News / Science & Technology

Volcano 'Screams' Could Lead to Better Eruption Predictions

Redoubt Volcano’s active lava dome as it appeared on May 8, 2009. The volcano is in the Aleutian Range about 110 miles south-southwest of Anchorage, Alaska. (Chris Waythomas, Alaska Volcano Observatory)
Redoubt Volcano’s active lava dome as it appeared on May 8, 2009. The volcano is in the Aleutian Range about 110 miles south-southwest of Anchorage, Alaska. (Chris Waythomas, Alaska Volcano Observatory)

Related Articles

Man-Made Earthquakes on the Rise

In the US, there were more than 300 earthquakes above magnitude 3.0 from 2010 to 2012

London Exhibit Shows Moving Picture of Pompeii Life, Death

Over 450 objects provide glimpse of everyday life before Mount Vesuvius erupted in AD79, burying the two Italian cities in volcanic ash
VOA News
New research indicates volcanoes often make odd noises scientists call “screams” just before they erupt, a discovery that could lead to better predictions about when a volcano will blow its top.

The screams are harmonic tremors, and researchers at the University of Washington believe they are caused when magma is forced through a narrow conduit at greater and greater pressure into the heart of the volcano.

The magma sticks to the rock surface of the conduit until there is enough pressure to move it again. Each of the movements causes a small earthquake, magnitude 0.5 to 1.5, and as the pressure builds, the frequency of the earthquakes increases until they “blend into a continuous harmonic tremor.”

The observations were made during the March 2009 eruption of Alaska’s Redoubt Volcano when harmonic tremors climbed to higher and higher frequencies and then stopped abruptly just before six of the eruptions, five of them coming in succession.

“Because there’s less time between each earthquake, there’s not enough time to build up enough pressure for a bigger one,” said Alicia Hotovec-Ellis, a University of Washington doctoral student in Earth and space sciences. “After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes.”

The initial “noises” start at about one hertz and move up to 30 hertz just before pausing. Humans can hear sounds starting at about 20 hertz, and while scientists say someone lying on the ground directly above the magma conduit might be able to hear the higher frequency harmonic tremors, they don’t advise doing so as the last tremors can be closely followed by an explosion.

Upward-gliding tremors immediately before a volcanic explosion also have been documented at the Arenal Volcano in Costa Rica and Soufrière Hills volcano on the Caribbean island of Montserrat.

“Redoubt [volcano] is unique in that it is much clearer that that is what’s going on,” Hotovec-Ellis said. “I think the next step is understanding why the stresses are so high.”

You May Like

N. Korea Sentences American to 6 Years Hard Labor

Matthew Miller's brief trial Sunday comes two weeks after 24-year old Miller and two other American detainees appealed to the US government to help free them More

Pakistan Rejects Afghan Criticism of 480-kilometer Border Trench

Military spokesman tells VOA the project is part of administrative and security measures taken to secure the mountainous border with Afghanistan More

Photogallery Typhoon Kalmaegi Makes Landfall in Philippines

Storm makes landfall late Sunday, cutting power and communications lines and forcing people to flee to higher ground More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Scotland Independence Bid Stokes Global Interesti
X
Henry Ridgwell
September 12, 2014 8:35 PM
The people of Scotland are preparing to vote on whether to become independent and break away from the rest of Britain, in a referendum being watched carefully in many other countries. Some see it as a risky experiment; while others hope a successful vote for independence might energize their own separatist demands. Foreign immigrants to Scotland have a front row seat for the vote. VOA’s Henry Ridgwell spoke to some of them in Edinburgh.
Video

Video Scotland Independence Bid Stokes Global Interest

The people of Scotland are preparing to vote on whether to become independent and break away from the rest of Britain, in a referendum being watched carefully in many other countries. Some see it as a risky experiment; while others hope a successful vote for independence might energize their own separatist demands. Foreign immigrants to Scotland have a front row seat for the vote. VOA’s Henry Ridgwell spoke to some of them in Edinburgh.
Video

Video Washington DC Mural Artists Help Beautify City

Like many cities, Washington has a graffiti problem. Buildings and homes, especially in low-income neighborhoods, are often targets of illegal artwork. But as we hear from VOA’s Julie Taboh, officials in the nation's capital have come up with an innovative program that uses the talents of local artists to beautify the city.
Video

Video Palestinians Turn to Rebuilding Gaza

After almost two months of conflict in Gaza, Palestinians are preparing to rebuild the isolated Mediterranean enclave with assistance from abroad. Meanwhile, an international human rights group has found that Israel likely violated international laws of war during some of its attacks on Gaza. Zlatica Hoke has more.
Video

Video US Muslim Leaders Condemn Islamic State

Leaders of America's Muslim community are condemning the violent extremism of the Islamic State group in Iraq and Syria. The U.S. Muslim leaders say militants are exploiting their faith in a failed effort to justify violent extremism. VOA correspondent Meredith Buel reports.
Video

Video Middle Eastern Church Leaders Highlight Christians’ Plight

Patriarchs of Eastern Rite churches came to Washington this week to draw attention to the attacks against Christians in Syria, Iraq and elsewhere in the Middle East. VOA’s religion correspondent Jerome Socolovsky has more.
Video

Video Americans' Reaction Mixed on Obama Strategy for Islamic State Militants

President Barack Obama’s televised speech on how the United States plans to “degrade and destroy” the group known as the Islamic State reached a prime-time audience of millions. And it came as Americans appear more willing to embrace a bolder, tougher approach to foreign policy. VOA producer Katherine Gypson and reporter Jeff Seldin have this report from Washington.
Video

Video Authorities Allege LA Fashion Industry-Cartel Ties

U.S. officials say they have broken up crime rings that funneled tens of millions of dollars from Mexican drug cartels through fashion businesses in Los Angeles. Mike O'Sullivan reports that authorities announced nine arrests, as 1,000 law enforcement agents fanned out through the city on Wednesday.
Video

Video Bedouin Woman Runs Successful Business in Palestinian City

A Bedouin woman is breaking social taboos by running a successful vacation resort in the Palestinian town of Jericho. Bedouins are a sub-group of Arabs known for their semi-nomadic lifestyle. Zlatica Hoke says the resort in the West Bank's Jordan Valley is a model of success for women in the region.


Carnage and mayhem are part of daily life in northern Nigeria, the result of a terror campaign by the Islamist group Boko Haram. Fears are growing that Nigeria’s government may not know how to counter it, and may be making things worse. More

AppleAndroid