Tsunamis

by John Carl Villanueva on September 19, 2009

Tsunamis, translated from Japanese to English as ‘harbor waves’, are giant waves caused by any major disturbance in a big body of water. Perhaps, for majority of the younger generations around the world, the most deadly natural disaster they’ve ever witnessed (firsthand, on the Web, or on TV) is the 2004 Indian Ocean Tsunami. That earthquake/tsunami combo claimed over 220,000 lives. The 2004 Indian Ocean Tsunami was caused by a 9.3-magnitude earthquake that lasted for about 10 minutes. Other causes are volcanic eruptions, underwater explosions, and landslides.

Tsunamis are hard to detect offshore because they may only initially rise up to about 30 cm. It is only when they approach land that they rapidly swell. The 2004 tsunami reached 30 meters high (that’s about 100 feet). This altitude is easily dwarfed by the biggest tsunami ever recorded: The Lituya Bay Tsunami.

Lituya Bay is found in Alaska. The tsunami that hit that area in 1958 climbed up to a height 524 meters. That’s nearly a hundred meters taller than the Empire State Building. Fortunately, its death toll was not proportionate to its size. This particular tsunami was directly caused by a landslide.

A number of the greatest earthquakes in recorded history resulted in tsunamis. The Great Chilean Earthquake of 1960, which also holds the record for the highest magnitude at 9.5, produced a series of gigantic waves that raced across the Pacific from Chile and finally slammed into the Philippines on the other side of the ocean.

The Great Alaska Earthquake of 1964 (magnitude = 9.2) also produced tsunamis that hit the coasts of Japan and Hawaii.

Extensive research, detection, and monitoring of tsunamis is being conducted by the USGS (US Geological Survey) and the NOAA’s Center for Tsunami Research. NOAA stands for National Oceanic and Atmospheric Administration.

Mainly because of the 2004 tsunami, deployment of detection devices have been accelerated. DART (Deep-Ocean Assessment and Reporting of Tsunamis) buoys have since been placed in strategic locations on the world’s oceans. Most of these buoys have been deployed along the Pacific Ring of Fire, where most earthquakes, and hence, tsunamis, occur.

Each buoy is attached to a bottom pressure recording (BPR) device, which monitors pressure changes below. Data from the BPR is sent to the buoy, then to a satellite. The satellite then sends the information to various NOAA facilities.

The presence of these monitoring systems can help reduce the damage (particularly to life) future tsunamis can make. Many of the deadly tsunamis had to travel great distances and take hours before slamming into shores and wreaking havoc. Once people manning the monitoring systems issue warnings, the public can be given ample time to evacuate to safer areas.

We have some articles in Universe Today that are related to tsunamis. Here’s an article about the biggest tsunami, and here are some famous earthquakes.

Tsunami articles brought to you by USGS. here are the links: