Tag Archives: pyroclastic density currents

Archive adventures in the US

I was in the USA for 2 weeks September-October on a hunt for more archival sources related to the historic eruptions of La Soufrière. I had never been to America before so I got distracted by all the ‘bigness’ of pretty much everything compared to where I grew up and lived in the UK.

I had two aims:

  1. Obtain copies of the diaries of the American Barrister Hugh Keane from the Virginia Historical Society in Richmond, VA and;
  2. Obtain field notebook copies of the American Geologist Dr Edmund Hovey from the American Museum of Natural History in New York City.

I have to say, I was very impressed with what I found.

My first stop was the Virginia Historical Society in Richmond. I was well aware of the rich history the city and the state itself so I was expecting great things.

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One of the entrances into the Virginia Historical Society archive.
Hugh Keane was a barrister in St Vincent in the early 1800s, but his family had been on the island since the late 1700s. His diary entries were in most part short (and small) but he does write on the 30th April about the beginings of the 1812 eruption.

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Interesting, if not annoying to transcribe, handwriting for a diary (Mss1 K197 a 3-30)
Although this is what I came for I did run into a few issues. One is the handwriting, in which I need to take a paleography course at The National Archives in London for (online thankfully). Another was I actually took most of the pages at a wrong angle (oops) making it harder to transcribe. Another is the language and abbreivations he uses. And a big one is that he doesn’t give a day-to-day running commentary on the eruption. Either Hugh was too busy to watch it (he was a barrister during the slavery era) or he got bored of it. Hopefully his entries will provide helpful insights in what the volcanic processes and hazards were, if not to gain an idea what the responses were.

In any case, I got what I went for so I was happy with that. For Edmund Hovey’s collection I did not know what to expect. All I knew was that he was ordered by the American Museum of Natural History to investigate the eruptions of Pelée and Soufrière.

Dr Edmund Hovey was a geologist and at the time, assistant curator in the palaeontology section of the museum.

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Statue of Theodore Roosevelt outside the entrance of the musuem.
Once I got to the room where the collection was held (after getting briefly lost in the museum naturally), the curator assisting my search showed me the list of what they had. It looked exciting. A small cool collection was artifacts that Edmund brought back from Martinique:

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A stack of 9 fused glasses retrieved from St Pierre, Martinique. A pyroclastic density current killed approximately 20,000 people. 1 man survived in a prison cell (AMNH: MPA018).
I got more excited when I opened up the field notebooks:

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First page of one of Edmund’s field notebooks (AMNH: Box 2, Item 17)
Anyone who has done a geoscience based degree or course, knows how important a field notebook is. I was quite impressed with the level of detail Edmund went into, like a true geologist: time, date, location, and detailed descriptions of the geology and any hazardous phenomena. If this was part of an assignment today he would get high marks on descriptions but not so much on sketches. At the beginning of each notebook he would also note down the adminstrative hierarchy (Governor, adminstrator, executive council etc.) and if he was accompanied by anyone. The most surprising find for me (and the most critical) was that he interviewed and gathered statements of those who observed volcanic activity. Reading these statements, another very important aspect became apparent, he was including more voices than the ‘white elite’ men. He spoke to black men and women whose voice I had so far not been able to read (granted he called them negroes and negresses but I guess that was the language at the time).

My most favourite statement, that I will share with you all, was from a surviour of a pyroclastic density current that flowed down the eastern flank of the volcano over the Orange Hill Estate House. People survived in a rum cellar, whilst a number died in the corridor leading to the cellar and the estate manager, his wife and nephew died on the verandah.

A cook told me that trash in front of cellar and some of the houses were set on fire by the hot stones. Taylor (who is a very intelligent black man) and the others said that the “cloud rolled down from the Soufriere along the ravines, struck the sea, burst into flames foof, foof, foof, and at once turned back toward the sugar factory striking the building with great force and forcing shut the heavy doors and the heavy wooden shutters of the window openings. Heat was very oppressive. Air suffocating. Smelled of sulphur (rotten eggs, one said). For four or five minutes it seemed as if everyone would die from suffocation and cries for water were heard on all sides. Then the air cleared a bit, though the rain of dust and stones continued”.

From all information gathered from my trip, I can understand the volcanic hazards better: what, where, when and their impacts. They will also help inform impacts on the agricultural and society, where possible.

Jazmin

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I like to thank the Royal Geographical Society for funding. 

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2014 Volcanism

What an explosive year 2014 was for volcanism (pun intended). In this post, I have picked 1 volcano for each month, those that made the international news and some that did not make it that far. It will be brief but I will provide some hyperlinks to places where you can read on further if you wish.

UPDATE: Glossary page has been updated to give a brief definition of some terms that are found in this post.

January

Cleveland, Chuginadak Island
Date: 28th December 2013 – 2nd January

Cleveland
Image by Anon. (2014). Taken from here.

Well I never heard about this one at all! According to the Alaska Volcano Observatory, an explosion was detected on seismic and infrasound instruments and increased surface temperatures following the explosion were also detected. The third explosion occurred on the 1st January and the next day the aviation colour code was changed to orange. The volcano erupted again in February.

February

Kelut (Kelud), Java
Date: 13th – 15th February

Image by Dzakaaul H. (2014).
Image by Dzakaaul H. (2014).

Ah yes I remember this picture. Satellites first detected the eruption plume at 23:09 local time (16:09 UTC) and parts of the ash plume reached just a short of 30 km. The large amount of heat emitted caused the plume to be buoyant over the equilibrium level which is pretty impressive but what I find interesting is that this buoyant plume did not produce any significant pyroclastic density currents (PDCs) especially since the eruption forced its way through a 2007 lava dome.
The eruption was classified as a 4 on the Volcanic Explosivity Index (VEI) making it a subplinian eruption. It was one of the largest eruptions since the Puyehue-Cordon Caulle eruption in Chile which happened in 2010.

March

Pacaya, Guatemala
Date: 5th March 2013 – ongoing

Image by Conred (2014). Taken from here.
Image by Conred (2014). Taken from here.

It is one of the most active volcanoes in Guatemala and can be easily seen from the capital, Guatemala City. Its common activity is strombolian activity and lava flows. On the 6th-7th and the 9th-10th March this year, small explosions generated ash plumes, a minor avalanche and during the 8th-9th lava flows were observed along with steam plumes rising 200 m above the crater.

April

Tungurahua, Ecuador
Date: 22nd November 2010 – ongoing

Image by Anon. (2014). Taken from here.
Image by Anon. (2014). Taken from here.

This volcano is impressively persistent. On the 2nd April, it was reported that there was an explosion in the morning and at night, with large incandescent blocks tumbling down the flanks. The explosion in the night ejected incandescent blocks and produced an ash plume. On the 4th, an explosion lasted for 5 minutes and generated PDCs.
Reports about the eruption continued throughout the month. Here is a news article where you can learn what Tungurahua means. Media can be informative sometimes.

May

San Miguel, El Salvador
Date: 29th December 2013 – 28th July

Image by Zelaya E. (2013). Taken from here.
Image by Zelaya E. (2013). Taken from here.

It is amazing how often national news does not make the international stage.
On the 10th May, the volcano emitted small amounts of ash that fell as less than 1 mm, but on the 19th, the activity increased greatly. There was an increased frequency and magnitude of gas emissions and small explosions along with ashfall. San Miguel continued the on/off activity until July.

June

Pavlof, Alaska
Date: 31st May – 23rd June

Image by the Alaska Volcano Observatory (2014). Taken from here.
Image by the Alaska Volcano Observatory (2014). Taken from here.

Pavlof is the most active volcano in the Alaskan region (current status is minor activity). Its eruptions are mainly strombolian to vulcanian and sometimes produces lava flows. In the above picture, to the right of Pavlof is its twin, Pavlof Sister.
On the 3rd June a steam plume was observed and PCDs generated a low-level of ash. Seismicity remained constant during this time and elevated surface temperatures were also observed. Lava fountaining was seen on the 4th. On the following day, two strong explosions were detected along with lightning. Activity continued until the 9th but at a diminished rate. Pavlof erupted again in November.

July

Sinabung, Sumatra
Date: 15th September 2013 – ongoing

Image by ATAR/AFP/Getty (2014). Taken from here.
Image by ATAR/AFP/Getty (2014). Taken from here.

People should remember the news story back in February. Evacuations were ordered when there was unrest in September 2013 but unfortunately there were still fatalities.
Activity was still persistent in July, with a white plume reaching up to 2,000 m above the crater during the 8th-14th July. The plume also changed colour between brown and blue (which is pretty awesome). PDCs were observed on the 10th, extending 3 km south and further PDCs on the 12th also travelled south by 3-4 km.
A lot of sulphur dioxide emissions (which causes the blue illumination) were emitted from Sinabung during this month: 1,252 tonnes/day between the 8th-14th July and up to 3,796 tonnes/day during the 11th to the 18th.
Although in February it was a ‘big’ eruption, it has still been categorised as a VEI 2 eruption. So 2 magnitudes smaller than Kelut.

August

Bárdarbunga, Iceland
Date: 29th August – ongoing

Image by Norddahl E. and Norddahl B. (2014).
Image by Norddahl E. and Norddahl B. (2014).

The media were all over this one in Europe because everyone thought it would be like EyafjallajÖkull back in 2011. I remember the excitement within the volcanology community and especially on my Masters course. The media left it alone when they learned it would not produce the same effect as Eya which is a shame because it is one beautiful eruption. One of the reasons why the eruptions differ from one another is due to the role of the ice.

September

Ontake, Honshu
Date: 27th September – ongoing

Image by BBC News (2014). Taken from here.
Image by BBC News (2014). Taken from here.

People started blaming the Japanese volcanologists for predicting the eruption that killed 57 people. Read my supervisor’s take on why it could not be predicted. I shall say no more, I can get passive aggressive another time.
A phreatic eruption occurred just before midday with only 11 minutes of precursory tremor and uplift detected beforehand. The eruption generated a PDC that travelled more than 3 km south and an ash plume that ascended 7-10 km and drifted east.
The eruption is still ongoing with waning strength but still…it has effectively disappeared from the international news has it not? (I am sure most people can detect my problem with the media…in another post I shall explain).

October

Turrialba, Costa Rica
Date: 29th October – 8th December

Image by BBC News (2014). Taken from here.
Image by BBC News (2014). Taken from here.

Seismic activity began in late September and in mid-October a 3 day volcanic earthquake swarm occurred. Degassing intensified on the 28th and 29th emitting sulphur dioxide up to 2,000 tons/day. A small phreatomagmatic eruption occurred at 23:10 and lasted for 25 minutes, ending with a strong explosion. This strong explosion generated an ash plume that rose 5.8 km and drifted westsouthwast.
I find it odd that some of the news articles say it is the ‘biggest eruption for the volcano in 100 years,’ because…well the Smithsonian has recorded it was categorised a VEI 2, with the previous 2 eruptions in 2013 and 2012 also at VEI 2. Like I have mentioned for Kelut already, that eruption was 2 magnitudes bigger.

November

Fogo, Cape Verde
Date: 23rd November – ongoing

Image by BBC News (2014).
Image by BBC News (2014).

I have been quite disappointed with the international media coverage of the destruction caused by Fogo, which last erupted in 1995.
This volcano’s destruction has impacted the island’s economy severely in the short term and long term. Like the activity update says, the consequences is the destruction of property, infrastructure, utilities, agriculture and tourism. It will take a considerable amount of time to get the destroyed villages of Portela and Banaeira to rebuild and for livelihoods to return back to normal. That is even if those that have been displaced are willing to return. The BBC provides some powerful photos of those displaced from the eruption.

December

Nishino-shima, Japan
Date: On-going

Image by the Japan Coast Guard (2013).
Image by the Japan Coast Guard (2013).

It is the baby volcano! The latest update is from the 27th December but the continuous Strombolian activity and lava flows has been building up the island throughout the year. Since November, the volcanic island has doubled in size. This blog post describes its evolution, comparing it to Surtsey off the coast of Iceland very nicely.

One to watch

Mayon, Philippines

Image by Esplana M. (2014). Taken from here.
Image by Esplana M. (2014). Taken from here.

A friend brought this volcano to my attention and I can see why: during August, the Philippine Institute of Volcanology and Seismology reported the growth of a new lava dome, ground deformation, increased volcanic gas emissions, earthquakes and rockfalls. From mid-August there was emission of white steam plumes. Inflation was observed in the edifice throughout September, along with the first signs of incandescence in the crater. Since then, the alert level has remained on 3 (out of 5).
She is gonna blow at some point.

Of course, the 12 volcanoes featured were not the only ones to erupt this year. About 60 or more eruptions happen each year and some are continuously erupting without any sign that they will stop. 2015 is a new year for volcanoes, with some grabbing the spotlight and others not so much.

A Q&A Sunday (brother suggested it because it rhymes) will appear in the near future and a glossary page will appear soon after and will be updated often.

Toodle-pip

Jazz