Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

2010 Chilean earthquake causes icequakes in Antarctica

11.08.2014

Technology allows scientists to hear seismic waves as they arrived on frozen continent

Seismic events aren't rare occurrences on Antarctica, where sections of the frozen desert can experience hundreds of micro-earthquakes an hour due to ice deformation. Some scientists call them icequakes. But in March of 2010, the ice sheets in Antarctica vibrated a bit more than usual because of something more than 3,000 miles away: the 8.8-magnitude Chilean earthquake.


High-frequency icequakes are shown at station HOWD in Antarctica during the distant waves of the 2010 magnitude 8.8 Chile earthquake. The triggered icequakes are indicated by the narrow vertical bands in the middle and lower sections of the graphic. They begin when the P wave arrives approximately 8 minutes (480 seconds) after the Chilean quake and continue through the arrival of the Rayleigh waves. The sound is generated by speeding up the HOWD's seismic data 100 times.

Credit: Georgia Tech

A new Georgia Institute of Technology study published in Nature Geoscience is the first to indicate that Antarctica's frozen ground is sensitive to seismic waves from distant earthquakes.

To study the quake's impact on Antarctica, the Georgia Tech team looked at seismic data from 42 stations in the six hours before and after the 3:34 a.m. event. The researchers used the same technology that allowed them to "hear" the seismic response at large distances for the devastating 2011 magnitude 9 Japan earthquake as it rumbled through the earth.

In other words, they simply removed the longer-period signals as the seismic waves spread from the distant epicenter to identify high-frequency signals from nearby sources. Nearly 30 percent (12 of the 42 stations) showed clear evidence of high-frequency seismic signals as the surface-wave arrived on Antarctica.

"We interpret these events as small icequakes, most of which were triggered during or immediately after the passing of long-period Rayleigh waves generated from the Chilean mainshock," said Zhigang Peng, an associate professor in the School of Earth and Atmospheric Sciences who led the study. "This is somewhat different from the micro-earthquakes and tremor caused by both Love and Rayleigh-type surface waves that traditionally occur in other tectonically active regions thousands of miles from large earthquakes.

Peng says the subtle difference is that micro-earthquakes respond to both shearing and volumetric deformation from distant events. The newly found icequakes respond only to volumetric deformation.

"Such differences may be subtle, but they tell us that the mechanism of these triggered icequakes and small earthquakes are different," Peng added. "One is more like cracking, while the other is like a shear slip event. It's similar to two hands passing each other."

Some of the icequakes were quick bursts and over in less than one second. Others were long duration, tremor-like signals up to 10 seconds. They occurred in various parts of the continent, including seismic stations along the coast and near the South Pole.

The researchers found the clearest indication of induced high-frequency signals at station HOWD near the northwest corner of the Ellsworth Mountains. Short bursts occurred when the P wave hit the station, then continued again when the Rayleigh wave arrived. The triggered icequakes had very similar high waveform patterns, which indicates repeated failure at a single location, possibly by the opening of cracks.

Peng says the source locations of the icequakes are difficult to determine because there isn't an extensive seismic network coverage in Antarctica.

"But at least some of the icequakes themselves create surface waves, so they are probably formed very close to the ice surface," he added. "While we cannot be certain, we suspect they simply reflect fracturing of ice in the near surface due to alternating volumetric compressions and expansions as the Rayleigh waves passed through Antarctica's frozen ice."

Antarctica was originally not on the research team's target list. While examining seismic stations in the Southern Hemisphere, Peng "accidently" found the triggered icequakes at a few openly available stations. He and former Georgia Tech postdoctoral student Jake Walter (now a research scientist at the Institute for Geophysics at UT Austin) then reached out to other seismologists (the paper's four co-authors) who were in charge of deploying more broadband seismometers in Antarctica.

###

This project is partially supported by a National Science Foundation CAREER grant (EAR-0956051). Any conclusions expressed are those of the principal investigator and may not necessarily represent the official views of the NSF.

Jason Maderer | Eurek Alert!
Further information:
http://www.gatech.edu

Further reports about: Antarctica Chilean earthquake earthquakes micro-earthquakes seismometers signals waves

More articles from Earth Sciences:

nachricht Scientists observe first signs of healing in the Antarctic ozone layer
01.07.2016 | University of Leeds

nachricht Climate study finds human fingerprint in Northern Hemisphere greening
30.06.2016 | DOE/Oak Ridge National Laboratory

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Mainz-based physicists find missing link between glass formation and crystallization

Densified regions with drastically reduced internal motion either act as crystal precursors or cluster and frustrate all further dynamics

Glasses are neither fluids nor crystals. They are amorphous solids and one of the big puzzles in condensed matter physics. For decades, the question of how...

Im Focus: Thousands on one chip: New Method to study Proteins

Since the completion of the human genome an important goal has been to elucidate the function of the now known proteins: a new molecular method enables the investigation of the function for thousands of proteins in parallel. Applying this new method, an international team of researchers with leading participation of the Technical University of Munich (TUM) was able to identify hundreds of previously unknown interactions among proteins.

The human genome and those of most common crops have been decoded for many years. Soon it will be possible to sequence your personal genome for less than 1000...

Im Focus: Optical lenses, hardly larger than a human hair

3D printing enables the smalles complex micro-objectives

3D printing revolutionized the manufacturing of complex shapes in the last few years. Using additive depositing of materials, where individual dots or lines...

Im Focus: Flexible OLED applications arrive

R2D2, a joint project to analyze and development high-TRL processes and technologies for manufacture of flexible organic light-emitting diodes (OLEDs) funded by the German Federal Ministry of Education and Research (BMBF) has been successfully completed.

In contrast to point light sources like LEDs made of inorganic semiconductor crystals, organic light-emitting diodes (OLEDs) are light-emitting surfaces. Their...

Im Focus: Unexpected flexibility found in odorant molecules

High resolution rotational spectroscopy reveals an unprecedented number of conformations of an odorant molecule – a new world record!

In a recent publication in the journal Physical Chemistry Chemical Physics, researchers from the Max Planck Institute for the Structure and Dynamics of Matter...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Quantum technologies to revolutionise 21st century - Nobel Laureates discuss at Lindau

30.06.2016 | Event News

International Conference ‘GEO BON’ Wants to Close Knowledge Gaps in Global Biodiversity

28.06.2016 | Event News

ERES 2016: The largest conference in the European real estate industry

09.06.2016 | Event News

 
Latest News

Mainz-based physicists find missing link between glass formation and crystallization

01.07.2016 | Physics and Astronomy

Scientists observe first signs of healing in the Antarctic ozone layer

01.07.2016 | Earth Sciences

MRI technique induces strong, enduring visual association

01.07.2016 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>