Space Application for Disaster Monitoring
Collection of Good Practice in Disaster Emergency Observation
by ALOS-2 “DAICHI 2”from 2014 to 2017
(Excerpts)©JAXA

The Advanced Land Observing Satellite-2

ALOS-2 (Advanced Land Observing Satellite-2)
Overview of ALOS-2
The earth observation satellite ALOS-2“DAICHI-2” was developed as the successor to ALOS “DAICHI”. It takes over the

mission of DAICHI contributing in various ways to our lives through utilization in mapping, regional observation, disastermonitoring and resource exploration.

DAICHI-2’s onboard instrument enhances DAICHI’s Phased Array type L-band Synthetic Aperture Radar (PALSAR).

Improved performance in aspects such as resolution and regions that can be observed, makes it possible to provide
information more accurately and swiftly.

Table 1: Main specifications of ALOS-2
Solar Array Paddle

Launch7.2m

Inter-orbit communications antenna
2.7m

Date

24 May 2014

Launch vehicle

H-IIA launch vehicle No. 24

Design life

5 years (target: 7 years)
Type

3.0m

628km (above the equator)
Operational Altitude
Local sun time at 12:00+/- 15minorbit
descending node
Revisit time
Satellite size (on orbit)

10.0m

Satellite mass
Phased Array type L-band Synthetic
Aperture Radar (PALSAR-2)

Direct transmission antenna©JAXA

Fig. 1: ALOS-2 in-orbit configuration

Sun-synchronous subrecurrent orbit

14 days
Approx. 10.0m ｘ 16.5m ｘ
3.7m
Approx. 2,100 kg

Phased Array type L-band
Mission instrument (frequency) Synthetic Aperture Radar
PALSAR-2 (1.2 GHz band)
ALOS-2 also carries the Space-based Automatic Identification
System Experiment 2 (SPAISE-2), and the Compact Infrared
Camera (CIRC) as technology demonstration missions.

Characteristics of ALOS-2

1 Observation of Wide Areas on the Earth
ALOS-2 satellite body can tilt right and left to observe on bothsides. It also uses the phased array method which can swing

radar waves (beams) electronically. Thus it is possible to expand
its observation range to 2,320 km, almost three times greaterthan DAICHI’s. ScanSAR Mode can achieve 490km swath which

is wider than 350km of ALOS/PALSAR.

2 High-resolution Observation Regardless of
Day or Night and Weather Conditions©JAXA

The greatest characteristic of Synthetic Aperture Radar (SAR)

is its ability to observe the Earth’s surface day and night,

regardless of weather conditions. As ALOS-2’s PALSAR-2 uses

L-band, influence by weather conditions is smaller comparedto X-band or C-band used by other satellites. PALSAR-2 also
has Spotlight Mode to achieve the resolution of 1m x 3m,allowing it to carry out observations at a higher resolution ascompared to ALOS.

1

Fig. 2: ALOS-2 observation coverage image
Yellow band: ScanSAR Mode (Swath width: 490km)
Red band:

ScanSAR Mode (Swath width: 350km)

Green band: Stripmap (10m) Mode (Swath width: 70km)
Pink band:

Stripmap (3m/6m) Mode (Swath width: 50km)

The Advanced Land Observing Satellite-2

3 Emergency Observation Response to
Disasters
ALOS-2 realizes emergency observation by left-

and-right looking capability, the significant

Beam scanning range:
Incident angle 8-60 deg.

［Earth pointing attitude[ALOS](with observation)］

reduction in revisit time (to target quickly on the

Flight direction

location to be observed) and improved data

[ALOS-2]transmission ability. In the case that the

emergency observation for natural disaster isrequired in Japan, images of the disaster area canbe obtained in two hours at the minimum. ALOS-2
emergency observation has contributed for

Sentinel Asia and International Disaster Charter inmutual collaboration with space agencies etc.

2

Beam scanning range:
Incident angle 8-70 deg.

［Earth pointing
attitude (withoutobservation)］
Nadir［Right looking］

©JAXA

Nadir

Flight direction［Left looking］

Fig. 3: ALOS-2 observation attitude

The Advanced Land Observing Satellite-2

Observation Modes
ALOS-2 has three observation modes. We can choose from Spotlight Mode with the resolution of 1m x 3m for the mostdetailed observation, Stripmap Mode with the resolution of 3-10m (swath width of 50-70km), and ScanSAR Mode to covera wide area in just one observation (resolution of 60-100m, swath width of 350-490km). It is possible to realize the optimal

observation by selecting the most appropriate observation mode according to your objectives.

Table 2: List of observation modes
Observationmode
Spotlight

Stripmap

ScanSAR

Fig. 4: Illustration of each observation mode

Resolution

Swath

1m (Azimuth)x
3m (Range)

25km (Azimuth)
x
25km (Range)

3m

50km

6m

50km

10m

70km

60m

490km

100m

350km

“Azimuth” means satellite flight direction.
“Range” means range direction in which beam is transmitted(at right angles to azimuth direction).

■Spotlight Mode
Adding Spotlight Mode as a new observation mode makes it

possible to obtain better quality images at the high resolutionof 1m x 3m on ALOS-2. Spotlight Mode enables to increase

Fig. 5: Image captured

the illumination time selecting observation areas locally. As ausing Spotlight Mode

result, it is now possible to capture the Earth’s surface in(around Maihama

more detail.

©JAXA

Station)■Stripmap Mode
Incorporating the dual-beam system into PALSAR-2 makes

it possible to maintain a high resolution and wide swath

Fig. 6: Image
captured using
Stripmap Mode
(Tokyo, Chiba area)

width in Stripmap Mode. Disaster monitoring is conducted
mainly using Stripmap Mode.

©JAXA■ScanSAR Mode
ALOS-2 can capture images over an extremely wide area of350km or 490 km swath. This ScanSAR Mode is utilized tocapture crustal deformations caused by massive
earthquakes.

©JAXA

3

Fig. 7: Image
captured using
ScanSAR Mode
(Kanto region)

The Advanced Land Observing Satellite-2

Emergency Observation Requests
ALOS-2 passes over Japan twice daily

at midday (day pass) and midnight(night pass) JST (with variation rangeof around 1.5 hours before or after).

Emergency observation requests may

be received until one hour before

command uplink. Automatic analysis
for disaster map can be provided withinaround two hours after observation anddisasterwithinaffectedaroundarea

fiveinformation

hours

after

Observation
around 12:00“Automatic analysis fordisaster map” in around 2hrs,
and “Disaster affected area
information” in around 5hrs ofobservation
Observation possible
twice daily

Observation request until one
hour before command uplink at
the shortest

Fig. 8: Observation time scheduleobservation for the disaster that occur
in Japan.

4“Automatic analysis for disastermap” in around 2hrs, and“Disaster affected area
information” in around 5hrs ofobservation
Observation
around 0:00

Observation request until one
hour before command uplink at
the shortest

The Advanced Land Observing Satellite-2

Overview of Image Analysis
Superimposition of images from different timings
SAR is an instrument that emits radio waves towards the

As shown in Fig. 1, the SAR image is obtained by imaging

returning to the satellite. In general, when the observed

the ground surface, in shades of black and white. The waterobservation target and measures the reflected wave

the intensity of the reflected wave, that is, the situation on

target has a smooth surface like water surface, reflectedsurface appears black, and the image becomes whiter aswaves are few, and when the surface is rough, the reflectedreflected waves increase.

waves increase. Especially when there are many branches

and leaves and dense trunks like forests, many reflected
waves are generated.

©JAXA

Fig. 1: How SAR image appears (left: aerial photograph, right: SAR image obtained by ALOS-2)

lost due to landslide, that area will be replaced by exposed

For example, as shown in Fig. 2, the exposed groundbefore the disaster appears relatively dark on the SAR

ground with less reflected waves, so it will appear dark. In

surface due to flooding, it appears very dark.

before and after the disaster, it is possible to estimate themountainous area, before the landslide, many reflection waves

and after the disaster.

this way, since the shading on the SAR image changes

image, but when the rough surface changes to water

affected area by comparing the two SAR images before

On the other hand, as shown in Fig. 3, in a forest-covered

are generated by the forest where the branches and leaves aredense, so it appears bright. But when a part of the forest isbrightslightly dark

after flood disaster(ground surface
flooded)very dark

Fig. 2: Brightness on SAR image before and after flood disasterslightly dark

after landslidedisaster (vegetation
removed)Fig. 3: Brightness on SAR image before and after landslidedisaster

5

The Advanced Land Observing Satellite-2

When superimposing images before and after the disaster, in order to extract the change before and after the disaster,

images from different timings are assigned three colors, red, green and blue respectively, and color composite display is

performed.

In Fig. 4, green and blue are allocated to the post-disaster image, and red to the pre-disaster image. You can see the part

displayed in red on a part that seems to be flat ground on this image. This is presumed to be because, compared to the pre-disaster earth surface assigned red, the reflected wave from the post-disaster earth surface assigned green and blue isextremely weakened by flooding. Therefore, the red area is extracted as area suspected of flooding damage.
Pre-disaster image expressed in red

Post-disaster image expressed in green & blue

©JAXA

Images from two timings superimposed

©JAXA

©JAXA

Fig. 4: Enhancement of disaster affected areas by color composite display of images from before and after the disasterFig. 5 shows an example of color composite image fromarea, and the area with suspected inflow of soil is extracted

two timings taking the case of flood. You can see wherein light blue. When conducting analysis by superimposing

the flooded area is spreading in red.

two images from different timing, as only the change in the

two timings taking the case of heavy rain and landslide.

extraction can be improved by setting the observation

Fig. 6 shows an example of color composite image fromobject observed is extracted, accuracy of disaster effectconditions (ascending/descending orbit, off nadir angle

Forests are displaced showing exposed soil in the redetc.) to be the same.

©JAXA

©JAXA

Fig. 5: Example of superimposition of images from two timings

Fig. 6: Example of superimposition of images from two timings(the case of flood)(the case of heavy rain and landslide)6

The Advanced Land Observing Satellite-2

Superimposition of images with different polarized waves
Radio waves are transverse waves that vibrate in a planeby switching between linear polarized wave oscillating

perpendicular to the direction of travel, and thehorizontally (H) and linear polarized wave oscillating

characteristic of polarization in which wave vibration isvertically (V) at the time of transmission and reception.

enhanced in a specific direction is known. There are types

Fig. 7 shows the combination of polarizations used forof polarized waves, such as elliptically polarized waves andobservation by ALOS-2. When transmission and reception

linearly polarized waves, but when the radio waves areare both H it is called “HH”, when transmission is H(V)reflected from the object, the characteristics of theand reception is V(H) it is called “HV”(“VH”), and whenpolarized wave may change depending on the type of thetransmission and reception are both V it is called “VV”.

object to be reflected. In ALOS-2, in order to capture thechange in polarization due to the ground object, we observe

ＨＨ
Transmit

Transmit

Transmit

Receive

Receive

Receive

Fig. 7: Polarized wave observation by SAR

Fig. 8 shows an example of observation image using two

polarized waves of HH and HV in mountains covered withvegetation. In this example, HH is assigned red and blue,and HV is assigned green, indicating that HV is dominant

in most areas. Generally, with L-band SAR, HH is known toshow high response to ground structure and bare ground,

HV to vegetation such as forest, and VV to bare ground. By
switching polarized waves and observing thecharacteristics of polarized waves by ground objects, it ispossible to estimate whether vegetation covers the ground©JAXA

or the ground surface is exposed.

Fig. 8: Example of polarized wave composite image

7

The Advanced Land Observing Satellite-2

Radio waves have the characteristics of waves as their

Such image obtained by calculating the phase difference

point in time between the two being called a “phase”) are

dimensional SAR image is called an "Interferometric SAR

name suggests, and peaks and troughs (the position of aobtained from two observations for each pixel on the two-

repeated at regular intervals. As Fig. 9 shows, the phase

image”. In this way, it is possible to capture how much thestate at reception will not change if the distance the radio

ground surface rises in the direction of the satellite. On the other

hand, when the terrain sinks, the distance between that point

wave travels from transmission by the instrument,

reflection by the observation target and return to theand the instrument becomes longer, so the sign of the phasesomehow changes, then the phase state at reception willinterferometric SAR analysis, it is possible to distinguishchange and the terrain rises as in Fig. 9, then the distancethe instrument. From this principle, it is possible to extract

difference will be the reverse of when the ground rises. So, by

instrument remains unchanged. If, however, this distance

topographical variation both approaching and moving away fromchange. For example, when the satellite position does not
between that peak and the instrument becomes shorter

crustal deformation on the scale of several centimeters byinterferometric SAR analysis.

than before the terrain rise.

When crustal deformation occurs, the distancefrom the satellite to ground surface changes→The phase state of received radio wave changes
Crustal deformation (change in distance between
satellite and ground surface)

Second observation
Phase
difference

Phase of second
observation

First observation

Phase of firstobservation

Crustal deformation component obtained by interferometric SAR analysis
Change in distance from the satellite to ground surface
Ground surface
Crustal deformation (uplift)

Interferometric SAR image
Source: Processed by Mitsubishi Space Software Co., Ltd. based on open document on GSI Japan Homepage

Fig. 9: Schematic diagram of crustal deformation component obtained by interferometric SAR analysis

On the other hand, in two observations, when a certain

The state of the phase difference between adjacent pixels

difference occurs before and after fluctuation (interferencehigh and in the latter random case the coherence is low.

surface shows a change that moves as a whole, a phaseis called coherence. In the former case, the coherence is

Coherence is sensitive to abrupt changes such as collapse

fringes are generated), but a phase difference between
adjacent pixels will not occur. However, for sudden changesof ground and buildings due to eruptions and earthquakes,
so it is one of the important methods of interferometric SAR

that make the ground surface uneven, adjacent phases differ

piecemeal, so interference fringes cannot be obtained andanalysis for damage situation before and after a disaster.

terrain change cannot be measured.

8

The Advanced Land Observing Satellite-2■Image analysis method and examples in this document
The methods of image analysis corresponding to the case of disaster described in this document are as follows.

No

Image analysis method

1

Interferometric SAR analysis

2
3
4Superimposition of images withdifferent polarized waves
Superimposition of images fromdifferent timings

Name of disaster caseType ofdisasterPage number

Mount Hakone, Japan

Volcano10

Kumamoto Earthquake of 2016

Earthquake

13

Kanto/Tohoku Torrential Rains of September 2015
Typhoon No.9 (Mindulle) of 2016 (Tokoro River Hokkaido)

9

Flood/
Landslide17
21

The Advanced Land Observing Satellite-2

Volcanos

Disaster Case - 1 [Volcano]2015

Mount Hakone
Volcanic earthquakes with epicenters at Owakudani increased from 26 April

2015, and on 6 May the volcanic alert was raised from level 1 (note that it is anactive volcano) to level 2 (Do not approach the crater). Thus, Hakone Town

issued evacuation instructions for the vicinity of Owakudani at 6:10 am of that
tended to decrease in mid-June, volcanic earthquakes again increased fromaround 7:30 on 29 June, and volcanic tremors, the first to be comfirmed in thehistory of its observation, was also confirmed. On 30 June, a small pyroclastic hill
was confirmed in Owakudani, and the volcanic alert was raised from level 2 to 3

Earthquakes

day and restricted entry around the crater. Although the number of earthquakes(Do not approach the volcano). From late August, the crustal deformation

indicating expansion of the mountain was considered to be slowing, and thevolcanic alert was lowered to level 2 on 11 September.

provided observed data upon request from the “Satellite Data Analysis Group (Volcano WG)” (secretariat: Japan
Meteorological Agency (JMA)) established under the Coordinating Committee for Prediction of Volcanic Eruptions. Resultsof analysis by the Volcano WG members Hot Springs Research Institute of Kanagawa Prefecture and the Geospatial
Information Authority of Japan (GSI), were reported to Hakone Town and the Hakone Volcano Coordinating Committee,
and was used for decision making of the re-opening of restricted areas and safety measures.

Radio wave emission direction

Satellite flight direction

First observation

Date & time: 2014/10/9 11:41
Mode：Stripmap (3m)
モード：高分解能 3m
Off nadir angle: 38.2°
オフナディア角：38.2°
Polarized wave: HH

Second observation

Date & time: 2015/5/7 11:40
モード：高分解能
3m
Stripmap (3m)Mode:
オフナディア角：38.2°
Offnadir angle: 38.2°
Polarized wave: HH

Fig. 1: Differential interferometry image (change between 9 Oct 2014 – 7 May 2015)
Shift towards the satellite of about maximum 6cm was observed within an extremely small area of 200m diameter inOwakudani. This shift could possibly have captured an expansion in a shallow place underground. The volcanic alert was
raised from level 1 to 2 on 6 May 2015.

10

Floods/Landslides

On 4 May, volcanic activity of Mount Hakone increased and JAXA conducted emergency observation by ALOS-2 andThe Advanced Land Observing Satellite-2

Radio wave emission direction

Satellite flight direction

First observation

Date & time: 2015/6/18 11:40
Mode：Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Second observation

Date & time: 2015/7/2 11:41

100m

Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Fig.2: Differential interferometry image (change between 18 June – 2 July 2015）
No significant change in the range and distribution of amount of change is seen. In two weeks, crustal deformation of
about maximum 10cm was observed. The volcanic alert was raised from level 2 to 3 on 30 June 2015.

Radio wave emission direction

Satellite flight direction

First observation

Date & time: 2015/7/2 11:41
Mode：Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Second observation

Date & time: 2015/8/27 11:42

100m

Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Fig. 3: Differential interferometry image (change between 2 July – 27 Aug 2015)
Around maximum 3cm shift away from the satellite was observed, although equivalent to noise level, in the area offluctuation (red area). There is a possibility of shrinking fluctuation occurring following the small-scale eruption at the end of June.

11

The Advanced Land Observing Satellite-2■Utilization at the Coordinating Committee for Prediction of Volcanic Eruptions
report at the 133rd Coordinating Committee for Prediction of Volcanic Eruptions held on 21 October 2015 . It was said thatit greatly contributed in volcanic activity evaluation and the JMA’s volcanic alert level decisions.

VolcanosInterferometry analysis result using ALOS-2 observation data was utilized in the Japan Meteorological Agency (JMA)’s■Report document at the 133rd Coordinating Committee for Prediction of Volcanic Eruptions

C

D

Floods/Landslides

B

Earthquakes

A

Fig. 4: Report at the 133rd Coordinating Committee for Prediction of Volcanic Eruptions
The position around Owakudani is indicated by the white circle, and thepeak of Mount Hakone by the white triangle. Significant phase change canbe observed around Owakudani in the pair before and after 29 June whenthe eruption occurred (Fig. B). Significant phase change is also observedin the area east to south-east of Owakudani, and abrupt phase change
can be recognized in certain parts (white dotted line). (Excerpt from 133rd
Coordinating Committee for Prediction of Volcanic Eruptions document)

Above left
First observation
Date & time: 2015/6/4 11:43
Mode: Stripmap (3m)
Off nadir angel 38.2°
Polarized wave: HH

Second observation

Date & time: 2015/6/18 11:40
Mode: Stripmap (3m)
Off nadir angel: 38.2°
Polarized wave: HH

Below left
First observation
Date & time: 2015/7/2 11:41
Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Second observation

Date & time: 2015/7/16 11:43
Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

12Above rightFirst observation
Date & time: 2015/6/18 11:40
Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Second observation

Date & time: 2015/7/2 11:41
Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH

Below rightFirst observation
Date & time: 2015/7/16 11:43
Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HH
Second observation

Date & time: 2015/8/27 11:42
Mode: Stripmap (3m)
Off nadir angle: 38.2°
Polarized wave: HHThe Advanced Land Observing Satellite-2

Disaster Case - 2 [Earthquake]2016

Kumamoto Earthquake of 2016
At 21:26 JST on 14 April 2016, an earthquake with a magnitude (Mj) of 6.5

occurred in the Kumamoto area of Kumamoto Prefecture, and observed seismic

intensity of 7 in Mashiki Town and 6- in Tamana and Kumamoto Cities etc. Then,

at 1:25 on 16 April, a larger earthquake of magnitude (Mj) 7.3 occurred withseismic origin in the same area, and observed seismic intensity of 7 in Mashiki

Town and Nishihara Village, 6+ in Minamiaso village, Kikuchi City etc., and 6- to
1 from the Kyushu region to parts of the Tohoku region. This earthquake

occurred in the crust, and is reported as a strike-slip fault type with a tension

axis in the north-south direction. A series of seismic activities occurred in thisarea between the two earthquakes and those with seismic intensity of 1 or more

occurred 4,068 times by 30 September. These earthquake activities caused

damage of 8,204 houses totally destroyed, 30,390 houses half destroyed, 139,320
houses partly damaged, 15 fires etc. (as of 30 September).

On 14 April 2016 following disaster occurrence, JAXA conducted emergency observation and provided observed data uponrequest from the “Earthquake SAR Analysis Working Group (Earthquake WG)” (secretariat: Geospatial Information Authorityof Japan (GSI)) established under the Coordinating Committee for Earthquake Prediction. Crustal deformation was observed

from differential interferometry results of image observed by ALOS-2, and used on the GSI’s website and in the report to
the Earthquake Research Committee (special meeting) (17 April 2016).

Satellite flight direction

Radio wave
emission direction

First observation

Date & time: 2015/2/10 00:46
Mode：ScanSAR
モード：広域観測(60m)
60m
Offnadir angle: 54.7°
オフナディア角：54.7°
Polarized wave: HH

Second observation

Date & time: 2016/4/19 00:45
モード：広域観測 60m
Mode: ScanSAR (60m)
オフナディア角：54.7°
Off nadir angle: 54.7°
Polarized wave: HH

10km

Fig.1: Differential interferometry image (change between 10 February 2015 – 19 April 2016)
On the north side of the Futagawa fault zone, sinking and eastward shift of up to 1 m or more, and on the south side uplift of up to 30
cm and westward shift of 50 cm or more can be seen. On the Hinagu fault zone, eastward shift on the northwest side and westward
shift on the southeast side can be seen, although on a smaller scale.

13

The Advanced Land Observing Satellite-2

Fig. 2: Principle of 2.5-dimensional analysis using

Source：GSI JapanFor details please see the GSI homepage below;
http://www.gsi.go.jp/BOUSAI/H27-kumamotoearthquake-index.html

Earthquakes

interferometric SAR image
It is possible to estimate the change value (purple arrow) of
the two dimensions (pink plane) from the easterly andwesterly observation results (blue arrow), and separate it
into the quasi-vertical component and the quasi-east-westcomponent (red arrow). This analysis method is called 2.5dimensional analysis by GSI.

Volcanos■Utilization in 2.5-Dimensional Analysis by GSI

Floods/Landslides

Fig. 3: 2.5-dimensional analysis using interferometric SAR image(left: change in vertical component, right: change in eastwest component) GSI Japan combined the results ofinterferometric SAR images (7 March 2016 - 18 April 2016, 10
February 2015 - 19 April 2016), conducted 2.5-dimensional
analysis and elucidated the quasi-vertical component and quasieast-west component of the crustal deformation.

Descending orbit/right-side observation
First observation
Date & time: 2016/3/7 12:17

Second observation
Date & time: 2016/4/18 12:17

Ascending orbit/right-side observation
First observation
Date & time: 2015/2/10 00:46

Second observation
Date & time: 2016/4/19 00:45

Mode: Stripmap (3m)
Off nadir Angle: 32.4°
Polarized wave: HH

Mode: ScanSAR (60m)
Off nadir angle: 54.7°
Polarized wave: HH

Mode: Stripmap (3m)
Off nadir angle: 32.4°
Polarized wave: HH

Mode: ScanSAR (60m)
Off nadir angle: 54.7°
Polarized wave: HH

Source: GSI Japan

Fig. 4: Utilization in the Kumamoto earthquake epicenter fault model (interim version)
2.5-dimensional analysis using ALOS-2 image and change in GNSS-based control stations were analyzed, and utilized
in the Kumamoto earthquake epicenter fault model (interim version).

14

The Advanced Land Observing Satellite-2■Landslide site near the Great Aso Bridge
Satellite flight direction

Radio wave emission direction
Observation before disaster
Date & time: 2 015/12/4 00: 11

Mode: Stripmap (6m)
Off nadir angle: 30.4°
Polarized wave: HH+HV+VH+VV
Observation after disaster
Date & time: 2016/4/22 00:11

©JAXA

©JAXA
Before disaster

Mode: Stripmap (6m)
Off nadir angle: 30.4°
Polarized wave: HH+HV+VH+ VV

After disasterFig. 5: Polarized wave superimposed images of before and after the disaster (change between 4 Dec 2015-22 Apr 2016）
In the yellow outline part near the Great Aso Bridge, it was covered in green before disaster, while it has changed to purple synthesized fromred and blue after the disaster. This shows that the HV image which responds brightly to forests became darker after the disaster, and it
can be estimated that there was landslide in part of the forest. Refer to Fig. A.
HV(Green)
Red, blue: HH polarized wave
Green: HV polarized wave

Brightness

HH(Red/Blue)
Woods area

Bare Land area

Woods area

Fig. A: Difference between Polarization HH and HV for land texture

200m

©JAXA

Observation before disaster(ALOS PRISM/AVNIR-2 pansharpened)
Date & time: 2011/4/6 11:02
Resolution: 2.5m
Observation after disaster(SPOT-6 pansharpened)
Date & time: 2016/4/16 10:38

200m

Resolution: 1.5m

©AIRBUS DS 2016
Before disaster

After disasterFig. 6: False-color image before and after disaster (change between 6 April 2011 – 17 April 2016)
In the false-color image, vegetation responds brightly to near infrared image and appears red. Where it was covered in
red before the disaster, is recognized to have changed brown with the landslide location after the disaster.
Red: near infrared wavelength
Green: red wavelength
Blue: green wavelength

300m©Mitsubishi Space Software Co., Ltd. 2016

© GSI Japan map
Photo 1: Vicinity of the Great Aso bridge
after disaster (aerial photo) (16 Apr 2016)

Photo 2: Vicinity of the Great Aso bridge after disaster(2 May 2016)15

The Advanced Land Observing Satellite-2

Satellite flight direction

Vlocanos■Landslide site near Kyoto University Volcanological Laboratory

Radio wave emission direction

©JAXA

©JAXA

Mode: Stripmap (6m)
Off nadir angle: 30.4°
Polarized wave: HH+HV+VH+VV

After disaster

Before disaster

Observation before disaster(ALOS PRISM/AVNIR-2 pansharpened)

200m

©JAXA

Before disaster

Date & time: 2011/4/6 11:02
Resolution: 2.5m
Observation after disaster(SPOT-6 pansharpened)
Date &time: 2016/4/16 10:38

200m©AIRBUS DS 2016

Resolution: 1.5m

After disasterFig. 8 False-color image before and after disaster (change between 6 Apr 2011 – 17 Apr 2016)
In the false-color image, vegetation responds brightly to near infrared image and appears red. Where it was covered in
red before the disaster, is recognized to have changed brown with the landslide location after the disaster.
Red: Near infrared wavelength
Green: Red wavelength
Blue: Green wavelength©Mitsubishi Space Software Co., Ltd. 2016

© GSI Japan map
Photo 3: Vicinity of the Kyoto University

Photo 4: Vicinity of the Kyoto University Volcanological

Volcanological Laboratory after disaster

Laboratory after disaster (2 May 2016)(aerial photo) (16 Apr 2016)16

Floods/Landslides

Fig. 7: Polarized wave superimposed images before and after the disaster (change between 4 Dec 2015 – 22 Apr 2016)
In the yellow outline part near the Kyoto University Volcanological Laboratory, it was covered in green before disaster, while ithas changed to purple synthesized from red and blue after the disaster. This shows that the HV image which responds
brightly to forests became darker after the disaster, and it can be estimated that there was landslide in part of the forest.
Red, blue: HH polarized wave
Green: HV polarized wave

300m

Earthquakes

Observation before disaster
Date & time: 2015/12/4 00:11
Mode: Stripmap (6m)
Off nadir angle: 30.4°
Polarized wave: HH+HV+VH+VV
Observation after disaster
Date & time: 2016/4/22 00:11

The Advanced Land Observing Satellite-2

Disaster Case - 3 [Floods]

2015

Kanto/Tohoku Torrential Rains of
September 2015
In September 2015, southerly moist winds flowing toward a low pressure

originally Typhoon No. 18 and the moist winds flowing from Typhoon No. 17

moving northward over the east sea of Japan produced many linear rainwaterbands in succession and record rainfall was observed in the Kanto and Tohoku

regions. Particularly, from 9 to 11 September, the maximum 24 hours rainfall at
16 observation points with more than 10 years of recording reached the highest,

such as Nikko and Imaichi Cities in Tochigi, Koga City in Ibaraki and Mt.
Izumigatake of Sendai City in Miyagi Prefectures. Flooding damages occurred in

Tochigi, Ibaraki and Saitama Prefectures and the Kinugawa River flowing throughTochigi and Ibaraki Prefectures caused catastrophic damages such as theembankment destruction in Joso City.

Typhoon No.
18 of 2015

Kinugawa River<Satellite data><Analysis>©Hiroshima Institute of Technology
Yuzo Suga Laboratory
Joso City

Fig. 1: Estimated flooded area extraction image by ALOS-2
An analysis example of flooded area estimation from images before and after disaster. Red is
assigned to the pre-disaster image of 31 Jul 2015, and blue and green to the post-disaster image of
11 Sep 2015. In this result, the red estimated flooded area is extracted.

Mode: Stripmap (3m)
Off nadir angle: 35.4°

Mode: Stripmap (3m)
Off nadir angle: 35.4°

Red: 31 July 2015
Blue, green: 11 September 2015

17

The Advanced Land Observing Satellite-2■Flooded area around Joso City

VlocanosUpon request from the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), JAXA conducted emergency
observation and provided analyzed data such as estimated flooded area extraction to disaster mitigation agencies. MLIT
considered ALOS-2 analyzed image together with optical satellite imagery and aerial photos, and grasped post-bank-rip
flooded area of Kinugawa River and conducted deployment and operation of water pump vehicles.

Satellite flight direction

Earthquakes

Radio wave emission direction

Floods/Landslides

Estimated flooded areas
Analyzed by© Hiroshima Institute of Technology, included©ALOS-2/JAXA

Source: GSI Japan homepage

Fig. 2: ：Estimated flooded area extraction image by ALOS-2(Left: enlargement of Fig. 1 Joso City, right: estimated flooded area up to 16 Sep 2015)
The area of Joso City which suffered catastrophic flooding due to embankment destruction isshown enlarged in Fig. 2. It can be seen that the results are similar to the Geospatial Information
Authority of Japan (GSI)’s estimated flooded area of 11 Sep 13:00 (brown). It is possible to obtainsuch analysis results regularly by SAR satellites such as ALOS-2 regardless of day/night or weather
conditions.

18

Area estimated to be
flooded (40km2)
Embankment
destruction
Embankment overflow

The Advanced Land Observing Satellite-2■Grasping the infrastructures damage situation upon disasterWith ALOS-2, it is also possible to grasp the damage situation of infrastructures using 3m resolution Stripmap mode.

The following are analysis examples concerning some infrastructures which suffered damage in this flooding.

■Utsunomiya City, Higashiosakabe-machi vicinity
Radio wave emission direction

Radio wave emission direction

Satellite flight direction

Satellite flight direction

Observation before disaster
Date & time: 2015/8/13 11:42
Mode: Stripmap (3m)
Off nadir angle: 35.4°
Polarized wave: HH
Observation after disaster
Date & time: 2015/9/10 11:42
Mode: Stripmap (3m)
Off nadir angle: 35.4°
Polarized wave: HH

NominalDIsplaced

Analyzed by © Mitsubishi Space Software Co., Ltd.,
included © ALOS-2/JAXA

Analyzed by © Mitsubishi Space Software Co., Ltd.,
included © ALOS-2/JAXA

Before disaster

After disasterFig. 3: Outflow of diving bridge at
Higashiosakabe-machi, Utsunomiya
City, Tochigi Prefecture
Analysis result of diving bridge
displacement. The bridge cannot
be recognized in the post-disaster
image with the possibility of its
outflow.

■Joso City Wakamiyado vicinity
Radio wave emission direction©2015 MITSUBISHI ELECTRIC CORPORATION

Source: GSI Japan homepage (GSI map)

Photo1: Diving bridge (1 Oct 2015
around 11:00 a.m.)Radio wave emission direction
Observation before disaster
Date & time: 2015/8/13 11:42

Satellite flight direction

NominalMode: Stripmap (3m)
Off nadir angle: 35.4°
Polarized wave: HH
Observation after disaster
Date & time: 2015/9/10 11:42

Satellite flight direction

Mode: Stripmap (3m)
Off nadir angle: 35.4°
Polarized wave: HH

Overflow

Analyzed by © Mitsubishi Space Software Co., Ltd.,
included © ALOS-2/JAXA

Analyzed by © Mitsubishi Space Software Co., Ltd.,
included © ALOS-2/JAXA

Before disaster

After disasterFig. 4: Embankment overflow at
Wakamiyado in Joso City, Ibaraki
Prefecture
Analysis result of embankment
overflow (10 Sep after 6 a.m.).
Embankment overflow can beextracted from the post-disaster
image.

Source: MLIT Kanto Regional Development
BureauPhoto 2: Point of overflow (10 Sep 2015
around 15:00)

19

Source: GSI Japan homepage (GSI map)

The Advanced Land Observing Satellite-2

Radio wave emission direction

Radio wave emission direction

Satellite flight direction

Satellite flight direction

10 Sep 11:42
NominalEmbankment destruction

Before disaster 2

After disaster

Observation before disaster 1
Date & time: 2015/8/13 11:42
Mode: Stripmap (3m)
Off nadir angle 35.4°
Polarized wave: HH
Observation before disaster 2
Date & time: 2015/9/10 11:42

Mode: Stripmap (3m)
Off nadir angle: 35.4°
Polarized wave: HH
Observation after disaster
Date & time: 2015/9/11 22:56
Mode: Stripmap (3m)
Off nadir angle: 35.4°
Polarized wave: HH

Source: MLIT Kanto Regional Development Bureau

Source: GSI Japan homepage (GSI map)

Photo 3: Point of embankment destruction(10 Sep 2015 around 15:00）

Fig. 5: Embankment destruction at Misaka-machi in Joso City,
Ibaraki Prefecture (10 September, 12:50)
Monitoring result of embankment destruction at Misakamachi. Embankment destruction can be extracted in the postdisaster image. As the observation direction is different in the
post-disaster image, it is necessary to note that the appearance
is different. In this case, it is deemed to be an embankment
destruction as the vicinity of the yellow circle has darkened
markedly.

Source: MLIT Kanto Regional Development Bureau

Photo 4: Point of embankment destruction(10 Sep 2015 around 15:00）

20

Floods/Landslides

Before disaster 1

Radio wave emission direction

Earthquakes

NominalSatellite flight direction

Volcanos■Joso City Misaka-machi vicinity

The Advanced Land Observing Satellite-2

Disaster Case - 4 [Floods]

2016

Typhoon No.9 (Mindulle) of 2016

(Tokoro River, Hokkaido)

Typhoon No.9 (Mindulle) which formed in the Mariana Islands on 19 August 2016,
grew and moved north in the south of Japan, and made landfall at around 12:30 on 22
August near Tateyama City, Chiba Prefecture. It then crossed the Kanto/Tohoku
regions accelerating and made landfall again at around 6:00 on 23 August in the
Hidaka region of Hokkaido. Due to the lingering fronts and approaching and passingof successive typhoons, record heavy rain was observed in a wide area and total
rainfall from 20 to 23 August was 296.0mm at Itokushibetsu in Nemuro region,
291.5mm in Rausu and Hidaka-monbetsu of Hidaka region. Due to heavy rain, many
rivers flooded, including the Tokoro River on the Sea of Okhotsk side, causing damage
such as above/below floor level inundation of houses. Landslides occurred in various
places, and partial damage to homes were also caused. Evacuation instructions andrecommendations were issued for several days in many cities, towns and villages forfear of floods and landslides, and traffic interruption of national highways and roadways and service suspension of Japan Railway(JR) occurred. Together with Typhoon No. 7, which landed near Erimo Cape on 17 August and Typhoon No. 11, which landed near
Kushiro City on 21 August, three typhoons landed in Hokkaido in a week.
With the overflow of Tokoro River in Hokkaido at 0:40 on 21 August 2016, JAXA received ALOS-2 emergency observation requestfrom the River Planning Division of the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). Although observation on 21
August was withheld as conditions were not satisfactory for both day and night passes, ALOS-2 day and night pass observation
was conducted upon request on 22 August when flooding increased in the same river, since investigation by helicopter etc. wasdifficult due to bad weather, and image product was provided. Automatic analysis for disaster maps together with flooding area
extraction polygon by manual interpretation were provided and, under cooperation with the Geospatial Information Authority ofJapan (GSI), shared information with the Hokkaido Regional Development Bureau via MLIT’s Integrated Disaster Information
Mapping System (DiMAPS). Also, estimation of flooding volume was conducted by GSI Japan using DEM (5m mesh).

Characteristics of Typhoon No.9 and 10 of 2016

(1) First in observation history (3 typhoons to make landfall in Hokkaido in a year, first to make landfall in Tohoku region from the
Pacific Ocean side)(2) First flood disaster since the Kanto/Tohoku Torrential Rain of September 2015 after MLIT expanded ALOS-2 utilization inflood disasters(3) Large scale flood and landslide disaster, occurring numerously and simultaneously all over Hokkaido, Tohoku region, etc.
(4) Bad weather conditions persisted and observation by helicopters etc. delayed. Not observable by commercial optical satellites

ALOS-2 observation and provided products, timeline(1) Conducted emergency observation mainly of flood disaster locations, upon request from MLIT River Planning Division(2) Conducted observation in the night of 30 August for landslide disaster inspection immediately after Typhoon No.10 passed
Tohoku region, upon request from MLIT River Planning Division
Observation date

2016/8/22 (Mon)

Products provided
Interpreted
Observation Automatic analysis fordisaster map
polygon/Analysis resulttime(provision time)(provision time)*nominal: observation *nominal: observation +5+2 hours
hours

Observation area

12:15

(15:26)(16:46)

2016/8/22 (Mon)23:11(01:26)-

Hokkaido

Hokkaido

Tokoro River

2016/8/23 (Tue)

12:35(14:06)(15:38)

Hokkaido

Bebetsu River (Ishikari River system)

2016/8/23 (Tue)

23:32(00:14)-

Hokkaido

Ishikari River

2016/8/30 (Tue)

11:48(15:06)-

Hokkaido

Coastal Akita Prefecture

2016/8/30 (Tue)

22:43(00:43)(next day 5:24)

Hokkaido

Coastal Iwate Prefecture
Tokachi River

Tokoro River

2016/8/31 (Wed)

12:08(14:03)-

Hokkaido

2016/8/31 (Wed)

23:04(23:53)(08:56)

Hokkaido

Tokachi River

2016/9/1 (Thu)

12:28(14:34)(17:31)

Hokkaido

Sorachi River (Ishikari River system)

2016/9/1 (Thu)

12:28(14:34)(17:31)

Iwate Pref. Omoto River

2016/9/1 (Thu)

23:24(11:29)(14:07)

Iwate Pref. Kuji River

2016/9/1 (Thu)

23:24(11:29)(14:07)

Hokkaido

21

Satsunai River (Tokachi River system)

The Advanced Land Observing Satellite-2

Volcanos■Extraction of flooded areas

Radio wave emission direction

Satellite flight

Earthquakes

direction

Tokoro River

Mode: Stripmap (3m)
Off nadir angle: 32.4°
Polarized wave: HH
Observation after disaster
Date & time: 2016/8/22 12:14
Mode: Stripmap (3m)
Off nadir angle: 32.4°
Polarized wave: HH©JAXA
Flooded area extraction image near Tokoro River
Red: 1 December 2014
Green, blue: 22 August 2016

Outline of Response to the Tokoro River Floods (21 Aug 2016 (Sun) 16:00)

Flooding

Flooding

Overflow

Flooding
Flooding

Location where entry
was not possible for onsite investigation

JAXA note on MLIT Hokkaido Regional Development Bureau press release document
Flooded area map by the Hokkaido Regional Development Bureau (21 August 2016)

Fig. 1: Flooded area extraction image by ALOS-2 (above: flooded area extraction image near Tokoro River, below: flooded
area map by the Hokkaido Regional Development Bureau)
Compared to the Hokkaido Regional Development Bureau’s flooded area map of 21 August 2016 16:00 based on onsite investigation, it can be observed from ALOS-2 observation of 22 August 12:00 how the flooded area is changing. It canbe seen that ALOS-2 has extracted flooding in upstream areas where entry was not possible in the on-site investigation of
21 August 16:00. The flooded area extraction results from constant and night time ALOS-2 observation data was evaluatedby the Hokkaido Regional Development Bureau as fully fit to be utilized.

22

Floods/Landslides

Location where entry
was not possible foron-site investigation

Observation before disaster
Date & time: 2014/12/1 12:14

List of Sources●The sources of figures and photographs used in this document are as follows:
No
1

2

3

Item
Overview of
Image Analysis

8

Figure, Photo
Fig. 9SourceProcessed by Mitsubishi Space Software Co., Ltd. based on Geospatial
Information Authority of Japan (GSI) homepage
http://www.gsi.go.jp/common/000095940.pdf
GSI Japan homepage

10, 11

Fig. 1, 2, 3

(Mount Hakone)

12

Fig. 4

Fig. 1, 3
Photo 1GSI Japan homepage
http://www.gsi.go.jp/BOUSAI/H27-kumamoto-earthquake-index.html

Case 2

13, 1415
16
14

Fig. 2

GSI Japan homepage
http://www.gsi.go.jp/common/000139926.pdf

14

Fig. 4

GSI Japan homepage
http://www.gsi.go.jp/common/000140781.pdf

18

Fig. 2 (right)

GSI Japan homepage
http://www.gsi.go.jp/common/000107669.pdf

19, 20Fig. 3, 4, 5
(map)

19, 20

Photo 2, 3, 4Case 1(Kumamoto

Earthquake of 2016)

4

Page

Case 3(Kanto/Tohoku
Torrential Rains of
September 2015)

Photo 3

http://www.gsi.go.jp/kikakuchousei/bousaichousei/h27-hakoneyama-index. html
Japan Meteorological Agency 133rd Coordinating Committee for Prediction ofVolcanic Eruptions document
http://www.data.jma.go.jp/svd/vois/data/tokyo/STOCK/kaisetsu/CCPVE/
shiryo/133/133_04.pdf

GSI Japan homepage

http://maps.gsi.go.jp/
Ministry of Land, Infrastructure, Transport and Tourism (MLIT), Kanto
Regional Development Bureau homepage

http://www.ktr.mlit.go.jp/bousai/index00000047.html(the photographs are no longer on the above homepage)
Case 4
5(Typhoon No.9
(Mindulle) of 2016)22

Fig. 1 (below)

MLIT, Hokkaido Regional Development Bureau document
https://www.hkd.mlit.go.jp/ky/saigai/press_h2808/21_houdou09.pdf(Tokoro River Hokkaido)

23

The Advanced Land Observing Satellite-2

Space Application for Disaster
Monitoring- Collection of Good Practice in Disaster Emergency Observation
by ALOS-2 “DAICHI 2” from 2014 to 2017 (Excerpts)
First published in Japanese in March 2018
Excerpts translated into English in July 2018
Japan Aerospace Exploration Agency (JAXA)
Satellite Applications and Operations Center (SAOC)
Japanese version editing assistance
Mitsubishi Space Software Co., Ltd.
Mitsubishi Electric Co., Ltd.
For questions concerning ALOS-2 utilization please contact
Satellite Applications and Operations Center
Space Technology Directorate I
Japan Aerospace Exploration Agency
Ochanomizu sola city 4-6 Kandasurugadai, Chiyoda-ku, Tokyo
101-8008 Japan
E-mail: sapc-info@ml.jaxa.jp
Copyright of ALOS-2 images used in this document is owned by the Japan Aerospace
Exploration Agency, unless otherwise provided and indicated.