Tung, B. D. et al.
Paper:Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
Bui Duc Tung∗1, Ngoc Ha Do∗2, Nguyen Kim Thanh∗3, Le Hong Luong∗3,Osamu Watanabe∗4, Kazunori Hayashi∗5, Akihiko Wakai∗6, and Shinro Abe∗5,†
∗1GEOS Construction Technology Consulting JSC141 Duong Van Be Street, Vinh Tuy Ward, Hai Ba Trung District, Hanoi, Vietnam∗2University of Yamanashi, Yamanashi, Japan∗3Institute of Transport Science and Technology (ITST), Ministry of Transport of Vietnam, Hanoi, Vietnam∗4Suimonkikaku LLC, Miyagi, Japan∗5Okuyama Boring Co., Ltd., Akita, Japan†Corresponding author, E-mail: abeshinro@gmail.com∗6Gunma University, Gunma, Japan[Received November 29, 2020; accepted April 12, 2021]
Landslide damage has been reported in many lime-stone areas in Europe, where the population lives closeto limestone areas, and in Guilin in southern Chinaand Ha Long in Vietnam, which are known for theirunique limestone landscapes. There are few studieson the mechanism and type of landslide motion inand around such limestone areas. The lack of basicdata is a problem for risk assessment and counter-measures in limestone areas. In this study, we sum-marized the causes and mechanisms of landslide oc-currence, including geology and groundwater, focus-ing on six landslides that occurred in limestone areasin northern Vietnam, and classiﬁed them into six typesof landslide movement. In the case of Japan, the oc-currence of landslides in limestone areas is rare de-spite the wide distribution of limestone, and it is dif-ﬁcult to classify the type of movement.Differencesin the landslide mechanisms are caused by the differ-ence between limestones generated in the pelagic envi-ronment of Japan and limestones developed along theTethys Sea coast, which are mixed with pelitic rocks asshallow-water sediments in Europe, China, and Viet-nam. It is necessary to elucidate the relationship be-tween landslides and the formation environment andsedimentary characteristics of limestone as an accre-tionary prism based on comparisons of a wide rangeof cases in future studies.
Keywords: limestone, landslide, karst, landslide move-ment type, groundwater
1. Introduction
Limestone is a carbonite rock, composed of carbonateminerals such as dolomite. It is a biogenic sedimentaryrock that contains more than 50% calcium CaCO3 and hasa calcareous shell, composed largely of corals and fora-minifera. The distribution of limestones is widespread inthe Northern Hemisphere, especially in North America,Europe, and Asia (Fig. 1). Limestone is easily dissolvedin rainwater containing carbon dioxide, and is known tohave features, such as karst topography, due to weatheringand erosion, and a large quantity of groundwater ﬂowingthrough its cavities. Landslide hazards in limestone ar-eas occur frequently in the vicinity of mountain rangesin Europe and North America, and in a wide limestonearea from southern China to the Indochina Peninsula [2].In recent years, the areas where slope disasters have oc-curred frequently in the Asian monsoon region have over-lapped with these limestone areas, and the relationship be-tween these disasters and meteorological conditions, suchas heavy rainfall, has attracted attention [3]. However,there is a lack of comprehensive discussions on the ge-omorphological and geological mechanisms and move-ment types of landslides in these limestone areas, there-fore, there is a lack of basic data on landslide initiationmechanisms necessary for risk assessment (e.g., [4]) andplanning landslide countermeasures.The purpose of this study is to clarify the kinematictypes of landslides that occur in such limestone areas,the depositional environment of limestone that forms thebackground of such landslides, the relationship in termsof deposition between limestone and pelitic rock, and theinvolvement of groundwater in the limestone area as a fac-tor in their occurrence.The landslides we studied were mainly those in north-ern Vietnam [5], which we have studied in the past, aswell as those in limestone areas in Europe and southwest-
646Journal of Disaster Research Vol.16 No.4, 2021
https://doi.org/10.20965/jdr.2021.p0646
© Fuji Technlogy Press Ltd.
Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
Fig. 1. Distribution of carbonate rocks. From Kano [1]. Thegray area indicates the distribution of carbonite rock.
ern China, which were deposited on the continental mar-gin of the Paleo-Tethys Sea [6] during the late Paleozoicand Mesozoic eras. We compared those areas with lime-stone areas in Japan, where there are few landslides de-spite the large distribution of limestones.
2. Deﬁnitions of Method and Terms
2.1. Method
Discussions on landslides in this study are basedon case studies of landslides in northern Vietnam, theMt. Reschberg and Rindberg landslides in Austria, andthe literature, which was surveyed in the ﬁeld from 2010to 2019. In this study, landslides in the limestone areacaused by earthquakes with different generation mecha-nisms were excluded. Since there is no data on limestonealone, the limestone distribution maps used are all basedon carbonite rock or karst area distribution maps instead.The age of the geological features in the landslide area inVietnam is based on a 1:200,000 geological map [7].In order to understand the relationship between ground-water in the limestone area and surface or groundwaterin the pelitic rock zone bordered by faults in Vietnam,groundwater analysis was conducted in the landslide area(B in Fig. 2) in the Mac Chau region, one of the studysites. Water temperature, pH, and electrical conductiv-ity were measured at the site. The samples were ﬁlteredthrough a 0.45 µm membrane ﬁlter and brought backin polyethylene containers for an analysis of the majorions and dissolved silicic acid. Major cations (Na+, K+,Ca2+, and Mg2+) were analyzed by atomic absorptionspectrophotometry, anions (Cl−, NO3−, and SO2−4 ) by ionchromatography, alkalinity (equivalent to HCO3− con-centration) by acid titration using the Gran method as theendpoint determination method [10], and dissolved sili-cic acid (silica SiO2) by molybdenum yellow absorptionspectrophotometry. The analytical results were organizedin stiff diagrams and tri-linear diagrams, and PHREEQC(an earth science code developed by the USGS) wasused to calculate the equilibrium partial pressure of car-bon dioxide (PCO2) in groundwater and the saturation in-
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Fig. 2. Limestone distribution area and study area in north-ern Vietnam. The distribution of limestone and the geologi-cal structure were developed based on Khang [8]. The land-slide distribution map was obtained from the Department ofGeology and Minerals of Vietnam [9]. The gray points oflandslides are not classiﬁed in terms of scale and may in-clude small-scale landslides such as boulders. Other pointsindicate landslides with a landslide volume of 1,000 m3 orlarger.
dex (SIc) for calcite.
2.2. TermsLandslides occurring in and around the limestone areaare hereafter referred to as “limestone area landslides.”The term “pelitic rock” used in this study is a generic termfor mudstone, marl, shale, or muddy schist intercalated inor faulted with limestone.
3. Case Examples of Landslides
3.1. Case Examples of Landslides in VietnamThe northern part of Vietnam has many mountainousslopes, and landslide disasters caused by typhoons andheavy rainfall during the rainy season are common an-nually. Most landslides occur in the weathered areas ofpelitic rock and granitic rocks, and few of them occur inlimestone areas. In recent years, however, landslides haveoccurred frequently along the national roads parallel tothe Laotian border in northern Vietnam, along the SongMa suture zone and the Red River fault, which was thecollision site of the South China and Indochina cratons inthe late Paleozoic and early Mesozoic (Fig. 2).These landslides are classiﬁed into two types: those oc-curring in the pelitic rock distribution area, which meetsthe limestone with a fault (A, B, C, and D in Fig. 2), andthose occurring in the limestone layer where the strati-graphic dip is more than 70◦ (E and F in Fig. 2).
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Slide surface
Residence
Landslide
Spring water
Limestone
Pelitic rock
cave, crack with groundwater
Slide surface
Fig. 3. Geomorphological and geological characteristics oflandslides (A, B, C, and D in Fig. 2) along the Song Masuture zone in northern Vietnam. Landslides occur in thepelitic rock zone, which is in contact with limestone at afault.
Fig. 4. Site A: Don Ban region – Landslide toe area –.
3.1.1. Landslides Occurring in a Pelitic Rock Distri-bution Area That Is in Contact with Limestoneat a Fault
As shown in Fig. 3, all these landslides occurred in theMesozoic pelitic rock distribution area, which is in con-tact at a fault with the Late Paleozoic to Early Mesozoiclimestone.In the Don Ban region (A in Fig. 2), a 40 m wide areacollapsed in 2012 (Fig. 4), killing two people on the na-tional road. About 200 m north of this point, cracks anddeformation were observed on the slope of the road thatwas being improved in 2007. About 100 m to the north,another landform above the slope in a village shows tracesof past landslide occurrence. Shale and crystalline schistare distributed on the road slope, and at the top of theslope Triassic limestone, which is in contact with thesestrata at a fault, forms a north-south ridge. Limestone
Fig. 5. Main scarp of landslide at site B (Moc Chau region).The arrow indicates landslide movement direction.
masses with stalactites are scattered under the steep lime-stone cliffs. During heavy rainfall, a large quantity of sur-face water ﬂows down from the limestone area to the roadslope, which is a major cause of landslide occurrence.In the Moc Chau region (B in Fig. 2), houses in thevillage were deformed and roads were cracked during theheavy rains in 2017. The Triassic limestone in the upper-most part of the slope is in contact, at a fault, with themudstone and siltstone in the middle and lower part of theslope, and the limestone area is bordered by groundwatersprings from cavities. The slope is covered with rainwa-ter gullies, and some of them are deeply scoured to formstreams. The slump type slides (Fig. 5) of 10–20 m width,occurring from the road slope to the village area, are allmoving toward the stream formed by such scouring.In 2010 and 2012, landslides occurred at site C in theMuong Lay region (C and D in Fig. 2), with a width ofabout 300 m and a length of about 100 m, due to roadwidening. A part of the landslide’s moving soil mass hitthe wall of a hospital located at the bottom of the slopeand stopped. The Devonian limestone at the top of theslope is connected to the pelitic rock (siltstone, shale, andcrystalline schist) from the middle to the bottom of theslope by a fault. The slope is dotted with springs, andsome basalt boulders are observed. The landslide occursin muddy rock, and a main scarp can be seen at the headand a slip surface at the toe (Fig. 6).In addition, a landslide with a width and length ofabout 300 m occurred at site D, about 10 km south ofsite C, during heavy rains in 2011, burying a road andpart of a river. The geology of the landslide slope con-sists of shale and siltstone as in site C, and limestone isdistributed at the top of the slope (Fig. 7). The landslide’smoving soil mass is mixed with shale, siltstone, and lime-stone gravel containing stalactites.
3.1.2. Landslides That Occur in the Limestone Layerwith a Steep Geological Slope
The landslide that occurred in the early morning ofOctober 12, 2017 at site E (Khanh Village region) inFig. 2, was about 120 m high, buried 4 houses, and killed
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Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
Fig. 6.Site C: Muong Lay region.Upper: Landslidemain scarp. The arrow indicates the direction of the slide.Lower: Slip surface appearing at the toe of the landslide.
Shale, siltstone
Limestone
Main crown
Fig. 7. Main scarp at site D. The arrow indicates the direc-tion of landslide movement.
18 people. The collapsed soil of the area, including theKhanh waterfall which is also known as a tourist attrac-tion, crossed the river ﬂowing down the lower slope andovercame the hill on the other side (left bank), with aheight of about 30 m, to reach the paddy ﬁeld (Fig. 8).As a result, the Khanh waterfall has now receded by 40–50 m. The geology of the area consists of Mesozoic Tri-assic limestone and shale. The strike of the stratum isN10◦–40◦W with a dip of 70◦–80◦E, which is close tovertical (Fig. 8).The Ha Long region (F in Fig. 2), which is well knownas a limestone tower karst landscape, has experiencedmany landslides in recent years. The geology of the areaconsists of shales with coal, gray massive limestones, silt-stones, and conglomerates of Carboniferous to Triassic.This site is on the extension line of the Red River fault(Fig. 2). The landslide, which occurred in 2017 on a slopeunder road construction, with a width of about 70 m and
Khangh waterfall
Kem river
Water fall
Landslide
Limestone
Shale 
Landslide
Fig. 8.Landslide and geological schematic cross sectionat site E (Khanh waterfall). Upper: Panoramic view. Theslide’s width was about 200 m. Lower: Geological schematiccross section. The bold arrow indicates the direction of land-slide movement.
a length of about 120 m, is located on the synclinal axisof the folding structure, and pelitic rock (coal, shale, andsiltstone) in a wedge shape, sandwiched by limestone lay-ers on both sides, was moved to the front. In the middleand lower areas of the landslide, several springs can beobserved from the cavity in the limestone layer. The mainreasons for the occurrence of landslides are the existenceof pelitic rock layers that are fractured into wedges dueto the folding structure, and the large quantity of springwater from the cavity of the limestone area during heavyrainfall (Fig. 9).
3.1.3. Relationship Between Groundwater in Lime-stone and LandslidesAll the aforementioned landslides in northern Vietnamseem to be inﬂuenced by limestone groundwater. In par-ticular, the groundwater in the limestone behind the slopesat A–D may play an important role in causing the land-slide of pelitic rock on the lower part of the slope. There-fore, we analyzed the groundwater quality of limestoneand pelitic rock (Fig. 10) in the Moc Chau region (B inFig. 2) [5].All the springs are rich in Ca2+ ion and HCO−3 ionand are classiﬁed as “alkaline-earth metals, bicarbonatetype” (Fig. 11). Of the six locations, G015 and G016 arespring water from cracks in the limestone or spring water
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Shale with coal
Siltstone-Silty shale
Limestone
Spring water
Ground water
Landslide body
GrounGuGrounGrououounund waterrund watewaterteund watwaoun
Springg
GroGrGrrGroGroGrGr
Landslide bodyodydybodyslndse bodeL
Conglomerate
Fig. 9.Panoramic view and modeled geological cross-sections of site F (Ha Long region). The dashed line in thephoto indicates the landslide area and the arrow indicates thedirection of landslide movement.
Mudsone area
Limestone area
LandslideSampling point for  water examinaion
GO15GO12GO21
Fig. 10.Groundwater test sample collection point in theMoc Chau region (site B).
from the area behind the limestone. The other locations,G012, G018, and G021, are all springs collected from theslope of pelitic rock, and G010 is water from a small riverﬂowing down the slope of pelitic rock. The groundwaterfrom the limestone area has higher electrical conductivitythan the groundwater in the mudstone zone (i.e., more dis-
GO15GO16
Ca2+2++ Mg
SO₄ + Cl
CATIONSANIONS
Ca2+2++ Mg
SO₄ + Cl
CO₃ + HCO₃-2-
Cl -Ca 2+
Na + K++
100100 100
Ⅳ：alkaline-earth metals(Ca² +; Mg²+) bicarbonate type
：alkaline-earth metals(Ca² +
+;Mg²) bicarbonate type
) bicarbonate typeⅡ : alkaline(Na+
KⅢ：alkaline(Na） chloride type
(Ⅴ: Mixed type)
1050510
SO42-,(NO3-)
Na++K+
G010: River water
1050510
G012: Spring water(Landslide area)
SO42-,(NO3-)
Na++K+
1050510
G016: Spring water(Limestone area)
SO42-,(NO3-)
Na++K+
1050510
G015: Spring water(Limestone area)
SO42-,(NO3-)
Na++K+
1050510
G021: Spring water (water supply)
SO42-,(NO3-)
Na++K+
1050510
G018: Spring water
SO42-,(NO3-)
Na++K+
Fig. 11.Stiff diagrams (upper) and tri-linear dia-gram (lower). Modiﬁed from Tung et al. [5].
solved ions), but has low SiO2 content (Fig. 12). Fig. 13shows the relationship between the HCO−3 ion concentra-tion and the concentrations of the major cations (Ca2+ ionand Mg2+ ion). The fact that both are plotted on a straightline passing through the origin suggests that dissolutionof minerals by dissolved CO2 (chemical weathering) isinvolved in the formation of the water quality of thesesprings.
CaCO3 +H2O+CO2 → Ca2+ +2HCO−3. . . . (1)(Calcite)CaAl2Si2O8 +2CO2 +3H2O(Ca-feldspar)→ Al2Si2O5(OH)4 +Ca2+ +2HCO−3. . . (2)(Kaolinite)
The lower SiO2 content in the limestone area, com-pared to that in the pelitic rock slope, can be explainedby the smaller contribution of chemical weathering offeldspars, as shown in Eq. (2).Table 1 shows the equilibrium partial pressure ofcarbon dioxide (SIc) in groundwater, calculated usingPHREEQC (USGS). The carbon dioxide concentration ishigher (0.04–2.2%) in soil than in air (0.04%) [11]. Insome places, such as near faults, the carbon dioxide con-centration is even higher due to the carbon dioxide supplyfrom deeper layers.The spring from a crack of lime-stone (G015) is characterized by a high PCO2 of 6.3%.The equilibrium partial pressure of carbon dioxide in the
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Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
102030
0200400
8001000(μS/cm)
(mg/L)
          GO12 
   Spring water
         GO15 
    Spring water
         GO16 
    Spring water
         GO18 
    Spring water
         GO18 
    Spring water
         GO21
    Spring water
          GO12 
   Spring water
         GO15 
    Spring water
         GO16 
    Spring water
         GO21
    Spring water
(water supply)
(Landslide (Limestone (Limestone (Water supply) area)
(Landslide area)
(Limestone area)(Limestone area)
Fig. 12. EC and silica concentration.
Ca2+2++Mg〔meq/L〕
〔meq/L〕HCO 3
GO12: Spring water (Landslide area)
GO15: Spring water (Limestone area)
GO21: Spring water (Water supply)
GO16: Spring water (Limestone area)
GO10: River waterGO18: Spring water
Fig. 13. Relationship between alkalinity and divalent cationconcentration.
spring water is low because the water is in the process ofdegassing and is close to the atmospheric partial pressureof carbon dioxide (0.04%). Since the solubility of cal-cite is proportional to the cube root of CO2 concentration,the SIc increases with degassing, and both slope springsare supersaturated with calcite (SIc > 0). Table 2 showsthe results of the calculation of PCO2 where SIc = 0. Thisis an estimation of the state before the inﬂow (before de-gassing). Among the spring waters from the slope of siltand mudstone, the PCO2 of the landslide edge spring wa-ter (G012) was found to be close to that of the spring waterfrom limestone (G015). G018, on the other hand, showeda value (2%) normally considered as that of groundwaterin soil.Among the three springs from the pelitic rock, thesprings with a high equilibrium partial pressure of car-bon dioxide (G012 and G021) are plotted between G018and the limestone groundwater group in the Tri-linear di-agram of Fig. 6. This indicates that the mixing of thesetwo groups is a possible explanation. In addition, thesetwo springs are also used as a water supply source, andthe ﬂow rate is relatively stable. Therefore, the ground-water on the slope of the pelitic rock is likely to be mixed
Table 1.Carbon dioxide equilibrium partial pressure ofspring water.
PCO2[%]
G015: Spring water(Limestone area)
G012: Spring water(Landslide area)
G018: Spring water
Table 2. CO2 equilibrium partial pressure calculated underthe calcite dissolution equilibrium condition (SIc = 0) (Sim-ulation result from PHREEQC).
PCO2[%]
G012: Spring water(Landslide area)
G018: Spring water
with the groundwater recharged by rainfall on the peliticrock slope, and undergoing shallow ﬂow (G018), and thegroundwater with a relatively high carbon dioxide con-centration, recharged by the limestone distribution areabehind it.
3.2. Landslides in Places Other than Vietnam
3.2.1. Examples in Europe
Landslides in the limestone zone in Europe are mostlyfound in the Alps, the Italian Peninsula, and the Pyreneesof the Iberian Peninsula to the Mediterranean coast. Theselandslides mostly tend to occur on the margins of the lime-stone area rather than on the limestone (Fig. 14).The most characteristic landslides in the Europeanlimestone area are lateral spread type landslides, such asthe Mt.Reschberg landslide in Austria [14] (Figs. 15and 16) and the Moute Verna landslide in Italy [16]. Theselateral landslides were caused by the sinking of soft peliticrock in the lower layer due to loading by limestone inthe upper layer. In addition to the occurrence of lateralspread, landslides of the debris ﬂow type, in which thelimestone itself overturns and the pelitic rock mixes withthe rock masses caused by falling rocks, have occurred.Such landslides have also been reported in the suburbanAlgiers landslide in North Africa [17] and at Turtle Moun-tain in Canada [18].In the case of pelitic rocks, such as marl, shale, andmuddy schist intercalated in limestone layers, or in thecase of their intercalation, translational rock slides haveoccurred, such as the Vaiont dam landslide in Italy [19]which claimed more than 2,000 victims in 1963, or theRindberg landslide in Austria [14], where Cretaceouslimestone and pelitic rock moved on a scale of 2,400 min length, 700 m in width, and a maximum slip surface
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01000kmLandslide
Fig. 14.Distribution of carbonite rock (blue) and land-slides (red dots) in Europe. Most damaging landslide casesfrom 1995–2014 and 2016. Adapted from Haque et al. [12],carbonite rock distribution from Goldscheider [13].
11001200
Stambach Earthflow
Sandling Earthflow
Rehkogl
Pichlern
Huttenckaim
Mt.Raschberg1487m
Fig.15.StambachandSandlinglandslidesonMt. Raschberg (the plane diagram is based on the UpperAustrian Sabo Bureau [15] with some modiﬁcations and ad-ditions).
Earth-flow
Earth-flow
Toppling
Shale, Marl
Limestone
Spread
Fig. 16.Lateral spread and debris ﬂow type landslides inthe Stambach and Sandling landslides. Created from UpperAustrian Sabo Bureau [15].
Fig. 17.Panoramic view of the Rindberg landslide. Fromthe Upper Austrian Sabo Bureau [15].
Fig. 18. Moving rock body exposed on the mid-slope of theRindberg landslide.
depth of more than 80 m (estimated at 120 m) (Figs. 17and 18).
3.2.2. Examples in China
In the southern part of China, there are extensive lime-stone belts, including in scenic areas such as Guilin. Thelandslides in the limestone belt are distributed aroundthe limestone distribution areas in Sichuan, Yunnan, andGuizhou provinces (Fig. 19). However, the occurrence oflimestone-related landslides is not as common as those inother formations in China [22, 23]. These landslides haveslightly different moving types due to the location of thecoal and shale formations intercalated in the limestone;however, limestone rock slides of more than 100 m haveoccurred, as in the case of the landslide represented by theWangxia rock slump [24] (Fig. 20). In addition, severalcases of limestone landslides, such as the Xintan land-slide [23, 26] and Guang’an Village landslide [25], havebeen reported to ﬂow as debris ﬂows over long distances
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Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
Landslide
Karst area 
1000 km
Fig. 19. Distribution of karsts and landslides in China. Karstdata is taken from Liu and Zhao [20]. Landslides are catas-trophic ones since the 20th century by Huang and Li [21](earthquake landslides are not included).
1000-1200m
1000-1500m
Landslide deposit
Lomestone
Shale, mudstone
Coal seam
Fig. 20.Conceptual diagram based on landslide cases inlimestone area in southeast China.Created by referenceto Feng et al. [24], Wang et al. [25], Luo [26], and Wenet al. [23].
(1.5 km or more) on the lower slopes composed of shaleand sandstone (Fig. 20).
3.2.3. Examples in JapanLimestones as an accretionary prism of seamount ori-gin [27] are widely distributed across the Japanese Islands(Fig. 21). The number of landslides in the limestone areain Japan is very small, although there were 6,785 des-ignated landslides in 1998 [28] (Fig. 21). Only a fewcases have been reported, such as the late Paleozoic tomid-Mesozoic limestone area landslide in the Shikokuregion (Fig. 22) [30], which is similar to the landslideshape along the Song Ma suture zone in northern Viet-nam (Fig. 3). Others include the colluvial landslide withslip surface on the weathered part of the Paleozoic lime-stone in the Hokuriku region [31], and the erosion land-slide with Pliocene to Pleistocene mixed mudstones and
300km0
Fig. 21. Designated landslide areas in Japan (red dots) andlimestone distribution (blue). The arrow indicates the pointof Fig. 22. Araiba et al. [28], Urushibara-Yoshino [29].
Limestone
Weathered slate
colluvial deposit
Slide surface
Spring water
Fig. 22.Example of limestone area landslide in Shikoku,Japan. Arrow point in Fig. 21 (modiﬁed from Utsunomiyaet al. [30]).
mixed limestone in Okinawa, Japan [32]. There are nocase reports for a slip surface of pelitic rock sandwichedbetween limestones, as seen in the aforementioned casesin Europe, China, and Vietnam.
4. Discussion
In the case of limestone, which is massive and poorlystratiﬁed, there are few cases of movement with a slip sur-face in the limestone except for rock falls and rock col-
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Fig. 23. Limestone area landslide types in Europe, China, Vietnam, and Japan.
lapses. Most of the landslides in the limestone areas oc-cur as landslides with slip surfaces in mudstone or coalbeds intercalated or interlayered with the limestone, or aslandslides of pelitic rock in the pelitic rock zone near thelimestone. If we summarize the shapes and movementsof landslides in the limestone areas of various regions,
we ﬁnd that in Vietnam, most landslides occur as slumptype landslides (Fig. 23, A) in the pelitic rock distributionarea, where the limestone is faulted. In Vietnam, otherunique types of landslides include a large-scale collapseof a waterfall formed during the development of a riverwhich erodes the boundary between limestone and pelitic
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Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
rock (B in Fig. 23), and a wedge-type slide of the peliticrock portion where limestone and pelitic rock meet at ahigh angle due to faulting and folding (C in Fig. 23). Thecommon causes for the landslides in these limestone ar-eas include erosion and the softening of muddy ground byspring water and surface water originating from ground-water ﬂowing through limestone cavities, and groundwa-ter supply into the landslide area.In Europe, the pelitic rock is deformed by the load oflimestone covering it in the form of cap rock, causing lat-eral spreading and then a transition to a ﬂow type land-slide (D in Fig. 23) or to a rockslide on a sliding surfaceof the pelitic rock sandwiched between limestones (E inFig. 23).In China, toppling and rockslide along the pelitic rocklayer, intercalated in the thick limestone layer, as well asthe debris ﬂow of a mixture of limestone masses collapseddown the cliff and pelitic rocks in the lower part of thecliff (F of Fig. 23), are commonly observed.The contact between limestone and pelitic rock, whichinﬂuences the landslide shape, is formed by the deposi-tional environment and geological structure of the geo-logical age.The limestones in the European Alps are frequently in-terrupted by pelitic rocks of Paleo-Tethys and continen-tal origin. The stratum is signiﬁcantly folding but rela-tively continuous, which provides a geological predispo-sition for the occurrence of large-scale rockslides alongthe bedding plane and lateral spread type landslides.The limestone area in south China, several kilometersin thickness, is also mixed with continental clastic debrisand pelitic rock from the Paleo-Tethys Sea.Currentlyhowever, there are more reports of limestone collapsesbounded by pelitic rocks, and debris ﬂows caused by col-lapsed limestones and pelitic rocks, than of rockslidessuch as those in the European Alps. Most of the land-slides in and around the limestones in northern Vietnamare located in the areas where faults and folding struc-tures are developed on the tectonic line (suture zone andRed River fault) where the South China and Indochinablocks collided across the Tethys Sea [33]. Such geolog-ical structures are geologically predisposed to landslidesin the pelitic rock zone bordered at faults by limestones,and to wedge-like movement of the pelitic rock betweenlimestones in folding structures.In this study, we mainly focus on limestone area land-slides at the collision site of continental massifs acrossthe Tethys Sea, but we also attempt to compare them withlandslides in Japan, where pelagic limestones are widelydistributed. As a result, we found that Japanese lime-stones, deposited in the pelagic environment with littlesediment supply from the continent, are characterized bya high purity of calcium carbonate, are lumpy and poorlystratiﬁed. This is why the number of slip cases in lime-stone areas in Japan is smaller than those in Europe andAsia.
5. Conclusions
The landslide shapes and movement types in the lime-stone areas discussed in this paper can be roughly classi-ﬁed as follows:
• Landslides of the limestone itself, such as a rock fall,toppling, or cavity collapse along a crack in the lime-stone.
• Rockslide, in which the slip surface is a muddy stra-tum that alternates with limestone or forms a thinlayer.
• Landslides that occur as a lateral spread caused bythe deformation of pelitic rock at the base due to theload of limestone, as well as landslides that occuras earth ﬂow or debris ﬂow of limestone and peliticrock.
• Slump type landslides that occur in pelitic rock whengroundwater is supplied from limestone with whichthe pelitic rock is in contact at a fault.
• Wedge type slides of pelitic rock in contact withlimestone due to folding or fault structure.
Landslides occurring in limestone areas often occur atthe margins of the limestone rather than the limestone it-self. A common cause is the inﬂuence of abundant surfacewater and groundwater ﬂowing down the limestone.The landslides described above occur with differenttypes of landslide movement, based on the geology andgeological structure formed under various conditions, in-cluding: where corals developed along the continentalmargin during the mid-Paleozoic and early Mesozoic,with continentally detritus ﬂowing into the Tethys Seaand pelitic rock of shallow-water sediments are sheared,fractured, and deposited as accretionary prisms by themovement and collision of land masses, or where they arefolded and ridden up.The limestones distributed across Japan are highly purecalcium carbonate limestones which were formed in apelagic environment with little sediment supply from thecontinent, and are characterized by massive and poorlystratiﬁed accretionary prisms, which is the reason for thelow occurrence of landslides.In the future, when assessing the risk of slopes in lime-stone areas, attention should be paid to the pelitic rock incontact with the limestone from the viewpoint of geologyand geological structure, and to the edge of the limestonefrom the viewpoint of topography. In addition, it is nec-essary to pay attention to the surface water and ground-water supplied to the slope from the limestone as a causeof landslides when considering countermeasure construc-tion.Limestone zones are widely distributed in other conti-nents, in addition to the areas targeted in this study, andmany of them are located outside human population ar-eas. It is assumed that landslides with various types ofmotion, other than those mentioned above, probably oc-cur in these areas. In the future, it is necessary to clarifythe relationship between the limestone formation process,the deposit shape of the accretionary prism, and the mech-
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anism of landslide occurrence based on a wide range ofcases, including pelagic cases common in Japan.
AcknowledgementsThis study was discussed in the “Vietnam Landslide Practi-cal Technology Group” of Japanese and Vietnamese researchersin Hanoi.We would like to express our sincere gratitude toProf. Kazuhisa Yoshimura, Professor Emeritus of Kyushu Uni-versity, for his many insights on groundwater in limestone areas.
References:[1] A. Kano, “Distribution of Carbonate Rocks,” Carbonate Atlas,2004,http://www-gbs.eps.s.u-tokyo.ac.jp/∼kano/Carb/1/110101.html [accessed September 1, 2020][2] Q. Z´aruba and V. Mencl, “Landslides and Their Control (Develop-ment in Geotechnical Engineering Vol.31),” 324pp., Elsevier, 1982.[3] T. Ozaki, A. Watanabe, A. Wakai, and F. Cai, “A Simple PredictionModel for Shallow Groundwater Level Rising in Natural SlopesBased on Finite Element Analysis,” P. D. Long and N. T. Dung(Eds.), “Geotechnics for Sustainable Infrastructure Development,”pp. 993-1000, Springer, 2020.[4] M. M. Mon, T. Naing, M. Numada, K. T. Yu, K. Meguro, andK. Z. Latt, “Analysis of Disaster Response During Landslide Dis-aster in Hakha, Chin State of Myanmar,” J. Disaster Res., Vol.13,No.1, pp. 99-115, 2018.[5] B. D. Tung, L. H. Luomg, P. V. Cuomg, N. K. Thanh, T. S. Manh,O. Watanabe, N. Fuzii, and S. Abe, “A Preliminary Study on theMechanism of Landslide in Limestone Formation Area in Son La.Northern Vietnam,” Proc. of 2016 Int. Conf. on Sustainability inCivil Engineering, Geotechnical Engineering, pp. 76-80, 2016.[6] F. Berra and L. Angiolini, “The Evolution of the Tethys RegionThroughout the Phanerozoic: A Brief Tectonic Reconstruction,”L. Marlow, C. C. G. Kendall, and L. A. Yose (Eds.), “PetroleumSystems of the Tethyan Region,” pp. 1-27, The American Associa-tion of Petroleum Geologists (AAPG), 2014.[7] Department of Geology and Minerals of Vietnam, “Geology andMineral Resources Map of Vietnam, 1:200,000,” 2004.[8] P. Khang, “The Development of Karst Landscapes in Vietnam,”Acta Geologica Polonica, Vol.35, Nos.3-4, pp. 305-324, 1985.[9] Department of Geology and Minerals of Vietnam, “Warning Systemof Geological Hazards and Natural Environmental Disasters in Viet-nam,” http://canhbaotruotlo.vn/index.html [accessed September 1,2020][10] G. Gran, “Determination of the Equivalence Points in Potentiomet-ric Titrations: Part II,” Analyst, Vol.77, Issue 920, pp. 661-671,1952.[11] K. Yoshimura and Y. Ikura, “Evolution of Groundwater Chemistryin the Hydrological Cycle of the Akiyoshi-Dai Plateau LimestoneArea,” J. of Groundwater Hydrology, Vol.34, No.3, pp. 183-194,1992 (in Japanese).[12] U. Haque, P. Blum, P. F. da Silva, P. Andersen, J. Pilz, S. R. Chalov,J.-P. Malet, M. J. Auﬂiˇc, N. Andres, E. Poyiadji, P. C. Lamas,W. Zhang, I. Peshevski, H. G. P´etursson, T. Kurt, N. Dobrev,J. C. Garc´ıa-Davalillo, M. Halkia, S. Ferri, G. Gaprindashvili,J. Engstr¨om, and D. Keellings, “Fatal Landslides in Europe,” Land-slides, Vol.13, No.6, pp. 1545-1554, doi: 10.1007/s10346-016-0689-3, 2016.[13] N. Goldscheider, “Karst Groundwater Vulnerability Mapping: Ap-plication of a New Method in the Swabian Alb, Germany,” Hydro-geology J., Vol.13, No.4, pp. 555-564, doi: 10.1007/s10040-003-0291-3, 2005.[14] H. Takeshita, T. Yamasaki, S. Abe, H. Marui, and J.L.S. ﬁeld work-shop group on landslides in Austrian Alps, “Landslides in AustrianAlps,” J. of the Japan Landslide Society, Vol.45, No.3, pp. 234-239,2008 (in Japanese).[15] Upper Austrian Sabo Bureau, “Distribution documents on Stam-bach and Sandling landslide,” 2007.[16] L. Picarelli, “Considerations about the Mechanics of Slow ActiveLandslides in Clay,” K. Sassa, H. Fukuoka, F. Wang, and G. Wang(Eds.), “Progress in Landslide Science,” pp. 27-45, Springer, doi:10.1007/978-3-540-70965-7
3, 2007.[17] M. Agard, “Les glissements et ´eboulements des quartiers Saint-Rapha¨el et T´elemly `a Alger et les travaux envisag´es en vue de lastabilisation des terrains,” Annales des ponts et chauss´ees, Vol.118,No.4, pp. 465-480, 1948 (in French).[18] R. G. McConnell and R. W. Brock, “Report on the Great Landslideat Frank, Alberta, 1903,” 17pp., Department of the Interior, Domi-nation of Canada, 1904.
[19] R. Selli and L. Trevisan, “Caratteri e interpretazione della franadel Vaiont,” Giornale di geologia: Annali del museo geologico diBologna, Vol.32, No.1, pp. 7-104, 1964 (in Italian).[20] Z. Liu and J. Zhao, “Contribution of Carbonate Rock Weathering tothe Atmospheric CO2 Sink,” Environmental Geology, Vol.39, No.9,pp. 1053-1058, 2000.[21] R. Huang and W. Li, “Formation, Distribution and Risk Controlof Landslides in China,” J. of Rock Mechanics and GeotechnicalEngineering, Vol.3, No.2, pp. 97-116, doi: 10.3724/SP.J.1235.2011.00097, 2011.[22] R. Huang, “Some Catastrophic Landslides Since the Twentieth Cen-tury in the Southwest of China,” Landslides, Vol.6, No.1, pp. 69-81,2009.[23] B. Wen, S. Wang, E. Wang, and J. Zhang, “Characteristics of RapidGiant Landslides in China,” Landslides, Vol.1, No.4, pp. 247-261,2004.[24] Z. Feng, B. Li, Y. P. Yin, and K. He, “Rockslides on LimestoneCliffs with Subhorizontal Bedding in the Southwestern Calcare-ous Area of China,” Natural Hazards and Earth System Sciences,Vol.14, No.9, pp. 2627-2635, 2014.[25] L. Wang, Y. Yin, B. Huang, Z. Zhang, and Y. Wei, “Formation andCharacteristics of Guang’an Village Landslide in Wuxi, Chongqing,China,” Landslides, Vol.16, No.1, pp. 127-138, 2019.[26] P. Y. Luo, “Xintan Landslide and its Prediction,” Division of RockEngineering of Chinese Society for Rock Mechanics & Engineer-ing and Division of Engineering Geology of Geological Societyof China (Eds.), “Typical Landslides in China,” Science Press,pp. 191-199, 1988 (in Chinese).[27] Y. Isozaki, S. Maruyama, K. Aoki, T. Nakama, A. Miyashita, andS. Otoh, “Geotectonic Subdivision of the Japanese Islands Revis-ited: Categorization and Deﬁnition of Elements and Boundaries ofPaciﬁc-Type (Miyashiro-Type) Orogen,” J. of Geography (ChigakuZasshi), Vol.119, No.6, pp. 999-1053, 2010 (in Japanese).[28] K. Araiba, T. Nozaki, B. Jeong, and Y. Fukumoto, “Distribution ofLandslides and Their Geological Characteristics in Japan – AnalysisReport Based on the Data of Nation–Wide Designated Landslide-Threatened Areas –,” J. of the Japan Landslide Society, Vol.44,No.5, pp. 38-43, 2008 (in Japanese).[29] K. Urushibara-Yoshino, “Preliminary Study on Solution Rate ofLimestone Tablets in Japan,” Regional Views (Chiikigaku Kenkyu),No.4, pp. 107-117, 1991 (in Japanese).[30] O. Utsunomiya, H. Onoyama, and R. Murakami, “Caprock Land-slides Around the Karst Area in Shikoku, Japan,” Proc. of Techni-cal Workshop, The Japanese Geotechnical Society Kansai Branch,2000 (in Japanese).[31] T. Masuyama, T. Yano, S. Minami, and T. Yashima, “Characteristicsof Clay at Slip Surface in Weathered Limestone,” J. of the JapanLandslide Society, Vol.49, No.1, pp. 43-46, 2012 (in Japanese).[32] C. Chen, S. Gibo, K. Sasaki, and S. Nakamura, “Classiﬁcationof Landslides Types Observed in the Area of Shimajiri-Mudstone,Okinawa Island – For the Risk Evaluation of Landslide –,” J.of the Japan Landslide Society, Vol.43, No.6, pp. 339-350, doi:10.3313/jls.43.339, 2007 (in Japanese).[33] M. Faure, C. Lepvrier, V. V. Nguyen, T. V. Vu, W. Lin, and Z. Chen,“The South China Block-Indochina Collision: Where, When, andHow?,” J. of Asian Earth Sciences, Vol.79, Part A, pp. 260-274,2014.
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Geometry and the Mechanism of Landslide Occurrencein a Limestone Area – Case Examples of Landslidesin Vietnam and from Europe, China, and Japan –
Name:Bui Duc Tung
Afﬁliation:Civil Engineer, JGC Vietnam Co., Ltd.Civil Engineer, GeoS Consultant JSCGeotechnical Engineer, SMEC Vietnam JSC
Address:Landmark 72 Tower, Pham Hung Street, Nam Tu Liem District, Hanoi,VietnamSelected Publications:• “A preliminary study on the mechanism of landslide in limestoneformation area in Son La. Northern Vietnam,” Proc. of 2016 Int. Conf. onSustainability in Civil Engineering, Geotechnical Engineering, pp. 76-80,2016.
Name:Ngoc Ha Do
Afﬁliation:Doctoral Course Student, University of YamanashiEngineer, Researcher, Institute of Transport Science and Technology(ITST)Address:4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan (University ofYamanashi)1252 Lang Street, Dong Da District, Hanoi, Vietnam (ITST)
Name:Nguyen Kim Thanh
Afﬁliation:Ph.D. Student, Tohoku Gakuin UniversityResearcher, Institute of Transport Science and Technology (ITST)Address:1252 Lang Street, Dong Da District, Hanoi, Vietnam
Name:Le Hong Luong
Afﬁliation:Institute of Transport Science and Technology (ITST)Address:1252 Lang Street, Dong Da District, Hanoi, Vietnam
Name:Osamu Watanabe
Afﬁliation:Suimonkikaku LLCAddress:2-17-3-205 Izumi-chuo, Izumi-ku, Sendai, Miyagi 981-3133, Japan
Name:Kazunori Hayashi
Afﬁliation:Assistant Manager, Okuyama Boring Co., Ltd.Address:13-18-306 Futsukamachi, Aoba-ku, Sendai, Miyagi 980-0802, Japan
Name:Akihiko Wakai
Afﬁliation:Professor, Gunma UniversityAddress:1-5-1 Tenjincho, Kiryu, Gunma 376-8515, Japan
Name:Shinro Abe
Afﬁliation:Technical Advisor, Okuyama Boring Co., Ltd.Address:10-39 Shinmei-cho, Yokote, Akita 013-0046, Japan
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