BOULDER FIELDS ON SAMAR ISLAND, PHILIPPINES DEPOSITED BY SUPER TYPHOON HAIYAN : IMPLICATIONS FOR THE STORM VS TSUNAMI DEBATE

In early November 2013, super typhoon (ST) Haiyan affected more than 16 million people, killed more than 6000 and destroyed more than a million dwellings in the central Philippines. The super typhoon represents the nation’s deadliest natural disaster since the Moro Gulf, Mindanao earthquake and tsunami (~8,000 fatalities) of 1976. Damage and losses from ST Haiyan were particularly high on Leyte and Samar Islands. Here we focus on the area around Hernani on Pacific coastline of eastern Samar. Along this coast fringing reefs with reef platforms up to 600 m wide exist and the open coast was exposed to storm surges exceeding 6 m with considerable input from superimposed storm waves. On the open reef platforms large fields of dislodged reef clasts provide testament to the combined power of the surge and waves. The largest clast exceeds 90 tons with several others weighing more than 60 tons. The large clasts on the Hernani coast provide further evidence that storm waves are capable of quarrying and transporting very large clasts and that invoking other processes such as tsunami as source of reef clasts requires more evidence than clast size alone.