Volcán de Colima dome collapse of July, 2015 and associated pyroclastic density currents

Abstract

During July 10th–11th 2015, Volcán de Colima, Mexico, underwent its most intense eruptive phase since its Subplinian–Plinian 1913 AD eruption. Production of scoria coincident with elevated fumarolic activity and SO2 flux indicate a significant switch of upper-conduit dynamics compared with the preceding decades of dome building and vulcanian explosions. A marked increase in rockfall events and degassing activity was observed on the 8th and 9th of July. On the 10th at 20:16 h (Local time = UTM − 6 h) a partial collapse of the dome generated a series of pyroclastic density currents (PDCs) that lasted 52 min and reached 9.1 km to the south of the volcano. The PDCs were mostly channelized by the Montegrande and San Antonio ravines, and produced a deposit with an estimated volume of 2.4 × 106 m3. Nearly 16 h after the first collapse, a second and larger collapse occurred which lasted 1 h 47 min. This second collapse produced a series of PDCs along the same ravines, reaching a distance of 10.3 km. The total volume calculated for the PDCs of the second event is 8.0 × 106 m3. Including associated ashfall deposits, the two episodes produced a total of 14.2 × 106 m3 of fragmentary material. The collapses formed an amphitheater-shaped crater open towards the south. We propose that the dome collapse was triggered by arrival of gas-rich magma to the upper conduit, which then boiled-over and sustained the PDCs. A juvenile scoria sample selected from the second partial dome collapse contains hornblende, yet at an order of magnitude less abundant (0.2%) than that of 1913, and exhibits reaction rims, whereas the 1913 hornblende is unreacted. At present there is no compelling petrologic evidence for imminent end-cycle activity observed at Volcán de Colima

Fault‐Associated Magma Conduits Beneath Volcán de Colima Revealed by Seismic Velocity and Attenuation Tomography Studies

“…This event destroyed the summit and produced a large crater that was later refilled by eruptive products. Volcán de Colima's recent activity is characterized by a large number of vulcanian eruptions with alternation of lava flows, dome formations, and dome collapses (Reyes‐Dávila et al, ). However, a catastrophic eruption similar to the event of 1913 or larger could threaten more than 300,000 inhabitants in the surrounding area, making Volcán de Colima one of the most hazardous volcanoes in the world (Saucedo et al, ).…”

Disruption of Long-Term Effusive-Explosive Activity at Santiaguito, Guatemala

“…transition to dome collapse and explosive activity in 2015 was linked to the arrival of relatively volatile-rich magma into the shallow magma column (Reyes-Dávila et al, 2016). Soufrière Hills volcano underwent multiple phases of effusive and explosive activity between 1995 and 2010 (Wadge et al, 2014).…”

“…Shifts in eruptive behavior at active lava domes present a significant challenge for monitoring and hazard assessment, particularly as transitions from effusive to explosive activity, and vice versa, can be rapid (e.g., Jousset et al, 2012) and often lack obvious geophysical precursors (e.g., Reyes-Dávila et al, 2016). Lava dome eruptions occur over a wide range of timescales, from months to decades, and are characterized by the slow extrusion of highly viscous, degassed magma that can eventually form voluminous edifices (>1 km 3 ; Fink, 1990).…”

“…Generally, the switch from effusive to explosive activity during lava dome eruptions have been characterized by variations in magma discharge rate (Sparks, 1997) and volcano-seismic activity associated with magmatic or fluid movement (e.g., Neuberg, 2000;Arámbula-Mendoza et al, 2011). Pressurization, due to gas fluxing (e.g., Johnson et al, 1998;Michaut et al, 2013) or fresh magma recharge (e.g., Reyes-Dávila et al, 2016), may trigger explosive activity and evolution in associated monitored signals (Sparks, 1997). It is commonly believed that the competition between gas pressure and the rheology of dome lavas controls the development of fractures (Lavallée et al, 2008;Scheu et al, 2008;Heap et al, 2015a), porosity (Heap et al, 2015b;Rhodes et al, 2018) and coherence (e.g., Tuffisites; Kendrick et al, 2016), and thus permeability (Scheu et al, 2008;Lavallée et al, 2013;Gaunt et al, 2014;Farquharson et al, 2015), leading to either fragmentation and explosive activity (e.g., Dingwell, 1996;Papale, 1999) or outgassing and effusive activity (e.g., Edmonds et al, 2003;Gonnermann and Manga, 2007).…”

Absence of Detectable Precursory Deformation and Velocity Variation Before the Large Dome Collapse of July 2015 at Volcán de Colima, Mexico

“…In contrast with the common behavior of the volcano (Arámbula-Mendoza et al, 2011), the July 2015 eruption was preceded by a decrease of the rate of LP events and explosions. The main precursory phenomenon was a marked increase of the number and energy of rockfalls and PDCs that accompanied the rise of the extrusion rate (Reyes-Dávila et al, 2016;Arámbula-Mendoza et al, 2018). Although the deformations and the velocity variations associated with the previous eruptions were small or undetectable, we may expect to detect stronger forerunners in the case of the 2015 exceptional events.…”