Suchergebnisse

Abstract. Recent tsunami have caused massive loss of life, destruction of coastal infrastructures and disruption to economic activity. To date, tsunami hazard studies have concentrated on determining the frequency and magnitude of events and in the production of simplistic flood maps. In general, such maps appear to have assumed a uniform vulnerability of population, infrastructure and business. In reality however, a complex set of factors interact to produce a pattern of vulnerability that varies spatially and temporally. A new vulnerability assessment approach is described, that incorporates multiple factors (e.g. parameters relating to the natural and built environments and socio-demographics) that contribute to tsunami vulnerability. The new methodology is applied on a coastal segment in Greece and, in particular, in Crete, westof the city of Herakleio. The results are presented within a Geographic Information System (GIS). The application of GIS ensures the approach is novel for tsunami studies, since it permits interrogation of the primary database by several different end-users. For example, the GIS may be used: (1) to determine immediate post-tsunami disaster response needs by the emergency services; (2) to preplan tsunami mitigation measures by disaster planners; (3) as a tool for local planning by the municipal authorities or; (4) as a basis for catastrophe modelling by insurance companies. We show that population density varies markedly with the time of the year and that 30% of buildings within the inundation zone are only single story thus increasing the vulnerability of their occupants. Within the high inundation depth zone, 11% of buildings are identified as in need of reinforcement and this figure rises to 50% within the medium inundation depth zone. 10% of businesses are located within the high inundation depth zone and these may need to consider their level of insurance cover to protect against primary building damage, contents loss and business interruption losses.

Abstract. Comprehensive analysis of 15 previously published regional databases incorporating more than 100 sources leads to a newly revised historical tsunami database for the northeastern (NE) region of the South China Sea (SCS) including Taiwan. The validity of each reported historical tsunami event listed in our database is assessed by comparing and contrasting the information and descriptions provided in the other databases. All earlier databases suffer from errors associated with inaccuracies in translation between different languages, calendars and location names. The new database contains 205 records of "events" reported to have occurred between AD 1076 and 2009. We identify and investigate 58 recorded tsunami events in the region. The validity of each event is based on the consistency and accuracy of the reports along with the relative number of individual records for that event. Of the 58 events, 23 are regarded as "valid" (confirmed) events, three are "probable" events and six are "possible". Eighteen events are considered "doubtful" and eight events "invalid". The most destructive tsunami of the 23 valid events occurred in 1867 and affected Keelung, northern Taiwan, killing at least 100 people. Inaccuracies in the historical record aside, this new database highlights the occurrence and geographical extent of several large tsunamis in the NE SCS region and allows an elementary statistical analysis of annual recurrence intervals. Based on historical records from 1951–2009 the probability of a tsunami (from any source) affecting the region in any given year is relatively high (33.4%). However, the likelihood of a tsunami that has a wave height >1 m, and/or causes fatalities and damage to infrastructure occurring in the region in any given year is low (1–2%). This work indicates the need for further research using coastal stratigraphy and inundation modeling to help validate some of the historical accounts of tsunamis as well as adequately evaluate the recurrence intervals of tsunamis along the now heavily developed coastlines of the region.