The School of Geography, Earth and Environmental Sciences organises a regular series of research seminars throughout the academic year to which everyone is welcome to attend. Speakers - both external and internal to the University - will talk on topics related to all aspects of Earth Sciences.
Today's speaker is Dr Ian M Watkinson from Royal Holloway, University of London.
The devastating magnitude 7.5 earthquake of 28th September 2018 north of Palu, Indonesia, resulted in a complex disaster dominated by secondary effects, leaving thousands dead, missing and displaced in central Sulawesi. In the minutes following the earthquake, huge swathes of suburban Palu were swept away by a remarkable set of landslides that translated towns, villages and fields up to 1 km down slopes of less than 2° gradient. In this talk Ian shows that the largest and most destructive of these landslides formed exclusively in an area of communal irrigation. They slipped along a shallow liquefied sediment layer rooted upslope in a canal that supplied water to the entire irrigation network. Liquefaction may have resulted from strong ground motion coupled with the modified ground water conditions in loose, young distal alluvial fan sands. This study highlights how human modification of the environment can affect slope stability and raises questions about the continued development of irrigation schemes in Sulawesi and other seismically active areas.