruption features and a steaming, milky-blue-coloured crater lake. Whilst standing on the crater rim, someone helpfully explained to me that this colour was caused by the chemical interaction between the volcanic gases and (rain) water which has accumulated in the crater, and that the water was very acidic! Not as stinky though as other volcanoes that I have visited; Vulcano in the Aeolian Islands / Italy and Askja volcano in Iceland take the prize for the worst rotten egg-type stench!

I re-visited Mount Nakadake in July 2013, but gone was this vista. The volcano, as it has also been on the webcam today, was mostly shrouded in mist, and the crater lake had dried up. As it turned out, the lake had evaporated due to increased heat from magma rising below, and the volcano erupted not long after.

April 11, 2018

Sinabung, Sumatra, Indonesia (Philippa)
The image (below) is from an explosive eruption which occurred at Sinabung volcano at 16:07 (local time) on 6th April 2018. MAGMA Indonesia, who are responsible for the official social media statements from (Indonesian volcano monitoring agency) PVMBG, reported that the eruption plume reached an elevation of 5 km above the summit area before collapsing and creating pyroclastic density currents (PDCs - avalanches of hot volcanic gases, ash and rocks), which reached an extent of ~3.5 km along the south-eastern slopes of the volcano.

Image via Endro Lewa (https://www.facebook.com/endrolewa/)

via PVMBG / Mbah Rono

Kilauea volcano, Big Island, Hawaii, USA (Philippa)
At 10:28 (local time) on 6th April, part of the Overlook Crater wall within Halema`uma`u Crater at the summit of Kilauea collapsed. This disturbed the surface of the lava lake, bursting bubbles of volcanic gas within the lava, and triggering an explosion of these gases, ash, and larger pyroclast ('hot rock') fragments.

via U.S. Geological Survey / Hawaiian Volcano Observatory / USGS Volcanoes (@USGSVolcanoes)

A video captured by one of the Hawaiian Volcano Observatory's (HVO) webcams can be seen here:

via USGS / HVO

Geologists and technicians from HVO were at the scene 40 minutes later to check on monitoring equipment on that side of the crater, including daytime / night time and thermal imaging webcams. Ballistics (materials thrown up and out) from the explosion had damaged the solar panels which power the monitoring kit.

via USGS / HVO

Here we can see how agitated** the surface of the lava lake still was within an hour of the explosion.
** Indicated by both the swirled appearance of hotter (black) and cooler (grey) lava, and the increased amount of bubbling (red) from the magmatic gases being release. An analogy would be shaking a bottle or can of soda so that it fizzes more vigorously.

via USGS / HVO

Samples of the materials erupted were also gathered from the network of collection buckets on the crater rim, and observations were made regarding the extent (distance outwards from the crater edge) of the deposits from this explosive event.

via USGS / HVO - One of the HVO geologists** labeling a sample collection bag. These materials will be analysed in the geology lab for their structure and composition, which amongst other things, will inform the observatory about the amount of gas within the magma in Kilauea volcano, and potential for other future explosive events should more of the crater wall collapse.

Explosive events such as these and the ongoing high emissions of volcanic gases from the (normally effusively de-gassing) lava lake, which are blown by trade winds in a south westerly direction, are the reason why Crater Rim Drive beyond the Jagger Museum has been closed to the public since the Overlook Vent and the lava lake in Halema`uma`u Crater came into being back in March 2008.

** NOTE: the volcanologist in the image (above) is wearing a hard hat and a gas mask. They and the other geologists and technicians also carry walkie talkies to keep them in contact with the observatory, which in turn alerts them to any further changes in eruptive activity whilst they are on fieldwork, particularly if there is an increase in seismicity. A volcanologist's/technician's senses have to be even more alert whilst conducting this work, particularly their hearing, This is highly dangerous work, and the volcanologists and technicians do not spend any more time doing on-site repairs, collections and observations than is necessary immediately following an explosive event.

Bisoke, Sabyinyo, and Muhabura volcano, Rwanda (Philippa)
A part of the world that we, regretfully, do not know so much about due to conflicts in the region during the past century, but a fantastic shot (below) of Bisoke, Sabyinyo, and Muhabura volcano, which are all within the Volcanoes National Park on the Rwanda side of the borders with the Democratic Republic of Congo and Uganda. This image was taken from an ascent of Kalisimbi.

We have tried to find more information on these three volcanoes but reports even from the Global Volcanism Program are someone confusing, stating both that these are dormant and that they have had effusive, parasitic cone-forming** eruptions within the last 10,000, i.e. this is a contradiction in terminology.

** Parasitic cones are formed from eruptions from side vents of much larger neighbouring volcanoes.

via Ben Tuyisenge (@ben_tuyisenge)

Volcanoes and Astronauts (Philippa)
A friend of mine, who is about to complete her PhD at university, recently asked what other jobs in volcanology exist other than at a volcano observatory (very difficult to get into), in academia, or in industry. I would say that the job featured in the article (below) is a pretty cool application of the different volcano-related sciences!

Jacob Bleacher is a research geologist (and formerly a research geophysicist) who helps to train astronauts in how to make observations of the Earth from the International Space Station (ISS).

Furthermore, Jacob is a planetary volcanologist - he remotely studies volcanic features on other planets and then compares them with volcanic features on Earth to try and better understand the formation of the planets and whether any of them potentially could support life as we know it.

But there is more! Jacob works for an organisation called Goddard, which creates equipment and instrumentation for NASA. Part of the technology development and astronaut training involves going to volcanological sites - predominantly in Hawaii, New Mexico, and Arizona - to test the equipment, which in 2009 included a rover.

Read the full article on Jacob's work here:

via NASA Goddard (@NASAGoddard)


(Left image): (Astronaut) Andy Thomas and Jacob Bleacher conducting an EVA (extra-vehicular activity) with a prototype rover in Northern Arizona in 2009. They were also testing out the Space suits to simulate what it would be like trying to conduct scientific research on another planet whilst wearing all the life support clothing and equipment. Manual dexterity (use of hands), for example, is hampered when wearing gloves. (Right image): Jacob Bleacher and a post-doctoral researcher during the HI-SEAS (Hawaii Space Exploration Analog and Simulation) exercise.

April 8, 2018

Weekly Volcanic Activity Report: 28 March to 3 April 2018
Via Smithsonian Institution - Global Volcanism Program / US Geological Survey

Aira | Kyushu (Japan)
JMA reported that there were 16 events at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 26 March-2 April, 12 of which were explosive. Tephra was ejected as far as 900 m from the crater. At 1541 on 26 March an explosion generated an ash plume that rose 3.4 km above the crater rim. An explosion recorded at 0740 on 1 April produced an ash plume that rose 3 km. Crater incandescence was visible the morning of 27 March and at night during 30 March-1 April.
During 30 March-2 April there were three events at Showa crater. An event at 1611 on 1 April ejected tephra 300-500 m from the crater, and produced a very small pyroclastic flow (the first since 3 June 2016) that traveled 800 m E. A plume rose 1.7 km above the crater rim, up into weather clouds. The previous eruption at Showa crater occurred on 8 January. The Alert Level remained at 3 (on a 5-level scale).Volcano index photo

Ambae | Vanuatu
Based on satellite data, webcam and VGO observations, and wind model data, the Wellington VAAC reported that during 28 March-3 April ash plumes from the vent at Ambae’s Lake Voui rose to altitudes of 2.3-6.1 km (8,000-20,000 ft) a.s.l. and drifted in multiple directions. News articles noted that ashfall continued to damage crops and buildings, and contaminate water.

Dieng Volcanic Complex | Central Java (Indonesia)
PVMBG reported that a phreatic eruption at the Sileri Crater lake (Dieng Volcanic Complex) occurred at 1342 on 1 April, ejecting mud and material 150 m high, and up to 200 m in multiple directions. The event was preceded by black emissions that rose 90 m, and then diffuse white emissions that rose 150 m. The report noted that there were not many tourists in the area due to rainy weather; tourists are not permitted within 200 m of the crater rim.

Kikai | Japan
JMA reported that the number of volcanic earthquakes at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was low during 27 March-2 April after an increase recorded during 22-23 March. White plumes rose as high as 1.8 km above the Iwo-dake lava dome. Incandescence from the crater was visible at night during 27-28 March. The Alert Level remained at 2 (on a 5-level scale).

Kirishimayama | Kyushu (Japan)
Based on observations during overflights on 28 March and 2 April, JMA reported that the crack on the W flank of Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, continued to widen. White emissions rose as high as 500 m above the crater rim. Several high-temperature regions around the margins of the lava in the crater, and from the flow on the NW flank, were detected on 28 March. The lava flow on the NW flank advanced 85 m from 9-29 March. Sulfur dioxide emissions were 300 tons/day on 30 March. The number of volcanic earthquakes began to decline after 26 March; though from 0014 to 1430 on 3 April the number increased to 239. Many low-frequency earthquakes with shallow hypocenters continued to be recorded. The Alert Level remained at 3 (on a scale of 1-5).

Piton de la Fournaise | Reunion Island (France)
OVPF reported that intermittent inflation at Piton de la Fournaise had been detected since the end of the last eruption on 28 August 2017. Seismicity began increasing the last two weeks in February. Seismicity fluctuated during March; peaks were recorded on 28 and 31 March, with volcano-tectonic earthquakes occurring less than 2 km below the summit area. An enrichment of carbon dioxide and sulfur dioxide in summit fumaroles was noted on 23 March.
A seismic crisis began at 0300 on 3 April, and along with deformation, indicted magma migration towards the surface. An eruption began at 1040 on the N flank, just below the rampart at the Nez Coupé de Sainte Rose area. During an overflight, scientist observed a 1-km-long fissure, divided in seven segments, with two active vents producing lava fountains. At 1600 many landslides were recorded by the seismic network in the active area. The eruption ended At 0400 on 4 April, though a few landslides were recorded through 1530.

April 5

Sileri crater complex, Dieng Batur volcano, Java, Indonesia (Philippa)
Effusive volcanic vapour emissions at Dieng volcano's Sileri crater complex turned suddenly into a much bigger phreatic (steam-driven) eruption on the afternoon of 1st April. Such eruptions are triggered by cool water coming into contact with hot ground rock, and flash-boiling into steam, causing an explosive, outward pressure towards the surface.

Mud and steam were catapulted ~150m in the air during the eruption, with mud pats landing between 50-200m around the crater. No poisonous volcanic gases were detected.

Dieng is a popular tourist destination. With the possibility of further phreatic activity, visitors are urged to show caution. It is currently too dangerous to go any nearer than 100m.

via Sutopo Purwo Nugroho (@Sutopo_PN)

Mount Merapi, Java, Indonesia (Philippa)
Not an eruption story, for once, but sad news that mining of the volcanic 'sand' from one of the flanks of Mount Merapi generated a landslide this week, which has killed 2 people, injured 4 others, and caused damage to a hamlet.

Deposits from volcanic eruptions, such as ash and boulders, are often mined and used as construction materials for buildings and roads, even though the quality of volcanic 'sand' is poor. Such mining destabilises the already unconsolidated earth, leading to slope erosion and landslides, and eroding historical lahar channels, which can cause longer lahar run-out distances when a volcano next erupts.

Mining of these volcanic materials is often out of financial necessity, e.g. to earn money to feed families.

via Sutopo Purwo Nugroho (@Sutopo_PN) - landslide in Habanero, near hamlet Cangkringan Kalitengrah Kidul

Manaro Voui, Ambae, Vanuatu (Philippa)
As reported previously on Earthquake-Report.com, Manaro Voui last week started a new eruptive phase. In retrospect, the image (below), which was taken beforehand on 11th March, shows a very visible precursor: a rapid colour change of the crater lake. This would have been caused by what is known as lake overturn. An increase in volcanic gases at the bottom of the lake produces bubbles, which rise, expand, and create a convection current in the lake. This causes yet more volcanic gas bubbles to rise, as well as 'dirt' (old ash) from the bottom of the lake, changing both the pH balance (to more acidic) and appearance of the lake water.

via Philipson Bani (@philipsonbani) / Dickinson Tevi

Sakurajima, Kagoshima prefecture, Kyushu, Japan (Philippa)
Video footage from 1st April of one of the daily eruptions at Sakurajima volcano in southern Japan, but this time erupting from two different vents at the summit: Minamidake is the vent just to the left / behind, whilst the Showa crater is the one to the right  foreground.

The last time that an eruption from the Showa crater was reported was in early December 2017.

via James Reynolds (@EarthUncutTV)

Mount Etna, Sicily, Italy (Philippa)
The image (below), taken at 19:39 (local time) on 1st April 2018 from the kitchen window of one of our volcanologist friends, shows the eastern flank of the New Southeast Crater on Mount Etna. They report that weak and infrequent emissions of brown-grey ash are occurring again from 'Puttusiddu' ('little hole').

via Boris Behncke (@etnaboris)

Mount Vesuvius, Italy (Philippa)
It was on 1st April 1748 that the buried ruins of Pompeii were discovered by miners. They were digging a shaft in what we now know to be ignimbrites, ashy deposits from multiple pyroclastic density currents, generated from eruptions at Mount Vesuvius 2000 years earlier.

These images show the (now) excavated city of Pompeii.

via David Bressan (@David_Bressan)

This video shows a simulation of how the start of the eruption may have appeared to someone living in Pompeii at the time.

via Historical Page / Melbourne Museum / YouTube

Kilauea volcano, Big Island, Hawaii, USA (Philippa)
A fantastic historical shot (below) of Kilauea volcano, showing that it is not just effusive 'red' lava eruptions which occur here. This particular explosive eruption occurred in 1924. Ash deposits examined by (esteemed volcanologist) Don Swanson within the Hawaii Volcanoes National Park suggest that there have been at least two other historic phases of explosive eruptions at Kilauea.

Alternating phases of effusive lava flow eruptions from the flanks and explosive eruptions at the summit are not uncommon at some volcanoes. I have seen evidence for this, for example, on Mutnovsky volcano in Kamchatka in the far east of Russia. But these types of volcanoes tend to be near subduction zones rather than over a so-called 'hot spot' or mantle plume. Hence why the 1924 eruption at Kilauea is unusual.

The main factor for a switch from effusive lava to explosive ash plumes is the addition of water, which makes a magma composition more silicic and more gassy. The question with Kilauea is whether the source was rain water accumulated beneath the surface over hundreds of years leading to this event, or whether there was a more sudden interaction between Kilauea's magma source and (sea)water within its volcanic 'plumbing system'. Only the ash deposits hold the answer...maybe.

The image (below) was taken from the overlook near the original Volcano House (a famous guest house within Hawaii Volcanoes National Park). Shortly after the photo was taken, the spectators were informed that this was not a safe spot to view the eruption from.

via Blasts From the Past (@EruptiveHistory) / Tai Sing Loo, 1924.

Mount St Helens, Washington State, USA (Philippa)
Another fantastic historical image, this time related to the volcano seismology monitoring at Mount St Helens prior to its infamous May 1980 eruption.

This U.S. Geological Survey (USGS) seismogram from 2nd April 1980 shows harmonic tremors, which are sustained duration, rhythmic earthquakes. Such signals are indicative of both magma being at shallow depths beneath the surface and volcanic gases resonating in cracks and conduits. Therefore, if the signals recorded on a seismogram change from volcano-tectonic (VT) and/or long period (LP) to harmonic tremor, as it did on this week in 1980 at Mount St Helens, this is an indication that an eruption is either imminent or already in progress.

via David Bressan (@David_Bressan) / US Geological Survey (@USGSVolcanoes)

A zoomed-in example of the harmonic tremor recorded at seismic station RAN on Mt St Helens on 2nd April 1980. via https://volcanoes.usgs.gov/index.html

Alaska Volcano Observatory, Alaska, USA (Philippa)
A big HAPPY 30th BIRTHDAY this week to the Alaska Volcano Observatory, which came into being on this week in 1988.

The work of the observatory is a collaborative effort between the U.S. Geological Survey (USGS), the University of Alaska Fairbanks Geophysical Institute (UAFGI), and the Alaska Division of Geological and Geophysical Surveys (ADGGS). Its objectives are: to monitor the volcanoes of Alaska; to assess volcanic hazards; to provide timely and accurate information. Although Alaska is relatively sparsely populated, the work of the observatory is particularly important to aviation. The airspace over the State is a busy route for commercial airplanes, which have to be re-diverted in the event of any explosive volcanic eruptions in the region.

The poster (below) provides more information on AVO.

via Alaska AVO (@alaska_avo)

April 4, 2018