title: A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity.
abstract: Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km×3 km×3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano's activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions.
authors.affiliation: Philippine Institute of Volcanology and Seismology.
authors.forename: Paul K B
authors.initials: PK
authors.lastname: Alanis
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamaya
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sasai
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Okada
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Nagao
mesh_terms: D005843:Geography; D049669:History, 16th Century; D049671:History, 18th Century; D049673:History, 20th Century; D060086:Hydrothermal Vents; D060328:Magnetic Phenomena; D010679:Philippines; D018707:Volcanic Eruptions / Q000266:history