Tag Archives: Mount Ontake

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

Sudden Eruption of Mount Ontake

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At 11.53am (local time) on Saturday, Mount Ontake, Japans second largest volcano erupted spectacularly sending pyroclastic material flying from the summit. The volcano is popular with hikers and tourists alike.

Eruption Saturday morning came with little warning.

1. Eruption Saturday morning came with little warning.

Many were on the flanks at the time and as of lunch time yesterday 31 bodies had been recovered. Search and rescue efforts had to be called off for a short while as activity has picked up again with strong tremors deeming it unsafe for the teams to venture near the area. They have since resumed with a further 180 volenteers headed towards the sumit to aid 24 hikers which had been previously spotted unconscience but yet to be declared dead untill seen by a medical officer.

2. Rescue efforts have been slow as Ontake continues to spew out hot rock and ash.

2. Rescue efforts have been slow as Ontake continues to spew out hot rock and ash.

Japan sits along a triple junction; where the Pacific and Philippian plates are subducting under the Eurasian plates. Subduction volcanoes are typically characterised by explosive eruptions due to the high amounts of silica in the melts. The Japaneese are some of the best prepared for natural disaster like this due to their high risk location and geology.

3. Once picturesque mountain lodges have be turned in to erery ghost towns.

3. Once picturesque mountain lodges have be turned in to eerie ghost towns.

A small elementary school in the nearby town of Kiso has been turned in to a tempory morgue for bodies being brought down from the mountain.

Further updates to follow.

 

1.  http://www.wpxi.com/photo/news/national/mount-ontake/pCQkr9/ Accessed 29/09/14

2. http://www.bbc.co.uk/news/world-asia-29392810 Accessed 30/09/14

3. https://nz.news.yahoo.com/news-gallery/photo/-/25126785/mount-ontake-erupts/25126795/ Accessed 30/09/14