Lecture 7 - 2 examples of how geomorphology can be useful in earthquake hazards

Question 1

How can direct dating of fault scarps be achieved?

Answer 1

Cosmogenic isotopes. Promising but expensive. E.g. Cl dating of Sparta earthquake (Bendetti et al (2001)

Question 2

What can 10Be exposure age of precariously balanced rocks be used to test? (four things)

Answer 2

• USGS NSHM PGA with 2% in 50 year probability; inconsistent with 1 in 2500 year San Andreas data.
• Basic hazard curves from USGS NSHM data; e.g. inconsistent with long term hazard over 10k year timescale
• USGS 2008 PSHA deaggregations; e.g. M7.5 San Andreas fault ruputres
• GM attenuation relations e.g. 14 km from San Andreas fault

Question 3

Geolmorphology is a powerful tool for earthquake hazards assessment. Give 7 examples of things that it can measure

Answer 3

1. Location and geometry of faults
2. Rate of fault motion
3. Size of co-seismic fault displacements
4. Fault life cycle
5. Timing and frequency of earthquakes
6. Spatial and temporal patterns of seismicity
7. Magnitude of ground motons