Last Updated : August 30, 2018

The 2018 Lombok Island, Indonesia Earthquake: Crustal deformation detected by ALOS-2 data

Crustal Deformation Observed by Synthetic Aperture Radar (SAR)

Released: Jul. 31, 2018, updated: Aug. 30, 2018, Japanese version of this page

Summary

[Update on August 30, 2018] 
An earthquake (Mw 6.9, USGS) occurred in Lombok island, Indonesia on August 19, 2018 (UTC). To measure the crustal deformation caused by this earthquake, we applied interferometric analysis using ALOS-2/PALSAR-2 data. The analysis result shows that the crustal deformation occurred in the northern part of the island.

[Update on August 17, 2018] 
An earthquake (Mw 6.9, USGS) occurred in Lombok island, Indonesia on August 5, 2018 (UTC). To measure the crustal deformation caused by this earthquake, we applied interferometric analysis using ALOS-2/PALSAR-2 data. The analysis result shows that the crustal deformation occurred in the northern part of the island.

[Update on July 31, 2018]
An earthquake (Mw 6.4, USGS) occurred in Lombok island, Indonesia on July 28, 2018 (UTC). To measure the crustal deformation caused by this earthquake, we applied interferometric analysis using ALOS-2/PALSAR-2 data. The analysis result shows that the crustal deformation occurred in the northern part of the island.

SAR Interferograms


Fig.1 SAR interferogram [PNG: 1.4MB]
※We applied the Split Spectrum method (Gomba et al.,2016) to reduce the ionospheric noise. Figure 4-a shows the image before the noise reduction processing.


Fig.2 SAR interferogram [PNG: 1.5MB]
※We applied the Split Spectrum method (Gomba et al.,2016) to reduce the ionospheric noise. Figure 4-b shows the image before the noise reduction processing.


Fig.3 SAR interferogram [PNG: 1.5MB]
※We applied the Split Spectrum method (Gomba et al.,2016) to reduce the ionospheric noise. Figure 4-c shows the image before the noise reduction processing.

 
           Fig.4-a [PNG: 1.5MB]                         Fig.4-b [PNG: 1.5MB]                         Fig.4-c [PNG: 1.4MB]
Fig.4 SAR interferogram (before the ionospheric noise reduction)

 
Fig.
#
Date Time
(UTC)
Flight
Dir.
Beam
Dir.
Obs.
Mode*1
Incidence Angle
(around epicenter)
Bperp KMZ
1 2018/08/12
2018/08/26
03:57 Des. Right W-W 29° -82m 0.8MB
2 2018/07/29
2018/08/12
03:57 Des. Right W-W 29° +10 m 0.9MB
3 2018/07/15
2018/07/29
03:57 Des. Right W-W 29° -58 m 0.9MB

*1 W: ScanSAR (Normal)
(cf. ALOS-2 Project / PALSAR-2 (JAXA))

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

The 2018 Lombok island Indonesia Earthquake

Date-Time August 19, 2018, 14:56(UTC)
Hypocenter
Location
8.330°S、116.631°E、Depth:25.2 km
(USGS, as of Auhust 30, 2018)
Magnitude Mw=6.9(USGS, as of August 30, 2018)
 
Date-Time August 5, 2018, 11:46(UTC)
Hypocenter
Location
8.260°S、116.436°E、Depth:31.0 km
(USGS, as of Auhust 17, 2018)
Magnitude Mw=6.9(USGS, as of August 17, 2018)
 
Date-Time July 28, 2018, 22:47(UTC)
Hypocenter
Location
8.274°S、116.491°E、Depth:6.4 km
(USGS, as of July 31, 2018)
Magnitude Mw=6.4(USGS, as of July 31, 2018)

                Fig. 5. Deformation predicted by CMT solution (Mw=6.4 July 28) [PNG: 1.7MB]

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
YAMADA Shinya : Researcher
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