Earthquakes remain unpredictable, despite decades of intense investigations into possible precursory phenomena. The main difficulty lies in our incomplete knowledge of the state of stress on active faults at seismogenic depths, and a full understanding of how rupture initiates and stops in a complex medium characterized by a variable stress field acting on complex fault geometries.
In the last decade, however, great advances have converged towards a much more complete picture of earthquake-related processes. The quality and quantity of seismic data, as well as their diffusion to research scientists through open-data policies, have been much improved, most recently owing to the development of very dense and / or very sensitive seismic networks, and a gain in location accuracy; the ubiquitous nature of aseismic slip has become apparent; and recent mega-thrust and continental earthquakes have provided the seismological community with very rich datasets that help illuminate possible relationships between seismic and aseismic processes.
This school will follow-on of the 1st Cargèse school on earthquakes, that was held in November 2014 (see http://earthquakes.sciencesconf.org/, as well as https://eos.org/meeting-reports/exploring-earthquakes-slow-slip-and-triggering for a report on this school), and had 98 participants (mainly PhD students and post-docs)from 18 countries following lectures given by 21 lecturers. The goal remains to give an accurate snapshot of our current understanding of earthquakes, in the light of recent advances. About 20 scientists from all around the world (mostly Europe and US), at the cutting-edge of earthquake research, will give lectures, covering various topics related to recent developments in earthquake processes, including nucleation, triggering, rupture, and the seismic cycle as a whole.
The school is intended to stimulate the emergence of a much wider understanding of the current issues and progress among young scientists (PhDs and post-docs), and will thus facilitate future collective progress towards earthquake preparedness and forecasting, as well as to the development of international research networks.
Session 1: Earthquake Nucleation
Earthquakes are the culmination of accelerating processes that may manifest as growing aseismic slip, as confirmed by recent laboratory experiments on rock, often accompanied by foreshocks, tremor, and other seismic phenomena. Additionally, recent observations of these and how they scale with magnitude suggest earthquake size may be strongly influenced by the nucleation process. An update on progress testing the robustness and uniqueness of these potentially important observations since 2014 is warranted.
Session 2: Earthquake Triggering and Rupture
New opportunities to discover what triggers earthquakes identified in 2014 include (1) experimentation on real crustal faults under the more controlled circumstances engendered by the growth of human activities, principally wastewater injection, and its consequent exponential increase in seismicity rates and (2) the development of new methods to image in four dimensions the physical conditions and properties that determine which fault slipmode is likely to dominate. Also, the questions as to how rupture propagates, in relation with structural constraints and past slipping history, remain widely open. Discoveries relevant to these opportunities, others, and new ones will be discussed.
Session 3: Beyond Earthquakes - Completing the Slip Spectrum
Slow aseismic slip acts as to relieve stress applied to faults and to accelerate stress accumulation on neighboring stuck fault patches that eventually break and radiate seismic waves. While innovative seismic waveform and statistical analyses have served as proxies for the more significant, but harder to observe, aseismic slip that drives them, challenges were acknowledged in 2014 and should be revisited. These include verification of the proxy status by detecting aseismic deformation directly and evaluation of how seismic and aseismic modes interact.
David Marsan (ISTerre, Université de Savoie, CNRS), Gregory Beroza (Stanford University), Michel Bouchon (ISTerre, CNRS, Univeristé Grenoble Alpes), Joan Gomberg (USGS Seattle), Anthony Sladen (GeoAzur, CNRS, Université de Nice Sofia Antipolis).
List of speakers (provisionnal)
Gregory Beroza (Stanford University), Michel Bouchon (CNRS, Université Grenoble Alpes), William Ellsworth (Stanford University), Joan Gomberg (USGS Seattle), Satoshi Ide (Tokyo University), Aitaro Kato (Tokyo University), Nadia Lapusta (CalTech), Raul Madariaga (ENS Paris), David Marsan (Université Savoie Mont Blanc), Hugo Perfettini (IRD, Université Grenoble Alpes), Jean Schmittbuhl (CNRS, Université de Strasbourg), Alexandre Schubnel (ENS Paris), Anthony Sladen (CNRS, Université Nice - Sophia Antipolis), Shinji Toda (Tohoku University).
Registration and fees
The school will be held at the Institut des Etudes Scientifiques de Cargèse, Corsica, France. All the details on the location and the facilities can be found at the IESC webpage.