Resumo

DELGADO-GRANADOS, Hugo  e  VILLALPANDO-CORTES, Roberto Е.. Método para pronosticar la localización de un nuevo volcán al sur de la Ciudad de México. TIP [online]. 2008, vol.11, n.1, pp.5-16. ISSN 1405-888X.

Forecast and prediction of eruptions or birth of volcanoes is still a hard-to-tackle issue, temporally and spatially. Statistical estimates of return period for large volcanoes and monogenetic volcanic fields do exist. However, estimating the location for a new volcano to be born is a complex task. In difference with large volcanoes, for which the location of their craters is known, in the case of volcanic fields it is difficult to forecast where the next eruption will take place. Monogenetic volcanic fields are regions whose geologic setting allows the birth of new volcanoes according to a given periodicity. Volcanoes are born at the intersection of faults and fractures, and they are used by the ascending magmas. At monogenetic volcanic fields, eruptive products from previous volcanoes cover the traces of faults and fractures. The Chichinautzin Volcanic Field (CVF), south of Mexico City, has an average return period for new eruptions of <1700 years. The last eruption in the region occurred ~1700-2000años years ago, according to the geologic studies reported so far. This implies that southern Mexico City is prone to witness a new eruptive event in the near future, and the probability for this to occur will increase with the time. Therefore, it is necessary to explore ways to identify the location of the next eruption for planning and prevention purposes to mitigate the effects of an eruption at the most populated region of the country. This study proposes a method to identify the most tectonically active zones in the CVF that might be used by ascending magmas, through the distribution patterns of the CO2 emission rates from soils of the region. We report here two zones of anomalous emission of CO2: the most important is nearby the Colegio Militar, and the second, less important in magnitude, near Tenango, Estado de México. These anomalies are associated to active tectonic features, which might act as conduits for ascending magmas, although no certainty can be claimed; they represent elements for mitigation planning. In addition, our results attest for activity of faults in the region. Further work is required to confirm the results presented here and, through the comparison with more measurements, observe the evolution of CO2 soil degassing in the mid- and long-term.

Palavras-chave : CO₂ from soil; CO₂ emission; faults; Sierra Chichinautzin; monogenetic volcanism.

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