Satellite radar data reveal short-term pre-explosive displacements and a complex conduit system at Volcán de Colima, Mexico

Abstract

The geometry of the volcanic conduit is a main parameter controlling the dynamics and the style of volcanic eruptions and their precursors, but also one of the main unknowns. Pre-eruptive signals that originate in the upper conduit region include seismicity and deformation of different types and scales. However, the locality of the source of these signals and thus the conduit geometry often remain unconstrained at steep sloped and explosive volcanoes due to the sparse instrumental coverage in the summit region and difficult access. Here we infer the shallow conduit system geometry of Volcán de Colima, Mexico, based on ground displacements detected in high resolution satellite radar data up to 7 h prior to an explosion in January 2013. We use Boundary Element Method modeling to reproduce the data synthetically and constrain the parameters of the deformation source, in combination with an analysis of photographs of the summit. We favor a two-source model, indicative of distinct regions of pressurization at very shallow levels. The horizontal location of the upper pressurization source coincides with that of post-explosive extrusion. The pattern and degree of deformation reverses again during the eruption; we therefore attribute the displacements to transient (elastic) pre-explosive pressurization of the conduit system. Our results highlight the geometrical complexity of shallow conduit systems at explosive volcanoes and its effect on the distribution of pre-eruptive deformation signals. An apparent absence of such signals at many explosive volcanoes may relate to its small temporal and spatial extent, partly controlled by upper conduit structures. Modern satellite radar instruments allow observations at high spatial and temporal resolution that may be the key for detecting and improving our understanding of the generation of precursors at explosive volcanoes.

Post-Eruption Deformation Processes Measured Using ALOS-1 and UAVSAR InSAR at Pacaya Volcano, Guatemala

“…As this system continues to "unzip," these intrusions and subsequent vent openings could facilitate future slope movement to the SW. Geomechanical studies have found that continued dike intrusions have the possibility of imparting mechanical damage to the rock [45], leading to edifice weakening and a higher probability of slope instability. Additionally, if several pathways bleed the main conduit, the lack of localized accumulation of degassed magma may not cause deformation measurable above InSAR detection limits until magma reaches the surface [46], such as the diking event near the 2010 vents (Figure 5a). This could account for a lack of measurable inflation due to magma intrusion into the cone prior to the 2010 eruptions (Figure 3a, [22]).…”

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

“…Álvarez and Yustis () also used gravity data to infer evidence for the southward migration of the volcanic front in CVC, which was previously proposed by Luhr and Carmichael () based on geological and petrological data. Ground deformations during recent eruption episodes were studied using satellite radar measurements (Salzer et al, ) and provided some information about the shapes and depths of active magma reservoirs. More information about the processes in the plumbing system beneath CVC was obtained based on the analysis of focal mechanisms of seismic events recorded by permanent stations (Núnez‐Cornú & Sánchez‐Mora, ).…”

Dome growth at Mount Cleveland, Aleutian Arc, quantified by time series TerraSAR‐X imagery

“…A noteworthy example of the value in SAR data for tracking lava dome growth is that of Merapi, Indonesia, in 2010, where amplitude imagery aided in the recognition of rapid dome growth and assessment of collapse potential despite persistent cloud cover that obscured other types of observations (especially at visible wavelengths) [ Pallister et al ., ]. Tracking dome growth and deformation (both of the dome and surrounding terrain) is critical for hazards assessment because dome growth rate has been tied to explosive potential [e.g., Pallister et al ., ], and localized transient deformation has been shown to immediately precede explosions at some dome‐building volcanoes [e.g., Salzer et al ., ].…”