Seasonal and diurnal patterns in the dispersion of SO2 from Mt. Nyiragongo

Mt. Nyiragongo is an active volcano located in the Democratic Republic of Congo, close to the border of Rwanda and about 15 km north of the city of Goma (~ 1,000,000 inhabitants). Gases emitted from Nyiragongo might pose a persistent hazard to local inhabitants and the environment. While both ground- and satellite-based observations of the emissions exist, prior to this study, no detailed analysis of the dispersion of the emissions have been made. We have conducted a dispersion study, using a modelling system to determine the geographical distribution of SO2.A combination of a meteorological model (WRF), a Lagrangian particle dispersion model (FLEXPART-WRF) and flux data based on DOAS measurements from the NOVAC-network is used. Since observations can only be made during the day, we use random sampling of fluxes and ensemble modelling to estimate night-time emissions.Seasonal variations in the dispersion follows the migration of the Inter Tropical Convergence Zone. In June-August, the area with the highest surface concentrations is located to the northwest, and in December-February, to the southwest of the source. Diurnal variations in surface concentrations were determined by the development of the planetary boundary layer and the lake-/land breeze cycle around lake Kivu. Both processes contribute to low surface concentrations during the day and high concentrations during the night. However, the strong northerly trade winds in November-March weakened the lake breeze, contributing to higher daytime surface concentrations along the northern shore of Lake Kivu, including the city of Goma. For further analysis and measurements, it is important to include both seasonal and diurnal cycles in order to safely cover periods of high and potentially hazardous concentrations

Thermal insights into the dynamics of Nyiragongo lava lake from ground and satellite measurements

We present new insights into the short- and long-term thermal activity of the Nyiragongo lava lake by ground-based and satellite infrared thermal imagery recorded in the first half of 2012. This is the very first time in which FLIR camera and SEVIRI data have been compared at this volcano. Maximum temperatures recorded at the molten lava were of ~1180 K, whereas the lake skin remained always below ~734 K in areas far from the upwelling zone and below ~843 K in those proximal to the source region. Ground-based imagery yielded mean radiative power values between ~0.80 and 1.10 GW. Consistently, satellite observations showed similar mean values of 1.10 GW. Overall the thermal activity of the lava lake was quite variable along the three days of field measurements at both daily and intradaily scale. SEVIRI radiative power values retrieved for the January-June 2012 period revealed fluctuations within the same variability range suggesting that no significant changes of the lava lake area had occurred over the six months. Comparison with previous radiative power estimates showed that our data well agree with the general increasing trend recorded since the reappearance of the lava lake after the last flank eruption in 2002. Key Points Validation of satellite data by ground-based thermal imagery Characterisation of the Nyiragongo lava lake surface activity in March 2012 Comparison between the March 2012 results and previous observations ©2013. American Geophysical Union. All Rights Reserved

Detailed multidisciplinary monitoring reveals pre- and co-eruptive signals at Nyamulagira volcano (North Kivu, Democratic Republic of Congo)

This paper presents a thorough description of Nyamulagira’s January 2010 volcanic eruption (North Kivu, Democratic Republic of Congo), based on a combination of field observation and ground-based and space-borne data. It is the first eruption in the Virunga Volcanic Province that has been described by a combination of several modern monitoring techniques. The 2010 eruption lasted 26 days and emitted ∼45.5 × 106 m3 of lava. Field observations divided the event into four eruptive stages delimited by major changes in effusive activity. These stages are consistent with those described by Pouclet (1976) for historical eruptions of Nyamulagira. Co-eruptive signals from ground deformation, seismicity, SO2 emission and thermal flux correlate with the eruptive stages. Unambiguous pre-eruptive ground deformation was observed 3 weeks before the lava outburst, coinciding with a small but clear increase in the short period seismicity and SO2 emission. The 3 weeks of precursors contrasts with the only precursory signal previously recognized in the Virunga Volcanic Province, the short-term increase of tremor and long period seismicity, which, for example, were only detected less than 2 h prior to the 2010 eruption. The present paper is the most detailed picture of a typical flank eruption of this volcano. It provides valuable tools for re-examining former—mostly qualitative—descriptions of historical Nyamulagira eruptions that occurred during the colonial period.The monitoring efforts and equipment were deployed in the framework of the following projects: GORISK (funded by the Belgian Science Policy and the National Research Fund of Luxembourg), NOVAC (funded under the EU-FP6 programme), ViSOR (funded by the US National Science Foundation and the US National Geographic Society) and the UN projects in Democratic Republic of Congo ‘Volcano Risk Reduction Unit’ (UNDP project funded by the British and the Swiss Cooperation) and ‘Analysis and Prevention of Natural Hazards’ (UNOPS project funded by the European Union and the Swiss Cooperation). Research by J. Fernández, J.F. Prieto, P.J. González and J.L.G. Pallero has also been supported by research project AYA2010-17448. P.J. González acknowledges the Banting Postdoctoral Fellowship (Canadian Government). It is a contribution for the CEI Campus Moncloa. K. Tiampo is funded by an NSERC Discovery Grant.Peer reviewe

Detailed multidisciplinary monitoring reveals pre- and co-eruptive signals at Nyamulagira volcano (North Kivu, Democratic Republic of Congo)

This paper presents a thorough description of Nyamulagira’s January 2010 volcanic eruption (North Kivu, Democratic Republic of Congo), based on a combination of field observation and ground-based and space-borne data. It is the first eruption in the Virunga Volcanic Province that has been described by a combination of several modern monitoring techniques. The 2010 eruption lasted 26 days and emitted ∼45.5 × 106 m3 of lava. Field observations divided the event into four eruptive stages delimited by major changes in effusive activity. These stages are consistent with those described by Pouclet (1976) for historical eruptions of Nyamulagira. Co-eruptive signals from ground deformation, seismicity, SO2 emission and thermal flux correlate with the eruptive stages. Unambiguous pre-eruptive ground deformation was observed 3 weeks before the lava outburst, coinciding with a small but clear increase in the short period seismicity and SO2 emission. The 3 weeks of precursors contrasts with the only precursory signal previously recognized in the Virunga Volcanic Province, the short-term increase of tremor and long period seismicity, which, for example, were only detected less than 2 h prior to the 2010 eruption. The present paper is the most detailed picture of a typical flank eruption of this volcano. It provides valuable tools for re-examining former—mostly qualitative—descriptions of historical Nyamulagira eruptions that occurred during the colonial period

Detailed multidisciplinary monitoring reveals pre- and co-eruptive signals at Nyamulagira volcano (North Kivu, Democratic Republic of Congo)

This paper presents a thorough description of Nyamulagira's January 2010 volcanic eruption (North Kivu, Democratic Republic of Congo), based on a combination of field observation and ground-based and space-borne data. It is the first eruption in the Virunga Volcanic Province that has been described by a combination of several modern monitoring techniques. The 2010 eruption lasted 26 days and emitted ~45.5 × 106 m3 of lava. Field observations divided the event into four eruptive stages delimited by major changes in effusive activity. These stages are consistent with those described by Pouclet (1976) for historical eruptions of Nyamulagira. Co-eruptive signals from ground deformation, seismicity, SO2 emission and thermal flux correlate with the eruptive stages. Unambiguous pre-eruptive ground deformation was observed 3 weeks before the lava outburst, coinciding with a small but clear increase in the short period seismicity and SO2 emission. The 3 weeks of precursors contrasts with the only precursory signal previously recognized in the Virunga Volcanic Province, the short-term increase of tremor and long period seismicity, which, for example, were only detected less than 2 h prior to the 2010 eruption. The present paper is the most detailed picture of a typical flank eruption of this volcano. It provides valuable tools for re-examining former-mostly qualitative-descriptions of historical Nyamulagira eruptions that occurred during the colonial period. © 2013 Springer-Verlag Berlin Heidelberg