The Hydrographic and Oceanographic Service of the Navy (SHOA) is the technical, permanent, and official agency 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 duty, SHOA started the implementation of the CITSU Project in 1997 (Inundation 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 event of near field tsunamigenic events.
In the field of prevention and mitigation of the impact of tsunamis, the inundation maps are directly linked to urban planning, carried out by the municipal authority, and 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 Response Plan in the event of a Tsunami.
In general terms, the Tsunami Inundation Maps (CITSU) developed by SHOA represent a known or probable extreme event, depending on the circumstances.
Since 2011, the presentation format changed, showing the flooded area in levels of depth of inundation in meters, and the topographic surface in hillshade, in order to achieve a better interpretation of this type of cartographic product.
Representation of the inundation
Currently, from the information available for public download (PDF and KMZ), the KMZ file allows displaying the inundation in the form of a line or an area, depending on whether the consulted CITSU corresponds to the old format (prior to 2011) or new format (after 2011), respectively. For this, the Google Earth software is necessary, from which you can consult the inundation delimited in the CITSU. For the new format, the difference is in the levels of depth and transparency on aerial images that are now available in this application. In addition, a link to FAQs is provided on the Website, which allows access to the inundation KMZ file, directly on the Google Maps map server, from any computer or mobile device with an Internet connection, and without the need to have any additional software installed.
It is worth mentioning that this information should only be considered as a reference, especially altitude regarding sea level, given that the CITSU are referred to the Mean Sea Level with high accuracy, while Google Earth presents general altitudes, therefore, not always equal.
Numerical simulation of tsunamis: conceptual aspects
To quantitatively assess the tsunami risk of tectonic origin in coastal areas, interdisciplinary research has been necessary in seismology, geology, geophysics, and oceanography, including the review of historical sources. Within this context, the modeling of tsunamis has been used to discriminate between different possible scenarios (i.e. source location and rupture mechanisms) that may affect a region, elaborating an Inundation Map for the most extreme seismic event, either known or probable.
Currently, numerical simulation is the best geophysical and hydrodynamic analysis technique available to study the tsunami risk in areas where historical records are insufficient. The model applied to develop the CITSU project, COMCOT (Cornell Multi-Grid Coupled Tsunami Model) designed by Dr. S.N. Seo, based on the Shuto's model (August 10, 1993) and Yongsik Cho (August 10, 1993), at the School of Civil and Environmental Engineering of the Cornell University.