S13E-08:
2011 Tohoku tsunami runup hydrographs, ship tracks, upriver and overland flow velocities based on video, LiDAR and AIS measurements
Monday, 15 December 2014: 3:25 PM
Hermann M Fritz1, David A Phillips2, Akio Okayasu3, Takenori Shimozono4, Haijiang Liu5, Seiichi Takeda3, Fahad Mohammed6, Vassilios Skanavis7, Costas Synolakis7 and Tomoyuki Takahashi8, (1)Georgia Institute of Technology, School of Civil and Environmental Engineering, Atlanta, United States, (2)UNAVCO, Boulder, CO, United States, (3)Tokyo University of Marine Science and Technology, Tokyo, Japan, (4)University of Tokyo, Tokyo, Japan, (5)Zhejiang University, Hangzhou, China, (6)Risk Management Solutions, Inc., Newark, CA, United States, (7)Technical University of Crete, Chanea, Greece, (8)Kansai University, Osaka, Japan
Abstract:
The 2004 Indian Ocean tsunami marked the advent of survivor videos mainly from tourist areas in Thailand and basin-wide locations. Near-field video recordings on Sumatra’s north tip at Banda Aceh were limited to inland areas a few kilometres off the beach (Fritz et al., 2006). The March 11, 2011, magnitude Mw 9.0 earthquake off the Tohoku coast of Japan caused catastrophic damage and loss of life resulting in the costliest natural disaster in recorded history. The mid-afternoon tsunami arrival combined with survivors equipped with cameras on top of vertical evacuation buildings provided numerous inundation recordings with unprecedented spatial and temporal resolution. High quality tsunami video recording sites at Yoriisohama, Kesennuma, Kamaishi and Miyako along Japan’s Sanriku coast were surveyed, eyewitnesses interviewed and precise topographic data recorded using terrestrial laser scanning (TLS). The original video recordings were recovered from eyewitnesses and the Japanese Coast Guard (JCG). The analysis of the tsunami videos follows an adapted four step procedure (Fritz et al., 2012). Measured overland flow velocities during tsunami runup exceed 13 m/s at Yoriisohama. The runup hydrograph at Yoriisohama highlights the under sampling at the Onagawa Nuclear Power Plant (NPP) pressure gauge, which skips the shorter period second crest. Combined tsunami and runup hydrographs are derived from the videos based on water surface elevations at surface piercing objects and along slopes identified in the acquired topographic TLS data. Several hydrographs reveal a draw down to minus 10 m after a first wave crest exposing harbor bottoms at Yoriisohama and Kamaishi. In some cases ship moorings resist the main tsunami crest only to be broken by the extreme draw down. A multi-hour ship track for the Asia Symphony with the vessels complete tsunami drifting motion in Kamaishi Bay is recovered from the universal ship borne AIS (Automatic Identification System). Multiple hydrographs corroborate the tsunami propagation through Miyako Bay and up the Hei River. Tsunami outflow currents up to 11 m/s were measured in Kesennuma Bay making navigation impossible. Further we discuss the complex effects of coastal structures on inundation and outflow hydrographs as well as associated flow velocities.
