The tragedy of the 2004 Indian Ocean tsunami has led to a rapid expansion in science directed at understanding tsunami and mitigating their hazard. A remarkable cross-section of this research was presented in the session: Tsunami Generation and Hazard, at the International Union of Geodesy and Geophysics XXIV General Assembly in Perugia, held in July of 2007. Over one hundred presentations were made at this session, spanning topics ranging from paleotsunami research, to nonlinear shallow-water theory, to tsunami hazard and risk assessment. A selection of this work, along with other contributions from leading tsunami scientists, is published in detail in the 28 papers of this special issue of Pure and Applied Geophysics: Tsunami Science Four Years After the Indian Ocean Tsunami. Part I of this issue includes 14 papers covering the state-of-the-art in tsunami modelling and hazard assessment. Another 14 papers are published in Part II focusing on observations and data analysis.

The 2004 Indian Ocean tsunami was triggered by a 9. 15 magnitude earthquake (MELTZNER et al. , 2006; CHLIEH et al. , 2007) that occurred at 0:58:53 GMT, 7:58:53 LT (USGS) (t ). The epicenter was located at 3. 3 N, 95. 8 E (Fig. 1) with a focal depth of EQ approximately 30 km. The earthquake was responsible for a sudden fault slip estimated on average from 12–15 m (SYNOLAKIS et al. , 2005; LAY et al. , 2005) to 20 m (FU and SUN, 30 2006). The seismic moment estimate (Mo = 1. 3 5 9 10 dyne-cm), based on the Figure 1 Locations of video recordings, recovered clocks, and reliable eyewitness observations. 1: Coastal plains ?ooded by the tsunami; 2: non-?ooded coastal plains; 3: uplands. Insert 3D-map showing the Sumatra Island, the studied area, and the epicenter of the 26/12/2004 earthquake. The video taken at Uteuen Badeue, on the eastern edge of the Banda Aceh Bay, was recorded by the chief of the Fishery Regional Of?ce from the top of a cliff. The movie that was shot near the Baiturrahman mosque in downtown Banda Aceh has been shown worldwide on TV. The one at Peukan Bada has been recorded during a wedding party. The last two movies were analyzed in detail in order to calculate the tsunami velocity (FRITZ et al. , 2006). Vol.

The Indian Ocean tsunami of December 2004 is considered to have been one of the worst natural disasters in history, affecting twelve countries, from Indonesia to Somalia. 175,000 people are believed to have lost their lives, almost 50,000 were registered as missing and 1.7 million people were displaced. As well as this horrendous toll on human life

Ten years ago, on December 26, 2004, one of the world’s most destructive natural disasters occurred. A magnitude Mw 9.1 earthquake (third strongest ever instrumentally recorded) generated a global tsunami that killed about 230,000 people along the coasts of 14 countries in the Indian Ocean and propagated as far as the North Pacific and North Atlantic Oceans. Since then, various countries from around the globe contributed major funding to tsunami research and mitigation, enabling the installation of hundreds of new high-precision instruments, the development of new technology and the establishment of more modern communication systems. As a result, incredible progress has been achieved in tsunami research and operation during the ten years after the 2004 Indian Ocean tsunami.The papers presented in this second of two special volumes of Pure and Applied Geophysics reflect the state of tsunami science during this time, including two papers devoted to global observations. Five papers provide new findings specifically in the Indian Ocean. Eight papers cover Pacific Ocean studies, focusing mainly on the 2011 Tohoku earthquake and tsunami. Remaining papers in the volume describe studies in the Atlantic and Mediterranean and general tsunami source studies.The volume is of interest to scientists and practitioners involved in all aspects of tsunamis from earthquake source processes to transoceanic wave propagation and coastal impacts. Postgraduate students in geophysics, oceanography and coastal engineering – as well as students in the broader geosciences, civil and environmental engineering – will also find the book to be a valuable resource, as it combines recent case studies with advances in tsunami science and natural hazards mitigation.