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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: Mar. 2, 2018, Japanese version of this page

Summary

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.

SAR Interferograms

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

Fig2. Descending InSAR
Fig.2 Descending SAR interferogram [PNG: 1.9MB]
*Note that this result may be affected by ionospheric noises.
 
Fig. Area  Fig. Area wide
Area of interest

 
Fig.
#
Date Time
(UTC)
Flight
Dir.
Beam
Dir.
Obs.
Mode*1
Incidence Angle
(around epicenter)
Bperp Pixel
Spacing
KMZ Geotiff
1 2017/07/31
2018/02/26
14:46 Asc. Right W-W 34°-42° +75 m ~200m 3.8MB 18.6MB
2 2018/02/01
2018/03/01
02:05 Des. Right W-W 36°-47° -120 m ~50m 21.7MB 171MB

*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 Papua New Guinea Earthquake

Date-Time February 25, 2018, 17:44 (UTC)
Hypocenter
Location
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)

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
MORISHITA Yu : Chief Researcher
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