The monitoring of seismic activity at Nyiragongo volcano through telemetered seismic network Goma Volcano Observatory (Democratic Republic of the Congo)

The eruption, in January 2002, of Mount Nyiragongo in eastern Congo, and the humanitarian disaster that followed in its wake, underlined the critical importance of accurate seismology to predict when such events will take place. Thus, a seismic telemeterd network, with centre in Goma Observatory, was built across Virunga area to help the moniotring of Volcano. Mount Nyiragongo is a volcano in the Virunga Mountains associated with the Great Rift Valley. The most prominent feature of the Democratic Republic of Congo's geology is the Western Rift Zone (WRZ), which runs through its eastern border regions and neighbouring countries (e.g. Uganda, Rwanda, Burundi, Tanzania) between 28°E to 32°E and 4°N to 12°S. The WRZ extends over a 1600 km arc, including lakes Albert, Eduard, Kivu and Tanganyika, until it joins the eastern branch. The Western Rift Valley of Africa has experienced severe earthquakes and volcanic eruptions in recent historical times. Earthquakes with magnitude >=6 are not frequent, but may cause significant destruction. They occur mostly in DRC and neighbouring countries (e.g. Uganda and Tanzania). In 1991, IAVCEI selected the Nyiragongo volcano as the ‘African decade volcano’ for the International Decade of Natural Disaster Reduction (IDNDR) program. Nyiragongo is located about 20 km north of Lake Kivu and 15 km north of Goma, a city of about 500,000 inhabitants. Goma is twinned to Gisenyi in Rwanda, which has a population of about 100,000. Several small villages are also located on the flank of the volcano. Population growth and poor or non-existent planning has led to relatively uncontrolled use of land for building, and the development of sites vulnerable to earthquake and/or volcanic risk.EUROPEAN CENTER FOR GEODYNAMICS AND SEISMOLOGY Royal Museum for Central Africa, B National Museum of Nat. History, LUnpublishedLuxembourg1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attiveope

Preliminary results from seismic monitoring at Nyiragongo Volcano (Democratic Republic Of Congo) through telemetered seismic network, Goma Volcano Observatory

Following the January 17, 2002 catastrophic eruption of the Nyiragongo Volcano (Democratic Republic of Congo) located in the western branch of the East African Rift, a great effort has been devoted to the seismic surveillance of this volcanic area. The 2002 eruption destroyed one/tenth of the city of Goma, leaving more than 100,000 homeless. In order to correctly monitor the seismic activity at Nyiragongo volcano for both scientific and civil defence purposes, the Istituto Nazionale di Geofisica e Vulcanologia in cooperation with GVO (Goma Volcanological Observatory), between November 2003 and May 2004 installed a new telemetered seismic network consisting of seven digital stations. The network is operational and seismic signals are continuously recorded at the GVO. In this study, we focus mainly on two aspects: (1) the deployment, in the field, of this new digital seismic network and the related real-time data acquisition system, and (2) the first results from a preliminary data analysis based on 6-month seismic recordings. Based on the waveforms and spectral analysis, long-period and very long period events (both, tectonic and volcanic-tectonic earthquakes), have been detected. Furthermore, we succeeded in locating more than 100 earthquakes. These results should strongly encourage the use of such a network data for seismotectonic studies of the area.Published117-1271.4. TTC - Sorveglianza sismologica delle aree vulcaniche attiveN/A or not JCRreserve

Preliminary results from seismic monitoring at Nyiragongo Volcano (Democratic Republic of Congo) through telemetered seismic network, Goma volcanological observatory

Following the January 17, 2002 catastrophic eruption of the Nyiragongo Volcano (Democratic Republic of Congo) located in the western branch of the East African Rift, a great effort has been devoted to the seismic surveillance of this volcanic area. The 2002 eruption destroyed one/tenth of the city of Goma, leaving more than 100,000 homeless. In order to correctly monitor the seismic activity at Nyiragongo volcano for both scientific and civil defence purposes, the Istituto Nazionale di Geofisica e Vulcanologia in cooperation with GVO (Goma Volcanological Observatory), between November 2003 and May 2004 installed a new telemetered seismic network consisting of seven digital stations. The network is operational and seismic signals are continuously recorded at the GVO. In this study, we focus mainly on two aspects: (1) the deployment, in the field, of this new digital seismic network and the related real-time data acquisition system, and (2) the first results from a preliminary data analysis based on 6-month seismic recordings. Based on the waveforms and spectral analysis, long-period and very long period events (both, tectonic and volcanic-tectonic earthquakes), have been detected. Furthermore, we succeeded in locating more than 100 earthquakes. These results should strongly encourage the use of such a network data for seismotectonic studies of the area. © 2009 - OGS

Preliminary results from seismic monitoring at Nyiragongo Volcano (Democratic Republic Of Congo) through telemetered seismic network, Goma Volcano Observatory

Following the January 17, 2002 catastrophic eruption of the Nyiragongo Volcano (Democratic Republic of Congo) located in the western branch of the East African Rift, a great effort has been devoted to the seismic surveillance of this volcanic area. The 2002 eruption destroyed one/tenth of the city of Goma, leaving more than 100,000 homeless. In order to correctly monitor the seismic activity at Nyiragongo volcano for both scientific and civil defence purposes, the Istituto Nazionale di Geofisica e Vulcanologia in cooperation with GVO (Goma Volcanological Observatory), between November 2003 and May 2004 installed a new telemetered seismic network consisting of seven digital stations. The network is operational and seismic signals are continuously recorded at the GVO. In this study, we focus mainly on two aspects: (1) the deployment, in the field, of this new digital seismic network and the related real-time data acquisition system, and (2) the first results from a preliminary data analysis based on 6-month seismic recordings. Based on the waveforms and spectral analysis, long-period and very long period events (both, tectonic and volcanic-tectonic earthquakes), have been detected. Furthermore, we succeeded in locating more than 100 earthquakes. These results should strongly encourage the use of such a network data for seismotectonic studies of the area

Cooperation on Congo Volcanic and Environmental Risks

On 17 January 2002, the Nyiragongo volcano (1.52°S, 29.25°E, 3469 meters above sea level), located about 18 kilometers north of Lake Kivu in the Democratic Republic of Congo, erupted, releasing a volume of 14-34 million cubic meters of lava. Lava flows originated from north-south oriented fractures that rapidly developed along the southern flank of the volcano. Two lava flows divided the nearby city of Goma (~500,000 people) into two parts, forcing a rapid exodus of the population into Rwanda. One of these lava flows ran into Lake Kivu, encroaching 60 meters below lake level with a submerged lava volume of 1 million cubic meters. About 15% of the town was directly affected, leaving approximately 120,000 people homeless. At least 170 people died as a direct consequence of the eruptio

THE JANUARY 2002 FLANK ERUPTION OF NYIRAGONGO VOLCANO (DEMOCRATIC REPUBLIC OF CONGO): CHRONOLOGY, EVIDENCE FOR A TECTONIC RIFT TRIGGER, AND IMPACT OF LAVA FLOWS ON THE CITY OF GOMA

International audienceOn January 17 2002 a series of fractures opened on Nyiragongo's (3470 m) upper southern flanks triggering drainage of magma stored in the crater lava lake, conduit and edifice and the emission of turbulent flows of highly fluid pahoehoe lava. A remarkable network of fractures propagated rapidly downslope up to 16 km from the crater triggering more pahoehoe but chiefly aa lava emissions from numerous dike-fed vents that reached the outskirts of the city of Goma (population 400 000), the airport and stopped within 4 km of Lake Kivu. A small volume of lava entered lake Kivu but had no significant consequences on the physico-chemistry of it's deep gas-charged waters. The eruption of 25 × 10 6 m 3 of magma formed a complex lava flow field which ultimately fed two main flows that destroyed about 15% of the large town of Goma. The 1669 ad eruption of Etna is the only other historical eruption that produced lava flows that destroyed a large city. Most of Goma's 400 000 inhabitants escaped the advancing lava flows crossing the border into neignboring Rwanda. The eruption that destroyed the homes of 120,000 people and caused between 70 and 100 victims was accompanied by unprecedented levels of felt high frequency seismicity of volcanic and tectonic origin. This eruption reactivated and formed new n-s oriented fractures, parallel to pre-existing structures of the main rift-related tectonic faults. Tectonic rift-related seismicity with epicenters trending ne-sw between Nyiragongo and Idjwi island has remained at very elevated levels since 2002, as evidenced by the largest earthquake in 20 years which occurred October 24 6.2 Mb earthquake localized on a normal rift fault 40 km sw of Goma. As detected by suden major rise in the lake level, this eruption was also remarquably associated with perhaps up to 0,6-1 m of ground subsidence in the Goma area along the axis of the rift and thus aligned with the newly formed fractures. Hazard assessment and adequate risk mitigation must consider: (1) whether the extensive tectonic-controlled fracture system of Nyiragongo's southern flanks will promote more frequent flank-eruptions near populated centers without the prerequisite of a long-lasting lava lake; (2) whether future rift-related migration of magma from the Nyiragongo conduit might proceeding faster and further towards the zone of water-saturated ground within 2 km of lake Kivu favorable to phreatomagmatic explosive eruptions, or ultimately below and into the deep gas-charged basin of lake Kivu to trigger subaqueaous volcanic eruptions and potential catastrophic degassing and lake-overturn. Geological evidence that volcanic centers have occurred on the sw and s volcanic rift zones at or below the level of the lake render such considerations fundamental as the volcano and rift integrated multidisciplinary monitoring system is further developed