{
  "id": "lake-nyos-1986",
  "title": "Lake Nyos: how a lethal gas release became an investigation",
  "country": "Cameroon",
  "category": "nature",
  "date": "1986-08-21",
  "date_label": "21 August 1986",
  "location": "Lake Nyos, Northwest Region",
  "lat": 6.44,
  "lng": 10.3,
  "location_precision": "region",
  "location_note": "Approximate lake-area marker for historical orientation. It is not a current hazard boundary or a field-access recommendation.",
  "summary": "A catastrophic gas release killed people and livestock near Lake Nyos. Scientific investigations separated a volcanic gas supply from the mechanism that released stored gas from the lake.",
  "verdict": "A natural gas-release disaster with a supported physical mechanism; the precise initial trigger requires separate treatment.",
  "sources": [
    {
      "id": "N1",
      "title": "USGS: final report of the United States scientific team",
      "url": "https://www.usgs.gov/publications/21-august-1986-lake-nyos-gas-disaster-cameroon-final-report-united-states-scientific",
      "kind": "Government scientific report record",
      "language": "en",
      "note": "Open-File Report 87-97; primary investigation reference with publication details."
    },
    {
      "id": "N2",
      "title": "USGS Open-File Report 87-97 — publication landing page",
      "url": "https://pubs.usgs.gov/publication/ofr8797",
      "kind": "Report and download record",
      "language": "en",
      "note": "Official publication entry for the report; use its download link for the complete file."
    },
    {
      "id": "N3",
      "title": "USGS: Lake Nyos was rigged for disaster",
      "url": "https://www.usgs.gov/publications/lake-nyos-was-rigged-disaster",
      "kind": "Scientific interpretation record",
      "language": "en",
      "note": "Discusses gas accumulation and evidence against a fresh volcanic eruption as the trigger."
    },
    {
      "id": "N4",
      "title": "USGS: origin and age of the Lake Nyos maar",
      "url": "https://www.usgs.gov/publications/origin-and-age-lake-nyos-maar-cameroon",
      "kind": "Geological research record",
      "language": "en",
      "note": "Geological setting and possible pathways of gas supply, distinct from the immediate release mechanism."
    },
    {
      "id": "N5",
      "title": "USGS: historical account including the 1986 gas disaster",
      "url": "https://pubs.usgs.gov/unnumbered/70039037/report.pdf",
      "kind": "PDF · retrospective institutional report",
      "language": "en",
      "note": "Broader USGS history; the Nyos section supplies context, not a second contemporaneous field survey."
    }
  ],
  "sections": [
    {
      "title": "Disaster brief",
      "text": "On 21 August 1986, a lethal gas release occurred at Lake Nyos. Scientific teams investigated the lake and surrounding damage. The USGS final report records the United States team’s inquiry. Later interpretation distinguishes gas supplied from below the lake from a fresh volcanic eruption: a reservoir of dissolved gas can accumulate before a rapid release. That distinction turns an apparently inexplicable disaster into a set of physical questions.",
      "refs": [
        "N1",
        "N3"
      ]
    },
    {
      "title": "Separate supply, storage, trigger and transport",
      "text": "The geological setting helps explain where gas can come from. Lake conditions determine whether it accumulates. An initiating disturbance concerns why release begins at a particular time. Topography and atmospheric conditions affect where the released gas travels. These are linked stages, not interchangeable explanations. Evidence for a deep gas source does not by itself identify the immediate trigger.",
      "refs": [
        "N3",
        "N4"
      ]
    },
    {
      "title": "Inspector’s assessment",
      "text": "Read the field report by measurement type: water sampling, chemistry, temperature, observations and spatial effects. For each result, retain sampling depth, date and method. A sample collected after the disaster is evidence of post-event conditions; reconstructing pre-event conditions requires additional assumptions. When summarising casualties or affected settlements, preserve the report’s scope and date instead of combining incompatible tallies.",
      "refs": []
    },
    {
      "title": "Why this belongs in the collection",
      "text": "An investigation should be able to reduce a mystery, not preserve it artificially. Lake Nyos is included as a case where natural mechanisms make concrete predictions. The dossier does not equate historical uncertainty about the trigger with uncertainty about the basic gas hazard. Its maps and documents are for historical study and do not certify present-day safety, access or the state of mitigation infrastructure.",
      "refs": []
    }
  ],
  "timeline": [
    {
      "date": "21 August 1986",
      "text": "The catastrophic release occurs at Lake Nyos.",
      "refs": [
        "N1"
      ]
    },
    {
      "date": "Following the disaster",
      "text": "Scientific field investigations gather evidence about the lake and gas release.",
      "refs": [
        "N1"
      ]
    },
    {
      "date": "1987",
      "text": "The US team’s final report and early interpretations are published.",
      "refs": [
        "N1",
        "N3"
      ]
    },
    {
      "date": "Subsequent geological work",
      "text": "Research examines the maar and longer-term gas supply.",
      "refs": [
        "N4"
      ]
    }
  ],
  "claims": [
    {
      "text": "The disaster was investigated through a government scientific field report.",
      "status": "Documented",
      "refs": [
        "N1"
      ]
    },
    {
      "text": "Gas source and immediate release trigger are the same question.",
      "status": "Incorrect causal simplification",
      "refs": [
        "N3",
        "N4"
      ]
    },
    {
      "text": "The historical dossier certifies current field safety.",
      "status": "Outside scope",
      "refs": [
        "N1"
      ]
    }
  ],
  "hypotheses": [
    {
      "title": "Rapid release of gas accumulated in lake water",
      "status": "Supported natural mechanism",
      "support": "The investigation and subsequent research examine stored gas and its release.",
      "limits": "The detailed initiating sequence must be considered separately.",
      "test": "Compare chemical and physical observations with the requirements of the release mechanism."
    },
    {
      "title": "A fresh volcanic eruption as the immediate cause",
      "status": "Challenged interpretation",
      "support": "The volcanic setting initially makes eruption-related explanations worth checking.",
      "limits": "A volcanic gas supply does not establish a contemporaneous eruption.",
      "test": "Look for the specific geological and thermal evidence an eruption should leave and compare it with the reported observations."
    }
  ],
  "tasks": [
    {
      "title": "Construct a measurement inventory",
      "body": "Index samples by depth, collection date, method and units. Note whether each value is measured, calculated or reconstructed from after-event observations."
    },
    {
      "title": "Draw a causal sequence with evidence",
      "body": "Give gas supply, storage, release and transport separate entries, each linked to a report passage. Mark the trigger uncertain if the evidence does not identify it."
    },
    {
      "title": "Compare early and later interpretations",
      "body": "Record which observations changed the explanation. Avoid treating all papers as equally current or turning an early hypothesis into a final finding."
    }
  ],
  "author": "Eklipsis",
  "content_languages": [
    "en"
  ],
  "path": "/enquetes/lake-nyos-1986",
  "source_url": "https://www.usgs.gov/publications/21-august-1986-lake-nyos-gas-disaster-cameroon-final-report-united-states-scientific",
  "location_source_url": "https://www.openstreetmap.org/?mlat=6.44&mlon=10.3#map=8/6.44/10.3",
  "reviewed_on": "2026-09-29",
  "edition": 1
}