Some people are saying that there is more volcanic and earthquake
activity than normal. Is this truly the case? Or is this just media hype and
completely wrong? What types of statistics are available on world wide
volcanic activity and how do you compare them? Thanks.
Bill England
Dear Bill,
You pose an interesting question that volcanologists have tried to
address. In general, I think most volcanologists would except that there
are episodic fluctuations in activity. For example, in an eight month
period in 1974, 5 of the 7 historically active volcanoes in the western
Bismarck arc erupted. There is also evidence that earth tides influence
the timing of some eruptions. Note that this activity is at a regional
or local scale.
Simkin and Siebert found no evidence for episodic volcanism on a global
scale in the data set they compiled for the last 10,000 years (this is
the most comprehensive data set available).
I don't know if hype is the right word but the media certainly covers
more eruptions (and the reporting/descriptions are often inaccurate). I
think some people infer this to mean that more volcanoes are erupting. I
think that the same number of volcanoes are erupting but more reporters
and better technology result in more volcano stories.
The types of statistics available include volcano name, location, type of
volcano, type of eruption, duration of eruption, volume of material
erupted, and number of fatalities. However, the further back in time the
more fragmental the record and the less accurate the date of the
eruption.
How to compare them? That's another problem. Some volcanologists find a
pattern. Others use a slightly different data set and get different
results that refute the previous study.
I think you would enjoy reading page 30 of Simkin and Siebert (and their
references).
Steve Mattox, University of North Dakota
Source of Information:
Simkin, T., and Siebert, L., 1994, Volcanoes of the world: Geoscience
Press, Tucson, Arizona, 349 p.
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