What are Tsunamis?

Prior to the devastating tsunami that occurred on December 26, 2004, many had little concern about tsunamis, or the possibility of one occurring in North America. Tsunamis, also referred to as tidal waves, are a series of massive waves that are enormous in height and strength. The intensity in the wake of these destructive natural phenomena’s is indescribable. Footage of the damage caused by the Indian Ocean tsunami replayed for weeks after it made landfall. Once the final death toll was calculated (over 200,000 lives lost), many began to inquire about these killer waves. What caused tsunamis? What are some features of tsunamis? Are there signs for forthcoming tsunamis? Can killer waves be predicted?

Tsunamis are strings of powerful waves that generate in the ocean. These waves are the effect of a geological disturbance. Tsunamis have the ability to be hundreds of miles long, and can reach heights up to 35 feet. The speed behind these waves is out of the ordinary. Tsunamis vary. Some travel virtually undetected, whereas others ay cause much devastation and lost of life. Waves of this sort likely moved at speeds comparable to a commercial jet, which does not allow much time to search for shelter.

What Causes Tsunami Waves?

Tsunamis are caused by disturbances that occur in the ocean. There are four primary causes of these deadly waves.

Earthquake: Earthquakes are sudden movements on the Earth’s surface. Quakes may originate on land or in the oceans. The earth consists of huge plates that are in constant, slow motion. Plates tend to move more rapidly along fault lines, which are cracks in the earth’s surface. The rapid movement of plates results in an earthquake. Underwater earthquakes may produce a tsunami when intense pressure from moving plates pushes water above seal level. Tsunami length and speed depends on the severity of the earthquake. For example, the Indian Ocean earthquake registered 9.0 on the Richter scale, and caused a tsunami that traveled at speeds in excess of 300 mph.

Landslides: Landslides are caused by ground movements that generate falling rocks, falling slopes, and debris flow. Many factors contribute to landslides. Common culprits include earthquakes, storms, or gravity. When mountains are located near a body of water, falling slopes that hit the water with great force may cause a wave, or mini-tsunami. These mini-tsunamis travel through the water toppling everything in its path. Although tsunamis caused by landslides are not as powerful as ones caused by underwater earthquakes. These types of tsunamis may cause devastation and lives lost to nearby boats and swimmers.

Volcano: A volcano is a mountain that releases magma from the earth. Magma is liquid rock located within the interior of the earth’s crust. This liquid is extremely hot and melts anything that comes in contact with it. During a volcanic eruption, the pressure and energy behind an explosion may cause volcanic rocks hitting the water’s surface to produce a massive tsunami.

Meteorite: Although not entirely proven, many scientists conclude that some tsunamis may be caused by meteors or comets hitting the earth’s surface.

Features of Tsunami Waves

Tsunamis appear significantly different from a common wave. Those observing a tsunami will likely agree that these dangerous waves are more comparable to a fast moving tide crashing into land. Common waves are wind-driven, whereas tsunamis are powered by a geological force. The initial wave of a tsunami is extremely tall; however, most damage is not sustained by this wave. It’s the power behind the waves, the endless rushing water that causes devastation and lost of life.

Once a tsunami hits land, it may continue to travel for several miles inland. Small islands hit by a tsunami are left unrecognizable. Escaping a tsunami is nearly impossible. As the water rushes toward land, it leaves very little time to map an escape plan. When the December 2004 tsunami occurred, the shore was lined with vacationers. As the water quickly receded, and came rushing back to the shore, many tourist and locals were unable to seek shelter in nearby hotels and businesses. Many underestimate the power behind killer waves.

Tsunamis include series of waves. After the initial wave, several smaller waves will follow, crashing into the surface like a speeding vehicle. The period between waves varies. In some cases, four or five smaller waves may immediately follow the first wave. However, it is possible for smaller tsunamis to continue days after initial impact.

Signs of an Approaching Tsunami

• Earthquake
• Observing bubbles in the ocean, may appear as if the water is boiling
• Unusually warm water
• Ocean has a foul odor
• Ocean water may slightly burn skin
• Roaring noise coming from the ocean (may indicate tsunami miles away)
• Ocean may suddenly recede
• As tsunami approaches, the wave may appear red from a distance

Seeking shelter on high ground is the key to surviving a tsunami. Once a tsunami hits land, the water will begin to slowly level. However, fast moving water flooding the mainland will bring down anything in its path. Do not attempt to drive a car or run faster than a tsunami.

Predicting Tsunamis

Currently, there is not accurate method for detecting or preventing tsunamis. After an earthquake occurs, seismologist can usually detect changes in the ocean floor that may indicate an impending tsunami. The Pacific Tsunami Warning System and the West Coast and Alaska Warning System continually monitor seismic activity. These areas of the earth are closely monitored because they have increased seismic activity, thus the odds of a tsunami occurring are high. Nevertheless, this does not imply that the Eastern coast of North America is out of harms way. In fact, many geologist and seismologist predict an earthquake that will affect the eastern part of the country from South Carolina to New York. Moreover, landslides that could potentially occur from mountains located off the coast of Africa put eastern states at risk for a major tsunami.

Today, scientists employ several tools for detecting tsunamis early. Buoys and tide gauges are positioned in the open ocean and monitor wave and tide movement. Tide stations are intended to measure any changes in sea level. If sea level rises above a certain height, this may indicate an approaching tsunami. Moreover, seismograph stations are also located in the ocean to monitor any underwater earthquake that cannot be felt on land. If an underwater earthquake measures 7.0 or higher, a tsunami watch goes into effect.