**Phone**+34 93 586 8511

**Position**Postdoctoral Researcher

**Funding**Santander Postdoctoral Fellow

**Other funding**AXA

**Group**Complex Systems

**Scientific Career and Education**

2020-2021 -- Santander Postdoctoral Fellow at the 'Group of Complex Systems' at Center for Mathematical Research (CRM), in Barcelona (Spain)

2018-2020 -- AXA Postdoctoral Fellow at the 'Group of Complex Systems' at Center for Mathematical Research (CRM), in Barcelona (Spain)

2017-2018 -- Postdoctoral Scholar at the Geosciences Department of the University of Calgary (AB,Canda)

2015-2017 -- Postdoctoral Fellow at the 'Complexity Science Group' (CSG) in the Physics and Astronomy Department of the University of Calgary (AB,Canda)

2013 -- Visiting Scholar at the 'Institute of Condensed Matter Theory' (ICMT) in the Universtiy of Illinois at Urbana-Champaign. (Ill, USA)

2011-2015 -- PhD in Physics at 'Estructura i Constitnuents de la Matèria' (ECM) at the 'University of Barcelona' (UB) (Spain)

2010-2011 -- Ms in Computational and Applied Physics by the 'Universitat Politècnica de Catalunya' (UPC) and Universitat de Barcelona (UB) (Spain)

2004-2010 -- Bachellor in Physics, 'Universitat de Barcelona' (UB) (Spain)

**On the Media**

Fracking and fluid-induced microseismicity: a toll for our energy thirst? by J. Baró

The Suspense in Failure: A Simple Model of Breakage Goes Universal by K. Redmond

Viewpoint: Little Earthquakes in the Lab by I. G. Main

**Research Field**

In general terms, my field of expertise is the modelling, experimentation and statistical analysis of avalanche dynamics in mechanical systems, bridging the theory of non-equilibriun statistical physics and condensed mater physics of disordered systems with the empirical laws in seismology, rock mechanics and engineering :

Statistical Analysis: Study of avalanche dynamics as point processes with specific scale-free relations and statistics. Focus on the characterization of power-law distributions and inter-event correlations (triggering), declustering techniques and statistical hazard assessment.

Modelling: Numerical and analytical resolution of conceptual toy models of frictional sliding and fracture incorporating specific and generalized mechanisms of inter-event triggering.

Experiments: Acoustic Emission recording during mechanical tests over small samples of natural and artificial nano-porous materials and rocks. Analysis of public seismic catalogs and microseismic catalogs induced by fluid injection operations.

**Keywords**

Avalanche dynamics; criticality; acoustic emission; mechanical failure; microseismicity; seismology; self-organization; quenched disorder; out-of-equilibrium statistical physics; metastability.

**Other Interests**

seismology, complex systems, pattern formation, socio- and econo-physics, complex networks.

**AXA Project: Stochastic Rheology Models of Mechanical Failure to Monitor the Resilience of Structures under Severe Conditions (RheMechFail)**

Within the framework of statistical physics, the mechanical failure of materials has been interpreted as a continuous phase transition. The deformation leading to failure is predicted to follow an avalanche process, consequence of microscopic mechanical instabilities, that can be detected by the recording of the released elastic (acoustic) waves. Although the prediction of individual acoustic emission events is not possible, the statistical properties of the whole population can be used to assess the state of the material and it’s proximity to failure - interpreted as a macroscopic avalanche event - based upon an stochastic spatio-temporal point process approach. This approach, requiring high statistics, has been questioned and even proven impractical at the geological scale, but the number recorded ultrasonic acoustic waves in lab experiments at the meso-scale and micro-scale are large enough to perform statistical analysis.

Project RheMechFail is the first attempt to develop a unified theoretical framework – conceptual models and detailed simulations – able to determine the parameters of a valid stochastic point process approximation from fundamental models of mechanical failure. I will validate the theory through the statistical analysis of AE experiments performed in partner institutions. The theoretical part of this project will study how transient hardening affects the mean field solutions of the families of models or universality classes (UC).

Fast and affordable microcomputers allows the development of in-situ SHM equipment able to analyze long AE series in real time. I intend to develop the basis of a point process approach to structural health monitoring (SHM), accounting for the presence of non-stationary correlations, based upon physical principles, to complement the current monitoring techniques. The long term objective of project RheMechFail is to improve current stochastic models by introducing the adequate history-dependent representation of the intensity. The intensity will be deduced from physical principles and fitted from the known properties of the materials. Specifically, project RheMechFail address the conceptual and experimental study of transient processes linked to the rheology of the material as a fundamental ingredient of the observed spatio- temporal correlations.

**Ongoing Projects**

Characterization of the spatio-temporal correlations in AE and microseismicity and discussion on the role of heterogeneity to the statistics of failure.

Effect of transient regimes associated to the physical sources of spatio-temporal correlations to the statistics of AE and microseismological data.

Identification of mean field behavior and universality classes associated to frictional and fracture avalanches under different driving conditions.

Study of topological self-organizion towards criticality in granular assemblies from discrete element simulations.

Determination of control parameters to model the branching processes simulating microseismicity and AE.

**Potential Future Projects**

Role of syntering conditions on the scale-free phenomena in AE and seismology.

Emergent mechanisms self-organized driving towards criticality.

Role of boundary conditions in the separation of scales found in critical systems beyond finite size scaling.

C Lord-May, J Baró, DW Eaton, J Davidsen

'Seismic hazard due to fluid injections'*Physical Review Research* 2 (4), 043324 2020

(2020)

J Baró

'Topological properties of epidemic aftershock processes'*Journal of Geophysical Research: Solid Earth* 125 (5), e2019JB018530

(2020)

J. Baró, K. A. Dahmen, J. Davidsen, A. Planes, P. O. Castillo, G. F. Nataf, E. K. H. Salje, E. Vives

'Experimental evidence of accelerated seismic release without critical failure in acoustic emissions of compressed nanoporous materials'*Physical Review Letters* 120 (24), 245501

(2018)

J. Baró, J. Davidsen

'Universal avalanche statistics and triggering close to failure in a mean field model of rheological fracture'*Physical Review E* 97, 033002

(2018)

J. Baró, J. Davidsen

'Are triggering rates of labquakes universal? Inferring triggering rates from incomplete information'*The European Physical Journal Special Topics* 226 (15), 3211-3225

(2017)

J. Baró

Thesis : 'Avalanches in Out of Equilibrium Systems: Statistical Analysis of Experiments and Simulations'

Universitat de Barcelona

(2015)

J. Baró, J.M. Martín-Olalla, F.J. Romero, M.C. Gallardo, E.K.H. Salje, E. Vives, A. Planes

'Avalanche correlations in the martensitic transition of a Cu–Zn–Al shape memory alloy: analysis of acoustic emission and calorimetry' *Journal of Physics: Condensed Matter* 26 (12), 125401

(2014)

J. Baró, Á. Corral, X. Illa, A. Planes, E.K.H. Salje, W. Schranz, D.E. Soto-Parra, E. Vives

'Statistical similarity between the compression of a porous material and earthquakes' *Physical Review Letters* 110 (8), 088702

(2013)

J. Baró, S. Dixon, R.S. Edwards, Y. Fan, D.S. Keeble, L. Mañosa, A. Planes, E. Vives

'Simultaneous detection of acoustic emission and Barkhausen noise during the martensitic transition of a Ni-Mn-Ga magnetic shape-memory alloy'*Physical Review B* 88 (17), 174108

(2013)

J. Baró, E. Vives

'Analysis of power-law exponents by maximum-likelihood maps'*Physical Review E* 85 (6), 066121

(2012)

An updated list of publications can be found at Scholar