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Monitoring of Ol Doinyo Lengaï volcano: new insights from photogrammetric and satellite data

Pierre-Yves Tournigand1, Benoît Smets2, 3, Matthieu Kervyn2

  • Affiliations: 1Laboratoire Magmas et Volcans, CNRS, IRD, OPGC, Université Clermont Auvergne, Clermont-Ferrand, France; 2Department of Geography, Vrije Universiteit Brussel, Pleinlaan 2, Brussels 1050, Belgium; 3Department of Earth Sciences, Royal Museum for Central Africa, Tervuren B-3080, Belgium 

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 230

  • Programme No: 3.17.16

  • Theme 3 > Session 17

Abstract

Ol Doinyo Lengaï (OL) in north Tanzania, is the only active stratovolcano in the world emitting natrocarbonatite lava and is characterized by semi-permanent activity with intermittent paroxysmal explosive events. The last paroxysm at OL occurred from September 2007 to April 2008, resulting in the formation of a 300 m wide and 130 m deep crater. This crater has since been filling up with the resumed OL's effusive activity. OL volcano is not equipped with monitoring stations and, hence, its eruptive and morphological evolution over time is not well constrained (e.g., emission rates, number of vents). Through photogrammetric analysis using crowd-source images, our recent study has shown a significant increase in OL's emission rate between 2008 and 2022, as well as several unstable features. We follow up on these observations by presenting new photogrammetric data for 2023 and 2024. These data consist of images acquired using an Unoccupied Aircraft Systems, processed to reconstruct 26 cm resolution Digital Elevation Models (DEMs). We also bring a complement of information using Sentinel-2 near-infrared satellites. These data have enabled us to estimate the radiance evolution and emission rates, and the occurrence of new collapse events at OL volcano. Our results indicate that the main lava emission area has remained stable over the past 3 years and that OL's emission rate has been decreasing since 2022, to reach 1.7x104 m3/month. These cost- and time-effective techniques allow us to follow the evolution of the OL volcano and show great potential for the monitoring of all remote volcanoes.