Last Updated : August 13, 2018

The 2018 Papua New Guinea Earthquake: Crustal deformation detected by ALOS-2 data

Crustal Deformation Observed by Synthetic Aperture Radar (SAR)

Released: Mar. 1, 2018, updated: Aug. 13, 2018, Japanese version of this page


A large earthquake (Mw 7.5, USGS) occurred in Papua New Guinea on February 25, 2018 (UTC). To measure the crustal deformation caused by this earthquake, we applied interferometric analysis using ALOS-2/PALSAR-2 data.

Results obtained from the data analysis are summarized as follows.
  • Significant crustal deformation has been detected in an area with the length of ~170 km in NW-SE direction, including the epicenter, consistent with aftershock locations (USGS).
  • Vertical deformation seems to be mainly uplift because both ascending and descending interferograms show line-of-sight shortening in the similar deformation area.
  • The considerably large displacement has been observed around Lake Kutubu, ~70km ESE of the epicenter, probably with > 1 m uplift.
  • The observed displacement pattern is consistent with a focal mechanism estimated from seismic waves.
  • In addition to the deformation associated with the fault slip, lots of localized displacements have been detected at mountain slopes, and they might have been triggered by the seismic motion.

[Update on August 13, 2018]
A descending interferogram to which ionospheric noise compensation by the split spectrum method (Gomba et al., 2016) has been applied (
Fig. 3) and two new ascending interferograms observed by the Fine [10m] mode were added.

SAR Interferograms

Fig1.Ascending InSAR
Fig.1 Ascending SAR interferogram [PNG: 2.0MB]

Fig2. Descending InSAR
Fig.2 Descending SAR interferogram [PNG: 1.9MB]

Fig.3 Descending SAR interferogram (Ionospheric noise compensation applied) [PNG: 1.9MB]

Fig.4 Ascending SAR interferogram (Fine [10m] mode) [PNG: 1.4MB]

Fig. Area  Fig. Area wide
Area of interest

Date Time
Incidence Angle
(around epicenter)
Bperp Pixel
KMZ Geotiff  
1 2017-07-31
14:46 Asc. Right W-W 34°-42° +75 m ~200m 3.8MB 18.6MB  
2 2018-02-01
02:05 Des. Right W-W 36°-47° -120 m ~50m 21.7MB 171MB  
3 2018-02-01
02:05 Des. Right W-W 36°-47° -120 m ~75m 11.1MB 112MB Ionospheric noise compensation applied
4 2018-01-01
14:46 Asc. Right F-F 39°-42° -270 m ~150m 575KB 4.1MB Ionospheric noise compensation applied
4 2018-01-29
14:46 Asc. Right F-F 34°-39° -30 m ~150m 452KB 4.3MB  

*1 W: ScanSAR (Normal), F:Fine[10m]
(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 Papua New Guinea Earthquake

Date-Time February 25, 2018, 17:44 (UTC)
6.149°N, 142.766°E, Depth: 35.0 km
(USGS, as of March 1, 2018)
Magnitude Mw=7.5
(USGS, as of March 1, 2018)


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

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YARAI Hiroshi : Head of Division
MORISHITA Yu : Chief Researcher