Last Updated : May 30, 2005

Coastal Changes in Nias Island and Banyak Islands,caused by 2005 Sumatra Earthquake

SUMMARY Emergence and Submergence: Coastal Change Inferred from Satellite Synthetic Aperture Radar Images(ENVISAT)

1. Coastal Change inferred from SAR
The image is derived from a comparison of intensity of reflected microwave observed by ESA ENVISAT satellite between February 4, 2005 (before Earthquake) and April 15, 2005 (after Earthquake).

2. Emergence
An area colored in cyan is a region where the reflective intensity is increased. The ribbons of cyan are distributed along the west coast of northwestern part of Nias Island and Bangkaru Island, Banyak Islands, Indonesia. The image indicates emergence of reefs or beaches due to uplift caused by a crustal deformation due to the March 28, 2005 Sumatra (Nias) , M8.7 earthquake.

The width of the cyan ribbon is about 1km at maximum.

The emergence had increased the size of small islets and even produced more than ten new small islets. The length of the maximum islet is approximately 1.5 km.

3. Submergence
An area colored in red is a region where the reflective intensity is decreased. The ribbons of red are distributed along the Tuangku Island, Banyak Islands, Indonesia. The image indicates submergence of reefs or beaches due to subsidence caused by a crustal deformation due to the 2005 Sumatra (Nias) earthquake.

4. Tide Level
Tide level at the northwestern Simeulue
 -10 cm and -4 cm for the first and second image acquisition, respectively.
image Coastal Change Inferred from Satellite Synthetic Aperture Radar Images

DETAIL Emergence and Submergence: Coastal Change Inferred from Satellite Synthetic Aperture Radar Images (ENVISAT)

Coastal Change Northern Tuangku Is.(1)Northern Tuangku Is. image Banyak Islands and Nias Island
Banyak Islands and Nias Island
Coastal Change Eastern Tuangku Is.(2)Eastern Tuangku Is.
Coastal Change Bangkaru Is.
(3)Bangkaru Is.
Coastal Change Nothwestern Nias Island
(4)Nothwestern Nias Island
Click on each image for larger view!
Areas colored in cyan and red denote emergence and submergence of reefs or beaches due to uplift and subsidence caused by a crustal deformation due to the 2005 Sumatra, M8.7 earthquake.

Satellite and Sensor Specification and Tide Level

Radar data used here are acquired by ENVISAT ASAR (ESA).
Processed by GSI, Japan using GAMMA software.
observation time 2005-02-04 15:51UTC 2005-04-15 15:51UTC
orbit Ascending
beam IS6
incidence angle ~ 41.5 degree
microwave frequency 5.33GHz (C band)
wave length of microwave 5.6235 cm
polarization VV VV
satellite altitude ~ 787km
data Signal Data (raw)
tide level -10 cm -4 cm

Details of Northwestern Nias Island

Details of Northwestern Nias Island
image1 Details of Northwestern Nias Island image2 Details of Northwestern Nias Island Click here for details! 2005 earthquake pushes up cluster of 10 new islands.
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