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Earthquake-induced soil displacements and their impact on rehabilitations.

Konagai K - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2011)

Bottom Line: Therefore one of what required of us is to deduce as much hidden signs as possible from observable changes of landforms.An attempt was made to convert changes in elevation in Eulerian description for images obtained from remote-sensing technologies to Lagrangian displacements, because Lagrangian displacements can directly describe behaviors of soils, which are typically history-dependent.This paper documents some big pictures of earthquake-inflicted landform changes obtained through this attempt.

View Article: PubMed Central - PubMed

Affiliation: Institute of Industrial Science, The University of Tokyo, Japan. konagai@iis.u-tokyo.ac.jp

ABSTRACT
A large earthquake can trigger long lasting geotechnical problems, which pose serious issues on both rehabilitations and land conservations. Therefore one of what required of us is to deduce as much hidden signs as possible from observable changes of landforms. Though serious, damage caused by the October 23rd 2004, Mid-Niigata Prefecture Earthquake has given us a rare opportunity to study the landform changes in mountainous terrain hit by this earthquake. An attempt was made to convert changes in elevation in Eulerian description for images obtained from remote-sensing technologies to Lagrangian displacements, because Lagrangian displacements can directly describe behaviors of soils, which are typically history-dependent. This paper documents some big pictures of earthquake-inflicted landform changes obtained through this attempt.

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Verification of the process for obtaining Δzk,triangulations.
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fig03: Verification of the process for obtaining Δzk,triangulations.

Mentions: Though the DEMs before and after the earthquake were carefully prepared, comparing DEMs from the two essentially different methods can cause some inevitable bias to be included in the result. Therefore for the target area discussed hereafter, the obtained elevation changes were compared with those at points of triangulations in order to verify the result (Fig. 3). There were total six triangulation points whose movements were not affected by landslides in the target zone. In this figure, open squares show Eulerian displacements directly obtained from DEMs, while open circles show the vertical components of Lagrangian displacements estimated through the process mentioned above. Between vertical components of soil displacement Δzk,triangulation at the points of triangulation and Lagrangian expression of Δzk,DEMs (open circles) obtained from the two DEMs, a linear regression analysis was carried to best-fit b+Δzk,triangulation to Δzk,DEMs, yielding[4]For the range of Δzk,triangulation from 0.3 to 1.0 m, this −0.033 m bias is considered to be small enough to validate the process for converting Eulerian displacements Δzk,DEMs to those in Lagrangian expression. Thus the present method is considered to allow for describing the entire view of tectonic displacements. However, discussing displacements for particular locations will require careful attentions given the standard deviation of 0.34 m that may be a reflection of some local conditions.


Earthquake-induced soil displacements and their impact on rehabilitations.

Konagai K - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2011)

Verification of the process for obtaining Δzk,triangulations.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3313688&req=5

fig03: Verification of the process for obtaining Δzk,triangulations.
Mentions: Though the DEMs before and after the earthquake were carefully prepared, comparing DEMs from the two essentially different methods can cause some inevitable bias to be included in the result. Therefore for the target area discussed hereafter, the obtained elevation changes were compared with those at points of triangulations in order to verify the result (Fig. 3). There were total six triangulation points whose movements were not affected by landslides in the target zone. In this figure, open squares show Eulerian displacements directly obtained from DEMs, while open circles show the vertical components of Lagrangian displacements estimated through the process mentioned above. Between vertical components of soil displacement Δzk,triangulation at the points of triangulation and Lagrangian expression of Δzk,DEMs (open circles) obtained from the two DEMs, a linear regression analysis was carried to best-fit b+Δzk,triangulation to Δzk,DEMs, yielding[4]For the range of Δzk,triangulation from 0.3 to 1.0 m, this −0.033 m bias is considered to be small enough to validate the process for converting Eulerian displacements Δzk,DEMs to those in Lagrangian expression. Thus the present method is considered to allow for describing the entire view of tectonic displacements. However, discussing displacements for particular locations will require careful attentions given the standard deviation of 0.34 m that may be a reflection of some local conditions.

Bottom Line: Therefore one of what required of us is to deduce as much hidden signs as possible from observable changes of landforms.An attempt was made to convert changes in elevation in Eulerian description for images obtained from remote-sensing technologies to Lagrangian displacements, because Lagrangian displacements can directly describe behaviors of soils, which are typically history-dependent.This paper documents some big pictures of earthquake-inflicted landform changes obtained through this attempt.

View Article: PubMed Central - PubMed

Affiliation: Institute of Industrial Science, The University of Tokyo, Japan. konagai@iis.u-tokyo.ac.jp

ABSTRACT
A large earthquake can trigger long lasting geotechnical problems, which pose serious issues on both rehabilitations and land conservations. Therefore one of what required of us is to deduce as much hidden signs as possible from observable changes of landforms. Though serious, damage caused by the October 23rd 2004, Mid-Niigata Prefecture Earthquake has given us a rare opportunity to study the landform changes in mountainous terrain hit by this earthquake. An attempt was made to convert changes in elevation in Eulerian description for images obtained from remote-sensing technologies to Lagrangian displacements, because Lagrangian displacements can directly describe behaviors of soils, which are typically history-dependent. This paper documents some big pictures of earthquake-inflicted landform changes obtained through this attempt.

Show MeSH
Related in: MedlinePlus