A tsunami (soo-NAH-mee) is an ocean wave or series of waves caused by a sudden disturbance of the ocean floor that displaces a large amount of water. Tsunamis are caused generally by earthquakes, less commonly by submarine landslides, infrequently by submarine volcanic eruptions and very rarely by large meteorite impacts in the ocean.
The word tsunami is taken from two Japanese words which mean harbour (tsu) wave (nami). Tsunamis are quite common in Japan.
No, all earthquakes do not cause tsunamis. There are four conditions necessary for an earthquake to cause a tsunami:
Although relatively infrequent, violent volcanic eruptions can displace a great volume of water and generate extremely destructive tsunami waves in the immediate source area. According to this mechanism, waves may be generated by the sudden displacement of water caused by a volcanic explosion, by a volcano’s slope failure, or more likely by a phreatomagmatic explosion and collapse/engulfment of the volcanic magmatic chambers. One of the largest and most destructive tsunamis ever recorded was generated in August 26, 1883 after the explosion and collapse of the volcano of Krakatoa (Krakatau), in Indonesia. This explosion generated waves that reached 135 feet, destroyed coastal towns and villages along the Sunda Strait in both the islands of Java and Sumatra, killing 36, 417 people. It is also believed that the destruction of the Minoan civilization in Greece was caused in 1490 B.C. by the explosion/collapse of the volcano of Santorin in the Aegean Sea. (Courtesy: UNESCO IOC – International Tsunami Information Center)
No. Strictly speaking, a tidal wave is related to ocean tides while a tsunami is triggered by earthquakes, landslides or volcanic events.
Click here for more information on how tsunamis differ from normal ocean waves.
Yes, all oceanic regions of the world can experience tsunamis, but in the Pacific Ocean large, destructive tsunamis occur much more frequently because of the many large earthquakes occurring in the margins of the Pacific Ocean.
The magnitude 9.0 earthquake which occurred on 26th December, 2004 off the west coast of northern Sumatra, was the fourth largest earthquake in the world since 1900. The tsunami triggered by that earthquake killed over 250,000 people in at least eleven countries. While it is possible for a similar tsunami to occur in the Caribbean, scientists currently believe that there is a very small chance of this happening. As far as we know, the largest tsunami to affect the Caribbean in the past 500 years was 8m in height.
Kick ‘em Jenny is a submarine (underwater) volcano located 9 km north of Grenada. Currently, scientists believe that there is a very small chance that an eruption of the volcano would trigger a tsunami. Measurements of the volcano were taken in 2003 and the results showed that the summit (highest point) of the volcano is quite deep below the surface of the sea, too deep for an eruption of the kind normally seen to trigger a tsunami.
The Cumbre Vieja Volcano is on the Island of La Palma in the Canary Islands (off the west coast of Africa). The institution in charge of the monitoring (INVOLCAN) does not recognise the volcano-edifice stability as a potential tsunami risk. Pyroclastic density currents that can cause tsunamis are unlikely to occur at these volcanoes. Even though they can occur, evidence shows that tsunamis produced, as a result of instability of the volcano-edifice, are generally localised. Trans-oceanic tsunami generated by eruptions are unlikely and as such the statement above cannot be considered true.