Virunga Volcanoes Supersite Biennial Report: 2022- 2023

For 2022 and 2023, the activity at Nyiragongo volcano has almost been at background level after the May 2021 eruption. The effusive activity that resumed inside the Nyiragongo main crater in September 2021 began with a sustained seismic activity and ground deformation to the southern flank of the volcano, has shown regular activity with lava presence in the crater captured several times by satellite when weather conditions allow. The degassing is permanent, in fact the two DOAS stations installed around Nyiragongo volcano (one in Rusayo and the other in Sake) indicate that the plume is permanent with 2943 tons/day as maximum daily flux for 2023 and a 300 kt as cumulative SO2 emissions for 2023, from the DOAS that measures only during the presence of sunlight. It has been challenging to access Nyiragongo summit, the May 2021 eruptive site and the lower parts of Nyiragongo volcano (e.g. for measuring temperature and gas in fractures) because of the ongoing war in the volcanic field, which has even prevented the UN helicopter to overflowing the volcanic field in support to the monitoring activities. Unlike Nyiragongo volcano, Nyamulagira volcano has been characterized by an intense activity inside its large caldera (~2,2x2 km wide), and as for Nyiragongo, Nyamulagira was not accessible for ground-based measurement or helicopter overflowing because of the security issues. The satellite-based monitoring has played an important role in responding to several unrests recorded during 2023 to 2023, especially in May, June and November 2023 when lava overflowed Nyamulagira’s caldera rim. Few local scientists are involved in the processing of the EO data, raison why there is still need to continue improving local capacities to process the EO data and for they interpretation. Discussions have been initiated for the capacities exchange between local and international members of the Supersite. Considering the fact that gases dissolved in the deep waters of Lake Kivu represent a real hazard for the millions of the populations living in its watershed especially those in the cities of Goma (DRC) and Gisenyi (Rwanda), efforts have been made for the studding the stability of this lake and how could a volcanic eruption and/or the movement of the western branch of the rift where the lake lies could affect its stability. Hence, studies on the imaging of the details of the crustal and the upper mantle structure along the Kivu Rift zone particularly the lake Kivu basin as well on the geochemical monitoring of Lake Kivu are ongoing. Finally, several local scientists had the opportunity to participate in abroad trainings related to volcano monitoring, as well as volcanic and climatic hazards assessment and mitigation. The Goma Volcano Observatory has also received a donation of 5 GNSS stations from the GEO-GNSL, under the Virunga Supersite umbrella, to improve local infrastructures for a better ground-based collection.