Geology

Can the Moon Cause Earthquakes?

Publication: National Geographic News   Date: May 23, 2005   View Article

Coast dwellers are accustomed to the daily rhythm of the tides, which are primarily lulled in and out by the gentle gravitational tug of the moon. Some scientists wonder whether the moon’s tugging may also influence earthquake activity.

“The same force that raises the ‘tides’ in the ocean also raises tides in the [Earth’s]crust,” said Geoff Chester, an astronomer and public affairs officer with the U.S. Naval Observatory in Washington, D.C.

Tsunami Proofing: Where to Put Walls, Why to Keep Trees

Publication: National Geographic News   Date: April 28, 2005   View Article

The images from the Indian Ocean tsunami that left nearly 300,000 dead or missing last December are striking. Amateur video shot in Phuket, Thailand, for example, shows huge ocean waves ripping across beachfront swimming pools and crashing through hotel lobbies.

“All of those videos were shot from the upper floors of hotels; [the buildings] survived,” said Gerard Fryer, a geophysicist and tsunami expert at the University of Hawai’i at Manoa in Honolulu.

Tsunami Region Ripe for Another Big Quake, Study Says

Publication: National Geographic News   Date: March 16, 2005   View Article

The earthquake that triggered the December 26 tsunami has increased stress on nearby faults, making another major South Asian quake more likely, scientists reported today.

The magnitude 9 earthquake was centered off the west coast of Sumatra, an Indonesian island. The quake shifted nearly 97,000 square miles (250,000 square kilometers) of terrain along the Sunda trench subduction zone, where the Indonesian and Australian tectonic plates dive beneath the Burma tectonic plate.

Mystery Undersea Extinction Cycle Discovered

Publication: National Geographic News   Date: March 9, 2005   View Article

Robert Rohde and Richard Muller are vexed. For the past 542 million years the number of animal species living in the world’s oceans has risen and fallen in a repeating pattern, and the scientists haven’t the foggiest idea why.

“I wish I knew what it all meant,” said Muller, who is a professor of physics at the University of California, Berkeley.

Tsunami-Battered Sumatra Ripe for More Disasters

Publication: National Geographic News   Date: January 7, 2005   View Article

The force of the magnitude 9 earthquake that struck northern Sumatra on December 26, 2004, may have caught much of the world by surprise. But scientists say the region has a violent geologic past and is ripe for more cataclysmic earthquakes and volcanic eruptions in the millennia to come.

The Indonesian island sits in an area of the Indian Ocean where several large chunks of Earth’s crust, known as tectonic plates, collide. Tectonic plates can slip past, beneath, and over the top of each other. In the Sumatra region, the Indian and Australian plates are slowly creeping alongside and—in a process called subduction—diving beneath, the Burma plate, part of the larger Eurasian plate.

Volcanoes May Have Sparked Life on Earth, Study Says

Publication: National Geographic News   Date: October 7, 2004   View Article

Before life evolved on Earth, most scientists believe that amino acids—molecules that are the basic building blocks of life—were first formed via interactions on Earth or brought to it via collisions with comets and meteorites.

“But how did [the amino acids] form peptides [which are necessary for living cells]? What is the condensing agent?” said Reza Ghadiri, a molecular chemist at the Scripps Research Institute in La Jolla, California. “That is a major problem.”

Why Does Earth’s Magnetic Field Flip?

Publication: National Geographic News   Date: September 27, 2004   View Article

Earth’s magnetic field has flipped many times over the last billion years, according to the geologic record. But only in the past decade have scientists developed and evolved a computer model to demonstrate how these reversals occur.

“We can see reversals in the rocks, but they don’t tell us how it happens,” said Gary Glatzmaier, an earth scientist and magnetic field expert at the University of California, Santa Cruz.

© 2008-2010 Collected Writings By John Roach