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The 2017 Iran-Iraq Earthquake: Crustal deformation detected by ALOS-2 data

Crustal Deformation Observed by Synthetic Aperture Radar (SAR)

Released: Nov. 15, 2017, Last updated: Nov. 16, 2017 Japanese version of this page

Summary

A large earthquake (Mw 7.3, USGS) occurred near the Iran-Iraq border on November 12, 2017. Serious damage such as building collapse and many deaths (> 500) has been reported around the epicenter. To measure the crustal deformation caused by the earthquake, we applied interferometric analysis using ALOS-2/PALSAR-2 data.

The results obtained from the data are summarized as follows.

[Features of the crustal deformation]
  • Large displacement (~90 cm upward and ~50 cm westward) has been detected around 20 km NNW of Sarpol-e Zahab (Figs. 1 and 2).
  • Around the epicenter, ~30 cm downward and ~35 cm westward displacement has been detected (Figs. 1 and 2).
  • The area with more than 10 cm displacement extends ~80 km in diameter (Figs. 1 and 2).
  • The detected deformation pattern implies that reverse slip on a low dip angle fault plane with the strike of NNW-SSE direction occurred (Fig. 7). This mechanism is consistent with the one estimated from seismic waves.
  • Apart from the deformation associated with the fault slip, lots of localized displacements have been detected at mountain slopes, and might have been triggered by the seismic motion (Figs. 4bc and 5bc).

[Fault model]
  • We constructed a fault model (slip distribution) from the crustal deformation measured by InSAR (Fig. 7).
  • The estimated slip centered at the south of epicenter, and reached 3 m.
  • The estimated moment magnitude (Mw) is 7.36 (seismic moment 1.4 x 1020 Nm).

Quasi up-down and east-west components of displacement

Fig1QUD

Fig. 1. Quasi UD [PNG: 2.67MB] [KMZ: 151KB]

Fig2QEW

Fig. 2. Quasi EW [PNG: 2.71MB] [KMZ: 155KB]

 

2.5-D analysis
Two or more line-of-sight displacements with different observing directions (Figs. 4 and 5) can be decomposed to quasi up-down and east-west components.
Fig3:geometry2.5d
Fig. 3. Geometry of 2.5-D analysis


SAR Interferograms

Fig4AscIfg
Fig. 4. [PNG: 6.72MB]

Fig5DesIfg
Fig. 5. [PNG:6.06MB]
 
Fig.
#
Date Time
(UTC)
Flight
Dir.
Beam
Dir.
Obs.
Mode
*1
Incidence
Angle
(Epicenter)
Bperp KMZ
4 2016/08/09
2017/11/14
20:59 Asc. Right W-W 47° -70 m (a)8.24MB
(b, c)2.33MB
5 2017/10/04
2017/11/15
08:49 Des. Right W-W 47° +160 m (a)4.37MB
(b, c)1.42MB

*1 W´╝ÜScanSAR (Normal)
(cf. ALOS-2 Project / PALSAR-2 (JAXA))


Fig. 6. Area of interest

Analysis by GSI from ALOS-2 raw data of JAXA.
These results were obtained through the activity of the SAR analysis working group of the Coordinating Committee for Earthquake Prediction.

Fault model

Fig7:Fault model
Fig. 7. Constructed fault model [PNG: 867KB]

The 2017 Iran-Iraq Earthquake

Date-Time November 12, 2017, 18:18 (UTC)
Hypocenter
Location
34.905°N, 45.956°E, Depth: 19.0 km
(USGS, as of November 15, 2017)
Magnitude Mw=7.3
(USGS, as of November 15, 2017)

Satellite

ALOS-2 (Advanced Land Observing Satellite 2) launched by Japan Aerospace Exploration Agency on May 24, 2014

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Contact

YARAI Hiroshi : Head of Division
KOBAYASHI Tomokazu : Chief Researcher
MORISHITA Yu : Chief Researcher
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