Sub-marine landslides are a significant risk for coastal communities (tsunami generation) and offshore engineering infrastructure. Storm triggered submarine landslides is a new area of scientific research and is of broad scientific and practical significance. Continental margins earthquakes are usually thought to be responsible for slope failure triggering. Recent work demonstrates that specific storm-induced sea states can impose significant cyclical pressure fluctuations on the sea floor. In this research theme we ask – should storms be considered as a viable slope failure trigger near offshore shelf breaks?
This research theme ismeasuring cyclical pressures on the sea floor using data from the iMARL offshore network, and is using 20 piston cores collected in 2010 to test the effects of measured pressure by subjecting samples to cyclical loading in a physical laboratory (examine material weakening as a function of frequency and amplitude of load cycles). This work is supported by laboratory work with numerical modelling in granular materials.
Karst environments change with time due mainly to water ingression and non-elastic changes in moduli under long term loads. Here we develop new methods for determining the temporal variation of moduli (on the 100s m spatial scale) on a 15 minute time scale, 24/7 for several months. Data will be streamed in real time so changes can be monitored remotely.
This research theme usesrepeat seismic shots using an airgun in a buried water tank (at 15 minute temporal resolution), and recorded on a nearby seismometer. Seismic Coda Wave Interferometry is applied to determine velocity changes as small as 0.1%. If the forcing is known (e.g. atmospheric pressure) we can determine large scale (e.g. 400m x 400m) average moduli changes for the rock volume.
- Storm induced cyclical seafloor pressure fluctuations effect on sea floor and offshore slope stability
- Time lapse geophysical monitoring in karst systems