When History Repeats Itself: Typhoon Haiyan and Its 1897 Predecessor in the Philippines

Friday, 19 December 2014
Janneli Lea Soria1, Adam Switzer1, Cesar Villanoy2, Hermann M Fritz3, Princess Hope Bilgera2, Olivia C Cabrera2, Fernando Pascual Siringan4, Yvainne Yacat-Sta. Maria2, Riovie Ramos1 and Ian Quino Fernandez2, (1)Earth Observatory of Singapore, Nanyang Technological University, Singapore, Singapore, (2)Marine Science Institute, University of the Philippines, Quezon City, Philippines, (3)Georgia Institute of Technology, School of Civil and Environmental Engineering, Atlanta, United States, (4)Marine Science Institute, University of the Philippines, Metro Manila, Philippines
Super typhoon (ST) Haiyan killed more than 6,000 and destroyed over a million dwellings in the central Philippines. It is the deadliest typhoon in the Philippines superseding the November 1991 Tropical Storm Thelma disaster in Ormoc City, on the western coast of Leyte Island. Damage and losses from ST Haiyan were particularly high along the coasts surrounding the shallow and funnel-shaped San Pedro Bay, including the coastal city of Tacloban. The first storm surge reconnaissance was conducted from 23 to 28 November 2013 in areas surrounding San Pedro Bay. Follow up surveys were conducted in January, May and June to cover larger and more remote coastlines in Samar Island facing the Leyte Gulf and the Philippine Sea. Digitized local bathymetric charts and Delft3D Flow were used to generate a coupled surge-tide-wave model to simulate the surge heights within San Pedro Bay. We corroborated eyewitness accounts, video recordings, and simulations with field measurements to characterize ST Haiyan’s inundation with flow depths, surge heights, timing and peak flood duration, and resulting damage extent. We also compared the surge heights from ST Haiyan with a similar event from an unnamed typhoon in October 1897 (Ty 1897). Strong winds estimated to be in excess of 280 km h-1 and a ‘tsunami-like’ surge with heights typically ranging from 5 m up to 7 m struck in the early hours of 8 November 2013. According to eyewitness accounts this represents an event in the region of unprecedented magnitude. Historical records, however, clearly indicate that Tacloban and nearby coastal communities were similarly devastated by another typhoon in 1897. The 1897 typhoon crossed the Philippines on a similar path of destruction, almost parallel to ST Haiyan but about 10 to 15 km farther north. Ty 1897 seemed less intense than ST Haiyan but generated a storm surge of comparable magnitude. Inundation heights in 1897 exceeded 4 m in most places with a maximum of 7 m. The Ty 1897 estimated death toll of 1228 corresponds to a similar fatality rate as Haiyan, given the massive population growth between the two events. This historical event demonstrates that ST Haiyan is not unprecedented and highlights the importance of ancestral knowledge, historical awareness and education for appropriate hazard mitigation, response and evacuation.