| Description |
Introduction
The Goma Volcano Observatory Seismic Network (GVOSNET) is a broadband seismic network built, operated, and managed by the Government of the Democratic Republic of the Congo (DRC) through the Goma Volcano Observatory (GVO). It is the first Congolese-operated telemetered broadband seismic network installed in the Virunga region. This network replaces the Kivu Seismic Network (KivuSNet), which ran from 2012 to the end of June 2022.
Geographic expansion
The network's geographic expansion is in the Eastern Democratic Republic of Congo (DRC) near the border with Rwanda and Uganda, West of Lake Kivu, North of the city of Bukavu on the South end of Lake Kivu, and South of Lake Albert. The network covers parts of North Kivu, South Kivu, and Masisi and surrounds a large area inside the Virunga National Park, including the Nyiragongo and Nyamulagira volcanoes, then follows the Western coastline of Lake Kivu from Goma to Lwiro. GVOSNET also has a station located on Idjwi Island in Lake Kivu and another at the top of the Nyiragongo volcano.
Mission
GVOSNET aims to monitor seismic activities in the Kivu Rift, facing a unique combination of natural hazards in a densely populated region. In particular, GVOSNET monitors the active volcanoes Nyiragongo and Nyamulagira and the tectonic seismicity of Lake Kivu. The Nyiragongo volcano hosts the world's largest semi-permanent lava lake, with a record diameter of 270 m in a crater of 1.2 km of diameter. It is only ten km from Goma and 20 km from Lake Kivu. The Nyiragongo's flank eruptions in 1977, 2002, and 2021 forced hundreds of thousands of people to flee from their homes and caused massive damage to local infrastructures. The Nyamulagira volcano is Africa's most active volcano. These volcanoes pose serious geohazards to the people of Goma, Sake, the territory of Nyiragongo in the Democratic Republic of the Congo, and the Gisenyi district in Rwanda. Destructive earthquakes also strike the region. Moreover, Lake Kivu is a significant geohazard in the area: it is one of only three lakes worldwide that might experience limnic eruptions due to high methane and carbon dioxide gas concentrations dissolved at depth in its water.
Deployment
GVOSNET deployment began in May 2022 with the first five telemetered stations. By the end of July 2022, it had grown to nine telemetered stations, twelve by September 2022, including one at the summit of the Nyiragongo volcano. The network reached 15 stations by November 2023 with the deployment along Lake Kivu in Bobandana, Lwiro, and Idjwi Island in Lake Kivu. While its deployment has been slowed due to ongoing conflicts in the North Kivu province, the network is expected to consist of seventeen stations when fully deployed with currently available equipment.
Equipment
Data is collected in situ at each station at 50Hz and 200Hz sampling frequencies and telemetered in real-time to the Goma Volcano Observatory station base at 50Hz sampling frequency.
Most seismic sensors are installed in the center of a hut on a concrete seismic pier with variable surface sizes (ranging from around 0.5 m to 1.5 m). The seismic piers have been anchored as profoundly as possible, reaching bedrock in most cases, and decoupled from the observation hut's concrete floor. At the GOM2 station, the sensor is installed in vaults 2-3 m deep. Using 110-150 W solar panels with appropriately sized batteries ensures a continuous power supply. Nanometrics Trillium Compact (120 s-100 Hz) seismometers are installed at each location, while new Nanometrics sensors are installed in Lwiro, Bobandana, and Idjwi islands.
The digitizers are all in the Nanometrics Centaur CRT4 series, with three or six sensor channels operating at a 200 Hz frequency sampling rate. Secondary channels at 50 Hz are transmitted in real-time to the Goma Volcano Observatory base station. Each station has an ABB ARG600 modem or a Sierra Wireless RV50X modem for wireless communication via local cellular data networks. An M2M gateway unit establishes secure VPN connections between the observatory and all stations. Each station is reachable via a dedicated VPN tunnel to secure communications of seismic data. Data is transmitted using the SeedLink protocol within the secured VNP network.
Partners and supports
GVOSNET exists thanks to the support of the DRC Government. The network is also thankful for the international partners, local corporations, nonprofit organizations, and the Congolese diaspora, which work together to support the Goma Volcano Observatory.
The DRC Government provides the central infrastructure, including a renovated computer laboratory hosting the IT equipment and the acquisition server at the seismic network. The DRC Government contributed five seismic stations, computers, and communication equipment. The DRC President's Office donated two vehicles to support the maintenance of the seismic stations. In 2023, the DRC Government purchased an additional complete data acquisition system (an acquisition server and an M2M gateway) for redundancy.
The United Nations Organization Stabilization Mission in the Democratic Republic of the Congo (MONUSCO, an acronym based on its French name "Mission de l'Organisation des Nations Unies pour la Stabilisation en République Démocratique du Congo") contributed four stations and a complete solar energy system at GVO. An internet connection was funded for 3 years.
The Lake Kivu Monitoring Program donated three seismic stations.
Raw Bank, a leading bank in the Democratic Republic of Congo, provided three seismic stations and donated a GEMPA package for automatically locating seismic events.
The Volcano Disaster Assistance Program (VDAP), a joint program of the United States Agency for International Development (USAID) and the United States Geological Survey (USGS) provided two seismic stations and pledged three more. VDAP donated the original acquisition server in 2021 and computers, training, and remote IT support through ISTI (Instrumental Software Technologies Inc), a geophysical software company providing custom software solutions, seismic monitoring, and consulting services. VDAP also offers remote support and training.
The Linda Project, a nonprofit of the Congolese scientific diaspora, designed the network telemetry, set up the VPN security, purchased essential communications equipment (M2M gateway ARM600, modems RV50X) and energy systems, contributed to surge protection equipment in the control room, and donated the GEMPA package for high-definition maps. At the network's inception, the Linda Project trained GVO technicians to set up modems and digitizers with support from VDAP. Since March 2023, the LindaProject has provided a dedicated high-speed internet connection for the seismic network.
The Virunga Park hosts observation huts in Kibumba, Kibati, and on top of the Nyiragongo volcano. The stations in Kalehe, Lwiro, Idjwi Island, Bulengo, and Goma are also located on properties owned by the DRC Government. MONUSCO hosts seismic stations in Sake, Kitchanga, and Munigi. The Catholic Church hosts network stations in Rusayo, Matanda, and Bobandana. Traditional chiefdoms and private individuals host other stations in Nyiabibwe and Luboga. The Baptist Protestant Church hosts an observation hut in Burungu.
Table 1 Station List for Goma Volcano Observatory Seismic Network
Station Latitude Longitude Elevation Datalogger Seismic Sensor Corner
(m) Frequency
BOB2 -1.7063 29.01320 1566 Centaur Trillium 120s
MTAN -1.54467 28.93200 1892 Centaur Trillium 120s
BURU -1.33857 29.02620 1879 Centaur Trillium 120s
IDJ2 -2.06422 29.06062 1566 Centaur Trillium 120s
KBT2 -1.56897 29.27844 1992 Centaur Trillium 120s
KTS2 -1.23839 29.04990 2029 Centaur Trillium 120s
LBGA -1.26202 29.11094 1809 Centaur Trillium 120s
LWI2 -2.23916 28.80249 1760 Centaur Trillium 120s
RGB2 -1.34518 29.36542 1610 Centaur Trillium 120s
RSY2 -1.57699 29.17984 1680 Centaur Trillium 120s
KAL2 -2.10710 28.92091 1508 Centaur Trillium 120s
NYA2 -1.92096 28.93674 1976 Centaur Trillium 120s
BUL2 -1.633014 29.14048 1482 Centaur Trillium 120s
MUN2 -1.625761 29.25526 1722 Centaur Trillium 120s
GOM2 -1.681242 29.22670 1477 Centaur Trillium 120s
SAK2 -1.58638 29.07305 1500 Centaur Trillium 120s
NYI2 -1.529757 28.97878 1931 Centaur Trillium 120s
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