Tsunami Warning System

Warning System And General Info

What Is A Tsunami?

A tsunami is a series of waves traveling at speeds of over 800 km/h in the deep ocean where they go unnoticed. Once the waves reach the shallow waters of the coast, the energy of the huge water body manifest themselves as they crash with devastating force across the shore and penetrates inland, particularly low lying areas, causing mass devastation in terms of lives and property on its way.. Tsunamis are generated primarily by earthquakes occurring on the ocean floor. Underwater volcanic eruptions, landslides or a meteorite can also generate tsunamis.

What Type Of Earthquake Generates A Tsunami?

Tsunamis are typically generated by earthquakes that occur along subduction zones. A subduction zone is an area on the earth where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the earth at rates typically measured in centimetres per year.

Is Mauritius At Risk?

There are various factors that determines the level to which a landmass or coastal area will be affected by an approaching tsunami wave. They are the onshore topography immediate to the coast, the topography under the sea (bathymetry) offshore and the directivity of the maximum energy waves.

So far Mauritius has not experience any major amplification of tsunami waves, but they do reach our coasts. For example, very minor inundation was experienced from the Tsunami of December 26, 2004 while Rodrigues was more affected. So far we have no record of any significant tsunami that has affected coastal areas in Mauritius or Rodrigues. Nevertheless, there is still a possibility that Tsunamis generated from either the Sumatra or the Makran source affect the coasts of Mauritius or Rodrigues and this calls for preparedness in the event of a potentially destructive tsunami.

Tsunami Warning System in Mauritius

As at now occurrence of aTsunami cannot be predicted and paradoxically it can occur at any time during a year and at any time during a day. The Tsunami Warning System in Mauritius has taken into consideration the degree of risk as well as the time factor. In virtue of its geographical location, Mauritius and Rodrigues have a lead-time of 5-7 hours before tsunami waves are likely to reach their coasts from either the Sumatra or the Makran source. The warning system  consists of the following stages:

1. Tsunami Watch
   This bulletin implies that a strong earthquake, generally of the magnitude greater than or equal to 7.0 on the Richter Scale, has occurred in a region adjacent to the Indian Ocean and the likelihood of a tsunami being generated is evoked. The bulletin is issued as a means of providing an advance alert to areas that could be impacted by destructive tsunami waves.
   
   At this stage, the public, sea-goers and fishermen in particular will be advised not to venture out at sea or on the beach, boats to be secured ashore and vessels to proceed off lagoon.
    
2. Tsunami Warning
   This bulletin confirms that a destructive tsunami will affect Mauritius / Rodrigues within the next 5-7 hours. In case the incident point is closer to Mauritius / Rodrigues, the lead-time will be correspondingly lesser. Plan for the evacuation of vulnerable coastal areas will be implemented.
    
3. Termination
   This bulletin will be issued after information from the Police, Fisheries post, Environment Officials, observations from tide gauges at Port Louis and Port Mathurin and general sea state observation confirm that significant tsunami waves are no longer being noted