Israel Tsunami Alert System

Israel Tsunami Alert System

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11047259_sIn December 2004 the greatest and hardest Tsunami in history hit the countries along Indian Ocean sea shores and brought about the death of about 250,000 persons.

After the disaster, it was observed that there is a need for a Tsunami warning system not only in the Indian Ocean and the Pacific Ocean where such a system already exists, but also in the Caribbean Sea, the area of North East Atlantic Ocean, and the Mediterranean (where the second largest amount of Tsunami events has been recorded). An international committee was formed for the establishment of the Tsunami warning systems in the mentioned seas, with the participation of Israel, headed by Dov Rosen of the Institute for Maritime and Lakes Research and Amos Salmon of the Geological Institute. Since November 2011 also Tatiana Meirova of the Geophysical Institute has joined the Israeli delegation.

It was decided that all the warnings will be given in the context of all-Mediterranean events, i.e. events arising from earthquakes or volcanic eruptions at the sea only. There will be no warning on local events (such as tsunami resulting from landslide following a ground based earthquake).

Since not each strong earthquake causes a tsunami, the warning system includes a seismic monitoring system and a system for monitoring and verification of tsunami waves by follow up of changes in the sea surface by means of water level monitoring stations. Dov Rosenne serves as coordinator of the Mediterranean and Black Sea water level monitoring program, MedGLOSS..

Tsunami waves can be created due to a number of reasons, including strong earthquakes with vertical displacement of the sea bottom, massive landslides at the sea, and even strong land earthquakes. In last thousands of years there were about 20 Tsunami events in the Mediterranean, and some waves even hit the shores of Israel.

Seafloor earthquakes with vertical movement
Seafloor earthquakes with vertical movement

According to a decision of the Ministry of Energy and Water in November 2008, the Seismologic Branch of the Geophysical Institute was appointed as the focal point of Tsunami warning (TWTP) that will receive and handle all messages of a Tsunami event or on the probability of a Tsunami event, and will distribute them to the national alarm systems (The National Emergency Authority (“Rachel”) and the Home Front Command). It will also serve as the national center for Tsunami warnings (NTWC) and will act around the clock during all year days, by means of the Situation Room for coping with earthquake events that was established at the Prime Minister Office. Dr. Tatiana Meirova was appointed a Head of the Israeli National Tsunami Warning Center.

A

The Tsunami warning system that will be established will be based on two main layers for detection and verification of Tsunami wave creation. The first one is the seismic element monitoring earthquakes the intensity of which is 5 or 6 in magnitude, a threshold above which there is a chance of local/regional Tsunami wave creation (depending on the location and direction of the trembling). The second layer is the execution of verification that Tsunami waves were created indeed. This verification is executed by means of level meters or pressure meters located at the sea bottom, or by means of special Radar.

B

Upon identification of an earthquake that has the potential of creating a Tsunami, pre-prepared scenarios of verifying Tsunami potential and the beaches to be affected will be examined. This information will be passed on to the recipients of Tsunami observations in each country via the corresponding national point of contact persons.

Israel's tsunami event Decision table
Israel’s tsunami event Decision table

Running of computerized scenarios of Tsunami events showed that a Tsunami event in the Hellenic Bow (Greece) area with a magnitude of 8.2 will cause a flooding at the Israeli shores with waves of 15 meters above sea level. In case of landslide after an earthquake in the Dead Sea area can cause flooding of the sea shores to the height of 6 meters above normal sea level.

The warning time that can be obtained by the radar tsunami monitoring system is 3-10 minutes. This will be an automatic warning since it is based on processed and verified information. The Situation Room at the Prime Minister Office and the Recording Room at the Geophysical Institute will receive the information from the radar stations.

C

Dr. Avi Shapira, head of the inter-office committee for preparation for earthquake events in Israel is responsible for warning announcement to the media and the public. According to Shapira, the main concern is from a strong earthquake in Israel that will cause the collapse of the land shelf. In this case the time till waves hit the shores is about a quarter of an hour, which means that there is no much time for discussions and in depth analyses. Therefore, if a strong earthquake occurs with clear criteria, an automatic warning will be passed on automatically to the population. Ultimately, if there is no tsunami “nothing happened”. According to Shapira, the most severe scenario is an earthquake on Saturday in August – when crowds of Israelis are spending at the beaches.



By Tomer Simon, MPH
Disaster and emergency preparedness expert
The Israeli website for disaster and emergency preparedness