Tag Archives: Japan

Today in Geological History; June 3rd – The 25th Anniversary of Unzen

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Today marks the 25th anniversary of the pyroclastic flow from Mount Unzen which claimed the lives of 43 people.

Mount Unzen

Mount Unzen is actually several over lapping volcanoes on Japan’s island of Kyushu. It was the cause of Japan’s largest ever volcanic disaster in 1792 when a lava domed collapsed and caused a mega tsunami which killed nearly 15,000 people. After this even the volcano lay silent until beginning to stir in 1989.

Seismic swarms began in the November of 89 about 10 km west of the summit and gradually migrated eastward until the first phreatic eruption a full year later in November 1990. By May 20th 1991 fresh lava began to flow from the highly inflated summit area prompting the evacuation of almost 12,000 locals.

volcano-unzenThe threat of another eruption to the scale of 1792 brought journalists and scientists alike flocking to the surrounding area to monitor the activity of Unzen and its potential threat. Sadly this curiosity resulted in the deaths of 43 when on June 3rd activity peaked due to a possible lava dome collapse. This sent a huge pyroclastic flow surging down its flanks and funnelled in to a valley point in the direction where volcanologists and journalists had set up a base at what was thought to be a safe distance, over 4.5 km, from the summit.

Activity continued well in to 1995 and over 10,000 pyroclastic flows were recorded over this period. By the end of the eruption a new lava dome was in place 1.2 by 8 km wide. Its volume was approximated at 0.1 cubic km.  In total, about 0.21 cubic km of plagioclase-phyric dacite magma was erupted over the course of the eruption at peak effusive rates of 7 cubic metres per second in 1991. Over 2000 buildings were destroyed by these flows in Shimabara City alone. Matters were further complicated between August 1992 and July 1993 when heavy rains caused multiple lahars destroying a further 1300 homes along the Mizunashi and Nakao Rivers, requiring the sudden evacuation of several thousand residents.

Mount Unzen has been placed on the official decade volcano list and is one of Japan’s most highly monitored areas.

Maurice and Katia Krafft

The Krafft’s were French volcanologists and soul mates who met at the University of Strasbourg. Their love for volcanology almost reviled their love for each other. The specialized in documenting eruptions as best and often as close as possible, their end was almost inevitable.

Their most famed contribution was the documentation of Nevado del Ruiz which when shown to the Phillipine president Corazon Aquino who was then convinced to evacuate the area surrounding Mount Pinatubo before its catastrophic 1991 eruption almost certainly saving hundreds if not thousands of lives. 

Over a 20 year period, when volcanology was still a relativity young science, the married couple documented hundred of eruptions. They fillmed over 300 hours of footage, took thousands of photos and published multiple books.

While in the Philippines during Pinatubo’s early stages, Maurice was interviewed by a local news agency where he told the journalist  “I am never afraid, because I have seen so much eruptions in 23 years that even if I die tomorrow I don’t care.” From here they flew out to Japan where activity was picking up at Unzen. The pair perished together when they were overcome by the pyroclastic flow on June 3rd.

Harry Glicken

Man wearing a coat and hat and holding a pad of paper sits on a rock , with a lake and several mountains visible in the backgroundHarry was an American volcanologist who although was based at USGS was funded by outside organisations. He specialised in volcanic debris flows and was closely involved with research on St Helens with his doctoral thesis ‘Rockslide-debris Avalanche of May 18, 1980, Mount St. Helens Volcano, Washington‘ being recognised as a leading paper on the event.

Glicken cheated death on St Helens as he was meant to be the volcanologist on duty May 18th however swapped with his then mentor David Johnston who was killed by the blast.

Figure 1; http://raredelights.com/top-28-worlds-important-volcanoes/mount-unzen-in-japan/

Figure 2; https://curiousmatters.wordpress.com/2014/05/23/curious-facts-31-of-the-strongest-volcanoes-known-to-man/

Figure 3; https://en.wikipedia.org/wiki/Mount_Unzen

Figure 4; https://volcanogeek.wordpress.com/2011/09/20/maurice-and-katia-a-love-story/

Figure 5; https://en.wikipedia.org/wiki/Harry_Glicken

Figure 6; https://www.youtube.com/watch?v=Cvjwt9nnwXY

 

 

 

 

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Kyushu Earthquake, Mt Aso and the Relationship between Volcanoes and Earthquakes.

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In the past week the Japanese Island of Kysushu has be ravaged by earthquakes.

2016-04-16Japan is a highly seismic area with noticeable quakes in some areas occurring nearly daily.  But things began to escalate for the Kyushu region on Thursday night when a magnitude 6.5 quake brought several buildings down. As rescue efforts began the region had two more huge after shocks during the night, one over Mg 6 and the other > Mg 5. By midday Friday the death toll stood at 9 with over 800 injured and although the aftershocks kept coming many >Mg 4 people were still being pulled from the rubble. Sadly these events were quite possibly a precursor to something larger.

At 01.25 local time (15.25 GMT) a Mg 7.3 struck just north of Kumamoto just kilometers from the large earthquakes which had already occurred. Much of the seismicity in the Kyushu region is related to the subduction of the Philippine Sea plate at great depth. However this series of earthquakes have occurred at very shallow depths several hundred kilometers northwest of the Ryukyu Trench. They have been cause by strike-slip faulting within the Eurasian plate.

Quake damaged houses in Kumamoto, Japan (16 April 2016)So far 22 more people have been reported dead but this is expected to rise in the coming days with at least 80 people known to betrapped in rubble. 11 of which are trapped in a Tokai university apartment in the town of Minami Aso.

 

The shallowness of the earthquakes means damage to the surface is high and it is not just collapsing building which are a hazard. People have fled the area down stream of a dam which collapsed soon after the earthquake. Landslides in the area have taken out roads and power lines and with heavy rain anticipated over the coming days JMA have advised mudslides will be a huge problem for rescuers.

 

 

 

 

 

 

The seismic problems of Kyushu may have also set in motion another geohazard in the form of Mt Aso. Yesterday one of my favorite volcanology bloggers Eric Klemetti tweeted “Quite a few volcanoes on Kyushu and these earthquakes have been centered near Unzen, Aso, Kirishima. This is NOT to say these earthquakes will trigger any eruptions, but could be worth watching over the next year.” Several hours late JMA reported a small scale eruption at Aso. Smoke plumes have migrated 100 meters above the summit and it is not yet clear if the activity is magmatic (caused by movement of magma towards the surface) or phreatic (steam explosion caused by heating of groundwater).

Eruptions and earthquakes do not always come hand in hand but each one can contribute to the other or not at all depending on the circumstances. One indication a volcano is about to erupt is volcanic tremors; these low frequency earthquakes are usually caused by the migration of magma or changes to magma chamber. Although they are rarely higher than a magnitude 4. On the other side large earth quakes can cause faulting in bed rock which allows magma to exploit a new weakness and find a path to the surface it previously could not intrude on. The same can happen for ground water with faulting caused by a quake allowing it to seep in to geothermal areas it previously did not have access to due to the impermeability of the rock. When earthquakes hit volcanic regions volcano observatories always keep a closer eye on vulnerable or highly active volcanoes as a precaution but it is not always needed.

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The Aso Caldera complex has one of the world’s largest calderas. It is comprised of a 25 km north-south by 18 km east-west Caldera and a central cone group comprised of Mt. Neko, Mt. Taka, Mt. Naka, Mt. Eboshi, and Mt. Kishima. Mt Naka where the eruption has just taken place is the most active with its most recent eruption taking place last October. Although much of Aso’s activity in the past century has been relatively small it has had a violent history with at least 4 VEI 7 events in the past 300,000 years.

It’s is not clear whether the earthquakes in the past few days did trigger the current current eruption but JMA are keeping a close eye on the situation and I will update this page as I know more.

 

 

Figure 1. http://earthquake.usgs.gov/earthquakes/map/

Figure 2; http://www.bbc.co.uk/news/world-asia-36061657

Figure 3; http://www.independent.co.uk/news/world/asia/japan-earthquakes-dozens-reported-dead-injured-second-quake-two-days-a6986931.html

Figure 4; http://mashable.com/2016/04/15/japan-earthquake-landslide-photos/

The Decade Volcanoes

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As I reblogged my last post, a revision of the Decade volcano list by the authors of VolcanoCafe, I thought before I bring you the new list I should really explain what the original one actually was!

As mentioned in one of my earliest articles, the list was complied in 1990 by the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) a nongovernmental society. The aim was to select the worlds most hazardous volcanoes and put measures in place to keep a closer eye on them and raise awareness across the globe on the threats they pose, for a decade (1991-2000 The UN’s International Decade of Natural Disaster Reduction). Based on varied criteria from historic eruptions to local populations, the following made the cut;

Figure 1. USGS map of the decade volcanoes.

15 Years on the list is still going all though monitoring in some areas may have slackened slightly. It has seen some success such as the diversion of a lava flow on Etna back in 1992 and has helped form a better understanding of phreatic eruptions on Taal. It has sadly also come at great loss on several occasions as well. Despite increased monitoring of Unzen in 1991 pyroclastic flows killed 43 including volcanologists Katia and Maurice Krafft and Harry Glicken.  And even closer to the project, in 1993 the Decade Volcano conference took place in Pasto, Columbia an expedition from the conference to the Galeras crater occurred on February 14th when the volcano suddenly erupted. 3 tourists and 6 volcanologists including Professor Geoff Brown, Head of Department of Earth Science at the Open University, all lost their lives.

Many volcanologist are sceptics and/or critics of the program, hence the call for a revamp. Personally I feel any thing which promotes volcanic awareness is great all though there are some which need much more than others. Volcanoes are ever evolving and unlike most geological features can change in minutes rather than millennia and therefore prehaps a decade is too long for reviews of such a program. I know which have made my list, it will be interesting to see what makes the cut for the guys at VolcanoCafe!

Figure 1. http://listas.20minutos.es/lista/volcanes-de-la-decada-decade-volcanoes-301649/

What Makes an Earthquake ‘Significant’?

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If you google “What is the definition of a significant earthquake?” you are met with Michigan Tech’s* response; Major – magnitude 7-7.9. However when looking at ‘significant’ earthquakes on the USGS** web page there are ones as low as magnitude 3.3. So to different people (and/or institutions) how we classify earthquakes seems to vary greatly and this occurs from top seismologists right through to media reporting and how we perceive the threat.

 

At 11.23 UTC on May 30th a Mg 7.8 earthquake struck off the coast of Japan. This is the same magnitude as that of Nepal’s April 25th quake but one managed to devastate an entire region and the other barely shook a few skyscrapers. Unless, like my self you concern your selves with the rumblings of our planet, or you live in Japan or the surrounding area you probably did not ever know last Saturdays earthquake even happened.

1. Aftermath of Nepal earthquake April 25th 2015.

The main difference between the two is the location of their foci. The focus of an earthquake (sometimes called the hyprocenter) is often confused with the epicentre, however the epicentre is the surface area directly over where the earthquake takes place, whereas the focus is the actual point at depth where the snap of energy takes place. With the Nepal earthquake the focus was just 15 km under a heavily populated region. The buildings on the surface were poorly built and unable to with stand the violent shaking, bringing them crumbling to the ground killing over 8000 people.

2. Displacement by Japan’s March 11th 2011 earthquake.

The Japan earthquake in contrast occurred off the coast, below the Pacific Ocean, although the some shaking was felt onshore. Many may assume this is safer than an earthquake under an urban area but several of the most deadly earthquakes occur at sea as they can induce tsunamis like that of March 11th 2011 which killed nearly 30,000 in Japan or the infamous Boxing Day Tsunami which killed as many as 230,000! Luckily on Saturday no tsunami alert was even issued, as the biggest difference between these two 7.8 earth quakes is depth.

Occurring at 677 km beneath the surface, this deep-focus (below 300 km) earthquake happened so deep its distance from focus to surface is only slightly shorter than travelling from London to Berlin (690 km)!!! As seismic waves travel they dissipate, loosing energy so are never as intense as what they are closer to the source.

3. Diagram of an earthquake, highlighting its focus and Epicenter.the waves lighten in colour with distance from the focus to show their loss of strength.

 

So so far we have magnitude, depth and location which impact on the devastation potential, but is there any thing else? Well we can expand on the last, location, to highlight other potential threats posed by an earthquake. A moderate sized earthquake in the heart of Los Angeles or Tokyo may stop the subway and send food flying off shop shelves but casualties should be low. The same earthquake in a country like Nepal or Haiti can kill thousands. Earthquakes don’t kill people per say, I have never heard of some on being shaken to death by a quake.What kills people is poorly constructed buildings collapsing, bridges failing, gas mains bursting causing fires. After past disasters such as San Fransisco’s great earthquake of 1906, wealthy countries which sit along active fault lines have put in place strict building codes and pumped millions in to disaster management programs and construction.   Obviously earthquake-proof is not always a possibility by earthquake-resistant definitely is and has saved the lives of many of the past few decades. Sadly not all at risk areas have that luxury of these safe guards at the expense of hundreds of lives.

4. Damage and fires caused by the Greath San Fransisco earthquake in 1906.

Seismology is a tricky business. With so much to take in to consideration when classify earthquakes, it is easy to see where there is often conflicting statements. Things are complicated further by the multitude of scales actually used to quantify them. When asked what scale is used, I can guarantee most will say the Richter scale (or local magnitude, ML), that is even what I was taught in school. Charles Richter first put his scale to use in 1935 to give a more scientific quantification for earthquakes than the previously used Mercalli scale which was solely based of human perspective and building damage (this is still used today but not as often). The Richter scale was limited in many ways being primed for nearby, mid-sized earthquakes (M 3-7). Seismologist Beno Gutenberg expanded on Richter’s work greatly enabling the scale to factor in greater distances and separated scales for surface waves (MS) and body waves (Mb).The revised scales still had difficulties and were particularly ineffective when looking at earthquakes which spanned great lengths of fault lines such the Aleutian Fox Island quake of 1952. The Richter scale was finally replaced by the Moment magnitude scale (MW) back in 1979 and this is the scale used by most institutes today including USGS.

Moment magnitude was born from elastic dislocation theory put forward in 1972 which suggests that energy release from a quake is proportional to the surface area that breaks free, the average distance that the fault is displaced, and the rigidity of the material adjacent to the fault. It is based on a similar logarithmic scale to the Richter scale with each step equating to an increase in the amount of energy released 101.5 ≈ 32 more than the previous. Earthquakes usually have similar Richter and moment magnitude numbers but rarely exactly the same and this can be one way one earthquake can be reported at different levels across the media if their sources used different scales. Another way which causes different figures  is precision; the more seismic stations used to calculate magnitude the more precise the result. When an earthquake is first recorded institutes are likely to only use their own data but as soon as they have access to the global seismic network they can give a more accurate classification. This happen with Japan’s earthquake on May 30th, initial reports put it over a magnitude 8 but this was quickly downgraded to 7.8.

As you can see an earthquakes significance is a matter for debate and in many cases personal opinion. Magnitude and location (not just geographically but also politically) are the main factors but it tends to vary earthquake to earthquake.

Station VRI seismogram

5. Example of a seismograph.

 

Mg 6.9 Iwate and Tsunami warning

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At 8.06 am local time a magnitude 6.9 submarinal earthquake occurred of the coast of Iwate, Japan. JMA have claimed it is an after shock from the mg 9, March 11th megathrust quake in 2011.

The following tsunami alert was released although this was played up by some media stations to a full blown warning.

This Tsunami Warning/Advisory was issued in the past
Occurred at 08:06 JST 17 Feb 2015
Region name Sanriku Oki
Depth about 10 km
Magnitude 6.9
Click the map to zoom in

Tsunami Forecast Region Category of Tsunami Warning/Advisory
IWATE PREF. TSUNAMI ADVISORY

Tsunami Warnings / Tsunami Advisories

Issued at 08:09 JST 17 Feb 2015

******************Headline******************
Tsunami Advisories have been issued for the following coastal regions of Japan:
IWATE PREF.

*******************Text********************
Tsunami Advisories have been issued for the following coastal regions of Japan:
<Tsunami Advisory>
IWATE PREF.

***********About Tsunami Forecast************
<Tunami Advisory>
Marine threat is in place.
Get out of the water and leave the coast immediately.
As the strong current will continue, do not get in the sea or approach coasts until the advisory is cleared.

<Tsunami Forecast (Slight Sea Level Change)>
Though there may be slight sea-level change in coastal regions, no tsunami damage is expected.

******* Earthquake Information ********
Occurred at 08:06 JST 17 Feb 2015
Region name SANRIKU OKI
Latitude 39.9N
Longitude 144.5E
Depth about 10 km
Magnitude 6.9

The following arrival times were issued;

Tsunami Forecast Region/
Tsunami Observation Site
High Tide Time Estimated Initial
Tsunami Arrival Time
<Tsunami Advisory>
  IWATE PREF. ( Area where tsunami is
expected to arrive first )
08:30 JST 17 Feb
    Miyako 13:28 JST 17 Feb 08:40 JST 17 Feb
    Ofunato 13:36 JST 17 Feb 08:40 JST 17 Feb
    Kamaishi 13:36 JST 17 Feb 08:40 JST 17 Feb
    Kuji-ko 13:23 JST 17 Feb 08:50 JST 17 Feb

The warning was then terminated at 10.21 local time.

Comparing Past and Present

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Over the last 12 months we have seen some amazing eruptions, felt the Earth shake on numerous occasions, and remembered some historic events. But was the active of 2014, both volcanically and seismically, more than any other year? I have read several spam articles recently, scare mongering that fracking has trebled earthquake numbers, God’s wrath has been shown by volcanic eruptions and even one drunken woman tried to tell me that Japans tectonic misfortune is due to the Pearl Harbor attack!

Lava field at Holuhraun, Iceland September 2nd 2014.

1. Lava field at Holuhraun, Iceland September 2nd 2014.

Now straight away I can assure you that karma or religious intervention has nothing to do with the science behind the mechanics of the planet beneath our feet. Fracking is up for debate and its effects on seismicity although even were proven the effects are still negligible. So has 2014 really been worse than previous?

Seismically

I found quiet a nice table to demonstrate this one courtesy of Wikipedia.

Number of Earthquakes Worldwide for 2004–2014

  Magnitude Ranging

Between

 2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014
8.0–9.9 2 1 2 4 0 1 1 1 2 2 1
7.0–7.9 14 10 9 14 12 16 21 19 15 17 11
6.0–6.9 141 140 142 178 168 144 151 204 129 125 144
5.0–5.9 1515 1693 1712 2074 1768 1896 1963 2271 1412 1402 1577
4.0–4.9 10888 13918 12838 12080 12292 6805 10164 13303 10990 9795 14941
Total 12560 15762 14703 14350 14240 8862 12300 15798 12548 11341 16674

2014 actually had the lowest number of strong, magnitude 7 and above earthquakes then in the past 5 years. On the flip side of this we had many more lower magnitude  4-5.9 giving us the highest total of quakes in the past 10 years by about 900 earthquakes. 2009 actually is the strangest year on this list with a good 4000 less earth quakes of any magnitude than any other year. 2007 also stands out with an exceptional number of stronger earthquakes. It could be theorized that the greater release of stress and strain with in the crust during 2007 gave us a quiet period the following years. All though this is a very short time scale it does show that yearly variation is great.

625 people were killed in earthquakes last year with most of these during August 3rd’s Ludian County earthquake in China. 6 lost their lives in the strongest quake of the year in Iquique, Chile which was mg 8.2. Nicaragua and Papua New Guinea also had one fatality each. This is actually quiet low value with over 1500 loosing their lives the previous year or as high as nearly 300,000 in 2004!

Uplift caused by Mg 8.2 Chile Earthquake.

2. Uplift caused by Mg 8.2 Chile Earthquake.

Volcanically

2014 was a pretty explosive year with Sinabung kicking us off with a bang January 3rd as it has done this year. In February the same volcano killed 11 as people began to cross the exclusion zones to take a closer look after the pyrotechnics the month previous.

Bárðarbunga stole the show over the summer. The sleeping giant started a ‘will it, won’t it’ game months before any real activity started in August. Many feared we would see an Eyjafjallajökull 2010 style explosion that would disrupt air traffic at the height of the summer period. Earthqaukes then began to indicate magma was on the move through a dyke heading north-west from the main vent. New fears struck as experts wondered would we see devastation similar to Laki 1783. August 29th saw the start of a large fissure breaking the surface, although it has not reached the status of Laki, the eruption is still continuing today

3. San Miguel

3. San Miguel

 

The next lot a fatalities happened when Mount Ontake surprised all with a phreatic blast on September 27th. 57 lost their lives as hikers and tourists where making their way to a shrine on the mountains flank.

Fogo was the volcano to cause chaos in the final month of the year forcing thousands from their homes. Media coverage of this even has been so light on this event, I am unable to find precise news to if the eruption is ongoing. At December 23rd lava was still pouring from the Pico vent and destroying all in its path.

Obviously these are but a few of the hundreds of volcanoes rumbling through 2014. Others include; Colinma, Etna, Aire, Asonsan, Manam, Merapi, Popcatepetl, Shishaldin, Cleveland, Sabancaya, Zhupanovsky, Sheveluch, Santa Maria, Mayon, Dukono, Turrialba, Poas, Fuego, Ubinas, Tungurahua, Reventador, Pacaya, Karymsky, Kelut, Stromboli, San Miguel, Pavlof, Chirpoi and even all that does not cover them all!

But is this more than usual?

In terms of lava output, last year is definitely high up there as we saw several huge effusive eruptions(with Bárðarbunga probably producing more material than most others put together!). However in the grand scheme of things there were few other major events.

68 people lost their lives which is relatively high thinking that on average maybe one or two die yearly unless there are major volcanic events, but then when thinking like that 68 is actually extremely low.

If we were to pull out any year for increased volcanic activity, for me it would have to be the events of 1902. In a list compiled by Wikipedia* of the most deadly eruptions, although none of the top 5 occurred in 1902, 4 in the list of 40 that occurred did, meaning 10% of the most fatal eruptions occurred in the one year. Well over 40,000 were killed over these four eruptions.

4. Somber scene after Mount Pelee eruption May 8th 1902.

4. Somber scene after Mount Pelee eruption May 8th 1902.

Just over 30,000 of these deaths were caused by Mount Pelee, Martinque on May 8th. Just hours before, La Soufriere a few islands away on Saint Vincent killed 1680.

There will always be years there is more geologically activity than others. The Earth is like a living breathing organism; it is ever-changing and adapting, this is part of the reason predicting events can be tricky.  People always look to blame or find meaning behind tragedy, it’s a coping mechanism, but rarely leads to scientific truth.

Figure 1. http://mashable.com/2014/09/11/iceland-bardabunga-volcano-eruption-photos/

Table 1. http://en.wikipedia.org/wiki/Earthquakes_in_2014

Figure 2. http://www.sneakymag.com/life/the-sneakington-post-3/

Figure 3.  http://www.telegraph.co.uk/news/10541931/El-Salvador-begins-evacuations-due-to-volcano-eruption.html

* http://en.wikipedia.org/wiki/List_of_volcanic_eruptions_by_death_toll

Figure 4. http://www.explorevolcanoes.com/Martinique-caribbean-volcano.html

The Science Behind the Unexpected Blast at Mount Ontake

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Saturdays eruption was completly unexpected which is what made it so fatal. So far 47 bodies have been accounted for and at least 16 hikers are still missing. Autopsies on those brought down from the summit have concluded most died from crushed skulls or ribs from the super heated rocks that were catapulted by the blast, other suffered internal burns from inhaling the ash. This has been coined as Japans worst volcanic disaster in living memory but why so in a country so prepared for such disasters.

1. This is the last photo  Izumi Noguchi ever took. His camera was found near his body, his wife released the last pictures he took in his memory.

1. This is the last photo Izumi Noguchi ever took. His camera was found near his body, his wife released the last pictures he took in his memory.

Mount Ontake is one of 47 Japanese volcanoes under constant monitoring. Seismicity, ground deformation and gas emissions are just some of the ways volcanologists can see if magma is migrating towards the surface so why was the 27th such a surprise? The answer is actually quiet simple; it was not a magmatic eruption.

Last weeks eruption was not caused by magma breaking through to the surface as most peoples ideas of volcanoes would expect. Instead it is what is know as a phreatic eruption/explosion. When water, whether it be on the surface or ground water, meets the super heated rock of a geothermal system it instantly turns to steam. It operates on a similar principle as geysers such as those in Iceland or the famed Old Faithful in the Yellowstone system.  Steam does not react well to be confined in the high pressure environments underground and will find any way out it can including smashing rock to smithereens.

1. Basic diagram showing a phreatic eruption/explosion

2. Basic diagram showing a phreatic eruption/explosion

Warning signs for such an eruption are minimal. There was some increased seismicity at Mount Ontake in the week leading up to the 27th but not enough to be classed more than “normal background levels”. In some instances the run up to a phreatic eruption may see slight temperature rises in bodies of water near to the system such as crater lakes, but other than this there are no real indicators for when a phreatic eruption will take place which can make them one of the more fatal styles of eruption.

A week on chances of finding any more survivors is slim, but rescue workers are still scaling the flanks in the area of the eruption as thoroughly as they can before Typhoon Phanfone takes hold of the region.

Figure 1. http://www.dailymail.co.uk/news/article-2779616/The-thing-saw-Hiker-s-photograph-captures-Japanese-volcano-s-ash-cloud-sweeping-moments-claimed-life.html Accessed