Disaster prevention Crustal deformation, land subsidence, floods, forest fires.
The movement of nature is closely related to our lives. Satellite data is indispensable to know the actual situation.
Capturing the actual state of natural disasters from space
It is not easy for us at the surface to understand the nature of a wide range of large-scale natural disasters. However, a variety of information can be obtained by using satellites that can overlook the whole from afar.
For example, ground surface movements such as land subsidence and crustal deformation can be known by measuring the distance from the satellite to the ground surface. Using a method called interference analysis with a microwave sensor, it is possible to capture the movement of the ground surface with an accuracy of several centimeters. In particular, the PALSAR radio wave (L-band) installed in ALOS has the advantage of high vegetation permeability and the ability to capture changes in the ground almost without being affected by vegetation on the ground surface. Therefore, it is especially useful in countries with many forests. In addition, for disasters such as slope failures and floods, the state of damage can be known by observing changes in the light reflection characteristics and radio wave scattering characteristics associated with changes in the state of the ground surface due to the spread of sediment and water. Satellite data has tremendous potential in preventing and countering disasters that have a significant impact on our lives.
Understand land subsidence
solution-subsidence
From this image, which shows the area around a coal mine, it can be inferred that the ground surface is deformed in two places where the oval is blue. The one on the right was a coal mine, and land subsidence had occurred around it. The ellipse on the left side caused ground subsidence due to heavy use of groundwater when excavating the coal mine. That is clearly captured by the satellite. Land subsidence greatly affects real life. Finding out where these fluctuations occur and what is happening with these images from satellites can also help in decision making in disaster prevention policies.
Understand sediment disaster
solution-landslide-on-Leyte-island
This is a PALSAR image of a large-scale landslide on the island of Leyte in the Philippines. ALOS is the first disaster observed by assigning images taken before the disaster to "red" and images taken after the disaster to "green and blue". There is a characteristic that the place where the earth and sand collapses looks bright. This is because microwaves are strongly scattered by the water contained in the earth and sand and the large rocks that roll down together. Even if you cannot go to the site immediately, analyzing these images will allow you to quickly grasp the actual situation.
know the flood
solution-floods
Synthetic Aperture Radar ( SAR ) has the property of observing the ground surface in cloudy weather, rainy weather, and even at night. It also has features that make it easy to distinguish between land and water areas, making it suitable for identifying flood inundation areas.
This is the 2006 flood on the Mekong River in Vietnam. PALSAR's wide-area observation mode (ScanSAR) can be used in large rivers such as the Mekong River with a large basin area. In this image, the images of September 27, October 2, and October 16 are superimposed to show the flooded area. The green area around the Mekong River in the figure is the inundated area, and the green color is strong, indicating that the water was inundated on September 27 and October 16, excluding October 2.
Capturing the actual state of natural disasters from space
It is not easy for us at the surface to understand the nature of a wide range of large-scale natural disasters. However, a variety of information can be obtained by using satellites that can overlook the whole from afar.
For example, ground surface movements such as land subsidence and crustal deformation can be known by measuring the distance from the satellite to the ground surface. Using a method called interference analysis with a microwave sensor, it is possible to capture the movement of the ground surface with an accuracy of several centimeters. In particular, the PALSAR radio wave (L-band) installed in ALOS has the advantage of high vegetation permeability and the ability to capture changes in the ground almost without being affected by vegetation on the ground surface. Therefore, it is especially useful in countries with many forests. In addition, for disasters such as slope failures and floods, the state of damage can be known by observing changes in the light reflection characteristics and radio wave scattering characteristics associated with changes in the state of the ground surface due to the spread of sediment and water. Satellite data has tremendous potential in preventing and countering disasters that have a significant impact on our lives.
Understand land subsidence
solution-subsidence
From this image, which shows the area around a coal mine, it can be inferred that the ground surface is deformed in two places where the oval is blue. The one on the right was a coal mine, and land subsidence had occurred around it. The ellipse on the left side caused ground subsidence due to heavy use of groundwater when excavating the coal mine. That is clearly captured by the satellite. Land subsidence greatly affects real life. Finding out where these fluctuations occur and what is happening with these images from satellites can also help in decision making in disaster prevention policies.
Understand sediment disaster
solution-landslide-on-Leyte-island
This is a PALSAR image of a large-scale landslide on the island of Leyte in the Philippines. ALOS is the first disaster observed by assigning images taken before the disaster to "red" and images taken after the disaster to "green and blue". There is a characteristic that the place where the earth and sand collapses looks bright. This is because microwaves are strongly scattered by the water contained in the earth and sand and the large rocks that roll down together. Even if you cannot go to the site immediately, analyzing these images will allow you to quickly grasp the actual situation.
know the flood
solution-floods
Synthetic Aperture Radar ( SAR ) has the property of observing the ground surface in cloudy weather, rainy weather, and even at night. It also has features that make it easy to distinguish between land and water areas, making it suitable for identifying flood inundation areas.
This is the 2006 flood on the Mekong River in Vietnam. PALSAR's wide-area observation mode (ScanSAR) can be used in large rivers such as the Mekong River with a large basin area. In this image, the images of September 27, October 2, and October 16 are superimposed to show the flooded area. The green area around the Mekong River in the figure is the inundated area, and the green color is strong, indicating that the water was inundated on September 27 and October 16, excluding October 2.
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