the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 06 Oct 2025
Mitigating Mazuku Hazards: Implementation and Effectiveness of Local Dry‑Gas Degassing Measures in the Goma Area (Virunga Volcanic Province)
Abstract. Mitigation of carbon dioxide diffuse degassing hazards remains underexplored in comparison to other volcanic hazards such as eruptions, despite their persistent and deadly impacts on communities living in active volcanic regions. This study uses a mixed-methods approach – combining quantitative surveys and qualitative interviews –to assess household perceptions of the implementation and effectiveness of risk mitigation measures against mazuku, a locally known hazard caused by emissions of carbon dioxide in the western part of Goma, Virunga Volcanic Province. Data were collected across three sampling zones, capturing demographic characteristics, eruption risk experiences, and perceptions regarding the implementation of mazuku risk mitigation measures.
Findings reveal three locally recognised categories of mitigation measures: (1) emission-limiting measures, such as blocking gas with waste materials; (2) adaptive measures, such as house ventilation or living on upper floors; and (3) awareness measures based on orally transmitted local knowledge. Financial resources, gender and prior risk experience – often linked to length of residence – emerged as significant positive determinants of both motivation and perceived efficacy for the first two categories. Perceptions of awareness measures showed no significant variation across zones even between demographic profile groups. Spatial patterns in perceived implementation and perceived efficacy appear to reflect collective community mitigation approach rather than based on individual risk mitigation assessment, with some measures perceived as effective despite limited physical evidence of reduced gas concentration.
The study underscores the importance of co-creating mitigation strategies with local communities, adapting interventions to socio-economic realities and avoiding the importation of external mitigation measures that may lack contextual relevance. It also calls for complementary research measuring the actual effectiveness of these measures through physical monitoring of mazuku concentrations. These insights, grounded in a Global South context, offer a valuable perspective for the development of inclusive and effective volcanic gas risk management strategies.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2025-4497', Francisca Vergara-Pinto, 24 Oct 2025
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AC1: 'Reply on RC1', Blaise Mafuko Nyandwi, 17 Nov 2025
Response to Referee 1
We sincerely thank the reviewer for their thoughtful and constructive comments, which have significantly strengthened the clarity and analytical depth of our manuscript. Following the recommendations, we have made substantial revisions to the paper and have now uploaded the full dataset (574 observations) associated with this study to Zenodo, where it is publicly accessible. We also attach a tracked-changes version of the revised manuscript showing all modifications made throughout the text.
Below, we provide a detailed response to each comment and explain the corresponding revisions introduced in the manuscript.
- Global South
Reviewer comment: Clarify the sense in which the term Global South is used.
Response:
To contextualise our use of the term Global South, we have added a definition directly supported by Quesada-Román (2022) in both the abstract and the introduction. These additions are underlined in the revised manuscript. The following passages were added:Abstract (added text):“These insights, grounded in a Global South context—characterised by rapid uncontrolled urbanisation, offer a valuable perspective for the development of inclusive and effective carbon dioxide diffuse degassing risk management strategies.”
Introduction (added text)“The rapid growth of Goma, as several cities in the Global South (Quesada-Román, 2022), driven by intense migration due mostly to recurring armed conflicts in the region and professional opportunities seeking (Pech et al., 2018; Pech & Lakes, 2017), has extended the city to the west part highly concentrated in mazuku, exposing a large population.”
This clarifies the conceptual grounding of the term and reinforces the contextual positioning of the study.
- Awareness campaigns and local knowledge
Reviewer comment: Discuss local knowledge and awareness in more detail.
Response:
We have added a photograph of the mazuku warning sign used locally, along with a full translation of the messages on the sign (see attached revised file). To further expand on the dimension of local knowledge, we introduced the following paragraph at the beginning of Section 3, drawing from interview and elder testimonies:“The Mazuku-affected area under study, which is now inhabited, was unoccupied three decades ago. At that time, the region was covered by an open woodland typical of the area. According to testimonies gathered from local elders, people used to cross it at dusk to reach Lake Kivu for fishing, or early in the morning when returning with their catch. It also served as a hunting ground for Gambian rats and as pastureland for livestock before it was settled. These activities mostly took place in the evening or early morning when the mazuku concentration is high. Therefore, many people, as well as livestock, lost their lives asphyxiated, which was then regarded as an evil wind—one that had neither a smell nor a visible form. Today, the area is inhabited by new residents with a more urban lifestyle than the earlier inhabitants and the term was kept (Pech et al., 2018; Vlassenroot & Büscher, 2009).”
This addition strengthens the historical and cultural interpretation of mazuku and situates awareness practices within long-standing local knowledge systems.
- Temporality and population sensitisation
Reviewer comment: The manuscript should better address the temporal aspects of mazuku occurrence and the associated sensitisation strategies.
Response:
After revisiting the interview transcripts and focus group discussions, we incorporated detailed local testimonies that highlight seasonal patterns, daily timing, and household strategies for raising awareness among children and newcomers. The following testimonies were added to the results section and reinforced in the discussion:“Mazuku incidents tend to be more frequent in the evening or early morning, and when the temperature is low during the rainy seasons. You cannot see the mazuku or detect any odour, but sometimes, on a path, you suddenly feel suffocated as though someone were pressing on your chest, and you cannot breathe. At that moment you must act quickly and leave the area while you still can…”
“Just after the dry season — at the beginning of September when children return to school — the first critical period begins and lasts until December. It is followed by a second critical period during the rainy season, from February to May every year. These periods are particularly hazardous because they coincide with the school term, when children have to leave home early for classes.”
“In this context, we do our best to inform our children, newcomers or everyone in the neighbourhood, about the locations of these mazuku zones: we encourage them to identify them and to stay well away from them, especially when it is cold.”
(A mother of four children at primary school, 13 years of residence in the area)These additions significantly enhance the temporal dimension of mazuku risk and underline the importance of everyday awareness mechanisms within households and neighbourhoods.
- Conclusion
Reviewer comment: Strengthen the conclusion and emphasise future research perspectives.
Response:
We reworked the final paragraph of the conclusion to highlight future research avenues and operational implications. The following has been added and refined:“This study offers novel insights into the implementation of risk mitigation practices addressing volcanic gas emissions in active volcanic zones—such as heating courtyards or blocking gas with household waste—examined through a Global South perspective characterised by rapid and largely uncontrolled urbanisation. It reinforces the call, made by other scholars, for the co-creation of mitigation strategies with local communities, rather than the imposition of externally derived solutions that may not be effective in the local context. Future research could complement these findings by assessing the actual effectiveness of such mitigation measures through physical measurements of mazuku concentrations—not only in public spaces but also within buildings—and by further examining local risk perception. Moreover, volcano monitoring programmes in Goma and the surrounding areas should diversify their focus to include systematic monitoring of mazuku and recognise it as a significant public risk requiring sustained attention.”
This revised conclusion better articulates the scientific and practical contributions of the study while outlining concrete directions for future work.
End
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AC1: 'Reply on RC1', Blaise Mafuko Nyandwi, 17 Nov 2025
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RC2: 'Comment on egusphere-2025-4497', Anonymous Referee #2, 18 Nov 2025
This paper presents a significant research topic within the scope of NHESS. It provides an impressive data collection conducted via a mixed-methods approach, incorporating qualitative interviews and focus group materials, as well as a quantitative questionnaire, reaching more than 500 people. It presents a key screenshot of the perceptions these communities have of the strategies used to mitigate the effects of mazuku. However, the paper's content and structure would greatly benefit from a restructure to highlight the excellent data collection and importance. I recommend this paper for publication, but suggest doing so after major structural changes.
Here some suggestions.
1) First of all, could move the limitation section to the beginning, rephrased clearly and explicitly, so that the intention is to focus on the analysis of population perception only. The content and structure of the paper can be then framed in this way.
2) In the introduction, a map would be helpful for the reader to identify the location. I suggest cutting off Line 43-44 from ‘such’ to ‘ Province’ ( it deflects the attention of the overview). Line 59 Starts with 'This paper focuses on the area of Goma'. Then explain the geographical/geological contexts, as well as the human context. I feel it is important for people who do not know the area to understand the location's complexity. If the content of section 3 is rephrased and placed in the introduction it becomes clear from the beginning what mazuko is and why understanding people's adaptation is important, and it will avoid some repetition.3) In the methodology, it could help to explicitly clarify what the questions and contributions of the interviews were, what the questions and contributions of the focus group were, and how these informed the questionnaire construction and distribution. A figure, or a table perhaps. Also, it would be interesting to see a brief clarification on the street leaders (if possible) for people unfamiliar with the location/use/culture
4) To improve the flow of the paper, the Results and Discussion could be combined into a single, cohesive section. My suggestion is to present the material in the chronological order of your research process: begin with the description and analysis of the key insights from the interview, then clearly outline the 12 mitigation strategies. This structure will clarify how the interview informed the focus group, how the focus group’s findings and highlights shaped the questionnaire, and how the questionnaire’s results further developed the study. If you want your focus to be on the questionnaire, this interview and focus group section can be short, could be a figure, or a graph, but I feel that a clear, explicit section will help the paper's flow. Incorporating the material currently placed in Section 6 into this 'Result and Discussion' unified structure would also create a smoother progression throughout the paper.
5) It would be valuable to explore, where available, examples of local knowledge that have been incorporated into risk-reduction strategies in other contexts, whether those efforts were successful or unsuccessful, to show that sometimes strategies can be shared and sometimes need to be location-culture specific.
This restructuring could enhance the paper presentation by highlighting the excellent research carried out in Goma. It will also contribute to research in disaster risk reduction worldwide.
Citation: https://doi.org/10.5194/egusphere-2025-4497-RC2
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- 1
This manuscript is well-documented and represents a significant contribution to the journal's scope. Understanding volcanic hazards, such as mazuku - 'evil winds' in native language, related to invisible, odourless carbon dioxide gas - and their impact on the daily lives of affected communities requires greater attention within disaster risk studies. This case study provides an opportunity to rethink the ways of assessing, understanding, and raising awareness about mazuku risk, particularly by integrating the lived experiences of individuals who encounter this hazard in contexts marked by territorial and socioeconomic inequality. Consequently, I recommend its publication with minor revisions. To enhance the quality of this work, I suggest considering minor changes (attached PDF). Below, I highlight some central topics:
1) Given that this hazard is known by the vernacular name mazuku or evil winds, I wonder whether awareness campaigns consider the perception of mazuku as a threat laden with beliefs. For instance, gas is perceived not only as harmful to health but also as associated with the 'evil' and the underground. Do the warning panels reference this notion of 'evil'? Additionally, it is noteworthy that, according to the interviews, people respect the danger but still approach it, mainly due to pressures from population growth and the need for livelihoods. This highlights a form of risk acceptability in contexts where the volcanic hazard is invisible, further explaining the complexities surrounding mazuku and its mitigation.
2) I suggest clarifying in the results whether people are aware of the volcanic origin of mazuku. This is important because mazuku is an invisible volcanic hazard that exists in people's daily lives, in their domestic and intimate spaces. This type of volcanic hazard differs significantly from others, such as tephra falls or lava fields that physically can destroy homes. Mazuku can be lethal and can infiltrate homes without causing physical destruction.
3) My previous point emerges from the tendency (within the data and results) to associate mazuku with atmospheric conditions (e.g., wind, rain, temperatures). I recommend looking for mentions of this in the interviews to better clarify the "risk acceptance". Is this acceptance of volcanic risk? Mazuku prevention and mitigation measures refer to volcanic risk, but do residents perceive it as such, or do they see it as a different type of risk?
4) I also suggest providing a better description of local knowledge (based on the case study), as the discussion and conclusion of the paper emphasize the importance of incorporating it into community-based mazuku mitigation measures.
5) Lastly, it would be valuable to raise critical questions: Is mazuku considered an area of interest for volcanology? Is it receiving little or much attention in research? Do existing studies on mazuku (regarding concentrations and locations) account for its presence in inhabited areas?
Incorporating these changes could enhance the mixed-methods nature of the article, providing greater emphasis on qualitative data, which appears to be less described and represented compared to quantitative data. Overall, this piece makes a valuable contribution to understanding mazuku, paving the way for informed decision-making in disaster risk reduction efforts in Goma, but also in other regions facing the hidden threats of volcanic gases in contexts marked by territorial inequalities.