Skip directly to content

Important announcement

Health Intelligence has a new domain name http://www.publichealthintelligence.org and the old one here http://healthintelligence.drupalgardens.com will end in few days. Please update our new URL and RSS feed.
Thank you for visiting and reading the content from Health Intelligence. 

Volcanic activity within the last 10,000 years

on Sat, 05/03/2014 - 20:11
In a previous post Volcanoes of the World, volcanoes recorded by the Smithsonian Institution’s Global Volcanism Program (GVP) were introduced. It includes an exploratory visualization that helps us to learn about where every volcano is located and what are their main physical characteristics. 
 
Today, other interesting aspect is going to be covered, the volcanic activity. A summary of some statistics about Holocene volcano eruptions (within the last 10,000 years) and two new interactive visualizations that allow you to explore all recorded eruptions will be provided in this post.

The dataset

The list of volcanoes (also used in the previous post) and the eruptions observed in the last 10,000 years datasets, both collected by the GVP will be used as data sources for this post. Both datasets are available to download here List of Volcanoes and Erutions search
 
The following screenshot shows some summary statistics of volcanic activity in the last 10,000 years.
 
Click on the screenshot or here to play with the interactive visualization
 
From the total of 1,550 volcanoes recorded, there are 960 that have erupted at least once in the past 10,000 years and the total number of eruptions observed in this period is 10,762.
 
The top chart shows the number of eruptions observed by century from 98 BC (BC centuries with negative values in x-axis) to 21st century. In most recent centuries the frequency of observed eruptions are higher, having 3,542 (33% of the total) eruptions observed in Twentieth Century, the highest eruption count. This might give the idea that the eruptions are more frequent now than before, but that is not true. Human knowledge, science discoveries and new technologies allow us to be better now observing eruptions. 
 
Looking at the top 20 volcano with highest number of eruption in history, five volcanoes accumulate the higher eruption frequency,  Etna volcano located in Italy has erupted the most with 241 eruptions, followed by Piton de la Fourmaise in France (184), Asosan (182) and Asamayama (145) in Japan and Katla in Iceland (132). 
 
The top 20 longest eruptions chart shows that a volcano could be erupting for years.  Four volcano eruptions were really outliers with durations greater than 68,000 days (more than 186 years). 

Magnitude of Volcanic Eruptions

Other interesting aspect to look at is the intensity or size of volcanic eruptions. There are several quantitative measures of the intensity of volcanoes but the most widely used is the volcanic explosivity index (VEI) proposed by Chris Newhall from the US Geological Survey and Stephen Self from the University of Hawaii in 1982. The VEI is a logarithmic scale of eruption size based on a combination of erupted tephra volume and eruption plume height.  VEI has a range of values from 0 (non-explosive eruption) defined as less than 10,000 m3 of tephra ejected, to 8 (largest volcano in history) representing a mega-colossal explosive eruption that can eject more than 1,000 km3 of tephra and have a cloud column height of over 50 km.  Each ascending level indicates a tenfold increase in severity.
 
Of the 10,762 eruptions, 2822 do not have value of VEI in the dataset (labeled in the chart as N/A). Vast majority of eruptions (3,859) have VEI 2 and fortunately the higher that magnitude 4 eruptions are less frequent, having observed 175 eruptions with VEI of 5, 51 with VEI of 6 and only 7 with VEI of 7. There have not been any Holocene (within the last 10,000 years) eruptions with VEI of 8. 
 
The chart located at the bottom of the visualization shows the number of eruptions per century and magnitude of VEI.  It shows a higher frequency of eruptions with VEI lower than 5 in the last six centuries.
 
The following visualization allows you to explore the volcanic activity in the most recent six centuries.  
 
Click on the screenshot or here to play with the interactive visualization
 
In the last six centuries, in 1892 Volcano Mount Tambora, Indonesia had an eruption with VEI of 7, the biggest and only one eruption of that magnitude in this period. Volcano Tambora was erupting during 1,291 days (3.5 years). 32 volcanic events with VEI of 5 and 7 eruptions with VEI of 6 have been observed in this period.  
 
The higher frequency of eruptions per VEI and century was 1,626 eruptions observed in Twentieth century with a VEO of 2. 
 
From 1500 to 2013, the top four volcanoes with the highest number of eruptions are Piton de la Fournaisse in France with 175 eruptions, Etna in Italy with 167 eruptions, Asosan in Japan with 133 eruptions and Asamayama in Japan with 131 eruptions.
 
Readers are encouraged to play with these two interactive data visualizations, use the top-right slider to show data and stats for specific period of centuries. 
 
Just to have an idea of scenes from volcanic activity, take a look at 2013: The Year in Volcanic Activity, published in The Atlantic on December 13th, 2013 showing a collection of 36 photos from the variety of volcanic activity on Earth over the year 2013. 
 
I hope readers find the information provided in this post about volcanic activity informative, interesting and useful.
 
Drop a comment with your thoughts and any other additional information you could provide.
 
Best
Ramon
 

Comments

Robin Diamond's picture

Is there data to demonstrate that eruptions have become for frequent or stronger in the last 2-3 years?

Post new comment