Public Talk in CapeTown on ‘Supervolcanoes………..

May 30, 2014 No Comments by

On 18th June, Prof Chris Harris, Department of Geological Sciences, UCT will present a talk entitled ‘Supervolcanoes, large igneous provinces, and their geological and historical significance’ at the SAAO Auditorium in Cape Town.
Absract:  The term “supervolcano” is not generally used by geologists in scientific publications, although the term is used by volcanologists in public presentations. There is no generally agreed definition, but one such is “any volcano capable of producing a volcanic eruption with an ejecta volume greater than 1,000 km3”. It is increasingly recognized that volcanic eruptions have played an important role in key historical events. For example, the year 1816 became known as “The year without a summer” a consequence of the 1815 eruption of the volcano Tambora, Indonesia. Approximately 160 km3 of material was erupted, more than 71,000 people were killed, and the volcano reduced in height from 4300 to 2850 m above sea level. The Laki fissue eruption, 1783, resulted in the longest lava flow in recorded history; it has been suggested that the effects of this eruption contributed to famine in Europe, one of the underlying causes of the French Revolution in 1789. Lake Toba, Sumatra, is the site of the largest eruption in the last 25 million years. This, the 2,800 km3 ‘Youngest Toba Tuff’ occurred approximately 70 thousand years ago, and was a climate-changing event with hypothesized global consequences for human populations. The danger posed by a particular volcano is dependent on more factors than just its size: I will discuss this with reference to currently active Indonesian volcanoes, which are considered particularly dangerous.

The ‘supervolcanos’ of the historical past, however, are relatively insignificant compared to so-called large igneous provinces (LIP’s),believed to form just prior to the break-up of continents. The Deccan traps of India resulted from the eruption of >500,000 km3 of magma over a period of ~ 1 million years; this LIP, and others like it, often appear to be related to major mass extinction events in the fossil record. I will outline possible mechanisms for the formation of these enormous volumes of magma, a subject of active research activity in geology and geochemistry. Studying the formation of LIP’s, offers a means of understanding processes in the Earth’s interior.

Date:     Wednesday 18 June 2014

Time:    17h00 (Tea will be served from 16h30)

Place:    South African Astronomical Observatory (SAAO) Auditorium, Observatory Road, Observatory*

*Directions to SAAO Auditorium : From the N2, turn off to the M57 – Liesbeek Parkway; turning in the direction of Cape Town and continue until the traffic lights with Hartleyvale (hockey and football) on your left. Turn right at traffic lights into Observatory Road, pass the River Club; the S A Astronomical Observatory is next on the left. Once through the security gates bear left following the SALT signs to the auditorium i.e. last building on the left (white with stoep & ramp).                                 NO BOOKINGS / ALL WELCOME

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