Landslide hazard assessment – magnitude-frequency Flashcards
What factors are used to produce susceptability?
preconditioning
What problem might arise from a concave slope?
Allows water accumulation increasing pore pressure and reducing friction
What is the frequency magnitude relationship for landslides?
Larger events are more rare (seen but looking at presence of large blocks on slope and how weathered they are as shows at rest longer- longer return period)
How is intensity of rock falls calculated?
Force/ energy from impact
Low- 30kj
Medium - 3–300kj
How is the intensity of slide processes classified?
cm/yr
low - <2cm/yr
Medium - 2 < x< 10
High - >10
What can area from analysis of past landslides be a proxy for?
Intensity
What does the slide processes intensity relate to?
Movement of slope before failure occurs
What is the power law scaling between for landslides?
size and frequency for medium to large landslides
What is the rollover for landsliide size?
very small slides might be missedbut there will be a peak in the intensity of viewable slides before a decrease
What is an example of silent witnesses for landslides?
Scratches and cuts in trees (sometimes several meters high showing energy bounce)
Impact craters
Caught boulders in net
Destroyed nets
What are the limitations of using satellitle imagery and computers for landslide inventories?
Affected by mapping errors
Resolution of imagery may not allow a representative sampling
Time elapsed (freshness of geomorphological features)
The intensity of an event is not taken into account directly
What can be done in areas where the type of landlside is homogenous across an area? (UK)
Look at landslides across different rock types
How can tracking paths and using return periods test the effectiveness of landslide nets?
For smaller events for lecture example every 10yrs they produced less then the 5000kj threshold but the larger 100yr events produced over the energy
