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

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.

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


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]

 
 
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
3	2018-02-01 2018-03-01	02:05	Des.	Right	W-W	36°-47°	-120 m	~75m	11.1MB	112MB	Ionospheric noise compensation applied
4	2018-01-01 2018-03-12	14:46	Asc.	Right	F-F	39°-42°	-270 m	~150m	575KB	4.1MB	Ionospheric noise compensation applied
4	2018-01-29 2018-05-21	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.

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)

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

• M 7.5 - 89km SSW of Porgera, Papua New Guinea (USGS)