Many Faults, Many Rupture Scenarios for So. NV

Many Faults, Many Rupture Scenarios for So. NV

J. Louie, EGGE 3/25/2011

Japan and Christchurch Lesson: Don’t Ignore Worst Case!

dePolo, 2008, NBMG Map 167

Frenchman Mtn. Fault M6.7 ShakeZoning

NSZ Peak Horiz.Ground Velocity Map

NSZ ShakingAnimation at 0.5 Hz

Effect of Parcel Map Over IBC Defaults- FMF M6.7

3D: ShakeZoning1D: IBC and ShakeMap

Pushing the Predictions Through HAZUS

• $8.6 Billion Loss• 287-610

Casualties

ShakeZoning ShakeMap

• $4.8 Billion Loss• 22-58

Casualties

Combine the Scenarios Probabilistically

λ = annual frequency of exceeding ground motion u0

rate(M, sourcej) = annual rate of occurrence for an earthquake with magnitude M at source location j

P = probability of ground motions u ≥ u0 at site i, if an earthquake occurs at source location j with magnitude M

After Frankel et al., USGS OFR 2007–1175

With Many Scenarios, Define Probabilistic Hazard

Recurrence Intervals: Black Hills- 15 ka Frenchman Mtn.- 45 ka

e.g., PGV at UNLV: ~20 cm/s from BHF ~15 cm/s from FMF

Combine rates per annum: >15 cm/s at 0.0001 p.a. >20 cm/s at 0.00007 p.a.

Conclusions Basin trapping leads to worst-case shaking. 10,721 Parcel Map measurements completed in

3 years for IBC compliance in Clark County. NSZ validated at 0.1-Hz for Las Vegas region

with 1992 LSM recordings. The Parcel Map has surprisingly large effects on

ground motions predicted from physics. Nevada ShakeZoning predicts twice the damage

and five times the casualties as ShakeMap, for the Las Vegas worst case.