Anne Sornette - Academia.edu (original) (raw)

Papers by Anne Sornette

Nonlinear Processes in Geophysics, 1995

In lines with diverse initiatives regarding scientific culture and education, the `O3E&am... more In lines with diverse initiatives regarding scientific culture and education, the `O3E&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; experience (http://O3E.geoazur.eu) has set up a permanent educational network of schools in the Alpine and Mediterranean areas, building an exchange of knowledge on natural risks prevention. The ``O3E&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; innovative project (European Educational Observatory for Environment) is established after 12 years (1996-2008) of regional and national original programs for

Bulletin of the Seismological Society of America, Oct 1, 1994

Pure and Applied Geophysics, 2015

Pure and Applied Geophysics, 2014

The present work is a continuation and improvement of the method suggested in [Pisarenko et al. 2... more The present work is a continuation and improvement of the method suggested in [Pisarenko et al. 2008] for the statistical estimation of the tail of the distribution of earthquake sizes. The chief innovation is to combine the two main limit theorems of Extreme Value Theory (EVT) that allow us to derive the distribution of T-maxima (maximum magnitude occurring in sequential time intervals of duration T) for arbitrary T. This distribution enables one to derive any desired statistical characteristic of the future T-maximum. We propose a method for the estimation of the unknown parameters involved in the two limit theorems corresponding to the Generalized Extreme Value distribution (GEV) and to the Generalized Pareto Distribution (GPD). We establish the direct relations between the parameters of these distributions, which permit to evaluate the distribution of the T-maxima for arbitrary T. The duality between the GEV and GPD provides a new way to check the consistency of the estimation of the tail characteristics of the distribution of earthquake magnitudes for earthquake occurring over arbitrary time interval. We develop several procedures and check points to decrease the scatter of the estimates and to verify their consistency. We test our full procedure on the global Harvard catalog (1977-2006) and on the Fennoscandia catalog (1900-2005). For the global catalog, we obtain the following estimates: max M = 9.53 ± 0.52;) 97. 0 (10 Q =9.21 ± 0.20. For Fennoscandia, we obtain max M = 5.76 ± 0.165;) 97. 0 (10 Q =5.44 ± 0.073. The estimates of all related parameters for the GEV and GPD, including the most important form parameter, are also provided. We demonstrate again the absence of robustness of the generally accepted parameter characterizing the tail of the magnitude-frequency law, the maximum possible magnitude M max , and study the more stable parameter Q T (q), defined as the q-quantile of the distribution of Tmaxima on future interval of duration T.

$Research paper thumbnail of Some consequences of a proposed fractal nature of continental faulting$

Journal de Physique, 1990

Solid State Phenomena, 1993

Pure and Applied Geophysics, 2008

We develop a new method for the statistical estimation of the tail of the distribution of earthqu... more We develop a new method for the statistical estimation of the tail of the distribution of earthquake sizes recorded in the Harvard catalog of seismic moments converted to m Wmagnitudes (1977-2004 and 1977-2006). For this, we suggest a new parametric model for the distribution of main shock magnitudes, which is composed of two branches, the pure Gutenberg-Richter distribution up to an upper magnitude threshold m 1 , followed by another branch with a maximum upper magnitude bound M max , which we refer to as the two-branch model. We find that the number of main events in the catalog (N = 3975 for 1977-2004 and N=4193 for 1977-2006) is insufficient for a direct estimation of the parameters of this model, due to the inherent instability of the estimation problem. This problem is likely to be the same for any other twobranch model. This inherent limitation can be explained by the fact that only a small fraction of the empirical data populates the second branch. We then show that using the set of maximum magnitudes (the set of T-maxima) in windows of duration T days provides a significant improvement, in particular (i) by minimizing the negative impact of time-clustering of foreshock / main shock / aftershock sequences in the estimation of the tail of magnitude distribution, and (ii) by providing via a simulation method reliable estimates of the biases in the Moment estimation procedure (which turns out to be more efficient than the Maximum Likelihood estimation). We propose a method for the determination of the optimal choice of the T-value minimizing the Mean Square Error of the estimation of the form parameter of the GEV distribution approximating the sample distribution of T-maxima, which yields T optimal =500 days. We have estimated the following quantiles of the distribution of T-maxima for the whole period 1977-2006: Q 16% (M max)= 9.3, Q 50% (M max)= 9.7 and Q 84% (M max) = 10.3. Finally, we suggest two more stable statistical characteristics of the tail of the distribution of earthquake magnitudes: the quantile Q T (q) of a high probability level q for the T-maxima, and the probability of exceedence of a high threshold magnitude ρ T (m*) = P{ m k ≥ m*}. We obtained the following sample estimates for the global Harvard catalog T Q (q=0.98) = 8.6 ± 0.2 and T ! (8) = 0.13-0.20. The comparison between our estimates for the two periods 1977-2004 and 1977-2006, where the later period included the great Sumatra earthquake 24.12.2004, m W =9.0 confirms the instability of the estimation of the parameter M max and the stability of Q T (q) and ρ T (m*) = P{ m k ≥ m*}.

Journal of Geophysical Research: Solid Earth, 1998

We test the concept that seismicity prior to a large earthquake can be understood in terms of the... more We test the concept that seismicity prior to a large earthquake can be understood in terms of the statistical physics of a critical phase transition. In this model, the cumulative seismic strain release increases as a power law time to failure before the final event. Furthermore, the region of correlated seismicity predicted by this model is much greater than would be predicted from simple elastodynamic interactions. We present a systematic procedure to test for the accelerating seismicity predicted by the critical point model and to identify the region approaching criticality, based on a comparison between the observed cumulative energy (Benioff strain) release and the power law behavior predicted by theory. This method is used to find the critical region before all earthquakes along the San Andreas system since 1950 with M≥6.5. The statistical significance of our results is assessed by performing the same procedure on a large number of randomly generated synthetic catalogs. The nu...

Journal of Geophysical Research: Solid Earth, 1999

We present realistic three‐dimensional numerical simulations of elastic bodies sliding on top of ... more We present realistic three‐dimensional numerical simulations of elastic bodies sliding on top of each other in a regime of velocities ranging from 0.1 to 10 m/s using the so‐called smoothed particle hydrodynamics method. This allows us to probe in detail the response of the bodies and the nature of the friction between them. Our investigations are restricted to regimes of pressure and roughness where only elastic deformations occur between asperities at the contact surface between the slider block and the substrate. In these regimes, solid friction is due to the generation of vibrational radiations which then escape to infinity or are damped out; in which case, energy is dissipated. We study periodic commensurate and incommensurate asperities and various types of disordered surfaces. In the elastic regime studied in this paper, we report evidence of a transition from zero (or nonmeasurable μ<0.001) friction to a finite friction as the normal pressure increases above 106 Pa. For l...

101: Earthquakes may be traumatic events and as many other environmental emergencies, like storm ... more 101: Earthquakes may be traumatic events and as many other environmental emergencies, like storm or floods, may cause more damages than expected when who experiences the phenomena does not know how to behave in the fall. Provided that it is always not feasible to rely on prediction when dealing with earthquakes or extreme meteorological events, preparedness proves to be an efficient (and certainly the most recommendable and cheap) way to face emergencies. Education and training are thus two ingredients to help citizens to perceive the scientific information formerly confined in the laboratories, in particular in the domain of the environmental risk. The “O3E” innovative program (European Observatory for Education and Environment) is established after 10 years (1997-2007) of regional and national original programs (“Sismos of the Schools”), and from Italian and Swiss experiences concerning environment tools for education. The project, that is a cooperation between France, Italy and S...

Europhysics Letters (EPL), 1989

We suggest that the concept of self-organized criticality (SOC) is relevant for understanding the... more We suggest that the concept of self-organized criticality (SOC) is relevant for understanding the processes underlying earthquakes. Earthquakes are an important part of the relaxation mechanism of the crust which is submitted to inhomogeneous increasing stresses accumulating at continental-plate borders. The SOC concept then implies that earthquakes in turn organize the crust both at the spatial and temporal levels. This idea allows to rationalize observations on occurrences and magnitudes of earthquakes. Variants of SOC as well as a novel type of dynamics based on *waiting times>> are discussed within a mean-field-like approach which shows the existence of lif noise in the time gap between large earthquakes. The corresponding long-time correlations have important implications for the statistical long-time forecasting of earthquakes.

&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;After a 6-month flight to Mars and a successful landing, InSight has deployed SEIS &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#8230; its seismometer designed to sit on the Martian surface. The goal of this mission is to investigate the dynamics of Martian seismic activity and understand the processes that shaped the Red Planet.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;SEIS InSight has engaged a generation of school kids, teens and students which, like scientists, follow the mission live. The data from InSight offers a chance to leverage existing Seismometers in Schools networks to allow a large and growing number of students to interact with seismic data recorded on Mars as soon as it is available on Earth.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#160; Students in these international networks have experience with seismic data and software and are primed to engage with this NASA Discovery mission.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;Seismic data in the classroom has provided both a hook for inquiry with real data as well as a common language for international collaboration.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;These resources input innovative educational strategies acculturating pupils in the acquisition, processing, display and exploration of seismic and weather data.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;A very large school network (middle and high schools) share resources and activities using InSight data. Networks are preparing lessons, software, web tools, data viewers, and other resources to allow students to explore and interrogate shaking on Mars to better understand the heart of the planet.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;In this presentation, we will show all the practical activities and all the different tools created for the kids, teens and students. This work has been developed by teachers, educators, and scientists in international cooperation, and can be found on dedicated websites.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;

Bulletin of the Seismological Society of America, May 21, 1999

It is well-known that the Gutenberg-Richter power law distribution has to be modified for large s... more It is well-known that the Gutenberg-Richter power law distribution has to be modified for large seismic moments, due to energy conservation and geometrical reasons. Several models have been proposed, either in terms of a second power law with a larger b-value beyond a cross-over magnitude, or based on a "hard" magnitude cutoff or a "soft" magnitude cutoff using an exponential taper. Since the large scale tectonic deformation is dominated by the very largest earthquakes and since their impact on loss of life and properties is huge, it is of great importance to constrain as much as possible the shape of their distribution. We present a simple and powerful probabilistic theoretical approach that shows that the Gamma distribution is the best model, under the two hypothesis that the Gutenberg-Richter power law distribution holds in absence of any condition and that one or several constraints are imposed, either based on conservation laws or on the nature of the observations themselves. The selection of the Gamma distribution does not depend on the specific nature of the constraint. We illustrate the approach with two constraints, the existence of a finite moment release rate and the observation of the size of a maximum earthquake in a finite catalog. Our predicted "soft" maximum magnitudes compare favorably with those obtained by Kagan [1997] for the Flinn-Engdahl regionalization of subduction zones, collision zones and mid-ocean ridges.

$Research paper thumbnail of Growth of fractal fault pattern$

Physical Review Letters, 1990