National Geophysical Data Center Historical Natural Hazard Event Databases

After a major event such as the 2004 Indian Ocean tsunami or the 2008 Chengdu earthquake, there is interest in knowing if similar events have occurred in the area in the past and how often they have occurred. The National Geophysical Data Center (NGDC) historical natural hazard event databases can provide answers to these types of questions. For example, a search of the tsunami database reveals that over 100 tsunamis have occurred in the Indian Ocean since 416 A.D. Further analysis shows that there has never been such a deadly tsunami anywhere in the world. In fact, the 2004 event accounts for almost half of all the deaths caused by tsunamis in the database. A search of the earthquake database shows that since 193 B.C., China has experienced over 500 significant earthquakes that have caused over 2 million deaths and innumerable dollars in damages. The NGDC global historical tsunami, significant earthquake, and significant volcanic eruption databases include events that range in date from 4350 B.C. to the present. The database includes all tsunami events, regardless of magnitude or intensity; and all earthquakes and volcanic eruptions that either caused deaths, moderate damage, or generated a tsunami. Earthquakes are also included that were assigned either a magnitude >= 7.5 or Modified Mercalli Intensity >= X. The basic data in the historical event databases include the date, time, location of the event, magnitude of the phenomenon (tsunami or earthquake magnitude and/or intensity, or volcanic explosivity index), and socio-economic information such as the total number of deaths, injuries, houses damaged, and dollar damage. The tsunami database includes an additional table with information on the runups (locations where tsunami waves were observed by eyewitnesses, tide gauges, or deep ocean sensors). The volcanic eruptions database includes information on the volcano elevation and type. There are currently over 2000 tsunami source events, 12500 tsunami runup locations, 5700 earthquakes, and 460 volcanic eruptions in the databases. The natural hazard event databases are stored in a relational database management system (RDBMS) which facilitates the integration and access to these related databases. For example, users can search for destructive earthquakes that preceded a volcanic eruption that then generated a damaging tsunami. The databases are accessible over the Web as tables, reports, and interactive maps. The maps provide integrated web-based GIS access to individual GIS layers including the natural hazard events and various spatial reference layers such as topography, population density, and political boundaries.