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Mechanism of a low-angle translational block slide: evidence from the September 2018 Naga landslide, Philippines


There is a general lack of understanding on the detailed processes and mechanism of low-angle translational block slides. The September 20, 2018 Naga landslide, with a volume of 27 M m3 and a runout distance of 1.34 km, provided new insights on the initiation, transport, and deposition mechanisms of this type of landslide. Drone photogrammetry, video footage, satellite images, slope stability analyses, and field evidence revealed that the landslide occurred as multiple block detachments along a series of tension cracks that formed and grew progressively prior to the main failure. Predominance of intact upright blocks traceable to the distal end of the deposit indicates dominant translational motion. Facies within the Naga landslide deposit revealed that at least three processes (slide, dry flow, and fall) occurred during the main movement. Post-slide processes immediately after emplacement included small avalanches and rockfalls related to the instability of the landslide deposit and the main scarp. Preliminary slope stability analyses showed that the slopes were marginally unstable (FoS 0.67–3.96) even in dry conditions. The low-angle profile of the slip surface (6°) favors stability, but low shear strength of the limestone bedrock and unsupported cut slopes may have contributed to the failure.

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  • Aurelio MA, Dianala JDB, Taguibao KJL, Paztoriza LR, Reyes K, Sarande R, Lucero A Jr (2016) Seismotectonics of the 6 February 2012 Mw 6.7 Negros earthquake, central Philippines. J Asian Earth Sci 142:93–108.

    Article  Google Scholar 

  • Baker R (1981) Tensile strength, tension cracks, and stability of slopes. Soils Found 21(2):1–17.

    Article  Google Scholar 

  • Beck H, Zimmermann N, McVicar T, Vergopolan N, Berg A, Wood E (2018) Present and future Koppen-Geiger climate classification maps at 1-km resolution. Nat Sci Data 5:180214.

  • Brown ET (1981) Rock characterization testing and monitoring. Pergamon Press, Oxford

    Google Scholar 

  • Bureau of Mines and Geo-Sciences (BMG) (1983) Geological map of Pardo quadrangle (1:50,000). Mines and Geosciences Bureau, Quezon City

    Google Scholar 

  • Corominas J (1996) The angle of reach as a mobility index for small and large landslides. Can Geotech J 33(2):260–271.

    Article  Google Scholar 

  • Cruden DM (1976) Major rock slides in the Rockies. Can Geotech J 13:8–20.

    Article  Google Scholar 

  • Cruden DM, Varnes DJ (1996) Landslide types and processes. In: Turner AK, Schuster RL (eds) Landslides, investigation and mitigation, Transportation Research Board, Special Report No. 247, National Academy of Sciences, pp 36-75

  • Davies TR, McSaveney MJ, Beetham RD (2006) Rapid block glides: slide-surface interaction in New Zealand’s Waikaremoana landslide. Q J Eng Geol Hydrogeol 39:115–129.

    Article  Google Scholar 

  • Fan X, Xu Q, Scaringi G, Dai L, Li W, Dong X, Zhu X, Pei X, Dai K, Havenith HB (2017) Failure mechanism and kinematics of the deadly June 24th 2017 Xinmo landslide, Maoxian, Sichuan, China. Landslides 14:2129–2146.

    Article  Google Scholar 

  • Goodman RE, Kieffer DS (2000) Behavior of rock in slopes. J Geotech Geoenviron Eng 126(8):675–684.

  • Guthrie RH, Friele P, Allstadt K, Roberts N, Evans SG, Delaney KB, Roche JJ, Jakob M (2012) The 6 August 2010 Mount Meager rock slide-debris flow, Coast Mountains, British Columbia: characteristics, dynamics, and implications for hazard and risk assessment. Nat Hazards Earth Syst Sci 12:1277–1294.

  • Hancox GT, McSaveney MJ, Manville VR, Davies TR (2002) The October 1999 Mt Adams rock avalanche and subsequent landslide dam-break flood and effects in Poerua river, Westland, New Zealand. New Z J Geol Geophys 48(4):683–705.

    Article  Google Scholar 

  • Hoek E (2007) Practical rock engineering. Accessed 5 Mar 2018

  • Hoek E, Bray JW (1981) Rock slope engineering, 3rd edn. Institute of Mining and Metallurgy, London

    Google Scholar 

  • Hoek E, Carranza-Torres C, Corkum B (2002) Hoek-Brown failure criterion-2002 edition. In: Proceedings of the North American Rock Mechanics Society Meeting in Toronto 1(1):267–273

  • Holcombe EA, Beesley MEW, Vardanega PJ, Sorbie R (2016) Urbanisation and landslides: hazard drivers and better practices. Proc Inst Civ Eng Civ Eng 169(3):137–144.

    Google Scholar 

  • Hungr O, Leroueil S, Picarelli L (2014) The Varnes classification of landslide types, an update. Landslides 11(2):167–194.

    Article  Google Scholar 

  • International Geotechnical Society UNESCO Working Party on World Landslide Inventory (WP/WLI) (1995) A suggested method for describing the rate of movement of a landslide. Bull Int Assoc Eng Geol 52:75–78.

    Article  Google Scholar 

  • Korup O, Clague JJ, Hermanns RL, Hewitt K, Strom AL, Weidinger JT (2007) Giant landslides, topography, and erosion. Earth Planet Sci Lett 261(3–4):578–589.

    Article  Google Scholar 

  • McDougall S, Boultbee N, Hungr O, Stead D, Schwab JW (2006) The Zymoetz River landslide, British Columbia, Canada: description and dynamic analysis of a rock slide–debris flow. Landslides 3(3):195–204.

    Article  Google Scholar 

  • Mines and Geosciences Bureau (MGB) (2010) Geology of the Philippines, 2nd edn. Mines and Geosciences Bureau, Quezon City

    Google Scholar 

  • Morales E, Camaclang M, Reyes G (2001) The Cherry Hills landslide tragedy. In: Proceedings of the 2nd Civil Engineering Conference in the Asian Region, Tokyo. 10 p

  • Rangin C, Müller C, Porth H (1989) Neogene geodynamic evolution of the Visayan Basin. In: Porth H, Daniels CH, Bausa GJ, Cepek P, Cosico R (eds) On the geology and hydrocarbon prospects of the Visayas Basin, Philippines. Reihe B Heft 70. Bundesanstalt für Geowissenschaften und Rohstoffe und den Geologischen Landesämtern, Hannover, pp 7–27

    Google Scholar 

  • Roberts NJ, Evans SG (2013) The gigantic Seymareh (Saidmarreh) rock avalanche, Zagros Fold–Thrust Belt, Iran. J Geol Soc Lond 170:685–700.

    Article  Google Scholar 

  • Schnabel JJ (1984) Evaluation of permanent cut slope stability in Potomac Formation deposits. In: Obermeier SF (ed) Engineering geology and design of slope for Cretaceous Potomac deposits in Fairfax County, Virginia and vicinity. Geological Survey Bulletin 1556. Department of the Interior, Washington, DC, pp 63–78

    Google Scholar 

  • Urlaub M, Talling PJ, Zervos A, Masson D (2015) What causes large submarine landslides on low gradient (< 2°) continental slopes with slow (∼ 0.15 m/kyr) sediment accumulation? J Geophys Res Solid Earth 120(10):6722–6739.

    Article  Google Scholar 

  • Varnes DJ (1978) Slope movement types and processes. In: Schuster RL, Krizek RJ (eds) Landslides, analysis and control, Transportation Research Board, Special Report No. 176, National Academy of Sciences, pp 11-33

  • Xu Q, Fan X, Huang R, Yin Y, Hou S, Dong X, Tang M (2010) A catastrophic rockslide-debris flow in Wulong, Chongqing, China in 2009: background, characterization, and causes. Landslides 7:75–87.

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We thank the following people and organizations for facilitating the field survey: Naga City officials most especially Mayor Kristine Chiong and Engr. Baltazar S. Tribunalo Jr. of the Cebu Provincial Disaster Risk Reduction and Management Office for their logistical support; Naga City BJMP for providing the original footage of the landslide; and Engr. Ariel Lazarte for sharing his drone orthophoto, which complemented our own drone data. We are also grateful to the residents of Sitio Tagaytay for the background information and eyewitness accounts on the September 20, 2018 landslide event. We thank the anonymous reviewer for critically reviewing our manuscript.

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Correspondence to Sandra G. Catane.

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Catane, S.G., Veracruz, N.A.S., Flora, J.R.R. et al. Mechanism of a low-angle translational block slide: evidence from the September 2018 Naga landslide, Philippines. Landslides 16, 1709–1719 (2019).

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