A new high-resolution topographic map of the top of the Etna volcano has been published in the Journal of Maps. It was created by a team of researchers from INGV and the Turin Polytechnic
Thermal images and 360° videos, supplemented by Terrestrial Laser Scanner surveys. These are the tools that have allowed a group of researchers from the National Institute of Geophysics and Volcanology (INGV) and the Turin Polytechnic to develop a new and innovative topographic map of the summit area of Etna on a 1:5000 scale, published in Journal of Maps (Taylor & Francis Group), and downloadable for free on the portal at:
http://www.tandfonline.com/doi/full/10.1080/17445647.2017.1352041?scroll=top&needAccess=true.
“Active volcanoes continuously change shape”, explains Marco Neri, INGV's first researcher. “Etna is no exception to this rule. It transforms, especially in the summit area of the volcano, the most active. In recent years, the volcano has changed its face, assuming different morphological profiles, following the growth of new craters and the filling of older depressions and vents".
Indeed, for volcanologists eruptions represent an opportunity to analyze new material, theories to develop, tools to design, install and test in the field.
“But these continuous changes”, continues Marco Neri, “quickly make the topographic and geological maps of the places affected by the eruptions obsolete. Not a secondary problem for those who have to orient themselves in those places to carry out monitoring and surveys, and also for the volcanological guides who accompany thousands of tourists visiting the volcano every year".
Therefore, the researchers put together different professionalism and skills, aimed at creating a new map of the summit area of Etna, also accompanied by further thermal and morphological maps of greater detail.
“Using a helicopter, a very high resolution aerial photogrammetry was created, integrated with 360° video (shot with immersive reality techniques), also acquiring thermal images to identify the most active areas of the volcano. At the same time, a topographic survey was carried out from the ground with a Terrestrial Laser Scanner of some key areas which formed the geodetic reference base for placing the images acquired from the helicopter on the ground”, explains Marco Neri.
The methodological approach used provided reliable, accurate, rapidly and safely acquired data. This latter aspect must be taken into account when working in areas exposed to potential dangers, such as the summit areas of active volcanoes.
“The same helicopter acquisition approach”, concludes Marco Neri, “is also currently being tested on images acquired from satellites with high spatial resolution (50-30 cm), for the generation of DEM (Digital Elevation Model) and 3D at very high resolution, through techniques of integration of photos taken from the ground, from an airplane and from a satellite”.
Extended
Neri M., De Maio M., Crepaldi S., Suozzi E., Lavy M., Marchionatti F., Calvari S., Buongiorno MF, (2017). Topographic Maps of Mount Etna's Summit Craters, updated to December 2015, Journal of Maps Vol. 13, Iss. 2, http://dx.doi.org/10.1080/17445647.2017.1352041.
New maps of the summit of Mount Etna volcano (1:5000–1:4000), derived from helicopter photogrammetry, thermal images and terrestrial laser scanner survey, are presented here. These maps indicate the main morpho-structural changes occurring during the powerful explosive and effusive eruptions involving the summit craters of Etna over the first two weeks of December 2015. The survey enabled identifying the proximal erupted volume (7.2 ± 0.14 × 106 m3) and the size and location of the vent causing the powerful explosive activity inside the Central Crater. Our survey also outlines the growth of a recent (2011–2015) summit cone on top of a former pit crater, named New SE-Crater. This new cone is by now comparable in size to the former SE-Crater. The shape and size of two small cinder cones that formed on the upper eastern flank of the summit zone in May–July 2014 are also shown. This approach can be used in fast and frequent monitoring of very active volcanoes.
Fig. 1 - Overview of the Etna summit area, taken from the south-west in December 2015
Fig. 2 - Interior of the Central Crater of Etna, seen from its western edge
Fig. 3 - Preparation of the cameras for 360° video acquisition, from which the immersive reality video was obtained
Fig. 4 - Data acquisition with Terrestrial Laser Scanner (Riegl VZ-4000 model), along the southern flank of the New Southeast Crater
Fig. 5 - Strombolian and effusive activity produced by the New South-East Crater on the night of 7 December 2015, seen from the north-eastern side of Etna
Fig. 6 - PLEIADES satellite image (50 cm resolution orthophoto), acquired in July 2015, (credits AIRBUS Defense and Space)
Fig. 7 – New topographic map of the summit area of Etna. The original high resolution pdf file is freely downloadable here:
http://www.tandfonline.com/doi/full/10.1080/17445647.2017.1352041?scroll=top&needAccess=true