Table 1.

Location, underlying lithology and topographic description of sampled slope failures in the study area

SiteLatitude (S)Longitude (E)Elevation (m)NZGS field descriptionTopography and vegetation
KR117°26′7.59"178°13′42.30"34Silty CLAY, some sand; light brown. Firm, moist, low plasticity (VG)Flatland with sparse vegetation
KR217°29′59.10"178°14′27.90"34Sandy SILT, some clay; yellowish brown, mottled black and white. Very soft, moist, low plasticity (SD)Hillslope with grassland
KR317°35′17.90"178°14′45.20"56Silty CLAY, minor sand; reddish brown, mottled black. Stiff, dry, low plasticity (BS)Adjacent to terrace with mixed vegetation
KR417°37′47.40"178°15′28.30"47Silty CLAY, some sand, trace organic matter; reddish brown, mottled black. Firm, moist, medium plasticity (RB)Adjacent to terrace with grassland
KR517°39′22.00"178°16′41.90"40Clayey SILT, some sand, minor gravel; light greyish brown. Firm, moist, low plasticity (WC)Hillslope near river terrace, mixed vegetation
KR617°39′28.26"178°16′48.66"38Silty CLAY, minor sand, trace gravel; orangish brown. Firm, moist, low plasticity (WC)Hillslope near river terrace with grassland
KR717°39′37.10"178°17′3.00"60Silty CLAY, some sand; reddish brown, mottled orange, white and black. Firm, moist, low plasticity (WC)Gentle hillslope with grassland
KR817°40′26.90"178°20′02.70"48Sandy CLAY, some silt; reddish brown. Soft, moist, high plasticity (LS)Steep hillslope with disturbed forest
KR917°44′14.94"178°23′24.48"34Silty CLAY, trace gravel; brownish orange. Firm, moist, high plasticity (WT)Adjacent to river terrace with scrubland
KR1017°46′52.88"178°26′23.52"145Silty CLAY, some sand; light brownish orange. Soft, moist, high plasticity (NS)Flatland with grassland
KR1117°58′07.80"178°31′40.00"58Silty CLAY, some sand; greyish orange. Soft, moist, medium plasticity (WS)Hillslope near floodplain with mixed vegetation
LR117°34′55.27"177°40′8.81"123Silty CLAY, minor sand; light brownish orange, mottled white. Firm, moist, low plasticity (UB)Gentle hillslope with disturbed pine forest
LR217°34′56.11"177°40′5.25"132Silty CLAY, minor sand; light brownish orange, mottled white. Firm, moist, low plasticity (UB)Gentle hillslope within disturbed pine forest
NR118°2′52.71"178°9′14.32"295Silty CLAY, minor sand; light grey, mottled yellow and white. Firm, moist, high plasticity (NA)Hillslope within forest
NR218°3′29.48"178°9′28.71"357Clayey SILT, minor organic matter; yellowish brown, mottled white. Soft, moist, low plasticity (NA)Hillslope within forest
NR318°6′37.15"178°10′58.31"275Silty CLAY, some sand, trace organic matter; reddish brown, black on fracture surface. Firm, moist, low plasticity (TT)Hillslope within forest
NR418°6′51.81"178°11′15.86"277Sandy SILT, some clay; light pinkish brown, mottled white. Firm, moist, low plasticity (TT)Hillslope within forest
NR518°7′48.85"178°12′6.92"70Silty CLAY, trace organic matter; reddish brown, black on fracture surface. Firm, moist, low plasticity (TT)Hillslope within forest

VG, Early Pliocene Vatukoro Greywacke (Ba Basaltic Group); SD, recent surficial deposits; BS, Mio-Pliocene Barotu Sandstone (Ra Sedimentary Group); RB, Early Pleistocene Rokavukavu Basalt (Ba Basaltic Group); WC, Late Miocene Wailoa Conglomerate (Ra Sedimentary Group); LS, Mid-Miocene Lawalevu Sandstone (Wainimala Group); WT, Early Miocene Wainimbuka Trachyte (Wainimala Group); NS, Early Pliocene Nacua Sandstone (Verata Sedimentary Group); WS, Mio-Pliocene Waidina Sandstone (Medrausucu Group); UB, Early Pliocene undifferentiated basaltic and derived flows (Ba Volcanic Group); NA, Mio-Pliocene Namosi Andesite (Medrausucu Group); TT, Mid-Oligocene Tawavatu Tuff (Wainimala Group).