Tsunami Warning System

Considering this potential threat of tsunami, INETER commissioned the development of a system of regional tsunami early warning, a national alert system in Nicaragua, which in turn could issue warnings to other countries in the region.

• INETER has an extensive seismic network in Central America (36 telemetry stations, 18 acelerográficas stations and the Central Seismic's highly computerized and automated broadband.

• This seismic network detects earthquakes not only in Nicaragua but throughout Central America

• The response time in case of an earthquake is less than 15 minutes

• A communication system exists that includes Internet, telephone, fax, radio systems

• Communication with neighboring countries is well developed, including direct access to the seismic core of these countries, via Internet.

• Nicaragua was integrated into the International Tsunami Warning in the Pacific Ocean, and is the only Central American country that is actively working on this system.  It integrates with the new radio system and the Civil Defense in Nicaragua. 

The system is based on information from the seismic network, the network acelerográfica and the broadband seismic station and the alert function with the following steps:

1. The seismic network detected a strong earthquake.

2. The event is located at lower depths in the Pacific Ocena Nicaragua or Central America

3. Through the network it is determined if a incidents reaches a Richter magnitude above 7.

4. It shall issue a initial warning message to the Nicaraguan Civil Defense (emergency committees and the other countries of the region)

5. The broadband seismic station, with a special software (TREMORS) automatically locates the earthquake, estimates the magnitude of seismic waves on the basis of long period, and issues its own warning message. (If it fails the seismic network, the message still could come from the broadband).

6. This message serves as a secondary confirmation, it helps to verify the probability for the occurrence of tsunami and is also transmitted automatically to the Civil Defense and Emergency Commission.

7. Civil Defense and Emergency Commission uses their own systems of communication with people on the Pacific coast to warn the population. Nicaraguan Civil Defense manages a system of radio communication with the people on the Pacific coast. Within minutes it is possible to inform the mayors or other people in the town about the danger. With local methods they inform them all. Nicaraguan Civil Defense is also developing a project to issue warnings with a siren system installed at sites along the coast.

Having detected the earthquake within the Central Seismic,  INETER connects via telephone with automatic tide stations in Corinto, Puerto Sandino and San Juan del Sur and begins to monitor sea level.  This measure will not help predict the tsunami but it serves to verify if a tsunami will hit the coast, or not.

if the earthquake occurs at regional distances, a special computer program estimates, based on the parameters of the earthquake, its likely arrival times and heights of the waves for a number of sites in the Pacific coast of Central America, and are reported to Civil Defense and the general public. They are also communicating with the Central Seismic Emergency Commission or port companies of neighboring countries to obtain reports on the real impact tsunami. This information would help to determine the real threat to the Pacific coast of Nicaragua.

1-4 Steps must be performed within 10 minutes and the chance to give information to the Civil Defense to inform the population on time. Assuming that civil defense needs 10 minutes to inform all the peoples of the Pacific coast of Nicaragua that have radio communication, it will be between 25 and 40 minutes until the arrival of the tsunami waves.

At this time, local authorities have to spread the message of warning to the population at risk. The population has to flee to safer places, without worrying about their belongings - only to save their lives.

The experiences in other countries indicate that the tsunami warning systems do not work without issuing false alarms. This is due to the short time allocated for making the decision on the possible occurrence of a tsunami. Earthquakes above magnitude 7 Richter, capable of generating a tsunami, could occur with a frequency of about 1-2 events in 10 years in Central America. Additionally, during this period 2-5 messages may be issued from the Tsunami Warning Center in the Pacific, which INETER would decide whether to assess wheter the coast of Nicaragua and Central America may be affected or not. It can be assumed that the warning system every two years would be confronted with the decision on issuing a warning message. For security,  INETER opts to pursue a conservative approach and prefers to deliver a message even if theirs a probability the tsunami event will not occur - rather than not deliver the message and tsunami devastates the people. The reasoning is that it is better to move once in five years to a safe location and wait 2 hours to presume a threat (although it might not happen at all) rather than suffer again as the tsunami of 1992.

It should be noted that the tsunami warning system will actually not only be used to monitor for the very rare case of a tsunami but the technical, communication and organization of varied types, and is also used for other phenomena such as earthquakes on land, volcanic eruptions, and seismic action. If the Central Seismic can work fast in order to issue a tsunami warning - it can also serve to inform the authorities and the population in Nicaragua and Central America on the epicenter, magnitude and potential impact in case of strong earthquakes on land..