Identification of structural controls in an active lava dome with high resolution DEMs: Volcán de Colima, Mexico

Abstract

Monitoring the topography of active lava domes is critical for detecting changes that may trigger or influence collapse or explosive activity. Internal dome structure and conditions are more difficult to elucidate, but also play vital roles. Here, we describe the exposure (following an explosion) of significant scarps in the active dome at Volcán de Colima, Mexico, that are interpreted as evidence of brittle failure planes and a complex internal dome morphology. In the first use of automated 3D computer vision reconstruction techniques (structure‐from‐motion and multi‐view stereo, SfM‐MVS) on an active volcanic dome, we derive high resolution surface models from oblique and archive photographs taken with a consumer camera. The resulting 3D models were geo‐referenced using features identified in a web‐sourced orthoimage; no ground‐based measurements were required. In December 2010, the dome (2.14 × 106 m3) had a flat upper surface, reflecting an overall ductile emplacement regime. Between then and May 2011, a period of low explosivity was accompanied by a small volume loss (0.4 × 105 m3) and arcuate steps appeared in the dome surface, suggesting the presence of localized planes of weakness. The complex array of summit scarps was exposed following a significant explosion in June 2011, and is interpreted to be the surface expression of fault planes in the dome. The 1‐m resolution DEMs indicated that the region of greatest volume loss was not coincident with the assumed location of the conduit, and that heterogeneity within the dome may have been important during the June explosion.

Blowing Off Steam: Tuffisite Formation As a Regulator for Lava Dome Eruptions

“…Throughout the dome growth there were, on average, nine explosions per day, but as growth slowed during the last 6 months this decreased, and in the last 2 months there was an average of just one explosion per day ( Figure 3B). The eruption eventually terminated on 21st June 2011 when there was a larger magnitude explosion which destroyed a small area in the central portion of the dome (James and Varley, 2012). The volcano then entered an exceptional, extended period of quiescence, which lasted until 6th January 2013 and that allowed access to the >2 million m 3 lava dome.…”

“…This slow extrusion rate left the dome riddled with tuffisites in the latter stages of activity. A larger, final explosion occurred on 21st June 2011, which exploited heterogeneities in the lava dome (James and Varley, 2012) and which likely drew upon pressurized gases from deeper in the magma column (e.g., Papale, 1999). (1) failure and fragmentation, in which (i) the magma rips apart, forming particulate material (pale pink circles) and (ii) the fragmentation horizon migrates, extending the damage zone, and fragmenting material layer-by-layer; (2) the pyroclastic material is deposited in fractures, sometimes preserving the fragmentation horizons, the material relaxes, and sinters and magma backfills into voids left in the tuffisite and finally; (3) some fragmental material is excavated, creating channels that are thought to be important outgassing pathways.…”

Using image-based modelling (SfM–MVS) to produce a 1935 ortho-mosaic of the Ethiopian highlands

“…From this dataset, improving the accuracy might be obtained when using GCPs that were recorded in the field with accurate GNSS receivers or when using higher resolution DEMs. However, as indicated by James and Varley (2012), using planimetric information from digital globes can yield accurate results. In addition, using GNSS receivers would limit the methodology to local studies, making the production of a country-wide 1935-1941 otho-mosaic unfeasible.…”

3D Multi-view Stereo Modelling of an Open Mine Pit Using a Lightweight UAV

“…Several interesting and useful examples from different research areas (some among many examples are Gimenez et al 2009;Niethammer et al 2010;James and Varley, 2012;Skarlatos and Kiparissi, 2012;Calakli et al 2012;Tuffen et al 2013;Bemis et al 2014;Forte, 2014;Bennet, 2015;Burns et al 2015;Haukaas, 2015;Shahbazi et al 2015;Van Damme, 2015;Vepakomma et al 2015;Tonkin et al 2016) are shaping, contributing and defining the limitations of the new modelling technique. James and Robson (2012) demonstrated the application of SfM-MVS modelling from decimeter to kilometer scale and presented a thorough discussion on the precision of the method.…”