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The 2018 Hualien (Taiwan) Earthquake: Crustal deformation detected by ALOS-2 data

Crustal Deformation Observed by Synthetic Aperture Radar (SAR)

Released: Feb. 9, 2018, updated: Feb. 16, 2018, Japanese version of this page


A large earthquake (Mw 6.4, USGS) occurred around Hualien in Taiwan on February 6, 2018. Serious damage such as building collapse and many deaths has been reported. To measure the crustal deformation caused by the earthquake, we analyzed ALOS-2/PALSAR-2 data.

The results obtained from the data are summarized as follows.
  • Large displacement has been detected along the Milun Fault and the northern part of the Lingding Fault with the length of ~15 km.
  • Remarkably large uplift and northeastward displacement has been observed at the east side of the Milun Fault. At the southwestern part of the Milun Fault, subsidence has been observed.
  • Discontinuity of the displacement is found along the Milun Fault through the center of Hualien city, which implies that surface ruptures may have appeared along the fault.

3D and 2.5D displacement

Fig1a 3D

(a) [PNG: 1.2MB]

Fig1b Zoom

(b) [PNG: 816KB]

Fig. 1. 3D displacement derived from Figs. 3(b)(c) and 4(b)(c), (a) overview, (b) around Hualien city*.

Fig2a Quasi vertical

(a) [PNG: 1.6MB]

Fig2b Quasi EW

(b) [PNG: 1.8MB]

Fig. 2. Displacement of (a) quasi vertical and (b) quasi EW components, derived from Figs. 3(a) and 4(a)*.

*These results may be affected by possible unwrapping errors (~12 cm ambiguity) at the east side of the Milun Fault in the used interferograms.

2.5D  Geometry of 2.5-D analysis

Results of InSAR and Pixel Offset

Fig3a DR

(a) [PNG: 3.8MB]

Fig3b Zoom

(b) [PNG: 934KB]

Fig3c Azimuth

(c) [PNG: 939KB]

Fig. 3. Descending/Right (a) InSAR (overview), (b) InSAR (zoom), (c) azimuth offset (Pixel Offset method).

Fig4a AR

(a) [PNG: 3.8MB]

Fig4b Zoom

(b) [PNG: 925KB]

Fig4c Azimuth

(c) [PNG: 946KB]

Fig. 4. Ascending/Right (a) InSAR (overview), (b) InSAR (zoom), (c) azimuth offset (Pixel Offset method).

Fig5a DL

(a) [PNG: 2.8MB]

Fig5b Zoom

(b) [PNG: 729KB]

Fig. 5. Descending/Left InSAR (a) overview, (b) zoom.

Date Time
Bperp KMZ
3 2017/06/18
03:48 Des. Right F-F 40° +223 m 1.4MB
4 2016/11/05
15:50 Asc. Right H-H 28° -159 m 1.5MB
5 2015/01/29
04:22 Des. Left W-U 35° -358 m 196KB

*1 F: Fine [10m], H: High Sensitive [6m], U: Ultrafine [3m], W: ScanSAR (Normal)
(cf. ALOS-2 Project / PALSAR-2 (JAXA))

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.

The 2018 Hualien (Taiwan) Earthquake

Date-Time February 6, 2018, 15:50 (UTC)
24.131°N, 121.659°E, Depth: 17.0 km
(USGS, as of February 16, 2018)
Magnitude Mw=6.4
(USGS, as of February 16, 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
KOBAYASHI Tomokazu : Chief Researcher
MORISHITA Yu : Chief Researcher

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