Open AccessExperimental study of fracture at geological scale velocities
Author(s) -
Mulargia F.,
Bonafede M.,
Boschi E.
Publication year - 1980
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1980.tb04810.x
Subject(s) - fracture (geology) , fracture mechanics , mechanics , stress (linguistics) , geology , tension (geology) , mineralogy , materials science , geotechnical engineering , composite material , physics , compression (physics) , linguistics , philosophy
Summary. It is well‐known that the chemical environment and the thermodynamical conditions play a fundamental role in the physics of the fracture properties of solids which in turn appear relevant in the understanding of the earthquake mechanism and related precursory phenomena. We designed and built an experimental apparatus capable of measuring the fracture velocities with control of the physical and chemical environment as well as of the applied stress. The apparatus consists of a chamber where both the total pressure and the partial pressure of gases can be controlled. The stress is applied in mode I (tension) configuration. The crack is detected optically on the surface of the sample with an ordinary microscope and the velocity of propagation is directly measured by the increase in length in the elapsed time. The very good stability of the system over very long periods allows us to measure crack velocities down to 10 −12 ms −1 . The propagation under such low‐velocity regimes appears interesting from a geological standpoint since it implies extremely low stress values, which are generally assumed to have no effect on crustal rocks. The first results obtained will be discussed, with particular regard to the apparent dramatic influence of the partial pressure of water vapour in the crack propagation velocity.