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Cooling‐dominated cracking in thermally stressed volcanic rocks
Author(s) -
Browning John,
Meredith Philip,
Gudmundsson Agust
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070532
Subject(s) - cracking , lava , volcano , geology , acoustic emission , thermal expansion , sill , isotropy , basalt , thermal , mineralogy , materials science , petrology , seismology , composite material , thermodynamics , physics , quantum mechanics
Most studies of thermally induced cracking in rocks have focused on the generation of cracks formed during heating and thermal expansion. Both the nature and the mechanism of crack formation during cooling are hypothesized to be different from those formed during heating. We present in situ acoustic emission data recorded as a proxy for crack damage evolution in a series of heating and cooling experiments on samples of basalt and dacite. Results show that both the rate and the energy of acoustic emission are consistently much higher during cooling than during heating. Seismic velocity comparisons and crack morphology analysis of our heated and cooled samples support the contemporaneous acoustic emission data and also indicate that thermal cracking is largely isotropic. These new data are important for assessing the contribution of cooling‐induced damage within volcanic structures and layers such as dikes, sills, and lava flows.