Compositional and textural tephra characteristics of the 1970 eruption at Deception Island (Antarctica): Implications for volcanic hazards

Deception Island is the most active volcano in the South Shetland Islands (Antarctica) with more than 20 explosive eruptive events registered over the past few centuries. The most recent eruption (August 1970) was severely violent with a volcanic explosivity index (VEI) of 3. The column height reached 10 km at its maximum, the estimated bulk eruptive volume was > 0.1 km³ and tephra fallout was reported as far as in King George Island (> 150 km distance). In this work, we perform a compositional and textural analysis of the 1970 tephra layers found at Livingston Island’s glaciers (between 25 and 40 km distance from Deception IsIand). Results obtained are then compared to the in situ pyroclastic deposits of the diverse vents active during this eruption. The objective is to establish a correlation between the eruptive phases occurred during the 1970 event and the physicochemical features observed in the tephra deposits. This will be used as a starting point for future studies of tephra layers found in glaciers and marine/lacustrine sediment cores outside the island, improving our capacity to reconstruct the eruptive dynamics of past eruptions. These results are fundamental to: (i) determine the size and explosiveness of past eruptive events; (ii) assess the extent of their related hazards (e.g., ash fall out); (iii) complete the eruption record of the island; and (iv) consequently, perform more accurate hazard assessments at the island. This is of special concern, since the South Shetland Islands are an important tourist destination and host numerous year-round and seasonal scientific stations and base camps.

 

This work is part of the CSIC Interdisciplinary Thematic Platform (PTI) Polar zone Observatory (PTI-POLARCSIC) activities. This research was partially funded by the MINECO VOLCLIMA (CGL2015-72629-EXP) and HYDROCAL (PID2020-114876GB-I00) MCIN/AEI/10.13039/501100011033 research projects. Sampling was founded by CICYT (ANT91-1270, ANT93-0852 and ANT96-0734).