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Analysis of earthquake-induced groundwater level change using self-organizing maps

Nakagawa, Kei LU ; Yu, Zhi Qiang; Berndtsson, Ronny LU and Kagabu, Makoto (2019) In Environmental Earth Sciences 78(15).
Abstract

For a better understanding of possible physical links between geophysical observables and earthquake characteristics, it is important to analyze statistical spatiotemporal patterns in nature related to such events. For this purpose, characteristic changes in groundwater level (GWL) were observed before and after the 2016 Kumamoto earthquake in Japan. Previous research has shown that self-organizing maps (SOM) can be used to classify complex patterns of GWL-change during different parts of the earthquake sequence. In this study, we used before and after earthquake GWL data as input vectors to SOM. In total, 64 observed GWLs were classified into 12 different clusters. Most shallow wells displayed GWL difference that was small during the... (More)

For a better understanding of possible physical links between geophysical observables and earthquake characteristics, it is important to analyze statistical spatiotemporal patterns in nature related to such events. For this purpose, characteristic changes in groundwater level (GWL) were observed before and after the 2016 Kumamoto earthquake in Japan. Previous research has shown that self-organizing maps (SOM) can be used to classify complex patterns of GWL-change during different parts of the earthquake sequence. In this study, we used before and after earthquake GWL data as input vectors to SOM. In total, 64 observed GWLs were classified into 12 different clusters. Most shallow wells displayed GWL difference that was small during the foreshock (first earthquake) and large during the main-shock (second earthquake). Upstream deep wells showed relatively large difference in water level from 1 to 2 days after the earthquakes. The GWL rapidly increased just after the earthquake, then tended to gradually decrease from September. Most of the shallow wells in the unconfined aquifer rapidly recovered to initial GWLs within several hours to several days, because of hydrostatic pressure. However, most of the deep wells in the confined aquifer needed longer time to recover, in some cases several weeks to several months. These findings are important for the physical understanding of earthquake effects on the groundwater environment, disaster prevention, and possibility for development of earthquake precursors.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cluster analysis, Groundwater level (GWL) change, Kumamoto earthquake, Self-organizing map (SOM)
in
Environmental Earth Sciences
volume
78
issue
15
publisher
Springer
external identifiers
  • scopus:85069538934
ISSN
1866-6280
DOI
10.1007/s12665-019-8473-z
language
English
LU publication?
yes
id
bd162f36-8ef6-4fd4-a09e-8709a6f18ad4
date added to LUP
2019-08-05 10:07:27
date last changed
2019-08-28 04:57:41
@article{bd162f36-8ef6-4fd4-a09e-8709a6f18ad4,
  abstract     = {<p>For a better understanding of possible physical links between geophysical observables and earthquake characteristics, it is important to analyze statistical spatiotemporal patterns in nature related to such events. For this purpose, characteristic changes in groundwater level (GWL) were observed before and after the 2016 Kumamoto earthquake in Japan. Previous research has shown that self-organizing maps (SOM) can be used to classify complex patterns of GWL-change during different parts of the earthquake sequence. In this study, we used before and after earthquake GWL data as input vectors to SOM. In total, 64 observed GWLs were classified into 12 different clusters. Most shallow wells displayed GWL difference that was small during the foreshock (first earthquake) and large during the main-shock (second earthquake). Upstream deep wells showed relatively large difference in water level from 1 to 2 days after the earthquakes. The GWL rapidly increased just after the earthquake, then tended to gradually decrease from September. Most of the shallow wells in the unconfined aquifer rapidly recovered to initial GWLs within several hours to several days, because of hydrostatic pressure. However, most of the deep wells in the confined aquifer needed longer time to recover, in some cases several weeks to several months. These findings are important for the physical understanding of earthquake effects on the groundwater environment, disaster prevention, and possibility for development of earthquake precursors.</p>},
  articleno    = {455},
  author       = {Nakagawa, Kei and Yu, Zhi Qiang and Berndtsson, Ronny and Kagabu, Makoto},
  issn         = {1866-6280},
  keyword      = {Cluster analysis,Groundwater level (GWL) change,Kumamoto earthquake,Self-organizing map (SOM)},
  language     = {eng},
  number       = {15},
  publisher    = {Springer},
  series       = {Environmental Earth Sciences},
  title        = {Analysis of earthquake-induced groundwater level change using self-organizing maps},
  url          = {http://dx.doi.org/10.1007/s12665-019-8473-z},
  volume       = {78},
  year         = {2019},
}