Download presentation
Presentation is loading. Please wait.
Published byBrendan Simmons Modified over 9 years ago
1
The 2003 Bam, Iran earthquake: what we knew, what we didn’t know and what we expect in the future Gareth Funning (University of California, Berkeley) with Eric Fielding (JPL), James Jackson (Cambridge), Barry Parsons & Richard Walker (Oxford), Morteza Talebian (Geological Survey of Iran)
3
26th December 2003, M w 6.6 Death toll 26,000 26th December 2003, 5.26 am local time M w 6.6 Official death toll 26,000 (some estimates 40,000+) Peak ground acceleration 0.97 g in city centre S-P time 1.9 s in city centre (i.e. 14 km from hypocentre)
4
Tectonic setting SRTM shaded- relief topography Bam
5
Tectonic setting SRTM shaded- relief topography Nayband fault Gowk fault Sabzevaran fault Jebal Barez mountains Dasht-e Lut Bam
6
Tectonic setting SRTM shaded- relief topography Nayband fault Gowk fault Sabzevaran fault Jebal Barez mountains Dasht-e Lut 2003, M w 6.6 1989, M w 5.8 1981, M w 6.6 1998, M w 6.6 1981, M w 7.1 2005, M w 6.3
7
Tectonic setting SRTM shaded- relief topography Nayband fault Gowk fault Sabzevaran fault Dasht-e Lut NEIC Jebal Barez mountains
8
Tectonic setting SRTM shaded- relief topography Nayband fault Gowk fault Sabzevaran fault Dasht-e Lut Jebal Barez mountains
9
The Bam fault LANDSAT-7 ETM 541 false colour green=vegetation Bam 10 km Baravat The Bam fault is a prominent ridge running between Bam and Baravat
10
Walker & Jackson, 2002
11
The Bam fault Post-earthquake field surveys found only minor cracking at the foot of the ridge… Bam Baravat
12
Preliminary InSAR data Bam 10 km Baravat First Bam interferogram (each colour cycle=2.8cm of deformation) Constructed from Envisat ASAR data released for free by ESA There is a prominent band of incoherence running S of Bam
13
The Bam earthquake main fault Interferometric coherence Red = high Blue = low Constructed from Envisat ASAR data released for free by ESA Bam 10 km Baravat Low coherence indicates vegetation and surface damage
14
The Bam earthquake main fault Surface rupture found in the field – right-lateral offsets of ~20 cm Bam 10 km Baravat
15
The Bam earthquake main fault Surface rupture found in the field – right-lateral offsets of ~20 cm Bam 10 km Baravat
16
The Bam earthquake main fault LANDSAT-7 ETM 541 false colour green=vegetation Bam 10 km Baravat There are no surface features corresponding to this fault – we didn’t know it existed Main fault is ~ 4km west of the mapped Bam fault
17
Coseismic interferograms There is an ‘extra’ amount of displacement in the SE quadrant Ascending interferogram Descending interferogram
18
Single fault model Strike 354 dip 84 rake -177 slip 2.2m length 12km top 1.1km b’m 9.3km Ascending model Descending model Funning et al., 2005
19
Single fault model Large residuals, especially in SE quadrant (rms = 25 mm) Ascending residual Descending residual Funning et al., 2005
20
Two fault model (uniform slip) A ‘teardrop’ feature is reproduced in the SE Ascending model Descending model Funning et al., 2005
21
Two fault model (uniform slip) Improved fit in SE quadrant (rms = 17 mm) Ascending residual Descending residual Funning et al., 2005
22
Two fault model (uniform slip) LANDSAT-7 ETM 541 false colour green=vegetation Secondary fault appears to be a southward continuation of the Bam fault
23
P SH Jackson, Bouchon, Fielding, Funning et al., 2006
24
P SH Jackson, Bouchon, Fielding, Funning et al., 2006
25
two sources one source PSH Jackson, Bouchon, Fielding, Funning et al., 2006
26
Aftershock distribution Seismogenic crust may extend ~10 km below the rupture Jackson, Bouchon, Fielding, Funning et al., 2006
27
Strong motions & directivity Rupture velocity of 2.8 km/s ≈ Rayleigh wave velocity Jackson, Bouchon, Fielding, Funning et al., 2006
28
Deformation is continuing Fault zone collapse and postseismic uplift resolved with InSAR Eric Fielding Jan 2004-Mar 2006
29
The Bam earthquake: findings The mainshock occurred on a blind fault; not the mapped fault Average slip was 2 m at 2–10 km The pattern of surface displacements suggests secondary oblique motion on a W-dipping fault Seismic data are consistent with 2 sub events Significant unruptured fault area may remain
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.