New chronological constraints on intense Holocene eruptions and landslide activity at Tacaná volcanic complex (Mexico)

Usual methods are unfortunately unsuitable to accurately date many Holocene deposits and landforms from active Mexican volcanoes. This is notably the case for Tacaná Volcanic Complex (TVC), located in State of Chiapas southern Mexico, San Marcos Department Guatemala. The complex consists Chichuj, Tacaná, Antonio volcanoes Ardillas dome. volcano, main summit TVC, collapsed 15 ± 5 ka ago (40Ar/39Ar), producing Agua Caliente Debris Avalanche. result was formation a horseshoe-shaped crater 600 m wide open northwest. Afterward, several undated effusive explosive eruptions occurred. All these likely Late Pleistocene age because derived that activity overlap crater. To corroborate this hypothesis, we used surface exposure dating with situ-produced cosmogenic 36Cl combined lichenometry dendrochronology domes, dome, crater's cliff, an andesitic lava. ages (9.3 1.9 ka; 8.9 0.9 8.6 1.7 ka) domes statistically indistinguishable within associated uncertainties suggest formed during Early Holocene. Instead, part yielded significantly younger ranging 5.3 0.6 7.0 0.8 ka. These assumed be minimum might indicate later rockfall instability, affecting lava (0.4 0.1 ka), emplaced SW good agreement (>347 yr). could represent gravitational collapse event phreatic explosions vented close scar collapse. dome (0.3 do not correspond its emplacement age. must older than pyroclastic dated at 760 30 yr BP (14C) cover surface. Strikingly, 36Cl, lichenometrical dendrochronological data “Andesitic” NE-SW landslide scars, explosion craters, vents, fumarolic activity, tensional fractures. features perpendicular NW-SE stress regime (σ3), TVC generating activity. Nowadays, collapses real threat surrounding populations can triggered only by volcanic but also seismicity extraordinary rains.