Vi-X Project – Study and monitoring of Virunga volcanoes using TanDEM-X
The Virunga Volcanic Province, in the western branch of the East African Rift, extends over 3 countries: D.R. Congo, Rwanda and Uganda. Among its 8 main volcanic edifices, two are very active: the Nyiragongo and the Nyamulagira, in D.R. Congo. Nyiragongo volcano and its semi-permanent lava lake threaten the city of Goma (± 1 Mo inhabitants) distant of ~ 12 km. Its silica-undersaturated lavas form low-viscosity flows that can reach 20 km/h in flat urban areas. The last eruption in January 2002 devastated approximately 10 % of the city, including major infrastructures (roads, airport, public and private buildings). Nyamulagira volcano is located 5 km NNW of Nyiragongo and erupts every ~ 2-4 years. Its lava flows repeatedly destroy large forested areas of the Virunga National Park. Beside the direct threat of volcanic products, other volcanic related hazards are affecting the region like gas emanation or the intense erosion of the dormant volcanoes that also often triggers dangerous mudflows during high precipitation events, which destroy villages and crops as it occurred in May 2010.
In this context, high-resolution SAR products are highly desirable and necessary to:
- Pursue the InSAR monitoring initiated with ENVISAT in 2006.
- Exploit the invaluable DEM that will be produced in the TanDEM-X mission.
Satellite SAR remote sensing is indeed constantly evolving. Recently, DLR launched the TanDEM-X SAR sensor that, with the already operational TerraSAR-X sensor, makes the TanDEM-X mission. This Tandem mission offers unprecedented possibilities in terms of SAR Remote Sensing. Since working in Tandem, both sensors allow acquiring interferometric signal free of temporal decorrelation. Therefore, it will be now possible to generate a full DEM of the whole studied area. Moreover, since being wide band sensors, they offered the possibility to perform split-band interferometric measurements on the lava lake, which are expected to allow lava lake levelling.
The main objectives of the Vi-X project are:
- The production and the geomorphological analysis of a high-resolution DEM covering the Virunga Volcanic Province and part of the Lake Kivu basin.
- The development and use of advanced InSAR techniques (i.e. Split-Band SAR Interferometry) in order to develop an innovative technique for the monitoring of the Nyiragongo lava lake.
- The InSAR ground deformation monitoring and modelling in the Virunga Volcanic Province.
This project is in line with continuous efforts of the ECGS, the National Museum of Natural History (NMNH) and the Royal Museum for Central Africa (Belgium) to monitor and understand the geodynamical processes of the Virunga Volcanic Province, in the frame of a global risk management/evaluation of the area.