Post-Tsunami Field Surveys are Essential for Mitigating the Next Tsunami Disaster (overview paper)
Over last five years, there have been 59 measured tsunamis, with nine causing deaths, most notably 26 Dec 2004 Indian Ocean tsunami (230,000 lives). In the Pacific, tsunami occurred in April 2007 (Solomon: 54 deaths, Chile: 3 deaths), September 2009 (Samoa 149, Am Samoa 34, and Tonga 9 deaths), February 2010 (Chile ~150), and March 2011 (Japan ~25000). After each tsunami, data were collected to quantify physical, environmental, and human impacts, response/recovery, improve numerical models, and engineering.
Tsunami disasters attract a large number of local, national, international professionals to investigate scientific, economic, social impacts. Some of these data are perishable making it essential to collect quickly. Important data may also be desirable from locations that are logistically difficult to assess without local assistance and access. At the same time, Emergency Agencies are focusing on public safety, critical support lifelines and infrastructure, resource mobilization to meet its citizens immediate post-event emergency response needs. Elected officials and the media must have accurate summaries of the tsunami impact to report to the public. To support all efforts, coordination and cooperation is critical, and efficient and useful data and information sharing is paramount. If data from science teams are made available, it will immediately contribute to better informed and ultimately, more practical and efficient response and recovery decision-making.
Since the 1992 Nicaragua tsunami, international tsunami survey teams (ITST) have conducted post-tsunami field surveys to collect data immediately after a destructive tsunami. The runup and inundation data collected are used to validate and benchmark tsunami numerical models Formation of a team was necessary to quickly gather perishable data. Although often focused on water height data, these early ITSTs recognized the importance of an interdisciplinary approach and included researchers from different fields. They also shared information about tsunamis with the people and officials in the affected country.
A major change in the study of tsunami hazards and in post-tsunami surveys followed the December 2004 Indian Ocean disaster. The scale of the event in area and impact was unprecedented in modern times. Dozens of teams and hundreds of researchers worked in the 16 affected countries over the following year (Synolakis and Kong, 2006). Not only was the amount of data much larger than ever collected in previous ITST efforts but it also included different types of data measured in different ways by different groups. With the increase in data volume came concerns about how to archive and process the data, and about quality issues, including collection methodology, terminology, base levels, and ambient tidal conditions. The 2004 tsunami made it clear that the ad hoc, informal way of conducting post-tsunami surveys was no longer adequate.
Tsunami research has also changed since 1998. There have been advances in modeling and the availability of space-based technologies, including satellite imagery and global positioning satellite navigation. Methods of recording impacts, such as the proliferation of amateur digital video and still imagery, need to be addressed. Tsunami sediments now play a new and important role as key data that extend the tsunami historical record back in time and thus provide an indication of its recurrence intervals. In addition to advances in techniques, many more disciplines have become involved in post-tsunami investigations, such as the social and economic sciences, ecology, and engineering. Post-tsunami surveys have moved beyond traditional approaches of measuring maximum inundation, runup, and flow depth to include a detailed, varied, rich, and contextual understanding of the effects of tsunamis at different places, such as upon people and their communities, infrastructure, agricultural systems, marine and terrestrial ecology, geomorphological systems, and engineered structures.
The recent tsunami disasters in the Pacific gathered many international scientists to conduct post-tsunami surveys. In past, ITST surveys were single-discipline efforts, conducted individually with moderate government coordination that left the country with a large integration from many scientific papers and no one coherent study that was immediately available. However, through coordinated International Tsunami Survey Teams (ITSTs), international scientists can assist governments in more efficiently responding to and recovering from tsunami disasters. Starting with the September 29, 2009, Samoa tsunami (Kong et al., 2009), this coordination role has been most actively led by the International Tsunami Information Center (ITIC) and the United Nations Educational, Scientific, and Cultural Organization’s Intergovernmental Oceanographic Commission (UNESCO-IOC).