Investigating the mechanical properties involved in catastrophic volcanic collapse

Volcanic flank collapse and subsequent landslides is a highly destructive phenomenon and tsunamis generated from such events extend the devastating reach of volcanic islands. Triggering such events can be attributed to a number of phenomena on volcanic islands; weak materials or structures, over steepened edifices, increased stresses or pressure build up due to intrusions and pore water interaction. Once triggered, the controlling components over a landslide involves the material properties, including the strength, friction and pore fluid pressures. By comparing three key volcanic islands it can be determined what is the main triggering cause, or whether this differs depending on the volcanic setting or due to the material make-up of the edifice. These locations will include Ritter Island, a recent historic collapse from a subduction setting and Fogo of the Cape Verde from an intraplate setting with a well exposed single giant scar and evidence of a tsunami. This project will use experimental laboratory procedures to determine sample rock properties from the scar and aim to find how the physical and hydraulic properties of volcanic formation affects the susceptibility to weakening flanks leading to collapse. This will allow comparison of the various volcanic islands and how the lead up to and the collapse itself is characterised.