Studying a Landslide in Its Paroxysmal Phase; the Reactivation of the Sebrango Landslide (Spain), June 2013

This paper deals about the activities carried out during the emergency developed in Liebana region, (Cantabrian Range, Spain) by the reactivation of the Sebrango landslide, on June 2013, in that the two localities and a road were affected. The methodology employed in analysing an active event (paroxysmal phase), is described. The tasks carried out during the emergency stage have involved the supporting of all decision-making, understanding of the paroxysmal phase, displacement analysis and finally, some urgent stabilization actions. The main conclusions of this work can be grouped in two sets: during the emergency phase the executive responsibility for the activities carried out corresponds to policy makers (the opinions of scientists are at the service of the authorities who make decisions); the most useful tools for the analysis of the landslide activity during paroxysmal phase are the traditional geological field methods combined with GPS measurements and images processed photogrammetrically. These tools enable a geomorphic analysis of the landslide features and give accurate information of the landslide activity. The drainage tasks done, in combination with the barrier made by the carboniferous olistoliths and cessation of precipitations led the progressive landslide slowdown.