2:30 PM - 2:45 PM
[U15-04] Estimation of slope failure/sediment distribution and tsunami inundation area associated with the 2024 Noto Peninsula Earthquake based on aerial photo interpretation
Keywords:slope failure/sediment distribution, tsunami inundation area, aerial photo interpretation
1. Introduction
The 2024 Noto Peninsula Earthquake, which occurred on January 1st, 2024, caused frequent slope failures and landslides mainly in the mountainous areas of the Noto Peninsula, as well as tsunami inundation damage mainly on the east and west coasts of the Noto Peninsula. The Geospatial Information Authority (GSI) of Japan began taking aerial photographs over a wide area of the Noto Peninsula on January 2nd. In addition, the aerial photographs were used to interpret slope failure/sediment distribution and tsunami inundation areas. In this presentation, we will report on the interpretation standards and issues in interpretation, and we consider the accuracy of interpretation by comparing with the results of a field survey. In addition, we will mainly compare slope failure/sediment distribution with geomorphology and geology, and we consider the distribution characteristics.
2. Slope failure/sediment distribution
The distribution of slope failure and sedimentation was interpreted using ortho- images created from aerial photographs taken from January 2nd to January 17th. The area of slope failures and sedimentation that are thought to have occurred due to this earthquake were obtained in polygon format. The criteria for acquiring the size was that the slope failure/sediment area was approximately 100 square meters or more. The interpretation results were provided as data on the GSI of Japan's website, and slope failure/sediment distribution maps were also created and published.
As a result of the field survey, it was found that while the information was mostly accurate, there were some omissions in the interpretation and misinterpretation of the logging sites.
Comparing the distribution of slope failure and sedimentation with the 1:200,000 seamless geological map (V2) provided by AIST, it is found that slope failures frequently occurred in areas with a sea consisting mainly of Neogene mudstone or dacite/rhyolitic lava/pyroclastic rock near the boundary between Wajima City and Suzu City and in the mountainous area of Noto Town. In the mountain area of Wajima City, slope failures occurred frequently or sporadically in areas with Paleogene andesite/basaltic lava/pyroclastic rock, non-marine alternation of sandstone and mudstone, and Neogene mixed marine/non-marine conglomerate layers.
3. Tsunami inundation area
The tsunami inundation area was interpreted using ortho-images created from aerial photographs taken from January 2nd to January 17th. Taking into consideration conditions such as washed away houses, fallen vegetation, accumulation of garbage, wet roads and fields, and altitude, we obtained the inundation area of the tsunami in polygon format. The area was acquired including the land outside the embankment, and the coastline was aligned with the coastline in the ortho-image. The interpretation results were provided as data on the GSI of Japan's website, and tsunami inundation area maps were also created and published.
As a result of the field survey, although there were many places where the tsunami inundation area could be accurately interpreted, there were also some places where the interpreting range were too large or too small.
4. Summary and challenges
We interpreted the slope failure/sediment distribution and tsunami inundation area associated with the earthquake and provided the data. As a result of on-site verification, while the slope failure/sediment distribution map was generally accurate, there were some omissions and misinterpretations of logging sites. Although many areas of the tsunami inundation area were accurate, there were also some areas where the interpreting range seemed to be too large or too small.
Because the frequency of interpreting tsunami inundation areas is low, there are few experienced operators, and it is currently difficult to secure workers. The future challenge is to succeed to the interpretation technique of tsunami inundation area.
The 2024 Noto Peninsula Earthquake, which occurred on January 1st, 2024, caused frequent slope failures and landslides mainly in the mountainous areas of the Noto Peninsula, as well as tsunami inundation damage mainly on the east and west coasts of the Noto Peninsula. The Geospatial Information Authority (GSI) of Japan began taking aerial photographs over a wide area of the Noto Peninsula on January 2nd. In addition, the aerial photographs were used to interpret slope failure/sediment distribution and tsunami inundation areas. In this presentation, we will report on the interpretation standards and issues in interpretation, and we consider the accuracy of interpretation by comparing with the results of a field survey. In addition, we will mainly compare slope failure/sediment distribution with geomorphology and geology, and we consider the distribution characteristics.
2. Slope failure/sediment distribution
The distribution of slope failure and sedimentation was interpreted using ortho- images created from aerial photographs taken from January 2nd to January 17th. The area of slope failures and sedimentation that are thought to have occurred due to this earthquake were obtained in polygon format. The criteria for acquiring the size was that the slope failure/sediment area was approximately 100 square meters or more. The interpretation results were provided as data on the GSI of Japan's website, and slope failure/sediment distribution maps were also created and published.
As a result of the field survey, it was found that while the information was mostly accurate, there were some omissions in the interpretation and misinterpretation of the logging sites.
Comparing the distribution of slope failure and sedimentation with the 1:200,000 seamless geological map (V2) provided by AIST, it is found that slope failures frequently occurred in areas with a sea consisting mainly of Neogene mudstone or dacite/rhyolitic lava/pyroclastic rock near the boundary between Wajima City and Suzu City and in the mountainous area of Noto Town. In the mountain area of Wajima City, slope failures occurred frequently or sporadically in areas with Paleogene andesite/basaltic lava/pyroclastic rock, non-marine alternation of sandstone and mudstone, and Neogene mixed marine/non-marine conglomerate layers.
3. Tsunami inundation area
The tsunami inundation area was interpreted using ortho-images created from aerial photographs taken from January 2nd to January 17th. Taking into consideration conditions such as washed away houses, fallen vegetation, accumulation of garbage, wet roads and fields, and altitude, we obtained the inundation area of the tsunami in polygon format. The area was acquired including the land outside the embankment, and the coastline was aligned with the coastline in the ortho-image. The interpretation results were provided as data on the GSI of Japan's website, and tsunami inundation area maps were also created and published.
As a result of the field survey, although there were many places where the tsunami inundation area could be accurately interpreted, there were also some places where the interpreting range were too large or too small.
4. Summary and challenges
We interpreted the slope failure/sediment distribution and tsunami inundation area associated with the earthquake and provided the data. As a result of on-site verification, while the slope failure/sediment distribution map was generally accurate, there were some omissions and misinterpretations of logging sites. Although many areas of the tsunami inundation area were accurate, there were also some areas where the interpreting range seemed to be too large or too small.
Because the frequency of interpreting tsunami inundation areas is low, there are few experienced operators, and it is currently difficult to secure workers. The future challenge is to succeed to the interpretation technique of tsunami inundation area.