The Hydrographic and Oceanographic Service of the Navy (SHOA) is the technical, permanent, and official entity of the state, responsible for the functioning, operation, and maintenance of the National Tsunami Warning System (SNAM).
As a fundamental element of support to its own operational duties, SHOA started the implementation of the Project CITSU in 1997 (Flood Maps for the Coasts of Chile). This tool allows defining the maximum flood levels expected for the main urban and port areas in the coasts of Chile, in the occurrence of an earthquake with tsunamigenic characteristics.
In the field of prevention and mitigation of the impact of tsunamis, the flood charts are directly linked to urban planning, carried out by the municipal authority, and also to the development of evacuation, and civil protection plans. These tasks are supervised by the National Emergency Office of the Ministry of Interior (ONEMI) in every city, through the Regional Offices for Civil Protection and Emergency (OREMI), and Local Emergency Committees, following basic methodology for the elaboration of a Community Plan for Response in the event of a Tsunami.
In general, Tsunami Inundation Maps (CITSU) developed by this Service represent a known or expected extreme event, depending on the circumstances.
Since 2011, the presentation format for the CITSU has changed, showing the flooded area in depth inundation levels in meters, and the topographic surface in hillshade, to achieve a better interpretation of this cartographic product.
Flood lines in KMZ format
From the KMZ published files, it is possible to obtain the flood line of each respective Tsunami Flood Map (CITSU), easily graphed using Google Earth. To visualize them, you must first install this software in your computer. The graphed flood lines must be considered only as reference, specially the information regarding the altitude in relation to the sea level, given that the flood maps are referred to the mean sea level with a high level of accuracy, while Google Earth presents very general altitudes, therefore, they don’t always match. The official information about the flood charts has been delivered to the respective Regional Governments with an explanatory report about its development.
To know the official information regarding the flood areas and their collection, CITSU and its corresponding explanatory memory should be reviewed.
Numerical simulation of tsunamis: conceptual aspects
To quantitatively assess the risk of tectonic originated tsunamis in coastal areas, it has been necessary to carry out interdisciplinary research in seismology, geology, geophysics, and oceanography, including the review of historical sources. Within this context, the modeling of tsunamis has been utilized to discriminate between possible scenarios (i.e. source location and rupture mechanisms) that may affect a particular region, elaborating a flood map for the most likely seismic event.
Currently, the numerical simulation is the best geophysical and hydrodynamic analysis technique available to study the risk of tsunami in the areas where historical records are insufficient. The model applied to develop the CITSU project, TSUNAMI-N, corresponds to the TIME project (Tsunami Inundation Modelling Exchange) of the IOC, (Intergovernmental Oceanographic Commission) designed by Dr. Nuobo Shuto at the Tohoku University Disaster Control and Research Center, Japan (IUGG/IOC, 1997).