Empirical Run-Out Analysis As Overview for Regional Scale Landslide Susceptibility Assessment AMCI Mine Site, Maco, Compostela Valley

Empirical Run-out Analysis as Overview for Regional Scale Landslide Susceptibility Assessment AMCI Mine Site, Maco, Compostela Valley

Darwin Edmund L. Riguer Surface Exploration and Drilling Department, Apex Mining Co,. Inc.

21 November 2019 66th Annual National Mine Safety and Environment Conference CAP-John Hay Trade and Cultural Center, Baguio City Some deadly landslides in the Philippines

1999 Cherry Hills landslide 60

2003 Panaon Island (Southern Leyte) debris flow 154

2006 Guinsaugon landslide 1200

2006 Mayon Volcano lahar 1200

2009 Cordillera landslides 120

2012 Pantukan landslide 42

2012 New Bataan (Compostela Valley) debris flow 128 (450 missing)

2014 Catbalogan landslide 9

2017 Biliran landslides 42

2018 Itogon, Benguet landslides 58

2018 Naga, Cebu landslide 29

Risk Assessment Landslide susceptilibity “a quantitative or qualitative assessment of classification, volume (or area), and spatial distribution of landslides which exist or potentially may occur in an area” (Fell, 2008)

Spatial only → susceptibility Landslide Susceptibility and Hazard Assessment

hazard inventories

susceptibility susceptibility Deterministic Methods Dynamic Methods • Complex nature

• Variable controlling factors

• Uncertainty in parameters

• High cost of data acquisition

→ NOT GOOD FOR REGIONAL SUSCEPTIBILITY MAPPING!

Regional susceptibility mapping Empirical approach → used for delineation of potentially threatened → Parameters can be transposed areas to similar environments → based on minimum data requirements → Calibrate model for small areas → very few can be used for regional scale (e.g., and apply optimal parameters 1:10,000) to whole region DFGridProb/Flow-R

ca. 2009 Horton et al., 2013 MGB, 2013 Location

Philippine Sea

Manila

Davao Gulf

Pujada Bay Riguer, 20189 Regional Geologic Setting GOLD-COPPER DISTRICTS Surigao

Agusan Norte Surigao Sur Maco Mine Barobo

Co-O

Diwalwal PMB Maco Maco Mine Pantukan

Mati

H. Ruelo, 2013. Modified from PHIVOLCS 10 Topography

Masara Porphyry Cu-Au Masara Epithermal Lake Leonard Au-Ag Diatreme- Maar

Amacan Porphyry Cu-Au/ Sediment hosted Cu-Au

1,650 masl Riguer, 201811 Digital Elevation Slope-Aspect

Flow Accumulation

Terrain Derivatives Travel Angle (°) 5 10 15 30 (friction loss function)

10 (Energy Limitation) (Energy 15 Velocity (< m/s) Velocity

30 5° & 5 m/s 15° & 15 m/s 30° & 30 m/s

mass movement source points

simulated 35° slope source areas Conclusions • Limitations – site-specific characteristics cannot be accounted – not suitable for individual event modeling – parameterization is empirical and according to hazard type

• Modeled propagation areas generally larger – Contains every possible event – Contains worst case scenario

• Susceptibility maps – Good overview to constrain field investigation – To establish detailed hazard map

• DEM data input is very important – Source area delineation (morphological criteria) – Basis of propagation Thank You