Geological and geomorphological features of deep-seated catastrophic landslides in tectonically active regions of Asia and implications for hazard mapping

Chigira, Masahiro

doi:10.18814/epiiugs/2014/v37i4/008

Cited by 24 publications

(6 citation statements)

References 38 publications

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“…This difference may be attributed to the Gorkha earthquake occurring in the dry season, with no heavy precipitation recorded at the time (Tsou et al 2017). Antecedent rainfall can contribute to landslide formation by raising the groundwater level and increasing the pore water pressure (Chigira, 2014;Higaki et al, 2015). Even though gigantic landslides were not induced by the 2015 Gorkha earthquake, Collins and Jibson (2015) conducted helicopter reconnaissance following the event and observed slope deformation such as ground cracks on ridge tops, which could develop into landslides and threaten downslope settlements.…”

Section: Methodsmentioning

confidence: 99%

Topographic characteristics of landslides induced by the 2015 Gorkha earthquake, Nepal

Tsou

Higaki

Chigira

et al. 2018

Journal of Nepal Geological Society

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The 2015 Gorkha earthquake and its aftershocks induced landslides in central Nepal. In this study, field surveys were conducted, and Google Earth satellite images were analysed for pre- and post-mainshock and aftershock scenarios to clarify the distribution of landslides. A total of 13,097 new landslides and 750 enlarged landslides were identified and mapped as polygon-based data over an area of 7.8 × 103 km2 between the epicenters of the main shock and the largest aftershock at the mountainous southern margin of the High Himalayas. Shallow-disrupted landslides were the most common type of mass movement. The areas of individual landslides ranged from 10 to 3.2× 105 m2, covering a cumulative area of 5.4 × 107 m2 or 0.7% of the study area. The landslide density was high in the Gorkha, Rasuwa, and Sindhupalchok districts, indicating that these areas suffered greater damage. Landslides occurred mainly on steep slopes (>35°) in V-shaped inner gorges, on geologically controlled steep slopes such as the scarp slopes (infacing slopes) of mountain ridges, and on terrace scarps. The results suggest that earthquake-induced landslides occur on slopes preconditioned by topographic and litho-structural factors. Based on our observations, recommendations for the mitigation of future landslide disasters are provided.

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Section: Methodsmentioning

confidence: 99%

Topographic characteristics of landslides induced by the 2015 Gorkha earthquake, Nepal

Tsou

Higaki

Chigira

et al. 2018

Journal of Nepal Geological Society

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“…The special role of sensitive soils is their pronounced post-failure 25 softening behavior, which may lead to progressive landslides with long runout distance that are difficult 26 to predict (Demers et al, 2014;Kvalstad et al, 2005;L'Heureux et al, 2014). Tephra deposits, encom-27 passing all pyroclastic materials of any grain size (Lowe, 2011), are highly susceptible to slope failure 28 and have been responsible for catastrophic landslides (Chigira, 2014;Sidle and Ochiai, 2006). Halloysite 29 is a common weathering product of rhyolitic (silica-rich) tephra (Churchman and and has 30 been found to dominate slide surfaces of rainfall-induced landslides in Hong Kong, Japan, New Zealand, 31…”

Section: Introduction 20mentioning

confidence: 99%

Rainfall threshold for initiating effective stress decrease and failure in weathered tephra slopes

et al. 2019

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Rainfall is one of the most important triggers of slope failure. Weathered pyroclastic (tephra) 2 deposits are especially vulnerable to slope failure because they commonly form slopes of high 3 porosity and high clay content. Empirically-derived thresholds for the triggering of landslides 4 are commonly based on rainfall conditions and have been widely applied in volcanic soils. However, so far only few researchers utilized pore water pressure in the slope as additional variable for the threshold calibration. Here we derived a new rainfall threshold for initiating the 7 decrease in effective stress in the slope by analyzing a long-term record of rainfall and piezom-8 eter data from a slide-prone coastal area in northern New Zealand that consists of clayey, hal-9 loysitic tephra deposits. The level of effective stress decrease increases with rainfall intensity 10 and duration. We observed highest effective stress decrease of up to 36 % during rainfall events 11 that triggered landslides in our study area. The effective stress threshold exhibits a satisfactory 12 predictive capability. The probability of correctly predicting a decrease in effective stress is 13 53 %. The effective stress threshold contributes towards the implementation of the decrease in 14 effective stress into rainfall thresholds for the occurrence of landslides.

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“…These landslides are 35 typically triggered by rainstorms or earthquakes, and are responsible for fatalities and 36 enormous property damage every year. Many destructive landslides have occurred in 37 pyroclastic deposits in Japan, Indonesia, Hong Kong, and New Zealand (Chau et al, 38 2004;Chigira, 2014;Moon, 2016), such deposits often containing layers rich in clay 39 minerals formed mainly by chemical weathering either during pedogenesis or diagenesis. 40…”

Section: Introduction 33mentioning

confidence: 99%

“…In regions with predominantly rhyolitic volcanism, halloysite is a common clay mineral 41 (Churchman and Lowe, 2012) and is therefore potentially a key geological factor 42 increasing the risk of landslides (Kirk et al, 1997;Chigira, 2014 Spheroidal halloysite, in particular, has been recognized in landslide-prone layers 47 of pyroclastic material in Japan (Tanaka, 1992) and New Zealand (Smalley et al, 1980). 48 Smalley et al (1980) linked a high content of spheroidal halloysite to high sensitivity.…”

Section: Introduction 33mentioning

confidence: 99%

A new attraction-detachment model for explaining flow sliding in clay-rich tephras

Kluger

Moon

Kreiter

et al. 2017

Geology

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12Altered pyroclastic (tephra) deposits are highly susceptible to landsliding, leading 13 to fatalities and property damage every year. Halloysite, a low-activity clay mineral, is 14 often associated with landslide-prone layers within altered tephra successions, especially 15 in deposits with high sensitivity, which describes the post-failure strength loss. However, 16 the precise role of halloysite in the development of sensitivity, and thus in sudden and 17 unpredictable landsliding, is unknown. Here we show that an abundance of mushroom-18 cap-shaped (MCS) spheroidal halloysite governs the development of sensitivity, and 19 hence proneness to landsliding, in altered rhyolitic tephras, North Island, New Zealand. 20We found that a highly sensitive layer, which was involved in a flow slide, has a 21 remarkably high content of aggregated MCS spheroids with substantial openings on one 22 (disaggregated) samples showed that the observable mushroom-caps were much more 131 abundant in the remolded samples, increasing from 4.4 ± 3.2% to 44.9 ± 11.6%. 132 ATTRACTION-DETACHMENT MODEL FOR FLOW SLIDING IN ALTERED 133 TEPHRAS 134The open-sided, mushroom-cap-shaped halloysite morphology has not been 135 reported previously. Because this particular morphology overwhelmingly occurs in the

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Geological and geomorphological features of deep-seated catastrophic landslides in tectonically active regions of Asia and implications for hazard mapping

Abstract: induced debris avalanches of pyroclastic fall deposits are not preceded by gravitational slope deformation but are of specific type and sequence of deposits, in which resilicified paleosol with halloysite may be the most important to accommodate a sliding surface.

Cited by 24 publications

References 38 publications

Topographic characteristics of landslides induced by the 2015 Gorkha earthquake, Nepal

Topographic characteristics of landslides induced by the 2015 Gorkha earthquake, Nepal

Rainfall threshold for initiating effective stress decrease and failure in weathered tephra slopes

A new attraction-detachment model for explaining flow sliding in clay-rich tephras

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