Seismically-induced landslides in Chile: New tools for hazard assessment and disaster prevention

Landslides are a major source of fatalities and damage related with strong earthquakes, particularly in mountain areas. Forecasting the distribution and impact of landslides induced by earthquakes is one of the greatest challenges in the earth sciences. The behavior of slopes during seismic excitation is exceptionally complex, being dependent upon geological, geomorphological, geotechnical and seismological factors. This project aims to identify the main characteristics of landslide occurrence during strong earthquakes in Chile, improving the understanding of their mechanics, spatial distribution and controlling factors, obtaining quantifiable inputs for the development of a methodology for earthquake-induced landslide hazard assessment. This will be achieved through compiling and analyzing inventories for two Chilean earthquakes (Aysén 2007 and Maule 2010) to be compared with foreign landslide inventories; running a laboratory testing scheme in UK for better understanding of the mechanical causes of seismic slope failure; and applying those results on the development of a method for assessing the seismic stability of slopes in Chile. The new methodology will be verified in the Santiago region, which presents the highest population of the country and where an active fault has been recently discovered (San Ramón Fault). The outputs will include scientific publications, advanced human resource training as well as a new technique of hazard assessment applicable to urban/territorial planning and natural disaster prevention strategies in the country.

Thus, at the end of each work package described in the Methodology section, we anticipate producing the following outputs:

Work Package One (WP1): compiling and analyzing inventories for two Chilean earthquakes

O1. Two new landslide inventories for earthquakes in Chile, both of which will be made available to other researchers;

O2: One or two papers, provisionally in the journals Geomorphology and/or Landslides, on the power law relationships for the Chile earthquake events, comparing these with pre-existing datasets and specifically exploring the role of depth and mechanism of rupture in determining the landslide distribution; and on the relationship between the landslide distribution and causative factors such as lithology, slope angle and relief.

Work Package Two (WP2): understanding the mechanical causes of seismic slope failure

O3. A new dataset on the behaviour of Chilean soils and weak rocks under static conditions and during seismic shaking'.

O4. A paper, provisionally to be published the Quarterly Journal of Engineering Geology, on the behaviour of Chilean soils and rocks during seismic shaking. We will publish this as an open access publication to provide access to practitioners.

O5. A paper on the role of horizontal versus vertical shaking in promoting slope instability (provisionally to be published in Engineering Geology).

Work Package 3: Developing a methodology for assessing the seismic stability of slopes in Chile
O6. A new technique for the development of seismic slope stability maps for Chile. This output will be published in the form of a guidance note to be made freely available;

O7. A seismic slope stability map for the area close to the San Ramón Fault in Santiago, to be available for regional and local authorities.

O8. One or two publications, provisionally intended for Natural Hazards and Earth System Science (which is an open access journal) and/or Engineering Geology, on the on the back analysis of the landslide hazard associated with the 2007 Aysen and the 2010 Maule earthquakes, the development of a new technique for mapping seismic slope hazard and the resulting hazard map for San Ramón Fault in Santiago.