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Ground deformation associated with the Ground deformation associated with the earthquake occurred in Solomon Islands on earthquake occurred in Solomon Islands on April 1, 2007 detected by ALOS/PALSAR April 1, 2007 detected by ALOS/PALSAR

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Ground deformation associated with the Ground deformation associated with the earthquake occurred in Solomon Islands on earthquake occurred in Solomon Islands on April 1, 2007 detected by ALOS/PALSAR April 1, 2007 detected by ALOS/PALSAR

Yousuke Miyagi (JAXA/EORC), Taku Ozawa (NIED), and Masanobu Shimada (JAXA/EORC)

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SLIDE 2

Outline of This Presentation Outline of This Presentation

  • M8.1 earthquake in Solomon Islands (April 1, 2007)
  • Observation by ALOS/PALSAR
  • Field investigation (Comparison with satellite data)
  • Ground deformation from DInSAR processing
  • Fault modeling
  • Post-seismic deformation?
  • Summary
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SLIDE 3

M8.1 Earthquake in Solomon Islands M8.1 Earthquake in Solomon Islands (April 1, 2007 (UTC)) (April 1, 2007 (UTC))

Tregoning Tregoning et al., JGR, 1998 et al., JGR, 1998

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SLIDE 4

M8.1 Earthquake in Solomon Islands M8.1 Earthquake in Solomon Islands (April 1, 2007 (UTC)) (April 1, 2007 (UTC))

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is. B B e e a a m m azimuth

Tregoning Tregoning et al., JGR, 1998 et al., JGR, 1998

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SLIDE 5

Importance of remote sensing (PALSAR) Importance of remote sensing (PALSAR) data in remote locations data in remote locations

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is. B B e e a a m m azimuth

  • A remote sensing technique

has advantage to observe and monitor a disaster occurred in a remote location.

  • PALSAR can acquire so

many data, and the data can be applied to DInSAR technique.

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SLIDE 6

Importance of ground truth for verification Importance of ground truth for verification

  • A remote sensing technique

has advantage to observe and monitor a disaster occurred in a remote location.

  • PALSAR can acquire so

many data, and the data can be applied to DInSAR technique.

  • Field investigation is helpful

for verification (if it is possible).

(Field investigation during July 25 (Field investigation during July 25-

  • 30, 2007)

30, 2007)

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SLIDE 7

Parara Island Parara Island before before the earthquake the earthquake

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is.

(March 1, 2007: low tide ~0.1m) (March 1, 2007: low tide ~0.1m)

Parara Is.

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SLIDE 8

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is.

Parara Island Parara Island after after the earthquake the earthquake

(April 16, 2007: middle tide ~0.5m) (April 16, 2007: middle tide ~0.5m) Slight increase of land area in spite of Slight increase of land area in spite of rising of tide level for the period. rising of tide level for the period.

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Parara Island Parara Island after after the earthquake the earthquake

(July 25, 2007) (July 25, 2007) From the field investigation, we could From the field investigation, we could confirm that uplift of coral reef around confirm that uplift of coral reef around Parara Island. Parara Island. (April 16, 2007: middle tide ~0.5m) (April 16, 2007: middle tide ~0.5m)

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SLIDE 10

Ranongga Island Ranongga Island before before the earthquake the earthquake

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is.

(January 31, 2007: low tide ~0.1m) (January 31, 2007: low tide ~0.1m)

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SLIDE 11

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is.

Ranongga Island Ranongga Island after after the earthquake the earthquake

(May 3, 2007: high tide ~0.7m) (May 3, 2007: high tide ~0.7m)

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SLIDE 12

Ranongga Island Ranongga Island before before the earthquake the earthquake

(January 31, 2007: low tide ~0.1m) (January 31, 2007: low tide ~0.1m)

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Ranongga Island Ranongga Island after after the earthquake the earthquake

(May 3, 2007: high tide ~0.7m) (May 3, 2007: high tide ~0.7m)

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SLIDE 14

Ranongga Island Ranongga Island after after the earthquake the earthquake

(July 28, 2007) (July 28, 2007) Significant uplift in the south part of Ranongga Significant uplift in the south part of Ranongga

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SLIDE 15

Ranongga Island Ranongga Island before before the earthquake the earthquake

(January 31, 2007: low tide ~0.1m) (January 31, 2007: low tide ~0.1m)

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SLIDE 16

Ranongga Island Ranongga Island after after the earthquake the earthquake

(May 3, 2007: high tide ~0.7m) (May 3, 2007: high tide ~0.7m)

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SLIDE 17

Ranongga Island Ranongga Island after after the earthquake the earthquake

(July 28, 2007) (July 28, 2007) Many landslides or mudslides in the west Many landslides or mudslides in the west coast of coast of Ranongga Ranongga. .

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Ranongga Island Ranongga Island before before the earthquake the earthquake

(January 31, 2007: low tide ~0.1m) (January 31, 2007: low tide ~0.1m)

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SLIDE 19

Ranongga Island Ranongga Island after after the earthquake the earthquake

(May 3, 2007: high tide ~0.7m) (May 3, 2007: high tide ~0.7m)

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Ranongga Island Ranongga Island after after the earthquake the earthquake

(July 28, 2007) (July 28, 2007) Significant uplifts in the north part of Ranongga Significant uplifts in the north part of Ranongga

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Simbo Island Simbo Island before before the earthquake the earthquake

Epicenter (Mw8.1)

Ranongga Is. Simbo Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is.

(January 31, 2007: low tide ~0.1m) (January 31, 2007: low tide ~0.1m)

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SLIDE 22

Epicenter (Mw8.1)

Ranongga Is. Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is.

Simbo Island Simbo Island after after the earthquake the earthquake

(May 3, 2007: high tide ~0.7m) (May 3, 2007: high tide ~0.7m)

Simbo Is.

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SLIDE 23

Tsunami damages at Tapurai Tsunami damages at Tapurai

(north part of Simbo Island) (north part of Simbo Island)

Tapurai Tapurai

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SLIDE 24

Tsunami damages at Tapurai Tsunami damages at Tapurai

(north part of Simbo Island) (north part of Simbo Island)

Tapurai Tapurai (July 28, 2007) (July 28, 2007)

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Importance of remote sensing (PALSAR) Importance of remote sensing (PALSAR) data in remote locations data in remote locations

Epicenter (Mw8.1)

Ghizo Is. Vella Lavella Is. Kolombangara Is.

Choiseul Is. New Georgia Is.

Rendova Is. Tetepare Is. Vangunu Is. Parara Is. B B e e a a m m azimuth

  • Big uplift in Ranongga, and no

uplift or subsidence and significant damage from tsunami in Simbo. There may be boundary of uplift and subsidence between them.

  • From just comparison of amplitude

images, we can see that something

  • ccurred or the pattern of
  • phenomena. However we can’t

understand what it is or how it is.

  • Ground movements resulted from

DInSAR technique are quite precise, and can be used for quantitative discussion.

Ranongga Is. Simbo Is.

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SLIDE 26

PALSAR Interferometric Images PALSAR Interferometric Images

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Fault modeling (Preliminary) Fault modeling (Preliminary)

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SLIDE 28

Slip Distribution Slip Distribution

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SLIDE 29

Slip Distribution Slip Distribution

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Fault modeling using seismic data Fault modeling using seismic data

Yamanaka (2007) also inferred slip distribution using teleseismic body wave data. The pattern that there are two eyed large slip area around the hypocenter and the northwest of it, is consistent with those induced from just DInSAR data.

http://www.seis.nagoya-u.ac.jp/sanchu/Seismo_Note/2007/RSVD1.html

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SLIDE 31

Residuals between obs. and calc. Residuals between obs. and calc.

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SLIDE 32

Summary Summary

  • ALOS/PALSAR could acquire favorable data to understand

phenomena associated with the large earthquake in Solomon Islands.

  • Comparison of amplitude images between before and after the

earthquake, it was revealed that something has occurred and it was confirmed by field investigation.

  • Huge uplift occurred in Ranongga Island, on the other hand,

subsidence or no uplift occurred in Simbo Island, so differently-damaged by tsunami.

  • Significant ground deformation over the wide area was

represented using DInSAR technique. From these geodetic data, we inferred fault model and slip distribution for the

  • earthquake. Although it is a preliminary results, it shows good

agreement with observed deformation.

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SLIDE 33

Post Post-

  • seismic deformation?

seismic deformation?

  • In interviews with inhabitants who lives in Ghizo

Island or its surroundings, we obtained witnesses that a sea level rose compared to it before earthquake in April, and witnesses that the sea level lowered in July. We wondered whether these witnesses are induced from their ambiguities, or these mean co-seismic subsidence and post-seismic rebound.

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Nishimura et al., [2007]

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PALSAR Data for Solomon Islands PALSAR Data for Solomon Islands Path Path-

  • 345

345 (

(2007/1/31 (FBS), 2007/5/3 (FBS), 2007/6/18 (FBD), 2007/8/3 (FBD) 2007/1/31 (FBS), 2007/5/3 (FBS), 2007/6/18 (FBD), 2007/8/3 (FBD), , 2007/9/18 (FBD) , 2007/11/3 (FBS), 2007/12/19 (FBS) 2007/9/18 (FBD) , 2007/11/3 (FBS), 2007/12/19 (FBS)) )

2006/12 2007/1 2007/2 2007/3 2007/4 2007/5 2007/6 2007/7 2007/8 2007/9 2007/10 2007/11 2007/12 2008/1

FBS FBD

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Ghizo Ghizo Island Island

2007/1/31 low tide (~0.1m) 2007/5/3 high tide (~0.7m) 2007/6/18 high tide (~0.8m) 2007/8/3 middle tide (~0.6m) 2007/9/18 middle tide (~0.5m) 2007/11/3 middle tide (~0.4m) 2007/12/19 low tide (~0.2m)

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SLIDE 37

Path Path-

  • 345

345

2007/5/3-2007/6/18 2007/6/18-2007/8/3 2007/8/3-2007/9/18 2007/9/18-2007/11/3 2007/5/3-2007/8/3 2007/6/18-2007/9/18 2007/6/18-2007/11/3

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SLIDE 38

Just on the boundary Just on the boundary

Briggs et al., [2007]

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PALSAR Data for Solomon Islands PALSAR Data for Solomon Islands Path Path-

  • 343

343 (

(2006/12/28 (FBS), 2007/2/12 (FBS), 2007/5/15 (FBS), 2007/6/30 (F 2006/12/28 (FBS), 2007/2/12 (FBS), 2007/5/15 (FBS), 2007/6/30 (FBD), BD), 2007/8/15 (FBD), 2007/9/30 (FBD), 2007/12/31 (FBS) 2007/8/15 (FBD), 2007/9/30 (FBD), 2007/12/31 (FBS)) )

2006/12 2007/1 2007/2 2007/3 2007/4 2007/5 2007/6 2007/7 2007/8 2007/9 2007/10 2007/11 2007/12 2008/1

FBS FBD

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PALSAR Data for Solomon Islands PALSAR Data for Solomon Islands Path Path-

  • 344

344 (

(2007/1/14 (FBS), 2007/3/1 (FBS), 2007/4/16 (FBS), 2007/7/17 (FBD 2007/1/14 (FBS), 2007/3/1 (FBS), 2007/4/16 (FBS), 2007/7/17 (FBD), ), 2007/9/1 (FBD), 2007/10/17 (FBD) 2007/9/1 (FBD), 2007/10/17 (FBD)) )

2006/12 2007/1 2007/2 2007/3 2007/4 2007/5 2007/6 2007/7 2007/8 2007/9 2007/10 2007/11 2007/12 2008/1

FBS FBD

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SLIDE 41

2007/4/16-2007/9/1 2007/4/16-2007/10/17 2007/9/1-2007/10/17

Path Path-

  • 344

344

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SLIDE 42

Path Path-

  • 343 Post

343 Post-

  • seismic

seismic

2007/5/15-2007/12/31

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Path Path-

  • 343 Co

343 Co-

  • seismic

seismic

2007/2/12-2007/5/15