integrated seismic hazard
TRANSCRIPT
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Ali O. Oncel Ali O. Oncel Earth Science Department, KFUPMEarth Science Department, KFUPM
Chile University, Department of Geophysics, June 23, 2008Chile University, Department of Geophysics, June 23, 2008
Integrated Seismic Hazard Integrated Seismic Hazard based onbased on
Seismicity and StrainSeismicity and Strain
Integrated Earthquake Hazard based on Integrated Earthquake Hazard based on Seismicity and Active FaultsSeismicity and Active Faults
Log N = a – b MLog N = a – b M
MAGNITUDE DISTRIBUTION
Log
N
0
1
2
3
4
0 2 4 6 8
MAGNITUDE
23-31°E
b-valueD15
D2
INTEREVENT DISTANCE R (KM)
CO
RR
EL
AT
ION
IN
TE
GR
AL
C( R
>r)
2-10km
10-40km
Full range
Full range 1.44 1.102-10 km 1.73 1.2210-40km 1.40 1.01
Range D2 D15
D (Fractal)-value D (Fractal)-value : : • DD22>D>D33>……>D>……>D1515 ⇒⇒
heterogeneous heterogeneous • DD22=D=D33=……=D=……=D1515 ⇒⇒
homogeneoushomogeneous
b-value b-value : : Material Material
heterogeneityheterogeneity• Applied shear stress Applied shear stress
levellevel• bbhighhigh ……>creeping ……>creeping• BBlow low …….> asperity…….> asperity
Fractal Statistics
A FR IC A N PLA TE
8
BLACK SEA
3
1
24
9
8 7
6 5
1312
11 10
15 14
1617
18
19
20
21
24
M >2.9h< 39km1981-1988
Shear Z oneE xtension al ZoneCom pressional ZoneGPS control points
23 24 25 26 27 28 29 30 3133
34
35
36
37
38
39
40
41
42
43
Mw 6.4 1995
Mw 5.8 1997
Mw 6.6 1982
Mw 6.6 1983
Mw 6.8 1981
Mw 6.2 1996
Mw 5.6 1996
25
Mw 5.5 1994
22
23
23 24 25 26 27 28 29 30 3133
34
35
36
37
38
39
40
41
42
43
23
87
6
12
11
15
17
18
19
20
21
24
25
23
22
23
1
4
9
13
5
10
14
16
0 20
40
60
80
10
0
12
0
14
0
16
0
18
0
20
0
22
0
24
0
26
0
28
0
Shear Strain
nstrain/a
23 24 25 26 27 28 29 30 3133
34
35
36
37
38
39
40
41
42
43
-70
-60
-50
-40
-30
-20
-10
0 10
20
30
40
50
60
70
80
90
10
0
11
0
87
6
12
11
15
17
18
19
20
21
24
Compr. Extens.
nstrain/a
25
23
22
23
1
4
9
13
5
10
14
16
Strain and earthquake hazardStrain and earthquake hazard
Contour maps of GPS derived shear and dilatation are shown in the maps above (middle and right maps, Contour maps of GPS derived shear and dilatation are shown in the maps above (middle and right maps, respectively). GPS strains were derived by Kahle et al. (2000) from GPS velocity data presented by respectively). GPS strains were derived by Kahle et al. (2000) from GPS velocity data presented by McCloskey et al. (2000) for the western Turkey and eastern Mediterranean area examined in this paper. McCloskey et al. (2000) for the western Turkey and eastern Mediterranean area examined in this paper. Average shear and dilatation in each seismic zone were estimated by averaging contour values of shear Average shear and dilatation in each seismic zone were estimated by averaging contour values of shear and dilatation observed on the regular grid of points highlighted in the map above.and dilatation observed on the regular grid of points highlighted in the map above.
GPS control points are shown along with events of magnitude M>3.0 recorded between 1981 and 1998. GPS control points are shown along with events of magnitude M>3.0 recorded between 1981 and 1998. The 25 seismic zones into which the area was subdivided for analysis and comparison are also outlined.The 25 seismic zones into which the area was subdivided for analysis and comparison are also outlined.
A FR IC AN PLATE
8
BLACK SEA
3
1
24
9
8 7
6 5
1312
11 10
15 14
1617
18
19
20
21
24
M >2.9h< 39km1981-1988
Shear ZoneExtensional ZoneCom pressional ZoneG PS control points
23 24 25 26 27 28 29 30 3133
34
35
36
37
38
39
40
41
42
43
Mw 6.4 1995
Mw 5.8 1997
Mw 6.6 1982
Mw 6.6 1983
Mw 6.8 1981
Mw 6.2 1996
Mw 5.6 1996
25
Mw 5.5 1994
22
23
D2 D15 D2 D15 D2 D15 b ML-
MU
Shear
Dilitation1 1.44 1.1 1.73 1.22 1.4 1.01 1.51 2.6-5.0 161.79 19.38
2 1.43 1.07 1.81 1.33 1.43 1.12 1.39 2.6-5.5 201.07 3.633 1.62 1.42 1.9 1.28 1.49 1.26 1.47 3.1-4.8 164.82 12.884 1.24 0.84 1.86 1.5 1.02 0.64 1.11 3.5-6.0 191.60 25.857 1.53 1.24 1.94 1.48 1.48 1.23 1.24 3.2-6.0 101.71 55.878 1.32 0.86 1.85 1.13 1.37 0.92 1.16 3.2-4.9 189.45 3.889 1.18 0.83 1.86 1.4 1.14 0.64 0.97 3.0-5.3 146.38 11.555 1.07 0.73 1.85 1.59 0.95 0.57 1.75 2.6-4.7 41.02 36.216 1.33 0.92 1.81 1.56 1.22 0.78 1.81 2.7-4.8 78.75 33.68
10 0.89 0.58 1.46 0.95 0.87 0.46 1.35 3.0-4.8 70.32 44.6911 1.48 1.2 1.83 1.37 1.53 1.24 1.39 3.0-5.8 102.35 40.9612 1.52 1.26 1.89 1.37 1.53 1.39 1.5 3.2-5.1 72.75 75.8313 1.36 1 1.86 1.71 0.75 0.41 1.1 3.1-5.5 89.26 25.5114 1.4 1.08 1.79 1.26 1.4 1.19 1.32 2.9-5.5 78.81 53.6615 1.57 1.26 1.93 1.36 1.59 1.31 1.28 3.1-5.4 78.25 54.3916 1.38 0.99 1.42 0.97 1.24 0.94 1.4 3.1-5.4 47.99 38.1217 1.42 1.05 1.78 1.44 1.37 1 1.22 3.2-5.4 50.59 37.2218 1.61 1.32 1.9 0.81 1.64 1.43 1.25 3.6-4.9 58.89 80.9119 1.43 1.18 1.88 1.16 1.2 0.88 0.67 3.5-5.2 38.75 22.0920 1.74 1.5 1.81 1.04 1.77 1.64 1.44 3.5-5.3 68.88 20.7621 1.44 1.09 1.79 1.51 0.92 0.55 1.21 3.7-5.0 95.04 18.2722 1.68 1.38 1.87 1.12 1.63 1.39 1.49 3.2-4.6 54.22 10.2123 1.63 1.04 1.82 1.27 1.61 0.99 1.24 3.8-5.7 107.79 -22.8724 1.65 1.23 1.57 0.93 1.75 1.47 1.08 3.7-5.5 103.39 -40.3925 1.45 1.09 2 1.07 1.55 1.08 1.21 3.5-5.8 75.28 -16.12
Complex VariablesComplex Variables
D2 D15 D2 D15 D2 D15 b Shear Dilitation
1.43/1.39 1.07/1.05 1.86/1.85 1.33/1.33 1.4/1.33 1.01/0.97 1.24/1.26 164.8/165.3 12.88/19
1.41/1.37 1.06/1.05 1.84/1.78 1.36/1.29 1.3/1.27 0.97/0.97 1.34/1.34 71.54/67.3 39.5/45.3
1.64/1.6 1.16/1.22 1.82/1.81 1.1/1.16 1.62/1.54 1.24/1.19 1.23/1.28 85.16/84.1 -3/-5
Median/mean values of multifractal correlation dimensions DMedian/mean values of multifractal correlation dimensions D22 and D and D1515 are are
tabulated for the full range, 2 to 10km range and 10 to 40 km range for each tabulated for the full range, 2 to 10km range and 10 to 40 km range for each tectonic subdivision of the study area (shear, extension, and compression). tectonic subdivision of the study area (shear, extension, and compression). The median/mean values of b, shear, and dilatation are also listed for each The median/mean values of b, shear, and dilatation are also listed for each tectonic region.tectonic region.
Over the full range:Over the full range: D D22 measured in the region of compression is statistically greater than measured in the region of compression is statistically greater than
DD22 in the regions of extension and shear. D in the regions of extension and shear. D1515 is less than D is less than D22 in all cases in all cases..Over the 2-10 km scaleOver the 2-10 km scale: Statistically significant differences between regions are not : Statistically significant differences between regions are not observed.observed.
Over the 10-40km scale:Over the 10-40km scale: The larger value of D in the region of compression suggests The larger value of D in the region of compression suggests that differences observed over the full range are primarily associated with variations that differences observed over the full range are primarily associated with variations occurring at larger 10-40km scalesoccurring at larger 10-40km scales..
Regional comparison betweenRegional comparison between seismicity and GPS strainseismicity and GPS strain
The correlation coefficient, r The correlation coefficient, r = 0.81= 0.81
The probability (p) that the The probability (p) that the slope of the regression line slope of the regression line could actually be zero is could actually be zero is 0.026 in this case. 0.026 in this case.
Cross-plot of b values and DCross-plot of b values and D22 from the from the Northern Anatolian Fault ZoneNorthern Anatolian Fault Zone
D2 D15 b Shear Dilat D2 D15 b Shear Dilat D2 D15 b Shear Dilat
D2 0.97 0.81 -0.29 0.28 0.5 -0.39 -0.49 0.49 0.96 0.74 -0.26 0.08
D15 0 0.75 -0.38 0.31 0.25 -0.4 -0.39 0.65 0 0.77 -0.28 0.23
b 0.03 0.05 -0.1 -0.06 0.39 0.37 -0.1 -0.06 0.06 0.05 -0.1 -0.06Shear 0.52 0.4 0.83 -0.79 0.26 0.39 0.83 -0.79 0.57 0.54 0.83 -0.79Dilat 0.55 0.5 0.9 0.03 0.26 0.12 0.9 0.03 0.86 0.63 0.9 0.03Over the full range: Over the full range: A significant positive correlation is observed between A significant positive correlation is observed between seismic clustering (D) and the Gutenberg-Richter b value along the NAFZ seismic clustering (D) and the Gutenberg-Richter b value along the NAFZ strike slip zone.strike slip zone.Over the 10 -40 km scale: Over the 10 -40 km scale: A A nearly significant relationship between b and nearly significant relationship between b and D is observed (r = 0.74, p = 0.06) and suggests that the relationship is D is observed (r = 0.74, p = 0.06) and suggests that the relationship is primarily associated with deeper or regional scale seismicity since primarily associated with deeper or regional scale seismicity since significant correlation is not observed significant correlation is not observed over the 2 to 10 km scaleover the 2 to 10 km scale..
No correlation was observed between seismicity ( b, DNo correlation was observed between seismicity ( b, D22, D, D1515) and GPS ) and GPS
strain.strain.
Seismicity and GPS strainSeismicity and GPS strain
NegativeCorrelation
Large-magnitude events
Izmit EarthquakeIzmit EarthquakeIncreased b and decreased DIncreased b and decreased DCC suggest that the suggest that the
rise in the level of low magnitude seismicity and rise in the level of low magnitude seismicity and high intensity clustering along the western high intensity clustering along the western portion of NAFZ did not completely release portion of NAFZ did not completely release stress transferred into this segment of the fault stress transferred into this segment of the fault zone (zone (Oncel et al., 1995, Oncel et al., 1995, Non.Lineer.Geophysics; Oncel and Wilson, Non.Lineer.Geophysics; Oncel and Wilson, 2001, BSSA2001, BSSA).).
This combination of factors - westward migration This combination of factors - westward migration along with increased levels of low magnitude along with increased levels of low magnitude seismicity and higherseismicity and higher intensity seismic clustering - intensity seismic clustering - are indicators of increased seismic risk in the area.are indicators of increased seismic risk in the area.
Low-magnitude events(Preshocks)
PositiveCorrelation
D2 D15 b Shear Dilat D2 D15 b Shear Dilat D2 D15 b Shear Dilat
D2 0.98 -0.29 0.18 0.4 0.48 -0.13 0.18 0.2 0.98 0 0.13 0.67
D15 0 -0.38 0.18 0.46 0.12 0.28 0.31 -0.44 0 -0.05 0.15 0.73
b 0.36 0.23 0.18 0.21 0.69 0.38 0.18 0.21 1 0.88 0.18 0.21Shear 0.57 0.59 0.57 0.13 0.57 0.34 0.57 0.13 0.68 0.65 0.57 0.13Dilat 0.19 0.13 0.51 0.67 0.54 0.15 0.51 0.67 0.02 0.01 0.51 0.67
Over the 2-10 km scale: Over the 2-10 km scale: Significant correlation is not observed between Significant correlation is not observed between seismic clustering and dilatation.seismic clustering and dilatation.
Over the full range: Over the full range: Significant correlation between b and D is not Significant correlation between b and D is not observed.observed.
Over the 10 -40 km scale: Over the 10 -40 km scale: In this subdivision, seismic clustering (DIn this subdivision, seismic clustering (D22 and and
DD1515) correlate positively with dilatation (r = 0.67 and 0.73 with p = 0.02 and ) correlate positively with dilatation (r = 0.67 and 0.73 with p = 0.02 and
0.01 respectively). The correlations suggest that increased rates of 0.01 respectively). The correlations suggest that increased rates of extension produce increasingly dispersed seismicity. extension produce increasingly dispersed seismicity.
Seismicity and GPS strain Seismicity and GPS strain
D2 D15 b Shear Dilat D2 D15 b Shear Dilat D2 D15 b Shear Dilat
D2 0.76 0.51 -0.25 0.03 0.21 0.44 -0.54 0.38 0.9 0.22 -0.22 -0.41
D15 0.08 0.71 -0.68 0.47 0.69 -0.02 0.26 0.46 0.01 0.39 -0.44 -0.1
b 0.3 0.12 -0.83 0.73 0.38 0.97 -0.83 0.73 0.68 0.45 -0.83 0.73Shear 0.64 0.14 0.04 -0.6 0.26 0.62 0.04 -0.6 0.68 0.39 0.04 -0.6Dilat 0.96 0.34 0.1 0.21 0.46 0.37 0.1 0.21 0.43 0.84 0.1 0.21
One would expect seismicity to correlate moreso with dilatation in a subduction zone. One would expect seismicity to correlate moreso with dilatation in a subduction zone. However, dilatation along the subduction zone is on average only slightly negative.However, dilatation along the subduction zone is on average only slightly negative. Dilatation is positive in the areas to the northeast (17 nstrain/a) and negative (-29 nstrain/a) Dilatation is positive in the areas to the northeast (17 nstrain/a) and negative (-29 nstrain/a) farther west along the subduction zone. This combination of positive and negative dilatation farther west along the subduction zone. This combination of positive and negative dilatation along the subduction zone is probably responsible for the lack of a more significant correlation along the subduction zone is probably responsible for the lack of a more significant correlation between b and dilatation. between b and dilatation. The change of dilatation from positive to negative as one goes east to west along the The change of dilatation from positive to negative as one goes east to west along the subduction zone suggests a transition in plate interaction from transtensional to transpressive.subduction zone suggests a transition in plate interaction from transtensional to transpressive.
Over the full range: Over the full range: Variations of b value correlate negatively with shear (r = -0.83, p = 0.04) Variations of b value correlate negatively with shear (r = -0.83, p = 0.04) in the zones of this subdivision. The correlation of b to dilatation is weakly positive (r = 0.73, p = in the zones of this subdivision. The correlation of b to dilatation is weakly positive (r = 0.73, p = 0.1). 0.1).
Seismicity and GPS strain Seismicity and GPS strain
Mean magnitude and Geodetical StrainMean magnitude and Geodetical StrainIntegrated Earthquake Hazard based on Integrated Earthquake Hazard based on Seismicity and Geodetical MomentSeismicity and Geodetical Moment
Seismic b-value and average dilatation are positively related (r=0.5, p=0.05). D2 correlates negatively with maximum Geodetic Strain and Shear Strain (r=-0.56. p=0.03 and r=-0.56, p=0.02).
A s p e r it y b a s e d H a z a r d M o d e l
TTLL(M) = dT/10 (M) = dT/10 (a-bM)(a-bM)
Oncel and Wyss, 2000Oncel and Wyss, 2000
Asperity Hazard Model
•• within the northern
Marmara Sea region.
Maps of recurrence interval are shown for (a) Hs = Maps of recurrence interval are shown for (a) Hs = 12.5km over the region of analysis conducted by 12.5km over the region of analysis conducted by Oncel and Wyss (2000) and (b) Hs =4km .Oncel and Wyss (2000) and (b) Hs =4km .
Geodetical Moment Rate Geodetical Moment Rate Kostrov 1974Kostrov 1974
Geodetical Strain Rate Geodetical Strain Rate Ward, 1994Ward, 1994
Oncel and Wilson, 2006Oncel and Wilson, 2006
NBFNBFCMFCMF