On March 11, 2011, at 14:46 (JST), a massive earthquake of magnitude 9.0 hit the coast of Tohoku, Japan. The earthquake was recorded at a seismic intensity of 7 in the northern part of Miyagi Prefecture, and just after an hour of the earthquake, a monster tsunami hit the shorelines from Aomori to Chiba Prefecture.
This earthquake was later named as The Great East Japan Earthquake 2011, which turned out to be the most powerful known earthquake to have hit the nation and one of the five most powerful earthquakes globally occurred. According to the report by the National Police Agency, the disaster caused 15,870 deaths, 6,110 injured and 2,846 people remained still missing, as of September 5, 2012.
A train washed away by tsunami
Hugeness of tsunami
PASCO’s effort for the disaster mitigation
Immediately after the earthquake, PASCO estimated the extent of damages by acquiring information utilizing variety of sensing technologies including satellites, aircraft, helicopters, vehicles and ships. Among them, the satellites’ data were widely utilized to obtain information over entire areas in a limited amount of time. PASCO cooperated with the domestic disaster prevention agencies, affected municipalities, private companies and media by speedily providing them with the earliest collected information and results and output of the detailed analysis. The collected and analysed information were also posted on the company’s homepage and assisted the common public to access the information on the real situation of the affected areas.
Heliborne imagery over Onagawa, Miyagi Prefecture acquired on 11, April, 2011 (JST)
PASCO publicized disaster information on the Internet https://www.pasco.co.jp/eng/disaster_info/110311/
Power of satellite based information
Among the various technologies adopted for the disaster mitigation activities, satellite technology proved its significance as the powerful source of information. After the earthquake triggered, almost all communication and transportation means to the disaster-stricken areas were cut off, and the areas had stayed unapproachable for several days. When facing to that kind of catastrophic situation, earth observation satellites demonstrated powerful tools to collect the disaster-relevant information highly effectively over wide range of areas in a shortest possible time,
PASCO acquired imagery by the synthetic aperture radar (SAR) satellite “TerraSAR-X” at 06:00 (JST) on March 14, 2011, and maps were created to indicate flooding (remaining water) caused by tsunami. TerraSAR-X imageries were acquired on March 24 and April 4 to detect how the flooding areas were retrieving over time. Additionally the deformation of earth surface was extracted by differential analysis of the post- and pre-earthquake imageries dated October 21, 2010, clearly indicating the deformation of earth surface.
Extraction of the flooded areas utilizing TerraSAR-X imageries
The colored areas show the flooding situation on March 13, 24 and April 4, 2011.
PASCO also acquired imageries from optical satellites and tsunami caused flooded areas were analyzed. A total of 194 scenes and about 560,000 sq km were collected, utilizing post-disaster post–disaster acquired data from WorldView-1&2, RapidEye, ALOS AVNIR2, Spot 5 , EROS-B and TerraSAR-X satellites. Products included: (i) Estimated flood area map (schematic), (ii) Estimated flood area map (detailed), (iii) Localized Flooded area estimates, (iv) Estimated flooded area maps, and (v) GIS polygon data (SHP, KML). All analysis works were accomplished from March 12 to 18 and information were supplied to the authorities.
Importance of archiving
Satellite is a powerful tool for collecting information and ideal for disaster mitigation, and further enhances its genuine power combined with archived information of normal periods. One of such examples is PASCO Satellite OrthoTM (PSO), pansharpened orthorectified product of 2.5m ground resolution generated from high-resolution panchromatic ALOS PRISM and multispectral AVNIR-2 imageries of simultaneous acquisition. Best quality cloud-free data with less snow coverage are selected from ALOS’s rich archive, which consists of over 6.5 million scenes covering entire globe, to create a seamless mosaicked product to meet the demand of “ready-to-use” data. PASCO has already completed to cover the entire Japan with PSO and is now expanding its archive to overseas regions. (https://www.pasco.co.jp/eng/products/pso/)
PASCO will continue making its optimal efforts to accumulate geospatial information from different resources and playing vital roles by forming the foundation of information for mitigating disasters.
PASCO Satellite OrthoTM (PSO)
PASCO has provided initial response for disasters and other support services for global regions also by utilizing information derived from satellites for the earthquakes of Great Sichuan (2008), Haiti (2010), Christchurch in New Zealand (2011), GLOF in the Himalayas (2008), overflow Kosi River in Nepal, flooding due to cyclone “ Aila” in Bangladesh (2009), flooding in Thailand (2011) etc.