7393 20250122113220.0 POSTER-2025-0030 Torres-Orozco, Rafael Combined pyroclast microtextures and seismic noise records demonstrate shallow andesite magma decompression drives different PDC mechanisms at Volcán de Colima, Mexico 2023 2023-12-11 Volcán de Colima, the most active andesitic stratovolcano in Mexico, last erupted explosively on July 10-11, 2015, producing pyroclastic density currents (PDCs) of different type. The July-10 PDCs formed dense block-and-ash flow deposits typical of Volcán de Colima's history of recurrent summit dome effusion and collapse. In contrast, the July-11 PDCs comprised hot and turbulent scoria-rich PDCs that were unforeseen, and whose triggers and precursors were unidentified. Here, chemical and microtextural analyses of the July-11 deposits via electron-microscopy and x-rays microtomography revealed that decompression of andesite magma at fluctuating rates (10-3-100 MPa s-1) from 2 km-depth triggered magma degassing and crystallization. The resulting extremely rheologically heterogeneous magma fragmented and powered the pulsating July-11 PDCs that released 100-300 m3 s-1 on surface. Seismic noise velocity variations identified in each day down to 2 km-depth support magma decompression from a shallow reservoir. The combined geological and seismological evidence suggest timescales of only hours to couple of days from conduit and dome cracking and collapse to magma decompression and eruption. NO Volcanology Eruption De Plaen, Raphael Capra, Lucia Marquez, Victor H. Sulpizio, Roberto Arambula, Raúl AGU Fall Meeting, San Francisco raphael.deplaen@ksb-orb.be https://ui.adsabs.harvard.edu/abs/2023AGUFM.V13B0111T/abstract CPOSTER