Volcanic mountains

Tarso Toussidé – Volcanic massif

The Tarso Toussidé volcanic massif is featured in this false color composite image captured by the Copernicus Sentinel-2 mission. Credit: Contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO

Tarso Toussidé, capped by the (potentially active) Toussidé stratovolcano, is located at the western end of the Tibesti Mountains in Chad. With an altitude of 3265 m above sea level, Toussidé is the second highest peak in Tibesti, after Emi Koussi.

Toussidé has undergone a number of eruptions and lava flows, with lava reaching lengths of 25 km and covering an area of ​​200 km2, appearing to have “stained” the ground in the process. The volcano ejected tephra, fragments of volcanic rock and glass, lava and ash. In the middle of the field is Pic Toussidé, a lava dome that can be seen emerging from the caldera.

Toussidé is considered one of the youngest volcanoes in Tibesti. A large number of fumaroles (openings in or near a volcano through which gases emerge) are active at its summit, mainly exhaling water vapor at temperatures of 40-60 ° C, suggesting that ‘it is the only active volcano in Tibesti.

Right next to Toussidé, on the far right of the image, is the Trou au Natron caldera, which sits at an altitude of around 2450m. A number of volcanic cones rest on the caldera floor, with numerous vents and hot springs on the caldera floor emitting hot steam.

Much of the caldera’s surface is lined with a white crust of salts, including sodium carbonite. These crusts usually form when mineral-rich vapor is emitted from small vents on the bottom of the crater, and when this evaporates under the heat, the minerals are left behind.

The caldera has an irregular diameter of about 6 to 8 km and reaches up to 1000 m in depth, and would have been filled by a freshwater lake during the last glacial maximum.

On the left of the image, the red shows sparse vegetation along the ephemeral coves.

Satellite imagery is a convenient way to study remote areas such as the volcanic regions of the Tibesti mountain range. The Copernicus Sentinel-2 mission carries a multispectral imager with 13 spectral bands and has wide swath coverage, providing data on Earth every five days.