Micromechanics, Statistics and Hazards of Mechanical Failure

This interdisciplinary workshop intends to identify common strategies, translate terminology and erode conceptual barriers between different academic and professional environments dealing with extreme events emerging from mechanical avalanche processes. We seek to establish a common understanding of the theoretical foundations and characterization of avalanche phenomena and failure, and to stimulate new interdisciplinary collaborations. 

We invite experts dealing with data processing, statistical and micromechanical modeling and hazard assessment related to avalanche phenomena in mechanical systems in the areas of soft-matter physics, statistical seismology, material, mechanical, and civil engineering, among others. Specifically, we are interested in experiments on mechanical stability and dynamics of granular, crystalline or amorphous matter; experiments on material failure, rock fracture or recording of acoustic emission; discrete element (DEM) simulation of amorphous, glassy or granular matter; theory, and micromechanical modelling of soft-matter, including mean-field solutions; geomechanical models of fracture and faulting; field studies on seismic and microseismic data; hazard assessment and failure forecasting in any of the aforementioned areas. 

We look for universal and particular aspects of each phenomena under study, the limitations and advantages of different experimental procedures and physical modelling approaches. 

We are also interested in the translation of definitions and statistical techniques and models to be used across research areas, as well as unified hazard models and comprehensive hazard measures. The goal is to achieve a common toolset able to provide unambiguous results and interpretations.

Finally, this workshop attempts to activate new communication channels with specialists from the public or private sector working on hazard assessment and risk management. We welcome contributions about past experiences and potential new collaborations between academic and non-academic institutions arising from the new breakthroughs of the topic.

The workshop is planned to be split in 3 themes and 6 focus sub-thematic sections, each one discussing different stages of research from empirical observations to practical application of scientific results. 

The themes are: (I) phenomena and experiments (II) physical modelling and micromechanics, (III) statistical models, hazard assessment and other applications. The focus sections are described below.

To acknowledge the compromise to the original call, all key participants from the cancelled workshop will be given preference to participate with an oral contribution. However, thanks to the flexibility of the new format, we open the call to a maximum of 50 participants. Please, feel free to share this information with anyone interested.

Given the thematic organization, and knowing our common interests in several research topics, we encourage each participant to submit an optional secondary abstract for a display or oral contribution in another area, or to organize and split your contribution in two talks to better fit the thematic structure. More details can be found in the abstract submission form.

Oral contributions: 

Each oral contribution will fit a time-slot of 25 min accounting for a few minutes for questions. Under request, some contributions can expand a 50 min time-slot. The sessions will be held in Zoom and will require an adequate hardware:

• A computer with an operating system and software compatible with Zoom (OS: Linux, MacOS or Windows. Doc:   https://support.zoom.us/hc/en-us/articles/206175806 ).
• A working microphone and webcam.
• High-speed internet connection (>  2.00 Mbps recommended)

Due to the different time zones at which the participants are located, oral contributions will be divided in three different sessions per day:

• Two time-slots between 14:00-15:00 Central European Time -CET- (5:00-6:00 Pacific Time -PT-).
• Three time-slots between 17:00-18:30 CET (8:00-9:30 PT).
• Two time-slots between 20:00-21:00 CET (11:00-12:00 PT).

Sessions are expected to be recorded, only with the expressed permission of all speakers, so all contributions will be available later to all participants regardless of their location. 

Display contributions:

We are still developing the infrastructure to submit and share ‘display’ contributions. The display will consist of a self-explanatory document in .pdf or .ppt format (or possibly, a small-sized video) presenting your research. The spirit of the display contribution is to participate in a way similar to a poster contribution in a classic face-to-face conference. However, the digital format allows for more flexibility in the presentation than a poster. Feel free to innovate!

You will be asked to upload the presentation material  in a dedicated server shortly before the workshop starts. Ideally, an individual chat-room will be activated for each display to encourage open discussion with other participants during and after the workshop. All the displays will be linked in a ‘webring’ simulating a poster hall, and connected by terms and themes. A time-slot will be open to all participant with a display contribution to summarize its contents in a brief, flash talk (1-2 mins).

Since not this workshop, nor the sections, are specific to research areas, we kindly ask the contributors to appeal the interest of a well educated but highly interdisciplinary audience. Do not be afraid to share your most stunning results, but remember that the goal is to build bridges between areas, and the basic concepts should be clear for a broad audience. We expect a proactive and dynamic venue that can extend in the talk-rooms and chat-rooms well beyond the scheduled times. We will leave all resources open for a longer period of time for this purpose. 

Abstract submissions should be completed before August 30. All contributions will be evaluated by the scientific committee. Resolutions will be announced by September 7. Do not hesitate to contact the organizers for any questions or alternative arrangements. We will try to accommodate as possible the needs and interests of all participants. Notice that we have a limited number of time slots for oral contributions, and some solicited talks might have to be accepted as displays instead.

The workshop is structured in three themes addressed in oral and display contributions: (I) phenomena, experiments and characterization; (II) physical modelling and micromechanics;  (III) hazard assessment and industrial applications. These themes are split in the following six sub-thematic sections.

Section 1: Common aspects and particular features of natural avalanche processes

Different phenomena in field and lab experiments can be related to avalanche processes in mechanical systems and/or mechanical failure of solids: fracture mechanics, acoustic emission, fatigue, creep, corrosion, jamming, interface deppining, frictional sliding, tectonic seismicity, fluid-induced and triggered microseismicity, landslides, rock-falls, snow avalanches, structural and magnetostructural phase transitions and a long list of other non-linear mechanical processes.

This section calls for new developments and reviews of the general state of the art in the theoretical and experimental study of the different natural or man-made avalanche phenomena. Special attention will be given to the features of each particular experimental approach, and the prospective societal impact derived from the understanding and characterization of the phenomena.

The goal is to provide an interdisciplinary and comprehensible overview of principles, field studies, experimental procedures, and their motivation. What phenomena mimics each experimental procedure? Are we extending the validity of some fundamental principles? Or reducing the phenomena to the minimal expression?

Section 2: Data processing, statistical analysis and empirical laws and models

Data recording and data processing techniques in non-linear mechanical processes differ depending on the underlying processes and field of study. Analytical toolsets are often designed to deal with the limitations imposed by data acquisition. In a best-case scenario, we know, record, or infer the microscopic internal fields and/or the microstructural rearrangements. Otherwise, full or partial time series from one or multiple devices can detect remotely acoustic, seismic, magnetic, optical or calorimetric signals in a narrow or broad-band spectrum. Individual events, or avalanches, are usually represented in stochastic models with explicit parameter dependencies. These usually include empirical observations, such as scale-free relations, distributions, and accelerations, temporal, and spatial correlations, etc..

This section calls for reviews and latest breakthroughs regarding empirical laws and the techniques used to characterize them: signal processing; match-filtering techniques; avalanche propagation profiles; internal measurements and remote inference of stress and displacement fields; magnitude distributions and magnitude relations; estimation of critical exponents; finite-size scaling; outlier detection; determination of other precursors to failure; identification of event-event correlations, spatial and temporal clustering, etc. We will discuss the possibility to extend analytical procedures to a generalized toolset to study numerical and experimental datasets.

Section 3: Micromechanical modeling from molecular dynamics to mean field

Different research areas rely on different physical approaches to study the micromechanical stability of materials and the nucleation and propagation of avalanche processes. These include coarse-grained elastoplastic or phase-field models in finite element (FEM) or lattice representations; discrete element (DEM) simulation of molecular dynamics representing amorphous or granular materials; fracture and interface propagation; simple conceptual representations of natural processes and solutions in the mean-field approximation. Some numerical and analytical results reveal a certain degree of universality across models and phenomena. Other features appear to be sensitive to the modeling approach, or its parameters. Of particular interest are the limitations of each modeling approach, such as the role of topological constraints in crystalline and granular matter, the dimensional embedding of the model and the range of interactions.

This section calls for recent results and reviews on the state of the art in the micromechanical modelling of avalanche dynamics across research areas, with an emphasis on universal features and the particular advantages, limitations and forecasting capabilities of each approach.

Section 4: Physical origin of precursors, correlations and heterogeneity

Some statistical features of avalanche dynamics preceding extreme events can be related to the onset of a phase transition. Other features are more difficult to reproduce at the conceptual level. This is the case of temporal correlations in the form of aftershock sequences as observed in earthquakes, interface deppining, acoustic emission experiments and structural phase transitions. Different micromechanical models reproduce such features by introducing  physically-based mechanisms: rheology of structural materials and internal fluids; rate-and-state friction; dynamic stress transfer, inertia, etc.. Recent studies also revealed non-trivial effects caused by small and large-scale heterogeneities in numerical simulations and experiments.

This section is a follow-up of section 3, focused on the experimental observation and modelling of second-order features such as precursors, sporadic or driven regime transitions, and the effects of temporal scales and heterogeneity. 

Section 5: Model-based hazard assessment and forecasting

The insights from empirical statistical models (Section 2) and micromechanical models (Sections 3 and 4) can be used to provide a comprehensive measurement of long- and short-term hazards and a reliable forecasting of extreme events in mechanical processes.

This section invites the presentation of data-based and/or model-inspired hazard models for seismic and microseismic events; non-intrusive techniques for structural health monitoring based on micromechanics or spontaneous acoustic emission; Bayesian inference of parameters in the point process representation of avalanche processes; proportional hazard models; hidden Markov and semi-Markov models; epidemic and branching aftershock models; real time parameter estimation; and any kind of data-based techniques, including machine learning, applied to failure forecasting, hazard assessment and damage diagnosis.

Section 6: Industrial and societal impact of avalanche modelling and mechanical failure

Models and new techniques for hazard assessment have a straightforward societal impact in the territorial planning, the development of safety and emergency protocols, and early warning systems. This practical application of fundamental research calls for the establishment of natural partnerships between public and private agents dealing with risk management and purely academic research teams. However, fundamental research is often motivated by merely academic reasons, in the pursuit for knowledge itself.

We invite public and private agents dealing with extreme-event forecasting and hazard assessment of phenomena related to mechanical failure and other avalanche processes to participate in this section. We also invite participants from academia to share their experience in knowledge and technology transfer and intersectorial projects with industry partners, agencies, and other public or private enterprises dealing with seismic hazard, early warning systems, protocols applied to the topics of natural hazards, such as earthquakes, rock-falls, landslides, snow avalanches, volcanic activity, anthropogenic fluid-induced seismicity, non-intrusive structural health monitoring in industry, critical infrastructures and building protocols, collapse prevention and monitoring of mine shafts, storage facilities, stockpiles and silos, urban resilience accounting for seismic microzonation, soil liquefaction, etc.. We also invite contributions regarding experiences in the use of third-party computational and big-data resources.

We are particularly interested in the following questions: Which are the main problems faced by public agents which remain unsolved with state-of-the-art technologies and procedures? How can new developments and breakthroughs in statistical and micromechanical modelling improve hazard forecasting in real settings? What information from field and experimental studies can improve current hazard protocols? Are scientists asking the right questions to address such practical problems? What opportunities exist to tighten the collaboration between public and private agents and academia? How can these be improved?

The workshop will take place between Oct 19-22, 2020, with the possible addition of a joint meeting for discussion on Oct 23. The following schedule is still incomplete.

	Mo 19	Tu 20	Wd 21	Th 22
	CET	session 3	session 6	session 9
	14:00	Marisol Monterrubio	Soumyajyoti Biswas	Mauro Cacace
	14:30	Osvanny Ramos	Silvia Bonfanti	Alexis Cartwright-Taylor
	15:00	(open discussion)	Jean Paul Ampuero	(open discussion)
CET	session 1	session 4	session 7	session 10
17:00	Eduard Vives	Chen Liu	Jonathan Barés	displays
17:30	Ramon Planet	Lucas Goehring	Grzegorz Kwiatek
18:00	Blai Casals	Adriano Gualandi	Ilya Zaliapin	closing
18:30	(open discussion)	(open discussion)	(open discussion)
	session 2	session 5	session 8
20:00	Aghil Abed Zadeh	Kamran Karimi	Omid Khajehdehi
20:30	Ezequiel Ferrero	Mehdi Pouragha	Robert Shcherbakov
21:00	(open discussion)	(open discussion)	(open discussion)

• Eduard Vives: Failure of porous materials under compression: two universality classes?.
• Ramón Planet, Juan M. López, Stéphane Santucci, Jordi Ortín : Spatiotemporal organization of correlated local activity within global avalanches in slowly driven interfaces.
• Blai Casals, Guillaume Nataf, Ekhard Salje : Avalanche criticality during ferroelectric switching.
• Aghil Abed Zadeh, Jonathan Barés : Seismicity in sheared granular matter.
• Ezequiel Ferrero: Avalanche statistics at the yielding transition of amorphous solids: elastoplastic models universality.
• Marisol Monterrubio-Velasco, J.C. Carrasco-Jiménez, F.R. Zúñiga, Q., Rodríguez-Pérez, J. de la Puente: Stochastic modelling for earthquakes, an alternative method for understanding the physical process?
• Osvanny Ramos: Towards reliable analogue experiments of earthquake statistics.
• Mehdi Pouragha: Genesis of Failure in Granular Materials: Bridging Physics and Engineering Perspectives.
• Lucas Goehring, Arnaud Hemmerle, Soumyajyoti Biswas, Yuta Yamaguchi : Cohesive granular media.
• Adriano Gualandi: Geodetic imaging of tectonic deformation: implications for earthquakes predictability.
• Kamran Karimi: From Plastic Flow To Brittle Fracture: Role Of Microscopic Friction In Amorphous Solids.
• Silvia Bonfanti: Elementary Plastic Events in Amorphous Silica.
• Alexis Cartwright-Taylor, Ian G. Main et al. : Catastrophic failure - how and when? Inside breaking rocks with 4D x-ray microtomography.
• Soumyajyoti Biswas, Lucas Goehring : Mapping heterogeneities via avalanche statistics.
• Jonathan Barés, Daniel Bonamy : Controlling crackling dynamics by triggering low intensity avalanches.
• Grzegorz Kwiatek, Stephan Bentz, Lei Wang, Maria Leonhardt, Patricia Martínez-Garzón, Marco Bohnhoff, Georg Dresen : Induced seismicity during hydraulic stimulations: From self-arrested to unbounded ruptures.
• Ilya Zaliapin, Yehuda Ben-Zion : Quantifying preparation process of large earthquakes: Damage localization and coalescent dynamics.
• Omid Khajehdehi, Kamran Karimi, Joern Davidsen : The effect of correlated permeability on fluid-induced seismicity.
• Robert Shcherbakov: A Bayesian framework for aftershock forecasting and testing.
• Mauro Cacace: Multiphysics of faulting, porosity evolution and damage in reservoirs: current status and open questions.
• Jonathan Barés, Dengming Wang , Dong Wang , Thibault Bertrand, Corey S. O'Hern, Robert P. Behringer : (as display) Crackling around the jamming transition : Local and global avalanches in a two-dimensional sheared granular medium.
• Ilya Zaliapin, Karla Henricksen, Konstantin Zuev : (as display) Hyperbolic geometry of earthquake networks.
• Silvia Bonfanti, Chattoraj Joyjit, Roberto Guerra, Itamar Procaccia, Stefano Zapperi : (as display) Oscillatory instabilities in three-dimensional frictional granular matter

Abstract submissions for talks is currently closed. Free registration for participation without oral contribution will open soon.

Please, contact us for any additional questions

For any abstract submission, use this latex template to compile the abstract in .pdf format.