This special edition of the tsunami impacts on coral reefs was made possible by the generous contribution of Khaled bin Sultan Living Oceans Foundation which is dedicated to the conservation and restoration of our living oceans (www.livingoceansfoundation.org). ATOLL RESEARCH BULLETIN NO. 544 TSUNAMIS AND CORAL REEFS Edited by David R. Stoddart ISSUED BY NATIONAL MUSEUM OF NATURAL HISTORY SMITHSONIAN INSTITUTION WASHINGTON, D.C., U.S.A. JULY 2007 !#+./7,%$'-%.4 4HE!TOLL2ESEARCH"ULLETINISISSUEDBYTHE3MITHSONIAN)NSTITUTIONTOPROVIDEAN OUTLETFORINFORMATIONONTHEBIOTAOFTROPICALISLANDSANDREEFSANDONTHEENVIRONMENT THATSUPPORTSTHEBIOTA 4HIS ISSUE IS PARTLY lNANCED AND DISTRIBUTED WITH FUNDS FROM !TOLL 2ESEARCH"ULLETINREADERSANDAUTHORS 4HE"ULLETINWASFOUNDEDINANDTHElRSTNUMBERSWEREISSUEDBYTHE0ACIlC 3CIENCE "OARD .ATIONAL !CADEMY OF 3CIENCES WITH lNANCIAL SUPPORT FROM THE /FlCE OF .AVAL 2ESEARCH )TS PAGES WERE DEVOTED LARGELY TO REPORTS RESULTING FROM THE 0ACIlC 3CIENCE"OARDS#ORAL!TOLL0ROGRAM ??????????????????????????????????? !LL STATEMENTS MADE IN PAPERS PUBLISHED IN THE !TOLL 2ESEARCH "ULLETIN ARE THE SOLERESPONSIBILITYOFTHEAUTHORSANDDONOTNECESSARILYREPRESENTTHEVIEWSOFTHE 3MITHSONIANNOROFTHEEDITORSOFTHE"ULLETIN ??????????????????????????????????? !RTICLESSUBMITTEDFORPUBLICATIONINTHE!TOLL2ESEARCH"ULLETINSHOULDBEORIGINAL PAPERSINAFORMATSIMILARTOTHATFOUNDINRECENTISSUESOFTHE"ULLETIN&IRSTDRAFTS OFMANUSCRIPTSSHOULDBEDOUBLE SPACEDANDCANBESENTTOANYOFTHEEDITORS!FTERTHE MANUSCRIPTHASBEENREVIEWEDANDACCEPTED THEAUTHORWILLBEPROVIDEDWITHAPAGEFORMAT WHICHWILLBEUSEDTOPREPAREASINGLE SPACEDCOPYOFTHEMANUSCRIPT #//2$).!4).'%$)4/2 )AN'-ACINTYRE.ATIONAL-USEUMOF.ATURAL(ISTORY MACINTYR SIEDU -2# 3MITHSONIAN)NSTITUTION !33)34!.430/"OX 7ASHINGTON $# 7ILLIAM4"OYKINS *R +AY#LARK "OURNE *ACK#HAPMAN +ASANDRA$"ROCKINGTON %$)4/2)!,"/!2$ 3TEPHEN$#AIRNS-2# .ATIONAL-USEUMOF.ATURAL(ISTORY +LAUS2ÓTZLER-2# )NSERTAPPROPRIATE-2#CODE -ARK-,ITTLER-2# 3MITHSONIAN)NSTITUTION 7AYNE.-ATHIS-2# 0/"OX *EFFREY47ILLIAMS-2# 7ASHINGTON $# 7ARREN,7AGNER-2# 2OGER"#LAPP-2# .ATIONAL-USEUMOF.ATURAL(ISTORY .ATIONAL"IOLOGICAL3URVEY -2# 3MITHSONIAN)NSTITUTION 0/"OX 7ASHINGTON $# $AVID23TODDART$EPARTMENTOF'EOGRAPHY %ARTH3CIENCES"UILDING 5NIVERSITYOF#ALIFORNIA "ERKELEY #! "ERNARD-3ALVAT%COLE0RATIQUEDES(AUTES%TUDES ,ABO"IOLOGIE-ARINEET-ALACOLOGIE 5NIVERSIT£DE0ERPIGNAN 0ERPIGNAN#EDEX &RANCE ATOLL RESEARCH BULLETIN NO. 544 PAGES Coral Reefs and the Tsunami of 26 December 2004: Generating Processes and Ocean-Wide Patterns of Impact Thomas Spencer 1 Tsunami Impacts in Aceh Province and North Sumatra, Indonesia Annelise B. Hagan, Robert Foster, Nishan Perera, Cipto Aji Gunawan, Ivan Silaban, Yunaldi Yaha, Yan Manuputty, Ibnu Hazam and Gregor Hodgson 37 Disturbance to Coral Reefs in Aceh, Northern Sumatra: Impacts of the Sumatra- Andaman Tsunami and Pre-Tsunami Degradation Stuart J. Campbell, Morgan S. Pratchett, Aji W. Anggoro, Rizya L. Ardiwijaya, Nur Fadli, Yudi Herdiana, Tasrif Kartawijaya, Dodent Mahyiddin, Ahmad Mukminin, Shinta T. Pardede, Edi Rudi, Achis M. Siregar and Andrew H. Baird 55 The Influence of the Indian Ocean Tsunami on Coral Reefs of Western Thailand, Andaman Sea, Indian Ocean Niphon Phongsuwan and Barbara E. Brown 79 Effects of the Tsunami of 26 December 2004 on Rasdhoo and Northern Ari Atolls, Maldives Eberhard Gischler and Reinhard Kikinger 93 Impact of the Sumatran Tsunami on the Geomorphology and Sediments of Reef, Islands, South Maalhosmadulu Atoll, Maldives Paul S. Kench, Scott L. Nichol, Roger F. McLean, Scott G. Smithers and Robert 105 W. Brander Effects of the Tsunami in the Chagos Archipelago 135 Charles R.C. Sheppard Tsunami Impacts in the Republic of Seychelles, Western Indian Ocean Annelise B. Hagan, Thomas Spencer, David R. Stoddart, 149 Maurice Loustau-Lalanne and Ronny Renaud ISSUED BY NATIONAL MUSEUM OF NATURAL HISTORY SMITHSONIAN INSTITUTION WASHINGTON, D.C., U.S.A. JULY 2007 ACRONYMS BAPPENAS Baddan Perencanaan Pembangundn (National Development Planning Agency, Republic of Indonesia) COADS Comprehensive Ocean-Atmosphere Data Set CORDIO Coral Reef Degradation in the Indian Ocean (programme of the Swedish International Development Cooperation Agency – SIDA) CRISP Computer Retrieval of Information on Scientific Projects DEWA Division of Early Warning and Assessment (UNEP) EPA Queensland Environmental Protection Agency (Queensland Government) EERI Earthquake Engineering Research Institute GHCN Global Historical Climatology Network IUCN World Conservation Union (formerly International Union for the Conservation of Nature and Natural Resources) NASA National Aeronautics and Space Administration NCDC National Climatic Data Center (USA) NGDC National Geophysical Data Center (division of NOAA) NOC National Oceanography Centre, UK NIWA National Institute of Water and Atmospheric Research (New Zealand) NOAA National Oceanic and Atmospheric Administration (US Department of Commerce) UNESCO United Nations Educational, Scientific and Cultural Organization WIIP Wetlands International Indonesia Programme (of Wetlands International and the Indonesian Ministry of Forestry) WWF Worldwide Fund for Nature (formerly World Wildlife Fund) CORAL REEFS AND THE TSUNAMI OF 26 DECEMBER 2004: GENERATING PROCESSES AND OCEAN-WIDE PATTERNS OF IMPACT BY THOMAS SPENCER INTRODUCTION The Indian Ocean tsunami of December 26, 2004 was the most catastrophic such event in recent history, killing more than 230,000 people in the near field and a further 70,000 in the Indian Ocean far field. This death toll was far in excess of the estimated 36,500 deaths associated with the tsunami waves generated by the cataclysmic explosion of Krakatau on August 26-27, 1883 (Abercromby et al., 1888; Winchester, 2003). It was also quite clearly the best-documented tsunami of all time, both scientifically and in terms of the very real human tragedies delivered in almost real-time by the global communications revolution. Scientific data gathered to understand this event, and thus to better predict future such catastrophes, have included not only the application of now well-established techniques at the local-to-regional spatial scale such as the remote sensing of coastal margins (CRISP, 2005) and ocean-surface heights (NOAA, 2005a), multibeam swath bathymetry of the earthquake zone (Wilson, 2005) and handheld GPS- controlled surveys both above and below water but also the products of newly emerging technologies at the global scale such as the spectacular seismic monitoring delivered by the Global Seismographic Network (Park et al., 2005a) of digital broadband, high dynamic range seismometers, the pattern of large-scale displacements revealed by the network of 41 continuously recording GPS stations throughout Southeast Asia (Bannerjee et al., 2005) and the detection of earthquake and tsunami-induced deep infrasound in the central Indian Ocean (Garces et al., 2005). It has also been the best mathematically modelled, simulated and visualized tsunami in history. At the same time, it has not always been easy to establish common points of reference between the many nation states impacted by the disaster, to set detailed local studies within wider regional pictures and to separate out anecdotal reports from scientific facts. This paper attempts to place the December 2004 tsunami in its contemporary, historical and possible near-future tectonic contexts. It also attempts to provide a regional synthesis which highlights the regional variability in tsunami wave characteristics. It is hoped that individual site reports on tsunami impacts of coral reefs and associated shallow marine ecosystems can be placed within this framework and thus better understood. Cambridge Coastal Research Unit, Department of Geography, University of Cambridge, Downing Place, Cambridge, CB2 3EN, UK. 2 WHY, WHERE AND WHY NOW: THE PLATE TECTONIC FRAMEWORK Southeast Asia is characterized by the convergence of the oceanic Indo-Australian plate, at an average rate of 7.0 cm a-1 in the direction 003 deg, with the extension of the continental Eurasian plate comprising the Malay Peninsula, Sumatra, the Sunda Shelf sea and parts of Borneo (Simandjuntak and Barber, 1996). Where the two plates meet, the oceanic plate is subducted beneath the continental plate. This tectonic setting is expressed in a nearly continuous arc of volcanic and non-volcanic islands and associated deep-water trench and back-arc basins, which extends from Myanmar and the collision zone with India and the Himalayas to Timor and the collision zone of Sumatra’s outer-arc ridge with Papua and Australia (Fig. 1; Hutchinson, 2005). The character of convergence changes from east-to-west. In the east, south of Java, relatively old (ca. 100 Ma) oceanic lithosphere is subducted in a direction perpendicular to the trench orientation. However, to the northwest, the relatively young (ca. 40 Ma) oceanic lithosphere behaves rather differently. Not only does the convergence rate reduce (from 7.8 cm a-1 at Sumbawa to 6.0 cm a-1 in the Andaman Islands) but the convergence also becomes increasingly oblique (Fitch, 1972). Thus convergence needs to be partitioned into two components comprising both trench-normal subduction and forces parallel to the trench which generate strike- slip motions along major fault systems (Fig. 2; McCaffrey, 1996). As a result of these dynamics, a sliver plate, the Burma plate, has sheared off parallel to the subduction zone and sits between the convergent plate margin to the west and great fault systems to the east which comprise (from south-to-north) the