Developing conceptual models for the recognition of coseismic landslides hazard for shallow crustal and megathrust earthquakes in different mountain environments – an example from the Chilean Andes

Landslides represent the most frequent geological hazard in mountainous environments. Most notably, landslides are a major source of fatalities and damage related with strong earthquakes. The main aim of this research is to show through three-dimensional engineer-friendly computer drawings, different mountain environments where coseismic landslides could be generated during shallow crustal and megathrust earthquakes in the Andes of Central Chile. From the comparison of local earthquake-induced landslide inventories in Chile, from the Mw 6.2, shallow crustal Aysén earthquake in 2007 (45.3° S) and the Mw 8.8, megathrust Maule earthquake in 2010 (32.5°S - 38.5°S), with others from abroad, as well as analysis of large, prehistoric landslide inventories proposed as likely induced by seismic activity, we have determined topographic, geomorphological, geological and seismic controlling factors in the occurrence of earthquake-triggered landslides. With these results, we have built four representative geomodels of coseismic landslide geomorphological environments in the Andes of central Chile. Each one represents the possible landslide types to be generated by a shallow crustal earthquake versus those likely to be generated by an megathrust earthquake. Additionally, the associated hazards and suggested mitigation measures are expressed in each scenario. These geomodels are a powerful tool for earthquake-induced landslide hazard assessment

An acoustic emission landslide early warning system for communities in low-income and middle-income countries

This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/Early warning systems for slope instability are needed to alert users of accelerating slope deformation behaviour, enable evacuation of vulnerable people, and conduct timely repair and maintenance of critical infrastructure. Communities exposed to landslide risk in low- and middle-income countries seldom currently instrument and monitor slopes to provide a warning of instability because existing techniques are complex and prohibitively expensive. Research and field trials have demonstrated conclusively that acoustic emission (AE) monitoring can be an effective approach to detect accelerating slope movements and to subsequently communicate warnings to users. The objective of this study was to develop and assess a simple, robust, low-cost AE monitoring system to warn of incipient landslides, which can be widely deployed and operated by communities globally to help protect vulnerable people. This paper describes a novel AE measurement sensor that has been designed and developed with the cost constrained to a few hundred dollars (US). Results are presented from physical model experiments that demonstrate performance of the AE system in measuring accelerating deformation behaviour, with quantifiable relationships between AE and displacement rates. Exceedance of a pre-determined trigger level of AE can be used to communicate an alarm to users in order to alert them of a slope failure. Use of this EWS approach by communities worldwide would reduce the number of fatalities caused by landslides

Varying constants, Gravitation and Cosmology

Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. It is thus of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We thus detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, Solar system observations, meteorites dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.Comment: 145 pages, 10 figures, Review for Living Reviews in Relativit

Monitoring mining subsidence in rural areas with a temperate climate using radar-interferometry

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