earthquake hazard class mapping by parcel in las vegas valley
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Earthquake Hazard Class Mapping by Parcel in Las Vegas Valley. John N. Louie Nevada Seismological Laboratory Satish K. Pullammanappallil Aasha Pancha , Travis West Optim Seismic Data Solutions Werner K. Hellmer Clark County Dept. of Development Services. - PowerPoint PPT PresentationTRANSCRIPT
Earthquake Hazard Class Mapping by Parcel in Las Vegas Valley
John N. LouieNevada Seismological Laboratory
Satish K. PullammanappallilAasha Pancha, Travis WestOptim Seismic Data Solutions
Werner K. HellmerClark County Dept. of Development Services
J. Louie et al., Structures Congress 4/14/2011
Parcel Map Enables“Next-Level ShakeZoning”
Goal is to predict earthquake shaking For hazard mapping, planning Building-code development and enforcement Provide time histories of shaking to designers
USGS ShakeMap Based on statistical averages; sparse data Most data came from California, Japan, Taiwan
Next-Level ShakeZoning for Nevada Based on: Wave Physics Geological & Geotech data: Parcel Map unsurpassed Validating against Nevada earthquake records
J. Louie et al., Structures Congress 4/14/2011
Clark County & Henderson Parcel Map10,721 Measurements Urban Areas of County
J. Louie et al., Structures Congress 4/14/2011
Parcel Mapping
Surface-Wave Arrays
Every One Hand-Modeled
J. Louie et al., Structures Congress 4/14/2011
Blind Tests of Parcel Map Different:
Equipment Field crew Dispersion
interpreter Vs(z) modeler
Match to Map Values:
6 of 93 blind tests >10% off
13.55% max diff. 0.26% bias of
average 4.92% RMS
differenceJ. Louie et al., Structures Congress 4/14/2011
Clark County & Henderson Parcel Map
Parcel Classification
for IBC
NEHRP C & D classes
“C+” class for NEHRP B
velocities with soft surface
J. Louie et al., Structures Congress 4/14/2011
Build Parcel Map into
ShakeZoningDoes it Make a
Difference?
ShakeZoning Geotech Map
Warmer colors: lower Vs30 (meter)
Parcel Map on top of IBC default Vs30
J. Louie et al., Structures Congress 4/14/2011
Adding Fault and Basin Geology
Black Hills Fault in Google Earth with USGS Qfaults trace
USGS Basin Map
J. Louie et al., Structures Congress 4/14/2011
Adding Physics
Black Hills M6.5 event Short trace but 4-m scarps
noted Viscoelastic finite-
difference solution 0.5-Hz frequency 0.20-km grid spacing A few hours on our small
cluster Mode conversion, rupture
directivity, reverberation, trapping in basins
J. Louie et al., Structures Congress 4/14/2011
Black Hills M6.5 Scenario Results
Max Peak Ground Velocity (PGV) >140 cm/sec
PGV over 60 cm/sec (yellow) bleeds into LVV through Railroad Pass
Large event for a short fault Unlikely, but add to hazard
probabilistically Need to know how unlikely
J. Louie et al., Structures Congress 4/14/2011
Surprising Effect of Parcel Map Over IBC Defaults1-D Amplification Used in IBC, ShakeMap
3-D Amplification from ShakeZoning
J. Louie, NESC 2/9/2011
ShakeMap versus ShakeZoning•Yellow is 60 cm/sec on both•Geotech estimated from topography
•ShakeZoning shows trapping in basins•Hazard map is difficult to predict
J. Louie, NESC 2/9/2011
Frenchman Mountain Fault M6.7 ScenarioPossible Scarp in Neighborhood
Event Inside the LVV Basin
J. Louie, NESC 2/9/2011
2-Segment Frenchman Mtn. Fault M6.7
J. Louie, NESC 2/9/2011
Effect of Parcel Map Over IBC Defaults
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.
J. Louie et al., Structures Congress 4/14/2011
With Many Scenarios, Define Probabilistic Hazard
J. Louie, EGGE 3/25/2011
Japan and New Zealand Lesson: Don’t Ignore Worst Case!
dePolo, 2008, NBMG Map 167