By: Dr. Jeff Masters , 3:47 PM GMT on May 08, 2014

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Category 5 Super Typhoon Haiyan, with satellite-estimated winds of 190 - 195 mph at landfall on November 8, 2013, pushed a massive storm surge of up to 23 feet (7 meters) into Tacloban, Philippines, newly-published storm surge survey results reveal. A team of researchers led by Yoshimitsu Tajima of the Department of Civil Engineering at the University of Tokyo found that at Haiyan's initial landfall point on the east coast of Samar Island, massive waves on top of the storm surge crashed against the coast, creating high water marks an astonishing 46 feet (14.1 meters) above mean sea level--some of the highest high-water marks ever recorded from a tropical cyclone. The world record is 13 - 14.6 meters (43 - 48 feet) from Australia's March 5, 1899 Bathurst Bay Cyclone. The greatest storm surge and high water mark recorded in an Atlantic hurricane are from Hurricane Katrina of 2005, which had a peak storm surge in Pass Christian, Mississippi of 27.8 feet (8.46 meters). The sea bottom was very flat in this region, so the waves on top of the surge were relatively small, and the highest high water mark from Katrina was just a few inches higher, at 28 feet (8.53 meters.) When deep water lies just offshore, as is the case for the east coast of the Philippines' Samar Island, huge waves will develop when the eyewall of an intense tropical cyclone moves over. These huge waves broke very close to shore during Haiyan, and were able to run-up the steep hillsides to incredible heights.





Figure 1. High water marks (in meters) in the wake of Super Typhoon Haiyan's storm surge in the Philippines on November 8, 2013. Numbers with "V" had significant waves on top of the storm surge; "R" indicates wave run-up height (where waves on top of the surge allowed the water to run-up onto shore much higher than the actual surge height), and symbols without letters are still water inundation (storm surge) heights. The high water marks are corrected for the tide levels at the time of the survey (tidal range in the Central Philippines is generally less than 1 meter, so this is a small correction in most cases.) The data is plotted from the survey results of Tajima et al., 2014.



Results of the storm surge survey

Andrew Kennedy, Associate Professor in Notre Dame's Department of Civil & Environmental Engineering & Earth Sciences, was part of a second Super Typhoon Haiyan storm surge survey done in January 2014 (whose results have not yet been published), and wrote this email to me: "We surveyed many locations concentrating on the open Pacific coast of Eastern Samar, just north of first landfall. The team was led by Professor Yoshimitsu Tajima of the University of Tokyo. We are still processing results, but found many locations with wave run-up in the 9 - 10 meter range. These waves and surge tossed palm trees, large boulders, and other debris up to elevations that would seem improbable if you had not seen the evidence. The communities affected by this storm remain devastated, and there is still no power in Guiuan, the largest city in Eastern Samar and our base for part of the survey.  In addition to the inundation, we also looked a lot at damage--mainly from waves and surge, but partly from wind. This included the small Barangay (town) of Hernani, the location of the frightening Nixon Gensis video showing waves washing away a house. We interviewed many people both in Hernani and other locations who described similar experiences of very sudden destructive inundation. I will say it again: ten meter run-up is hard to believe if you haven’t seen it."





Video 1. Nickson Gensis, Plan Philippines Community Development Worker, filmed what is probably the most remarkable video of storm surge ever taken. The video was taken from the from the top floor of a boarding house during Super Typhoon Haiyan in Hernani, in Eastern Samar, Philippines on November 8, 2013. Australian tropical cyclone expert Bruce Harper had this to say about the remarkable "tsunami-like" storm surge observed at 46 seconds into the video: This site at Hernani is quite exposed on the eastern coast of Samar, and has a fringing reef. My guess is that we are seeing the sudden exposure to deep water ocean swell waves that were triggered by the tide and sea level increase due to the storm surge. There is a critical water level where waves impacting on reefs can suddenly cause a massive increase in wave setup in the form of a tsunami-like effect such as we see in the video. A similar effect was reported at Basey, ten miles to the northeast of Tacloban across the San Juanico Strait, in this news report: "Edgar dela Cruz, 45, of Barangay Mercado, recounted to The STAR the sight of what looked like a tsunami. During the strange lull in the typhoon, he went out of his house. Jinamok Island was a kilometer across the sea from his village, he said. The sea receded about halfway to the island. 'There was a kind of low black cloud moving toward us,' Dela Cruz said. 'We heard a loud boom, like an explosion. And then we saw the giant waves--four giant waves--it was horrible.' Their house was destroyed. He said he and his family escaped with only the clothes on their backs." In this case, the reports suggest that northeast winds ahead of the center of Haiyan caused an initial “negative surge” effect in the shallow waters in this area, followed by the winds turning to E and SE as the center came closer. You can then develop quite a gradient in the water levels capable of producing this effect. The fast speed of the storm may also have contributed to this specific phenomenon. Yao Zhang of Notre Dame's Department of Civil & Environmental Engineering & Earth Sciences has modeled the waves and surge at Hernani, Eastern Samar, using a one-dimensional Boussinesq model. These show periodic surges and recessions very similar to those seen by Nickson Gensis. Magnitudes are quite large--over 5 meters--which does not include any initial storm surge. The simulations are not perfectly accurate, due to the lack of perfect bathymetry and incident waves. A video of one of his model runs may be seen at http://www.youtube.com/watch?v=KPYGQCE3778. The middle plot is a zoomed-in version of the larger-scale version shown in the top panel.





Figure 2. Storm surge damage from Super Typhoon Haiyan on Victory Island, Samar. Image credit: Getty Images.



A deadly storm surge for Tacloban

Tacloban (population 221,000) is the largest city on the Philippines' east coast, and is low-lying, with much of the city at less than ten feet elevation. Its position at the pointy end of a funnel-shaped bay makes its location particularly vulnerable to storm surge, since the topography acts to concentrate water at the apex of the funnel. The storm surge in Tacloban from Haiyan ranged from 4.6 - 7.0 meters (15 - 23 feet) according to the survey results, and caused catastrophic loss of life. An April 17, 2014 report from thePhilippine National Disaster Risk Reduction and Management Council listed 7,361 people dead or missing from Haiyan, making the typhoon the deadliest disaster in Philippine history. Most of these deaths occurred due to the storm surge in the Tacloban region. According to storm surge expert Dr. Hal Needham, the record highest storm surge in modern history in East Asia was 24 feet (7.3 meters) in 1897 on Samar Island, Philippines--the same location where Haiyan initially hit. 





Video 2. This animation by Deltares shows computed storm surge levels and wind vectors as Super Typhoon Haiyan makes landfall near Tacloban City, The Philippines. Surge levels were computed using Delft3D two days after landfall. The wind fields are based on Joint Typhoon Warning Center data, and generated a simulated storm surge of over 16.4 feet (5 meters) for Tacloban.



Links

Tajima, Y., et al., 2014, Initial Report of JSCE-PICE Joint Survey on the Storm Surge Disaster caused by Typhoon Haiyan, Coastal Engineering Journal Volume 56, Issue 01, March 2014.



A detailed look at Haiyan's storm surge, my December 2013 blog post.



(An interesting side note: I talked to a journalist who traveled to Eastern Samar after Haiyan hit. She talked to a worker who sheltered at the radar site in Guiuan that had its radome blown off during the height of the storm. The worker reported that they measured a pressure of 892 mb as the eye passed over. I haven't heard anything official out of the Philippines about this measurement, though, and the official landfalling pressure of Haiyan remains the 895 mb estimated via satellite by the Japan Meteorological Agency.)





Video 3. Palo, Philippines, located just south of Tacloban, was located in a more intense part of the eyewall of Super Typhoon Haiyan, as is evident by the remarkable extreme winds and storm surge captured in this video. According to storm chaser Josh Morgerman, the most extreme damage occurred a little farther south than Palo, in Tolosa and Tanauan.





Video 4. The storm surge in Tacloban, Philippines during the landfall of Super Typhoon Haiyan is captured at about the 3:30 - 4:20 mark in this video shot by ABSCBN News of the Philippines.