Project GORISK
Nyiragongo volcano - Goma
The combined use of Ground-Based and Remote Sensing techniques as a tool for volcanic risk and health impact assessment for the Goma region (North Kivu, Democratic Republic of Congo)
Research funded by the Belgian Science Policy Office in the frame of the STEREO II programme – Project SR/00/113
Execution
Period: 03/2007 – 03/2009
- Laboratory
Royal Museum for Central Africa - Musée Royal d’Afrique Centrale : Coordination, InSAR, GIS, …
National Museum of Natural History - Musée National d’Histoire Naturelle du Luxembourg : InSAR, tilt, GPS
University of Luxembourg (Lab. de Physique des radiations): air/subsurface/spring water gas monitoring
Second University of Naples : geochemical monitoring of volcanic fallouts
Goma Volcanological Observatory - Observatoire Volcanologique de Goma : Local User
UNOPS « Volcanic Risk Mitigation Programme »: Local User
CEMUBAC (Centre scientifique et medical de l'ULB pour ses activités de coopération) : Local User
- Studied area
Democratic Republic of Congo / Nyiragongo volcano – Goma area (North Kivu)
Context and objectives
The region of Goma lies under the direct threat of volcanic hazards with the Nyiragongo and Nyamulagira volcanoes that are amongst the most active in Africa. The recent eruption that occurred in January 2002 produced a spectacular lava flows that destroyed part of the city. Although the amount of casualties was limited, hundred thousands of refugees were pushed out of the area which added some more pressure in a highly politically sensitive area at the border with neighbouring Rwanda. The mitigation of the direct volcanic risks is depending on the availability of an efficient volcanic activity monitoring system.
The GORISK project is oriented towards the improvement and implementation of techniques dedicated to the study and monitoring of the Nyiragongo. An important GORISK segment concerns the ground deformations monitoring that are amongst the most important parameters to monitor; it is addressed by both space borne and ground based observations. Volcanic plume fallouts are also a big concern as it causes damage to vegetation and cultivations. GORISK takes benefit from the ongoing EU project NOVAC and US-NSF project VISOR that are focused on ground based and space borne respectively monitoring of the plume. These observations are combined to additional geochemical ground measurements of water quality. In situ measurements can provide useful and sometime crucial clues. Carbon dioxide (CO2), methane (CH4), and radon (Rn), together with other gases, can migrate from deep reservoirs and exhale through micro seepages to the surrounding areas therefore producing significant enrichments in the atmosphere. CO2 for example can locally concentrate and become a major concern for the population. GORISK also involves the study of the possible impact on health of the volcanic activity. A Belgian NGO, the CEMUBAC is providing an epidemiological study based on data acquired in health centres for the last ~10 years, and on plume dispersion maps created from the VISOR and NOVAC projects.
Methodology
- Ground-based deformation monitoring systems involve a network of 5 telemetred tiltmeters deployed on the southern flank of the volcano, in areas selected based on preliminary space borne InSAR measurements (through the SAMAAV – ESA Cat-1 3224 project). Continuous InSAR measurements are performed using ENVISAT ASAR data acquired on a regular basis.
- The project also benefits from a GPS network currently under construction installed by the Luxembourg MNHN GORISK partner.
- Geochemical measurements are made for meteoric and spring waters. These systematic measurements are intending to study the eventual fluctuations of the geochemical parameters and the modelling of the aqueous and hydrothermal systems in relation to the volcano.
- Gas measurements are made in the air, in water (springs), and in the subsurface. The simultaneous recording of various gases (e.g. CO2 , and CH4 ) together with continuous measurements of radon will be performed in the air at the surface and (deleted) in the soil. Radon is a very valuable tracer in connection with its carrier gases, it is easy to measure continuously produces very sensible responses. The analyses of micro seepage of these gases from natural gas reservoirs will be performed by exhalation measurements.
- Health data are studied by using a probabilistic approach for the plume dispersion. Health data are gathered in centres located in plume prone and free areas.
- GORISK data are integrated into a common GIS platform as a tool to be exploited by the local users (GVO, CEMUBAC, and UN-RMU)
The sustainability of the methods is ensured by training of the GVO staff members.
Results expected
GORISK will strengthen the capacity of GVO to observe ground deformations. Previous works, especially the one developed under SAMAAV, has evidenced the efficiency of InSAR in detecting regional scale deformations related to the Nyiragongo eruption in 2002, Nyamulagira in 2002 and 2004. More recently, in November 2006, a large scale deformation occurred with the eruption of Nyamulagira. GORISK is expected to demonstrate that routine InSAR monitoring is providing valuable data for the study of these two active volcanoes. The telemetred ground based measurements will provide in near real time deformation information which will be combined to the other data (seismic network, geochemistry, visual observations… ). That systematic measurement will help in the understanding of the mechanisms which in turn will contribute to the mitigation of the associated risks.
New field of investigation are developed for the monitoring of subsurface gas emanation; that will provide new information datasets. In particular the monitoring of the radon may provide valuable information to be interpreted with the other data.
The monitoring of the environmental impact is also of a major importance as the area is under high demographic pressure and needs a real management. Much is expected from the epidemiological investigation which should be facilitated by the large available database provided by the health centres and the monitoring of the plume direction and SO2 content.
Products and services expected
GORISK provides the user GVO with new tools that are improving the quality of the observations. In particular for detecting ground deformations associated to volcanic eruptions. The selection of sites for ground based monitoring will take benefit from InSAR observations: in high coherence areas where deformations are detected or in low/no coherence areas where additional measurements may help to constrain InSAR observations. The understanding of the mechanisms leading to such deformations will help in the assessment of the areas where fissural eruptions could develop.
GORISK will also address the problem of the volcanic plume and its impact on the environment by monitoring geochemical parameters of water, and the air. This will also contribute to better understand the hydrological system and the relations with the geological structures.
Filling the gap between the volcanic risk and the public health sector is also an important output of GORISK as it could open new perspective of collaborations between partners with the common sake of helping the population.
Various output products will be delivered mainly as maps: deformation maps, InSAR coherence maps, updated map of Goma, plume dispersion..., but also reports as for example on the epidemiological study and the links with the volcanic plume dispersion.
All the outputs are integrated in a common GIS platform.
