Detection and Characterization of Precursors to Shear Failure

Interdisciplinary Areas: Data/Information/Computation, Smart City, Infrastructure, Transportation

Project Description

One of the most important limitations in research and engineering practice on brittle materials is our inability to detect accurately the presence of defects and discontinuities inside the material and to determine the evolution of discontinuities with stress from external agents. Current knowledge of damage strongly relies on experiments in the laboratory where direct observations of the surfaces of the specimens are made to observe new crack formation. Advances in our ability to detect impending damage in the form of cracks or slip along pre-existing discontinuities are critical for a variety of engineering applications.
The objective of the research is to establish the relationship between mechanical and geophysical responses of brittle materials under loading to provide a basis for seismic monitoring techniques, and to enable the development of analysis tools to evaluate the condition of a material at different stages of loading. The promise of using elastic wave propagation through fractured material as an effective monitoring technique is rooted in previous work that discovered the presence of precursors prior to shear failure of frictional discontinuities, in the form of either distinct maxima or minima in transmitted and reflected waves, respectively. 

Start Date

January 2019

Postdoc Qualifications

We seek a dynamic individual with expertise at the interface of Geophysics and Geomechanics, with excellent communication and management skills. The candidate will collaborate with the research group in performing laboratory tests, analysis of results and numerical modeling of fracture and wave propagation through fractured media, and will supervise graduate and undergraduate research assistants.
Qualified individuals should have a Ph.D. in Geophysics, Geomechanics, or a related field at the time of appointment. 


Antonio Bobet, Professor of Civil Engineering,

Laura Pyrak-Nolte, Professor of Physics, 


1. Hedayat, A., Pyrak-Nolte, L.J. and Bobet, A. (2014). Seismic Precursors to the Shear Failure of Rock Discontinuities. Geophysical Research Letters, Vol. 41, pp. 5467-5475, DOI: 10.1002/2014GL060848.

2. Modiriasari, A., Bobet, A. and Pyrak-Nolte, L.J. (2017). Active Seismic Monitoring of Crack Initiation, Propagation, and Coalescence in Rock. Rock Mechanics and Rock Engineering, Vol. 50, No. 9, pp. 2311-2325,

3. Modiriasari, A., Jiang, L., Yoon, H. Bobet, A. and Laura J Pyrak-Nolte, L.J. (2017). Effect of Layering on Cracking Initiation and Propagation under Uniaxial Compression. Abstract No. H13A-1344 presented at Fall Meeting AGU (American Geophysical Union), New Orleans, LA,11-15 December.

4. Jiang, L., Modiriasari, A., Bobet, A. and Laura J Pyrak-Nolte, L.J. (2017). P-S & S-P Elastic Wave Conversions from Linear Arrays of Oriented Microcracks. Abstract No. H13A-1343 presented at Fall Meeting AGU (American Geophysical Union), New Orleans, LA,11-15 December.

5. Modiriasari, A., Bobet, A. and Pyrak-Nolte, L.J. (2017). Use of Seismic Wave Conversions (S-to-P wave) to Monitor Shear Crack Growth. 51st US Rock Mechanics / Geomechanics Symposium held in San Francisco, CA, USA, 25-28 June, Paper 17-411.