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SUMMARY:Monitoring Coastal Cliff erosion using Distributed Sensing - Dr Je
 ss Johnson\, UEA
DTSTART:20251103T180000Z
DTEND:20251103T190000Z
UID:TALK240463@talks.cam.ac.uk
CONTACT:Candela Gil
DESCRIPTION:Coastal erosion is widespread and around 28% of the English an
 d Welsh coastline experiences erosion rates of at least 10 cm/year. Enviro
 nmental change due to a changing climate will almost certainly lead to a s
 ignificant increase in these erosion rates. For cliff coasts\, much existi
 ng protection is expected to be abandoned. The stretch of coastline on the
  North Norfolk Coast has some of the highest rates of retreat in Europe. L
 ocal authorities are trying to address this challenge. However\, it is cur
 rently difficult to forecast where and when hazardous collapses will occur
 \, rendering management and mitigation of the risk extremely challenging.\
 nTraditional methods of subsurface monitoring are restricted in either tim
 e or space. Distributed Sensing is a new technology that utilises optical 
 fibre. The interrogator sends a series of pulses into the fibre at up to 1
 00 kHz and records the return of the naturally occurring scattered signal.
  In doing this\, the distributed sensor measures at all points along the f
 ibre\, with samples as closely spaced as 25 cm. In summer of 2023\, we dep
 loyed 2 km of fibre optic cable on the North Norfolk Coast to monitor coas
 tal processes.\nUsing machine learning techniques\, we are constructing a 
 database of micro-earthquakes associated with subsurface cracking and rock
 falls and creating a local magnitude scale related to the volume of rock a
 ffected along with a real-time map to show regions that are more seismical
 ly active and therefore more likely to see movement. We are also using amb
 ient noise from the nearby crashing waves to monitor the geomechanical pro
 perties of the subsurface as they evolve using seismic tomography.\n
LOCATION:Harker 1 lecture room\, Department of Earth Sciences\, Downing Si
 te
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