Featured Research

from universities, journals, and other organizations

Sea floor earthquake zones can act like a 'magnifying lens' strengthening tsunamis beyond what was through possible

Date:
March 7, 2013
Source:
University of Southern California
Summary:
Until now, it was largely believed that the maximum tsunami height onshore could not exceed the depth of the seafloor. But new research shows that when focusing occurs, that scaling relationship breaks down and flooding can be up to 50 percent deeper with waves that do not lose height as they get closer to shore.

The earthquake zones off of certain coasts -- like those of Japan and Java -- make them especially vulnerable to tsunamis, according to a new study. They can produce a focusing point that creates massive and devastating tsunamis that break the rules for how scientists used to think tsunamis work.
Credit: Zacarias da Mata / Fotolia

The earthquake zones off of certain coasts -- like those of Japan and Java -- make them especially vulnerable to tsunamis, according to a new study. They can produce a focusing point that creates massive and devastating tsunamis that break the rules for how scientists used to think tsunamis work.

Related Articles


Until now, it was largely believed that the maximum tsunami height onshore could not exceed the depth of the seafloor. But new research shows that when focusing occurs, that scaling relationship breaks down and flooding can be up to 50 percent deeper with waves that do not lose height as they get closer to shore.

"It is as if one used a giant magnifying lens to focus tsunami energy," said Utku Kanoglu, professor at the Middle East Technical University and senior author of the study. "Our results show that some shorelines with huge earthquake zones just offshore face a double whammy: not only they are exposed to the tsunamis, but under certain conditions, focusing amplifies these tsunamis far more than shoaling and produces devastating effects."

The team observed this effect both in Northern Japan, which was struck by the Tohoku tsunami of 2011, and in Central Java, which was struck by a tsunami in 2006.

"We are still trying to understand the implications," said Costas Synolakis, director of the Tsunami Research Center at the USC Viterbi School of Engineering and a co-author of the study. "But it is clear that our findings will make it easier to identify locales that are tsunami magnets, and thus help save lives in future events."

During an earthquake, sections of the sea floor lift up while others sink. This creates tsunamis that propagate trough-first in one direction and crest-first in the other. The researchers discovered that on the side of the earthquake zone where the wave propagates trough-first, there is a location where focusing occurs -- strengthening it before it hits the coastline with an unusual amount of energy that is not seen by the crest-first wave. Based on the shape, location, and size of the earthquake zone, that focal point can concentrate the tsunami's power right on to the coastline.

In addition, before this analysis, it was thought that tsunamis usually decrease in height continuously as they move away from where they are created and grow close to shore, just as wind waves do. The study's authors instead suggest that the crest of the tsunami remains fairly intact close to the source.

"While our study does not preclude that other factors may help tsunamis overgrow, we now know when to invoke exotic explanations for unusual devastation: only when the basic classic wave theory we use does not predict focusing, or if the focusing is not high enough to explain observations," said Vasily Titov, a researcher at NOAA's Pacific Marine Environmental Laboratory and study co-author.

Animation of a formation and focusing of a Tsunami: http://www.youtube.com/watch?v=BUS4dsBf8BI&feature=youtu.be


Story Source:

The above story is based on materials provided by University of Southern California. Note: Materials may be edited for content and length.


Journal Reference:

  1. U. Kanoglu, V. V. Titov, B. Aydin, C. Moore, T. S. Stefanakis, H. Zhou, M. Spillane, C. E. Synolakis. Focusing of long waves with finite crest over constant depth. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2013; 469 (2153): 20130015 DOI: 10.1098/rspa.2013.0015

Cite This Page:

University of Southern California. "Sea floor earthquake zones can act like a 'magnifying lens' strengthening tsunamis beyond what was through possible." ScienceDaily. ScienceDaily, 7 March 2013. <www.sciencedaily.com/releases/2013/03/130307124800.htm>.
University of Southern California. (2013, March 7). Sea floor earthquake zones can act like a 'magnifying lens' strengthening tsunamis beyond what was through possible. ScienceDaily. Retrieved March 30, 2015 from www.sciencedaily.com/releases/2013/03/130307124800.htm
University of Southern California. "Sea floor earthquake zones can act like a 'magnifying lens' strengthening tsunamis beyond what was through possible." ScienceDaily. www.sciencedaily.com/releases/2013/03/130307124800.htm (accessed March 30, 2015).

Share This


More From ScienceDaily



More Earth & Climate News

Monday, March 30, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Solar Impulse Departs Myanmar for China

Solar Impulse Departs Myanmar for China

AFP (Mar. 30, 2015) Solar Impulse 2 takes off from Myanmar&apos;s second biggest city of Mandalay and heads for China&apos;s Chongqing, the fifth flight of a landmark journey to circumnavigate the globe powered solely by the sun. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
The Future Of Japanese Whaling: Heritage Vs. Conservation

The Future Of Japanese Whaling: Heritage Vs. Conservation

Newsy (Mar. 30, 2015) In 2014, the International Court of Justice ruled Japan could no longer engage in whaling in the Antarctic, but Japan has plans to return this year. Video provided by Newsy
Powered by NewsLook.com
New Arthropod Fossil Might Be Relative Of Spiders, Scorpions

New Arthropod Fossil Might Be Relative Of Spiders, Scorpions

Newsy (Mar. 29, 2015) A 508-million-year-old arthropod that swam in the Cambrian seas is thought to share a common ancestor with spiders and scorpions. Video provided by Newsy
Powered by NewsLook.com
Vietnam Rice Boom Piles Pressure on Farmers and the Environment

Vietnam Rice Boom Piles Pressure on Farmers and the Environment

AFP (Mar. 29, 2015) Vietnam&apos;s drive to become the world&apos;s leading rice exporter is pushing farmers in the fertile Mekong Delta to the brink, say experts, with mounting costs to the environment. Duration: 02:35 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins