RAPID: Environmental impacts of Cyclone Pam on Vanuatu: implications for long-term cyclone and tsunami records for the South Pacific

RAPID: SEDIMENTARY RECORD OF CYCLONE PAM FROM VANUATU: IMPLICATIONS FOR LONG-TERM CYCLONE AND TSUNAMI RECORDS FOR THE SOUTH PACIFIC

This proposal is a co-funding effort between the Sedimentary Geology and Paleobiology Program/EAR and the East Asia and Pacific Program/OISE/IIA.

Nontechnical explanation of the project:

Land-falling tropical cyclones (TCs) pose an economic and environmental hazard to coastlines of the South Pacific, however, little is known about their long-term variability. The uncertainty surrounding TC hazards in this region was tragically underscored on 6 March 2015 when TC Pam, one of the most intense storms to impact the South Pacific, made landfall on Vanuatu as a Category 5 cyclone. Records of past cyclones, developed from the sedimentary deposits they leave behind, improve our understanding of processes and frequency by expanding the age range of events to include centennial and millennial timescales. However, one of the major obstacles associated with using sedimentary deposits to reconstruct reliable records of past storms is that sediments deposited by land-falling TCs can often be confused with those deposited by tsunamis. PIs will address this obstacle by comparing the impact and associated sedimentary deposits of TC Pam and the 2009 South Pacific tsunami. This study is an important step towards improving the assessment of hazard risk for coastlines that are vulnerable to both forms of marine inundation.

Technical description of the project:

PIs developed a unique opportunity to compare the impacts of a known storm (TC Pam on Vanuatu in 2015) and tsunami (South Pacific tsunami in 2009) in a region where the event record is fragmentary and incomplete. A comparison of the impact of TC Pam and the 2009 South Pacific tsunami (previously documented by members of the team) enables an assessment of two extreme events of similar magnitude, but different genesis. To carry out this comparison PIs will rapidly dispatch a four-person survey team to the islands that sustained the greatest impact (Efate and Tanna in Vanuatu). They will collect vital physical characteristics of the cyclone?s storm surge (e.g., surge height, inundation distance) and its associated sedimentary deposits (e.g., lithology, thickness, spatial extent). Through detailed stratigraphic, grain size, and micropaleontological (foraminiferal taxonomy and taphonomy) analyses PIs aim to identify differences in the sedimentary deposits emplaced by these events and that these differences can be used to improve hazard assessment for coastlines impacted by both forms of marine inundation.