Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis

Mapping methods for loosened rock mass in mountainous areas are useful for risk management of landslide disasters. Depending on the type of aircraft and sensor, there are several different aerial electromagnetic measurement methods for estimating subsurface structures. Helicopter-borne electromagnet...

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Main Authors: Atsuko Nonomura, Shuichi Hasegawa, Akira Jomori, Minoru Okumura, Haruki Ojyuku, Hiroaki Hoshino, Tetsuya Toyama, Atsuyoshi Jomori, Yoshiyuki Kaneda
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/13/2184
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author Atsuko Nonomura
Shuichi Hasegawa
Akira Jomori
Minoru Okumura
Haruki Ojyuku
Hiroaki Hoshino
Tetsuya Toyama
Atsuyoshi Jomori
Yoshiyuki Kaneda
author_facet Atsuko Nonomura
Shuichi Hasegawa
Akira Jomori
Minoru Okumura
Haruki Ojyuku
Hiroaki Hoshino
Tetsuya Toyama
Atsuyoshi Jomori
Yoshiyuki Kaneda
author_sort Atsuko Nonomura
collection DOAJ
description Mapping methods for loosened rock mass in mountainous areas are useful for risk management of landslide disasters. Depending on the type of aircraft and sensor, there are several different aerial electromagnetic measurement methods for estimating subsurface structures. Helicopter-borne electromagnetic methods are commonly used. Recently, unmanned aerial vehicles (drones) have been used. By understanding the characteristics of each method, it is possible to choose a suitable method for the target of observation. In this study, resistivity from the frequency-domain helicopter-borne electromagnetic (HEM) method and resistivity from the time-domain drone-grounded electrical-source airborne transient electromagnetic (D-GREATEM) method were compared to estimate loosened zones in mountainous areas. The resistivity cross-sectional profiles were largely similar, but differences were observed near the surface in some zones. The comparative analysis of both methods with outcrop observations revealed that D-GREATEM resistivity data can detect both loosened rock mass from the surface to an approximately 30 m depth located above the groundwater and saturated rock mass. It is because D-GREATEM resistivity was obtained by assuming five layers from the surface to a depth of 40 m. This indicates that D-GREATEM is suitable for estimating near-surface loosened rock mass distribution in the valleys. However, D-GREATEM has a limited observation range. Therefore, it was concluded that the D-GREATEM method is suitable for a detailed and localized estimation of landslide susceptibility near the surface, whereas the HEM method is suitable for wide-area analysis.
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spelling doaj-art-ae4c93b5ac4348a3aa52eecc0defe9182025-08-20T03:50:21ZengMDPI AGRemote Sensing2072-42922025-06-011713218410.3390/rs17132184Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility AnalysisAtsuko Nonomura0Shuichi Hasegawa1Akira Jomori2Minoru Okumura3Haruki Ojyuku4Hiroaki Hoshino5Tetsuya Toyama6Atsuyoshi Jomori7Yoshiyuki Kaneda8Faculty of Engineering and Design, Kagawa University, Takamatsu 761-0396, JapanInstitution of Education, Research and Regional Cooperation for Crisis Management Shikoku, Kagawa University, Takamatsu 760-8521, JapanNeoScience Co., Sennan 590-0521, JapanDia Nippon Engineering Consultants Co., Ltd., Tokyo 102-0075, JapanGraduate School of Science for Creative Emergence, Kagawa University, Takamatsu 761-0396, JapanWest Nippon Expressway Co., Ltd., Osaka 530-0003, JapanNeoScience Co., Sennan 590-0521, JapanNeoScience Co., Sennan 590-0521, JapanInstitution of Education, Research and Regional Cooperation for Crisis Management Shikoku, Kagawa University, Takamatsu 760-8521, JapanMapping methods for loosened rock mass in mountainous areas are useful for risk management of landslide disasters. Depending on the type of aircraft and sensor, there are several different aerial electromagnetic measurement methods for estimating subsurface structures. Helicopter-borne electromagnetic methods are commonly used. Recently, unmanned aerial vehicles (drones) have been used. By understanding the characteristics of each method, it is possible to choose a suitable method for the target of observation. In this study, resistivity from the frequency-domain helicopter-borne electromagnetic (HEM) method and resistivity from the time-domain drone-grounded electrical-source airborne transient electromagnetic (D-GREATEM) method were compared to estimate loosened zones in mountainous areas. The resistivity cross-sectional profiles were largely similar, but differences were observed near the surface in some zones. The comparative analysis of both methods with outcrop observations revealed that D-GREATEM resistivity data can detect both loosened rock mass from the surface to an approximately 30 m depth located above the groundwater and saturated rock mass. It is because D-GREATEM resistivity was obtained by assuming five layers from the surface to a depth of 40 m. This indicates that D-GREATEM is suitable for estimating near-surface loosened rock mass distribution in the valleys. However, D-GREATEM has a limited observation range. Therefore, it was concluded that the D-GREATEM method is suitable for a detailed and localized estimation of landslide susceptibility near the surface, whereas the HEM method is suitable for wide-area analysis.https://www.mdpi.com/2072-4292/17/13/2184aerial electromagnetic methodloosened rock masslandslide susceptibilityresistivityHEMdrone
spellingShingle Atsuko Nonomura
Shuichi Hasegawa
Akira Jomori
Minoru Okumura
Haruki Ojyuku
Hiroaki Hoshino
Tetsuya Toyama
Atsuyoshi Jomori
Yoshiyuki Kaneda
Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis
Remote Sensing
aerial electromagnetic method
loosened rock mass
landslide susceptibility
resistivity
HEM
drone
title Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis
title_full Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis
title_fullStr Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis
title_full_unstemmed Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis
title_short Estimation of Near-Surface Loosened Rock Mass Zones in Mountainous Areas by Using Helicopter-Borne and Drone-Borne Electromagnetic Method for Landslide Susceptibility Analysis
title_sort estimation of near surface loosened rock mass zones in mountainous areas by using helicopter borne and drone borne electromagnetic method for landslide susceptibility analysis
topic aerial electromagnetic method
loosened rock mass
landslide susceptibility
resistivity
HEM
drone
url https://www.mdpi.com/2072-4292/17/13/2184
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