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LABORATORY EARTHQUAKES

 

A.J. Rosakis1, K. Xia2 and H. Kanamori3

1Graduate Aeronautical Laboratories, California Institute of Technology, Pasadena, CA

2Graduate Aeronautical Laboratories and Seismological Laboratory, California Institute of Technology, Pasadena, CA

3Seismological Laboratory, California Institute of Technology, Pasadena, CA

 

ABSTRACT

 

Earthquake dynamics and, in particular, the mechanics of dynamic shear rupture are two relatively under-investigated sub-fields of seismology.  Most efforts to date have focused on analytical studies (Rice 2001) and on the numerical modeling of dynamic rupture processes using finite element, finite difference, and boundary element methods (e.g., Ben-Zion and Andrews, 1997).  As clearly elucidated by Rice (2001), the nature and stability of the predicted process depends very strongly on the choice of frictional laws employed in the modeling and, as a result, validation of the fidelity of such calculations becomes of primary importance.

 

The goal of the present study is to create model laboratory experiments mimicking the dynamic shear rupture process.  We hope to use such experiments to observe new physical phenomena and to create benchmark comparisons with existing analysis and numerics.  The experiments use high-speed photography, photoelasticity, and infrared thermography as diagnostics.  The fault systems are simulated using two photoelastic plates (Homalite) held together by friction.  The far field tectonic loading is simulated by pre-compression and the triggering of dynamic rupture (nucleation) is achieved by an exploding wire technique.  The fault forms an acute angle with the compression axis to provide the shear driving force necessary for continued rupturing. 

 

Our goals are to investigate the dependence the characteristics of rupturing, such as rupture speed, rupture mode on experimental conditions such as far-field biaxial compression, tilt angle of the fault to the compression axis, as well as on the frictional properties of the fault interface.

 

Results on both homogeneous and bimaterial interfaces are reported.  For bimaterial interfaces, various combination of dissimilar materials, including Homalite/polycarbonate pairs, are chosen to mimic wave speed mismatch conditions that are reported to exist across mature, crustal faults.

 

In the present lecture we concentrate on the experimental observation of the phenomenon of, spontaneously unrelated, supershear rupture on the visualization of the mechanics of sub Rayleigh to supershear rupture transition in such frictionally held interfaces.  The results suggest that under certain conditions supershear rupture propagation can be facilitated during large earthquakes (e.g. the 2001 central Kunlunshan earthquake in Tibet or the 2002 Denali earthquake in Alaska).

 

 

 

 

Biographical Sketch for Ares J. Rosakis

 

ARES J. ROSAKIS

Director of the Graduate Aeronautical Laboratories (GALCIT),

Theodore von Kármán Professor of Aeronautics and Professor of Mechanical Engineering

 California Institute of Technology, Graduate Aeronautical Laboratories

 1200 E. California Blvd., Mail Stop 105-50, Pasadena, CA  91125                                        

Tel : 626-395-4523, Fax: 626-449-6359, rosakis@aero.caltech.edu

 

B.A. and a M.A. degree in Engineering Science - Oxford University; Sc.M. and Ph.D. degree in Solid Mechanics - Brown University.  Author of over 130 works on quasi-static and dynamic failure of metals, composites, and interfaces with emphasis on dynamic fracture and dynamic localization.  Recent interests include dynamic fragmentation; shear dominated intersonic rupture of inhomogeneous solids, rupture mechanics of crustal earthquakes, and reliability of thin films.  His awards include: IBM Faculty Development Award; NSF Presidential Young Investigator Award; Rudolf Kingslake Medal and Prize from SPIE; Hetenyi, Lazan, and Frocht awards from SEM; Excellence in Teaching Award from the Caltech Graduate Student Council.  He is a past Chairman of the Fracture & Failure Mechanics Committee of the Applied Mechanics Division, a Fellow of the ASME and the New York Academy of Sciences and awarded the Murray Medal from the Society of Experimental Mechanics.

 

Fields of Interest:

 

Major Field:                Mechanics of Solids

Experimental Mechanics, Dynamic Failure Modes in Materials, Continuum Mechanics, Elasticity, Plasticity, Nonlinear Fracture, Dynamic Fragmentation and Fracture of Metals and Polymers, Dynamic Localization, Dynamic Decohesion of Bimaterials and Layered Systems, Impact Response of Composite Materials, Hypervelocity Impact, Mechanics of Geological Fault Rupture, High Speed Optical Diagnostics and Metrology, Mechanics of Thin Film Structures, Reliability of Microelectronic Devices, Operation of Optoelectronic Devices

 

Minor Field:                Materials Science

Micromechanics of Damage, Failure Mechanisms of Amorphous Metals (Metallic Glasses), Dynamic Deformation of Geomaterials, Microelectronic and Optoelectronic Materials

 

 

HONORS AND AWARDS:

June 1975                Athens College Physics Prize

May 1977                Oxford University College Prize for Excellence in Engineering Science

1980-82                               General Electric Foundation Fellowship and University Scholarship, Brown University   

1984 and 1985         IBM Faculty Development Award

1985                          Presidential Young Investigator Award, National Science Foundation

1989                                       Rudolf Kingslake Medal and Prize, International Society of Optical Engineering (SPIE)

1992                          Hetényi Award, Society of Experimental Mechanics (SEM)

1995                          Fellow of the American Society of Mechanical Engineers (ASME)

1995                          Plenary Lecturer, ASME Summer Meeting, Los Angeles, CA

1996                          B.L. Lazan Award, Society of Experimental Mechanics (SEM)

1997                          Keynote Speaker, Ninth International Conference on Fracture, Sydney, Australia

1997                                       Keynote Speaker, International Conference on Advanced Technology in Experimental

                                  Mechanics, Wakayama, Japan

1998                          Plenary Lecturer, U.S. National Congress of Applied Mechanics, Gainesville, Florida

1998                                       Excellence in Teaching Award, Caltech Graduate Student Council

1998                          Speaker, Midwest Mechanics Seminar Tour

2000                          Plenary Lecturer, Southeastern Theoretical and Applied Mechanics Conference,

                                  SECTAM XX, Pine Mountain, GA

2000                          Alumni Association Seminar Day Speaker, Caltech, Pasadena, CA

2002                          Keynote Speaker, 14th US National Congress of Applied Mechanics, Virginia Polytechnic

                                  Institute, Blacksburg, VA

2002                          Plenary Lecturer, 14th European Conference on Fracture, ECF 14, Cracow, Poland

2003                          Frocht Award, Society for Experimental Mechanics

2003                          James F. Bell Memorial Lecturer, The Johns Hopkins University, Baltimore, MD

2004                        Keynote Speaker, 7th National. Congress on Mech. (HSTAM2004), Chania-  Crete, Greece

2004                        Distinguished Lecturer, Boeing Co., Huntington Beach, CA

2004                        Distinguished Lecturer, UC Riverside, CA

2005                        Murray Medal, SEM Annual Conference, Portland, OR

 

 

 

 

Selected Publications:

 

1.        Huang, Y., Wang, W., Liu, C. and Rosakis, A.J. “Intersonic Crack Growth in Bimaterial Interfaces: An Investigation of Crack Face Contact”, Journal of the Mechanics and Physics of Solids, 46, 2233-2259, 1998.

2.        Rosakis, A.J., Samudrala, O. and Coker, D. “Cracks Faster than Shear Wave Speed”, Science, 284, 1337-1340, May 21, 1999.

3.        Bouchon, M., Bouin, M.P., Karabulut, H., Nafi Toksöz, M., Dietrich, M. and Rosakis, A.J. “How Fast is Rupture During an Earthquake?  New Insights from the 1999 Turkey Earthquakes,” Geophysical Research Letters, 28, 2723-2726, 2001.

4.        Samudrala, O., Huang, Y. and Rosakis, A.J. “Subsonic and Intersonic Shear Rupture of Weak Planes with a Velocity Weakening Cohesive Zone,” Journal of Geophysical Research, 107, 7-1 – 7-32, 2002. 

5.        Rosakis, A.J., Samudrala, O., Singh, R.P. and Shukla, A. “Intersonic Crack Propagation in Bimaterial Systems”, Journal of the Mechanics of Physics of Solids, Special Volume on Dynamic Deformation and Failure Mechanics of Materials (G. Ravichandran, A.J. Rosakis, M. Ortiz, Y.D.S. Rajapakse and K. Iyer, Guest Eds.), 46, 1789-1813, 1998.

6.        Needleman, A. and Rosakis, A.J. “The Effect of Bond Strength and Loading Rate on the Attainment of Intersonic Crack Growth in Interfaces”, Journal of the Mechanics and Physics of Solids, 47, 2411-2449, 1999.

7.        Coker, D. and Rosakis, A.J. “Experimental Observations of Intersonic Crack Growth in Asymmetrically Loaded Unidirectional Composites Plates,” Philosophical Magazine A, 81, 571-595, 2001.

8.        Guduru, P.R., Ravichandran, G. and Rosakis A.J. “Observations of Transient High Temperature Vortical Microstructures in Solids During Adiabatic Shear Banding,” Physical Review E, 64, 036128-1-6, 2001.

9.        Rosakis, A.J. “Intersonic Shear Cracks and Fault Ruptures,” Advances in Physics, 51, 1189-1257, 2002.

10.   Xu, L. and Rosakis, A.J., “Impact Failure Characteristics in Sandwich Structures; Part I: Basic Failure Mode           Selection,” International Journal of Solids and Structures, 39, 4215-4235, 2002.

11.   Xu, L. and Rosakis, A.J., “Impact Failure Characteristics in Sandwich Structures; Part II: Effects of Impact

        Speed and Interfacial Strength,” International Journal of Solids and Structures, 39, 4237-4248, 2002.

12.  Rosakis, A.J. “Intersonic Shear Cracks and Fault Ruptures,” Advances in Physics, 51, 1189-1257, 2002.

13.   Coker, D., Rosakis, A.J. and Needleman, A., “Dynamic Crack Growth Along a Polymer Composite-Homalite  

        Interface,” Journal of the Mechanics and Physics of Solids, 51, 425-460, 2003.

14.   Rousseau, C.-E. and Rosakis, A.J., “On the Influence of Fault Bends on the Growth of Sub-Rayleigh and Intersonic Dynamic Shear Ruptures,” Journal of Geophysical Research, 108, 2411-2431, 2003. 

15.   Yu, C., Ortiz, M. and A.J. Rosakis, “3-D Modelling of Impact Failure in Sandwich Structures,” Fracture of Polymers Composites and Adhesives II (B. Blackman, A. Pavan and J.G. Williams, Eds.), Section 3.4 Composites Modelling, pp. 527-538, 2003.

16.    Park, T.-S., Suresh, S., Rosakis, A.J. and Ryu, J., “Measurement of Full-Field Curvature and Geometrical  

         Instability of Thin Film-Substrate Systems through CGS Interferometry,” to appear in Journal of the  

        Mechanics of Physics of Solids, Special Volume on Dynamic Failure and Thin Film Mechanics (A.J. Rosakis,    

        G. Ravichandran and S. Suresh, Guest Editors), 2003.

17.   Xia, K., Rosakis, A.J. and Kanamori, H., “Laboratory Earthquakes: The Sub-Rayleigh-to-Supershear Rupture Transition,” Science, 303, pp. 1859-1861, 2003.

18.   Coker, D. Needleman, A. and Rosakis, A.J., “Frictional Sliding of Incoherent Bimaterial Interfaces Under  

        Dynamic Loading,” in preparation 2003.

19.   Rittel, D. and Rosakis, A.J.

        “Dynamic Fracture of Berylium-Bearing Bulk Metallic Glass Systems: A Cross-Technique    

 Comparison,” accepted by Engineering Fracture Mechanics, August 2004.

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