Brittle-Ductile Deformation and Tensile Rupture of Dome Lava During Inflation at Santiaguito, Guatemala
Chigna, Gustavo
DOI: https://doi.org/10.1029/2018JB017253
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9230
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9230
Hornby, Adrian J.; Lavallée, Yan; Kendrick, Jackie E.; De Angelis, Silvio; Lamur, Anthony; Lamb, Oliver D.; Rietbrock, Andreas; Chigna, Gustavo, 2019: Brittle-Ductile Deformation and Tensile Rupture of Dome Lava During Inflation at Santiaguito, Guatemala. In: Journal of Geophysical Research: Solid Earth, Band 124, 10: 10107 - 10131, DOI: 10.1029/2018JB017253.
|
Dokument öffnen: |
Gas-and-ash explosions at the Santiaguito dome complex, Guatemala, commonly occur through arcuate fractures, following a 5- to 6-min period of inflation observed in long-period seismic signals. Observation of active faults across the dome suggests a strong shear component, but as fault propagation generally proceeds through the coalescence of tensile fractures, we surmise that explosive eruptions require tensile rupture. Here, we assess the effects of temperature and strain rate on fracture propagation and the tensile strength of Santiaguito dome lavas. Indirect tensile tests were conducted on samples with a porosity range of 3–30% and over diametral displacement rates of 0.04, 0.004, and 0.0004 mm/s. At room temperature, the tensile strength of dome rock is rate independent (within the range tested) and inversely proportional to the porosity of the material. At eruptive temperatures we observe an increasingly ductile response at either higher temperature or lower displacement rate, where ductile deformation is manifest by a reduction in loading rate during constant deformation rate tests, resulting in slow tearing, viscous flow, and pervasive damage. We propose a method to conduct indirect tensile tests under volcanic conditions using a modification of the Brazilian disc testing protocol and use brittleness indices to classify deformation modes across the brittle-ductile transition. We show that a degree of ductile damage is inevitable in the lava core during explosions at the Santiaguito dome complex and discuss how strain leading to rupture controls fracture geometry, which would impact gas pressure release or buildup and regulate explosive activity.
Statistik:
ZugriffsstatistikSammlung:
- Geologie [930]
Schlagworte:
tensile strengthSantiaguito
Brittleness Index
brittle-ductile
indirect tensile tests
Brazilian disc tests
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.