Evaluation of coseismic landslide hazard on the proposed Haast-Hollyford Highway, South Island, New Zealand

Tom R. Robinson, Tim R. H. Davies, Thomas M. Wilson, Caroline Orchiston, Nicolas Barth
2015 Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards  
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more » ... . Please consult the full DRO policy for further details. Abstract 10 Coseismic landsliding presents a major hazard to infrastructure in mountains during large 11 earthquakes. This is particularly true for road networks, as historically coseismic landsliding 12 has resulted in road losses larger than those due to ground shaking. Assessing the exposure 13 of current and planned highway links to coseismic landsliding for future earthquake 14 scenarios is therefore vital for disaster risk reduction. This study presents a method to 15 evaluate the exposure of critical infrastructure to landsliding from scenario earthquakes from 16 an underlying quantitative landslide hazard assessment. The method is applied to a 17 proposed new highway link in South Island, New Zealand for a scenario Alpine Fault 18 earthquake and compared to the current network. Exposure (the likelihood of a network 19 being affected by one or more landslides) is evaluated from a regional-scale coseismic 20 landslide hazard model and assessed on a relative basis from 0-1. The results show that the 21 proposed Haast-Hollyford Highway (HHH) would be highly exposed to coseismic landsliding 22 with at least 30-40 km likely to be badly affected (the Simonin Pass route being the worse 23 affected of the two routes). In the current South Island State Highway network, the HHH 24 would be the link most exposed to landsliding and would increase total network exposure by 25 50-70% despite increasing the total road length by just 3%. The present work is intended to 26 provide an effective method to assess coseismic landslide hazard of infrastructure in 27 mountains with seismic hazard, and potentially identify mitigation options and critical network 28 segments. 29
doi:10.1080/17499518.2015.1077974 fatcat:q6fitdpdd5a5bltnj75h54ydsy