Dyke apertures record stress accumulation during sustained volcanism

Abstract

The feedback between dyke and sill intrusions and the evolution of stresses within volcanic systems is poorly understood, despite its importance for magma transport and volcano instability. Long-lived ocean island volcanoes are crosscut by thousands of dykes, which must be accommodated through a combination of flank slip and visco-elastic deformation. Flank slip is dominant in some volcanoes (e.g., Kilauea), but how intrusions are accommodated in other volcanic systems remains unknown. Here we apply digital mapping techniques to collect > 400,000 orientation and aperture measurements from 519 sheet intrusions within Volcán Taburiente (La Palma, Canary Islands, Spain) and investigate their emplacement and accommodation. We show that vertically ascending dykes were deflected to propagate laterally as they approached the surface of the volcano, forming a radial dyke swarm, and propose a visco-elastic model for their accommodation. Our model reproduces the measured dyke-aperture distribution and predicts that stress accumulates within densely intruded regions of the volcano, blocking subsequent dykes and causing eruptive activity to migrate. These results have significant implications for the organisation of magma transport within volcanic edifices, and the evolution and stability of long-lived volcanic systems.

Late complex tensile fracturing interacts with topography at Cumbre Vieja, La Palma

“…Dike intrusions are widespread on the Canary Islands, an archipelago with seven main islands located in the Atlantic Ocean. Dikes in the Canaries have mainly been studied in deeply eroded valleys and excavated road cuts and tunnels, indicative of ancient principal stress fields, rift zones and flank movements [Carracedo 1994;Day et al 1999;Gudmundsson et al 1999;Ablay and Martı 2000;Walter and Schmincke 2002;Ancochea et al 2003;Fernández et al 2006;Ancochea et al 2008;Galindo and Gudmundsson 2012;Thiele et al 2020]. Mapping of hundreds to thousands of dikes on La Palma showed that they have a median thickness of ∼1 m at depth [Thiele et al 2020], which is in agreement with measurements done at other Canary Islands [Marinoni and Gudmundsson 2000].…”

Shallow magmatic intrusion evolution below La Palma before and during the 2021 eruption

“…Previous studies indicate that short-term storage reservoirs formed at shallow depths (2–5 km) weeks-to-days before the eruptions 36 , 37 . Our results show that the shallow accumulation of magma below Jedey (at ~ 1–5 km) started ~ 3.5 months before the eruption, which can be related with the earliest eruption products 35 .…”

Reactivation of Magma Pathways: Insights From Field Observations, Geochronology, Geomechanical Tests, and Numerical Models

“…The Taburiente dykes radiate from a focal point in the southern part of the caldera, as described in detail in Thiele et al. (2020). Along the northern side of the caldera these dykes crosscut an earlier NE striking and shallower‐dipping (∼45–60°) dyke set interpreted to have formed relatively early in the growth of Volcán Taburiente (Thiele et al., 2020).…”

“…Bemis et al., 2014; Dering et al., 2019). These digital outcrop models and details of the methods used to construct them are described in (Thiele​ et al., 2019, 2020). For this study, we focus on three surveys from a site known locally as Hoyo Verde (Figure 1a), where dykes of different orientations intersect to form multi‐dykes (Figure 1b).…”