Avaliação dos riscos vulcânicos do Oldoinyo Lengai num contexto de escassez de dados (Tanzania)
DOI:
https://doi.org/10.14195/1647-7723_28-2_6Palavras-chave:
Lahares, cinza, lava, Rift, MaasaiResumo
O objectivo do nosso estudo é estabelecer uma avaliação de quatro processos vulcânicos num país ameaçado pela erupção do vulcão Oldoinyo Lengai. A última grande erupção data de 2007-2008, mas uma actividade mais forte em 2019 reavivou a memória das ameaças vulcânicas às comunidades Maasai e Bantu e às actividades humanas (agro-pastoril e turismo). Os métodos escolhidos exigiram uma adaptação aos dados escassos e incompletos. Os processos vulcânicos e a sua probabilidade de ocorrência foram analisados com base nos dados disponíveis na literatura científica e foram complementados por duas missões de campo combinando geografia e hidrogeomorfologia. O nosso estudo permitiu-nos mapear os riscos de queda de cinzas, fluxos de lava, lahares e avalanches de detritos. Cada processo foi espacializado com a atribuição de uma intensidade. Por vezes estão sincronizados com a erupção, mas outras vezes ocorrem vários meses ou vários anos após uma erupção vulcânica. Os resultados são o primeiro passo no desenvolvimento de uma estratégia de gestão do risco vulcânico, especialmente para as comunidades pastoris que vivem em redor de Lengai e para as actividades turísticas crescentes nesta área.
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