Earthquakes: nucleation, triggering, rupture, and aseismic processes.

School outline

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 1^st 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.

Registration and fees

Pre-registration is now closed.

Maximum capacity is fixed to 79 participants. Selection of the pre-registrated participants should take place within one or two weeks after this maximum capacity has been reached. Final registration and payment of the fees will then follow.

Participants will have the opportunity to give oral (10 to 15 minute long) or poster presentations. In either case, please submit a pdf file indicating the title, the authors, the type (oral / poster) of presentation, and a short abstract.

Participation fees are 242 € for the whole week (arriving sunday 1/10 in the afternoon and leaving saturday 7/10 in the morning), and include transportation from Ajaccio airport, accommodation in double rooms (6 nights), breakfasts, breaks, lunches, but do not cover dinners (but one). More information can be found here. Payement should be done at
https://www.azur-colloque.fr/DR11/inscription/inscription/135

CNRS staff (including PhD students and post-docs paid by CNRS) are supported by CNRS and do not pay any fees.

Financial support by the NSF exists for US participants only (in the form of a contribution to travel expenses). Please fill out the "Financial support" box when pre-registering if you would like to apply for this support.

Sessions

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.

List of speakers

Gregory Beroza (Stanford University), Michel Bouchon (CNRS, Université Grenoble Alpes), Michel Campillo (Université Grenoble Alpes), Cristiano Collettini (Roma Sapienza University), Shamita Das (Oxford University), William Ellsworth (Stanford University), Joan Gomberg (USGS Seattle), Agnès Helmstetter (CNRS, Université Grenoble Alpes), Satoshi Ide (Tokyo University), Aitaro Kato (Tokyo University), Nadia Lapusta (CalTech), Raul Madariaga (ENS Paris), Chris Marone (Penn State University), 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), Nicholas van der Elst (USGS, Pasadena), Aldo Zollo (Naples University).

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