Written records of historical tsunamis in the northeastern South China Sea – challenges associated with developing a new integrated database

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.