response at regional scale focusing on 2005 Kashmir Earthquake - - PowerPoint PPT Presentation
Impact of topography on amplification of seismic response at regional scale focusing on 2005 Kashmir Earthquake Muhammad Shafique Faculty of Geo-Information Science and Earth National Centre of Excellence in Geology, Observation, University of
Impact of topography on amplification of seismic response at regional scale focusing on 2005 Kashmir Earthquake Muhammad Shafique
National Centre of Excellence in Geology, University of Peshawar, Peshawar, Pakistan Faculty of Geo-Information Science and Earth Observation, University of Twente Enschede, The Netherlands
Natural Hazards
Floods Landslides Hurricanes Typhoons Earthquakes Tsunamis
Earthquakes in action
Indian plate movement in time
Source: USGS
Topography and active tectonics in Pakistan
54 +/- 5 mm/yr
Seismicity in Pakistan and Surroundings since 1901
Location of past earthquakes and seismic gaps around Indian plate
Source: Aydan, 2006
Earthquake secondary hazards
Earthquakes Tsunami Liquefaction Fire Floods Landslides Ground Shaking
Surface
. . . . . . . . . . .
Hypocenter
MEDIUM EFFECTS SITE EFFECTS SOURCE EFFECTS Bed rock Topographic effects Regolith thickness effects Geologic effects
Earthquake ground shaking
IMPACT OF TOPOGRAPHY ON SEISMIC RESPONSE
INCIDENT SEISMIC WAVES
Kashmir earthquake
Date: 8th October 2005 Magnitude: 7.6 Depth: 10 Km Epicenter: 34.43ºN, 73.53ºE Death Toll: 80,000 Economic Loss: 5 billion US$
Pakistan
80°E 80°E 60°E 60°E 70°E 70°E 30°N
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Kohistan Mansehra Ghizer Neelum Buner Haripur Bagh Diamir Swabi Shangla Muzaffarabad Abbottabad Batagram Attock Poonch Rawalpindi Mardan Upper Dir 74°0'0"E 74°0'0"E 73°0'0"E 73°0'0"E 35°0'0"N 34°0'0"N
20 40 60 80 10 Kilometers
Location Map
Pakistan
Framework of the study
Topographic seismic response at regional scale
Seismic Modeling
Topographic Parameters
Seismic Parameters
Topographic seismic response at regional scale
Seismic Modeling
Topographic Parameters
Seismic Parameters
Framework of the study
Data utilized
(90m)
Reflection Radiometer (ASTER) DEM (30m)
Numerical models Literature on topographic seismic modeling Slope Angle Height from local base level Aspect
SRTM & ASTER DEMs Kashmir earthquake induced seismic waves wavelength Topographical Seismic Zonation Sensitivity analysis
TAF from ASTER & SRTM
Uncertainty in TAF Horizontal and vertical TAF
Methodology
Digital Terrain Representation
Vector Representation Raster Representation Point Contour DSM DTM TIN DEM
Uncertainities with Satellite Remote Sensing DEM
Absolute Horizontal Accuracy Relative Horizontal Accuracy Absolute Vertical Accuracy Relative Vertical Accuracy Random Errors Systematic Errors Blunders Edge Matching Errors Slope Errors Areas of Constant Error
General Errors Specific Errors
DEM Uncertainties
void areas suspect areas water bodies
Disparity of SRTM and ASTER DEMs
Correlation ( SRTM-ASTER) Minimum Mean Standard Deviation Maximum
32.80 71.11 1621
Impact of DEM resolution on aspect computation
N.W N.W W N.W E S S.W E N.E 1 m S N.W E N.E 5 m S N.W E N.E 15 m S W E N.E 30 m S N.W E E 90 m 10.82 0.86 1.22 10.20 31.30 1 m 9.20 0.86 0.74 10.10 24.23 5 m 7.04 1.74 0.62 10.55 20.24 15 m 8.04 1.65 0.43 2.18 15.10 30 m 6.35 3.39 0.61 2.15 8.04 90 m
Impact of DEM resolution on slope computation
Impact of DEM uncertainty on topographic attributes using Monte Carlo Simulations
Random numbers field Filtered random error field
Original DEM + Filtered random error field
Slope Aspect Aspect Slope Original DEM
Subtract Subtract
Statistical summary Statistical summary Residual slope Residual aspect
Step1 Step 2 Step 3 Step 4 Step 5
INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION
Step 1 Step 4 Step 3 Step 2 Step 5
Disparity Atb from
Realisa- tion Error + DEM Filtered E.M Error Map Random numbers Minus Terrain Attributes Plus L.P Filter DEM RMSE
Uncertainties in Slope computation ASTER
6.001 0.595 2.853 0.005 Slope (degrees) Max Stand Dev Mean Min
SRTM
1.67 0.17 0.93 0.03 Slope (degrees) Max Stand Dev Mean Min
Uncertainties in Aspect computation ASTER
179.68 45.94 41.41 Aspect (Degrees) Max Stand Dev Mean Min
SRTM
179.61 38.68 22.69 0.2 Aspect (Degrees) Max Stand Dev Mean Min
TAF vs crest/base ratio comparison amplification
9 . 1 02 . 2 225 . 1
3 6 2 4 . max ,
I I I H Ah
5 . 5 5 . 8 . max ,
15 . 1 5 . 1 75 . I I H A
v
Models for horizontal and vertical TAF prediction
Horizontal TAF Vertical TAF Source: Bouckovalas et al. (2006)
Where H = Height from base level I = Slope angle = Wavelength ξ = Material damping Ah,,max = Horizontal TAF Av,max = Vertical TAF
Seismic waves behavior in the assumed scenario
H
H Incident SV seismic waves
Homogenous soil and geological environment
Free Field Free Field Crest Crest Toe Toe "
#
" " "
# #
Local minima for terrain height estimation
Interpolate local Minima Base level DEM – Base level Height from local minima
Instrumental Ground Shaking Records Decay of Wavelength with Distance
Average Decay of Wavelength Per meter = 0.055m
Epicenter
Wavelength Estimation
Abbotabad accelerograph
Time of peak acceleration 0.8 s Sv velocity 3.2 km/s Dominant wavelength (using eq. 4.3) 0.8 x 3200 = 2560m Distance from epicenter 48.028 km Wavelength decay per meter 0.053302
Muree accelerograph
Time of peak acceleration 1.2 s Sv velocity 3.2 km/s Dominant wavelength (using eq. 4.3) 1.2 x 3200 = 3840m Distance from epicenter 69.218 km Wavelength decay per meter 0.055477
Nilore accelerograph
Time of peak acceleration 1.8 s Sv velocity 3.2 km/s Dominant wavelength (using eq. 4.3) 1.8 x 3200 = 5760m Distance from epicenter 99.519 km Wavelength decay per meter 0.057878 Average wavelength damping per meter
0.053302 + 0.055477 + 0.057878 = 0.166658 / 3 = 0.055553
Spatial distribution
Horizontal aggravation of topographic seismic response
SRTM Horizontal TAF ASTER Horizontal TAF
Epicenter Epicenter
Sensitivity analysis
Model Parameter Predicted results Sensitivity analysis TAF Base model Slope 60º Height 400m Wavel 200m Damping 10%
Slope 30º Ah,max 1.10 1.17 1.14 1.08 1.06 Height 200 m Wavel 100 m Av,max 0.76 2.85 1.33 0.44 0.69 Damp 5%
Wavel = Wavelength Ah,max = Horizontal TAF Av,max = Vertical TAF
Slope angle is predicted to be sensitive terrain feature to topographic seismic response
Impact of DEM Inherent errors on TAF prediction
TAF Slope (30º) Slope (32.853º) Slope (27.147º) Uncertainty Ah,max 1.104 1.103 1.105 0.002 Av,max 0.765 0.831 0.708 0.123 TAF Slope (30º) Slope (30.935º) Slope (29.065º) Uncertainty Ah,max 1.104 1.104 1.104 0.001 Av,max 0.765 0.786 0.746 0.040
ASTER SRTM
Impact of DEM resolution on TAF prediction
SRTM DEM ASTER DEM Disparity Min Max Min Max Min Mean Max Ah,max 1 1.43 1 1.66
0.003 0.227 Av,max 12.04 23.71
0.030 6.521
Impact of direction of incident waves on seismic induced ground failures during Kashmir earthquake
100.00 14604800 Total 26.42 3859200 West 30.19 4409600 Southwest 23.71 3462400 South 8.94 1305600 Southeast 3.72 544000 East 2.98 435200 Northeast 3.94 576000 North 0.09 12800 Flat
% of total Area Area (m2) Direction Ground failures map courtesy of , HIC-Pakistan
80.32% of seismic induced landslides were facing away from epicenter
SRTM is more consistent in slope and aspect computation than ASTER, but not necessarily more accurate! Slope geometry is sensitive topographic parameter to the topographic seismic response DEM inherent errors and resolution have less impact on predicted TAF Significant impact of direction of incident seismic waves on ground amplification and seismic induced landslides
Recommendations for follow up
Tracing of seismic waves in 3D topographic model Predict impact of direction of incident seismic waves on TAF prediction Predict role of soil type and depth on seismic response Predict impact of local lithology on seismic response Near real time seismic ground shaking maps
9 . 1 02 . 2 225 . 1
3 6 2 4 . max ,
I I I H Ah
5 . 5 5 . 8 . max ,
15 . 1 5 . 1 75 . I I H A
v
Models for horizontal and vertical TAF prediction
Horizontal TAF Vertical TAF Source: Bouckovalas et al. (2006)
Where H = Height from base level I = Slope angle = Wavelength ξ = Material damping Ah,,max = Horizontal TAF Av,max = Vertical TAF
Impact of DEM Inherent errors on TAF prediction
TAF Slope (30º) Slope (32.853º) Slope (27.147º) Uncertainty Ah,max 1.104 1.103 1.105 0.002 Av,max 0.765 0.831 0.708 0.123 TAF Slope (30º) Slope (30.935º) Slope (29.065º) Uncertainty Ah,max 1.104 1.104 1.104 0.001 Av,max 0.765 0.786 0.746 0.040
ASTER SRTM
Location map of study area
Epicenter
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Athmuqam Bala Kot Abbottabad Mansehra Hattian Muzaffarabad Dhir Kot
73°40'0"E 73°40'0"E 73°20'0"E 73°20'0"E 34°20'0"N 34°0'0"N
Epicenter
5 10 15 20 25 2.5 Kilometers
Histogram of SRTM and ASTER DEMs disparity
INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION
(Pedersen et al., 1994) (Assimaki et al., 2004) (Bouckovalas et al., 2005) (Ashford et al., 1997)
D B C A
Approaches of Estimating Height for Topographic Seismic Modeling
Procedure for Executing Monte Carlo Simulations
Sensitivity of Slope and Aspect to Flat and Steep Areas