Vulkanológiai kutatások...

About the Research Group

Vulkán

Modern volcanological and volcano geomorphological research started at the Department of Physical Geography in the 1990’s. On this webpage you can find the colleagues and students participated – or currently participating – in the research work, and some information on the most important projects in the past years.


Volcanological research traditionally involves understanding processes triggering, leading to, or characterizing volcanic eruptions, and reconstructing the environment as well as paleogeographic conditions during volcanic activity. The resultant, primary volcanic landforms and their post-eruptive surface processes  are  studied by volcanic geomorphology.  At
our department,  the latter  approach was  initiated  by
previous colleagues  several years ago,  but have been
refined and completed significantly during our work.

Vulkán


In the Carpathian Basin and, within this, Hungary, we investigate volcanoes that went extinct many millions of years (in Hargita Mountains in the East Carpathians several thousands of years) ago; by contrast, we are working abroad mostly on active volcanoes. To name a few of the most important study areas: in Hungary and the Carpathian Basin: Börzsöny–Visegrád Mts, Mátra Mts, East Carpathians; in other countries: Etna, Aeolian Islands (Italy); Auvergne (France); Arizona (USA); Santorini (Greece); case studies in Japan; Mexico; Central Andes (Chile, Argentina).





Vulkán

Images and photos on the right hand side display features of one of the most exciting volcanic phenomena: block-and-ash flows or nuée ardentes related to lava dome collapse, which are being studied by our research group as well. In the uppermost photographs, you can see an active lava dome, and a block-and-ash flow (baf) rushing down after fragmenting and collapsing of a dome. Block-rich part of this flow is moving on the valley floor, obscured by an expanded ash cloud above. Apart from blocks and fragments coming from the lava dome, baf contains a significant amount of gas as well, which makes it one of the most dangerous volcanic phenomena,  because  the  concentrated  gas currents
may  move   much   farther   than  the   solid   material
deposited closer to the vent. Baf activity is  typical  of
lava domes such as at Mount Merapi, Indonesia, e.g. in
November 2010 causing more than  150 fatalties.  Such
processes  also  characterized  the  Börzsöny–Visegrád
Mts 13-15 million years ago.

Vulkán



The third image is a shot taken on a baf deposit in the Gendol river at the lower flanks of Merapi volcano. Deposit consists of dm to m-sized blocks set in middle-grained ash and fine lapilli matrix. Together with colleagues at Keele University, England, we investigate how the orientation of clasts changes with distance from vent, and what differences there are between the various facies of baf deposits. On the basis of the rose diagram shown here, R (orientation) = 0,6, having 92-272 azimuth directions. The relatively high R value is due to yield strength, which develops in response to cohesion in particle-rich mass flow.



Finally, two pictures on bottom show breccia towers of 15 million years-old block-and-ash flow deposit of the Visegrád Mts (photo and interpretation). Due to the clastic texture, the block-rich flow material is resistant to erosion, eventually forming positive landforms „exhumed” from their environment (normally a valley infill). Similar rock towers are widely distributed in the Hungarian volcanic mountains.