Ground deformation reveals the scale-invariant conduit dynamics driving explosive basaltic eruptions

Abstract

The mild activity of basaltic volcanoes is punctuated by violent explosive eruptions that occur without obvious precursors. Modelling the source processes of these sudden blasts is challenging. Here, we use two decades of ground deformation (tilt) records from Stromboli volcano to shed light, with unprecedented detail, on the short-term (minute-scale) conduit processes that drive such violent volcanic eruptions. We find that explosive eruptions, with source parameters spanning seven orders of magnitude, all share a common pre-blast ground inflation trend. We explain this exponential inflation using a model in which pressure build-up is caused by the rapid expansion of volatile-rich magma rising from depth into a shallow (<400 m) resident magma conduit. We show that the duration and amplitude of this inflation trend scales with the eruption magnitude, indicating that the explosive dynamics obey the same (scale-invariant) conduit process. This scale-invariance of pre-explosion ground deformation may usher in a new era of short-term eruption forecasting.

Volcanic CO 2 tracks the incubation period of basaltic paroxysms

“…The paroxysmal explosion on 3 July 2019 started at 14:45:42 UTC. Although not preceded by any evident change in eruptive behavior (regular Strombolian activity level continued until the blast), ground inflation of ~14 μrad occurred over a period of ~10 min immediately before the event ( 18 ). The explosion generated a ~8-km-high eruptive column in a few tens of seconds ( Fig.…”

“…The summer 2019 eruptive crises thus present a unique opportunity to study two closely spaced events with apparently contrasting (bottom-up versus top-down) source mechanisms. The paroxysm on 3 July 2019 was not preceded by any noticeable precursory change in surface volcanic activity ( 47 ) and, since ground inflation anticipated the event by only 10 min ( 18 ), no alert warning was issued. Although real-time early-warning systems based on tiltmeter measurements have now been installed on Stromboli ( 18 ), identifying midterm precursors to paroxysms is urgently needed.…”

Tsunami risk management for crustal earthquakes and non-seismic sources in Italy

“…Landslides and tsunamis triggered by paroxysms usually occur a few minutes after the explosion. Such explosions typically do not have precursors in the hours or days preceding the event in terms of changes in the parameters recorded by the monitoring networks, but deformation of the edifice in the very short-term (minutes) [34,[289][290][291][292][293][294]. Tsunamis may be triggered also during effusive phases, for which ground deformation is crucial for the early detection of magma intrusions and consequent flank instability, as part of a slow and progressive dynamics that could be detected even days before it occurs [290,291,295,296].…”

“…In terms of emergency management, this area is densely inhabited and it represents the exposed area that will be evacuated in case of (i) evidence of magma intrusions and deformations in the SdF, potentially leading to a collapse and subsequent tsunami (e.g., 2007 eruptive crisis described in [306]); (ii) automatic activation of the acoustic warning system (sirens) due to the detection of a tsunami. Noteworthy, also an automatic early warning system for paroxysmal explosions is in place [294]. This system triggers sirens locally at the villages of the island of Stromboli (Stromboli and Ginostra) [305].…”

Using dense seismo-acoustic network to provide timely warning of the 2019 paroxysmal Stromboli eruptions

“…On August 28th, short-time ground deformation precursors allowed an alert to be issued 5 min before the onset of the eruption 30 and a Volcano Observatory Notice for Aviation (VONA) was sent by INGV about 30 min after the paroxysmal explosion, alerting for the presence of an ash plume rising up to 5 km above sea level (http:// www. ct. ingv.…”