ANALYSIS OF INDIAN REMOTE SENSING SATELLITE DATA FOR SIKKIM EARTHQUAKE (18 SEPT 2011)
Earthquake Details (Source: USGS)
Date Earthquake EpicentreSunday, September 18, 2011 at 06:10:48 PM at epicentre
6.9 magnitude 27.723°N, 88.064°E19.7 km (12.2 miles)68 km (42 miles) NW of Gangtok, Sikkim, India
Sunday, September 18, 2011 at 06:41:57 PM at epicentre
4.8 magnitude 27.446°N, 88.391°E20 km (12.4 miles)25 km (15 miles) WNW of Gangtok, Sikkim, India
Sunday, September 18, 2011 at 07:24:18 PM at epicentre
4.6 magnitude 27.377°N, 88.266°E20.1 km (12.5 miles)34 km (21 miles) W of Gangtok, Sikkim, India.
Major effected areas in India : Entire Sikkim (Mangan, Chungthang, Singtam, Gangtok etc.), North Bengal (Darjeeling, Kalimpong etc.)
Details of analysis
• Pre and Post-earthquake Satellite data (optical and microwave) were acquired to assess the damage caused by the earthquake (Table 1).
• Optical data received within 24 hours were covered with cloud.
• All the microwave data (Table 1) acquired by NRSC and International charter were analysed for damage assessment. But microwave data could not be interpreted for damage and landslides because of foreshortening and layover effects due to ruggedness of the terrain.
• The latest cloud free IRS data sets were available on 29 and 30, September (Table 1) and the same were analysed for mapping the landslides which occurred after the event.
• Total 354 new landslides were mapped using pre and post CARTOSAT-1 stereo data sets.
Table 1Country Sensor Type Satellite Date of Acquisition Remark
India Optical Cartosat -2 (Mono) 19-sept-2011 Cloudy
India Optical Resourcesat-2 LISS 4 (Mono) 19-sept-2011 Cloudy
India Optical Resourcesat-2 AWiFS 19-sept-2011 Cloudy
Canada Microwave Radarsat-2 (C-band) 19-sept-2011 Layover and foreshortening effect because of terrain
India Microwave RISAT-2 (X-band) 20-sept-2011 Layover and foreshortening effect because of terrain
Germany Microwave TerraSAR-X (X-band) 21-sept-2011 Layover and foreshortening effect because of terrain
India Optical Cartosat 2A 23-sept-2011 Cloudy
India Optical Cartosat-1Cartosat-2AResourcesat-2
24-sept-2011 Cloudy
India Optical Cartosat-1 29-sept-2011 Partly cloudy
India Optical Cartosat-2B 30-sept-2011 Mostly cloud free
India Optical Resourcesat-2 LISS-IV Mx 03-oct-2011 Partly cloudy
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NADOM
BRANG
LACHEN
LACUNG
LINGMORALANG
GEZING
BHENOL
THANGGU
SINGTAM
DONGKUNG
SAKKYONG
PHENGTANG
CHUNGTHANG
NAYA BAZAR
Mangan
Namchi
GANGTOK
Synoptic view of Sikkim from Resourcesat-1 LISS III
±
0 8 16 24 324Kilometers
Area analysed for post-earthquake landslides using Cartosat-1 data of 30-sept-2011
Earthquakeepicentre
Satellite image shown here is acquired on 13-apr-2005
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NADOM
BRANG
LACHEN
LACUNG
LINGMORALANG
GEZING
BHENOL
THANGGU
SINGTAM
DONGKUNG
SAKKYONG
PHENGTANG
CHUNGTHANG
NAYA BAZAR
Mangan
Namchi
GANGTOK
Landslide inventory in Sikkim after the earthquakeDetails:Date of event: 18 september 2011Date of cloud free data acquisition: 29, 30 september 2011Type of data: Cartosat-1 and Cartosat-2bNo. of landslides identified: 354 new and 48 old landslides
±
0 8 16 24 324Kilometers
LegendOld landslidesNew landslides
See figure 1
See figure 2
See figure 3
See figure 4
See figure 5
88°50'0"E88°40'0"E88°30'0"E88°20'0"E88°10'0"E
28°1
0'0"N
28°0
'0"N
27°5
0'0"N
27°4
0'0"N
27°3
0'0"N
27°2
0'0"N
27°1
0'0"N
See figures 1 to 5 for illustrations
Chungthang
Post-earthquake Cartosat – 1(30-Sept-2011)
Reactivatedlandslides
Pre-earthquake Cartosat – 1(22-March-2011)
Lachen ChuRiver
Cloud Cloud
New Landslides
New Landslides
Road Chungthang to
LachenOldLandslide
Figure 1
Landslides near to road
Road from Nadom to
Chungthang
New Landslides
New Landslide
New Landslides
TistaRiver
Figure 2
Pre-earthquake Cartosat – 1(22-March-2011)
Post-earthquake Cartosat – 1(30-Sept-2011)
Landslides near to road
Newlandslides
Newlandslides
Cloud
Chungthang
Road towards Lachung
Newlandslides
LachungRiver
Cloud
Figure 3
Pre-earthquake Cartosat – 1(22-March-2011)
Post-earthquake Cartosat – 1(30-Sept-2011)
Landslides near to road
Hydelpower site
Newlandslides
Oldlandslides
Tist
a River
Figure 4
Pre-earthquake Cartosat – 1(22-March-2011)
Post-earthquake Cartosat – 1(30-Sept-2011)
Cloud
Cloud
Newlandslides
Newlandslides
Figure 5
Pre-earthquake Cartosat – 1(22-March-2011)
Post-earthquake Cartosat – 1(30-Sept-2011)
Landslides near to road