BSc Arbeit Katrin Hagen

The active volcanic area of the eastern Trans Mexican Volcanic Belt (TMVB) in Central Mexico surrounds the cities of Toluca, Mexico and Puebla which count a total population of about 28 million. Several volcanoes in close proximity of these metropolitan areas have shown Strombolian to Plinian eruptions during the Holocene, in case of the stratovolcano Popocatépetl this includes recent activity in the last decades. At least 25 eruptions within the last 12,000 years have been documented, several of which showed Plinian activity with a VEI ≥ 4 that produced extensive tephra layers and block- and ash-flow deposits. These records of ash fallout, pyroclastic current and lahar deposits can be used to recreate past eruptions and therefore also determine possible future hazards arising from the volcanic events. This paper will give an overview of Holocene eruptions and resulting hazard assessment for the cities of Toluca, Mexico and Puebla since each of these densely populated areas lie close to the slopes of active stratovolcanoes which include the Nevado de Toluca, Jocotitlán, Popocatépetl and La Malinche as well as the Sierra Chichinautzin, a monogenetic volcanic field south of Mexico City.

Siebe and Macías (2007) already combined several possible hazards for the metropolitan area of Mexico City but the hazard potential is not limited to this metropolitan area. Especially smaller settlements of several thousand inhabitants along the stratovolcanoes` slopes are exposed to the high risk of volcanic activity such as pyroclastic density currents (PCDs) or lahars. Therefore, this paper also focusses on investigating possible pathways for these hazards. Since they are dependent on the morphology of the volcanic edifice, ArcGIS Spatial Analyst and Hydrology Toolboxes could be used to determine possible hazard zones along the volcano`s flanks reaching up to several 10s of km, correspondent with past deposits.

At least one volcanic event, the 10,500 yrs. BP Plinian eruption at the Nevado de Toluca, is associated with major stratospheric and climatic changes, showing the potential of global effects arising from explosive events within the TMVB, in addition to the multiple dangers for settlements close to the volcanoes.