By: Gisell Munoz
What is a tsunami? What happens in a tsunami?
A tsunami is a geohazard where there are a series of ocean waves that will send surges of water, and they look like actual walls of water. Tsunamis can reach heights over 100 feet, and when they crash, they can cause a lot of destruction to nearby places.
What causes a tsunami?
A tsunami is caused by undersea earthquakes. When a tectonic plate boundary rises or falls, it will displace the water that is above it and cause the waves that form a tsunami. Tsunamis can also be caused by underwater landslides or volcanoes that erupt. Many people think that the moon can cause tsunamis, but in reality, the moon pulls gravity on the earth, and just influences the daily tidal cycle. Other than that, the moon has nothing to do with tsunamis.
Why are tsunamis dangerous to humans?
Tsunamis can be very dangerous to humans for a number of reasons. To begin with, tsunamis are very difficult to predict, since they have a small wave height off shore, and a long wavelength. Another thing that makes tsunamis a hazard for us humans is their size and speed. When the waves are reaching shallow water, they will grow in their height and the speed. Tsunamis can cause massive deaths and injuries to people, as well as destroy environments around such as buildings, and flood large areas of land.
What regions are most vulnerable?
About 80% of tsunamis happen in the pacific ocean. Or another way to call it in the "Ring of Fire." In the Ring of Fire, many volcanoes and earthquakes are common. Countries that can be mostly affected are Russia, Japan, North & South Korea, China, Thailand, Indonesia, India, Turkey, Greece, Morocco, Mexico, Columbia, Ecuador, Peru, and Chile. Another region that can be affected by tsunamis is the west coast of the United States.
How is a tsunami measured?
Since the waves of a tsunami are undetectable to the human eye, there are many instruments that can detect tsunamis.
- Tide Gauges- Tide gauges measure tide levels. Tide gauges have an acoustic sensor that is connected to a vertical tube open at the lower end that is in the water. The sensor will give off a sound pulse that will travel from the top of the tube to the water surface back to the tube. This device has the capacity to measure sea-level changes within 1 mm accuracy.
- There are satellites that can measure the height of the ocean surface by using electro-magnetic pulses. The height of the surface will be determined by knowing what the speed of the pulse is, what the location of the satellite is, and measuring how much time it takes the pulse to return back to the satellite.
- GNSS stations- These receivers that are located all over the planet will record movement in the Earth's crust. They record movements by triangulated signals with a constellation of satellites. This has a tsunami scale from 1 to 10. A tsunami that measures 5 or more, is a basin-wide warning.
Japan Tsunami 2011:
One of the most recent and harmful tsunamis was the one that happened in Japan in 2011. It started on March 11th, 2011, when a magnitude- 9 earthquake hit northeastern Japan, which caused the tsunami. The tsunami started less than an hour after the earthquake hit. The tsunami waves reached up to 128 ft in height, and traveled onto land about 6 miles. There were about 15,891 deaths caused by this tsunami. One very serious thing that happened was that this tsunami caused a nuclear meltdown. The tsunami caused the cooling system at the Fukushima Daiichi Nuclear Power Plant to stop working, and this released many radioactive materials. Now, there is radioactive water, and even still, some of this water is still leaking.
2004 Indian Ocean Tsunami
December 26th of 2004, one of the biggest earthquakes ever struck off the western coast of northern Sumatra and caused a tsunami that caused many deaths. The earthquake had a magnitude of 9.1. It is said that the energy released of the tsunami was equal to 23,300 Hiroshima atomic bombs. 14 countries were affected by this disaster. India. Indonesia, Malaysia, the Maldives, Myanmar, Somalia, Sri Lanka, Thailand, Bangladesh, South Africa, Madagascar, Kenya, Tanzania, and the Seychelles were the countries that were affected by this earthquake and tsunami. Around five million people were affected, there were 500,000 people that were injured, and over 230,000 people died.
How can humans prepare or protect themselves for this type of event?
Signs that there is a tsunami:
- If there is a strong earthquake that lasts 20 seconds or more near the coast.
- If there is a noticeable rapid rise or fall in coastal waters
How to protect yourself:
- Move to high ground, or away from water asap
- Do not go to the beach to watch a tsunami !!!
- If you evacuated from your home, do not go home until officials say it's safe to do so
- Avoid disaster areas