Inform@Risk Documentation

The risk assessment in the project partly follows the Swiss Risk Assessment Model. In the project three scenarios are distinguished: a scenario with a return period of up to 30 years and a low intensity (smaller event, most likely to happen), a scenario with a return period of appr. 100 years and a medium intensity (medium-sized event, less likely to happen) and a scenario with a return period of 300 years or more and a high intensity (big event, very unlikely to happen). The first and second scenario are defined as moderate hazard, the third scenario is defined as residual hazard, since these events are very unlikely to occur. The following steps were taken to assess the probability and size of potential landslides and, therefore, the risk in all parts of the study area.

To understand and define the typical events happening in Bello Oriente, past landslides still visible on the surface were mapped. Additionally, community members gave input on past events not visible anymore due to intense construction in the barrio. The resulting landslide map depicts all landslides recorded.

All mapped events were plotted with size against age and divided into three groups representing the three scenarios. A landslide representing the 300 year event or residual hazard was not mapped. Therefore, its dimensions can only be presumed. 30 year event:
- area of up to 4000 m²
- length of appr. 50 m
- depth of up to 10 m

100 year event:
- area of 4000 - 15000 m²
- length of appr. 150 m
- depth of 10 m

Residual Hazard (complex failure):
- area of more than 100000 m²
- length of appr. 500 m
- depth of 10 - 30 m