(Press-News.org) Contact information: F.Ossing
ossing@gfz-potsdam.de
49-331-288-1040
GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre
What drives aftershocks?
High-resolution GPS signals provide new insights into the mechanisms of stress transfer in subduction zones
On 27 February 2010 an earthquake of magnitude 8.8 struck South-Central Chile near the town of Maule. The main shock displaced the subduction interface by up to 16 meters. Like usually after strong earthquakes a series of aftershocks occurred in the region with decreasing size over the next months. A surprising result came from an afterslip study: Up to 2 meters additional slip occurred along the plate interface within 420 days only, in a pulse like fashion and without associated seismicity. An international research group lead by GFZ analysed the main shock as well as the following postseismic phase with a dense network of instruments including more than 60 high-resolution GPS stations (Earth and Planetary Science Letters ,Dec. 01, 2013).
The aftershocks and the now found "silent" afterslip are key to understand the processes occurring after strong earthquakes. The GPS data in combination with seismological data allowed for the first time a comparative analysis: Are after-shocks triggered solely by stress transfer from the main shock or are additional mechanisms active? „Our results suggest, that the classic view of the stress re-laxation due to aftershocks are too simple" says Jonathan Bedford from GFZ to the new observation: „Areas with large stress transfer do not correlate with af-tershocks in all magnitude classes as hitherto assumed and stress shadows show surprisingly high seismic activity."
A conclusion is that local processes which are not detectable at the surface by GPS monitoring along the plate interface have a significant effect on the local stress field. Pressurized fluids in the crust and mantle could be the agent here. As suspected previously, the main and aftershocks might have generated perme-abilities in the source region which are explored by hydrous fluids. This effects the local stress field triggering aftershocks rather independently from the large scale, main shock induced stress transfer. The present study provides evidences for such a mechanism. Volume (3D) seismic tomography which is sensitive to fluid pressure changes in combination with GPS monitoring will allow to better monitor the evolution of such processes.
The main shock was due to a rupture of the interface between the Nasca and the South American plates. Aftershocks are associated with hazards as they can be of similar size as the main shock and, in contrast to the latter, much shallower in the crust.
###
Jonathan Bedford et al.: "A high-resolution, time-variable afterslip model for the 2010 Maule Mw=8.8, Chile megathrust earthquake", Earth and Planetary Science Letters 383 (2013), pp. 26, 01. December 2013
DOI: http://dx.doi.org/10.1016/j.epsl.2013.09.020
Pictures in a rintable resolution can be found here:
http://www.gfz-potsdam.de/medien-kommunikation/bildarchiv/erdbeben-in-chile/
What drives aftershocks?
High-resolution GPS signals provide new insights into the mechanisms of stress transfer in subduction zones
2013-12-02
ELSE PRESS RELEASES FROM THIS DATE:
Marine reserves enhance resilience to climate change
2013-12-02
Marine reserves enhance resilience to climate change
A new study, led by a University of Southampton scientist, highlights the potential for fish communities in marine reserves to resist climate change impacts better than communities on fished coasts.
The ...
Oregon researchers shed new light on solar water-splitting process
2013-12-02
Oregon researchers shed new light on solar water-splitting process
Fundamental discovery could speed development of efficient semiconductor-catalytic junctions
EUGENE, Ore. -- With the help of a new method called "dual-electrode photoelectrochemistry," University of Oregon ...
Koalas' low-pitched voice explained by unique organ
2013-12-02
Koalas' low-pitched voice explained by unique organ
VIDEO:
This video shows the velar fold vibration at 10-45 Hz.
Click here for more information.
...
Microplastics make marine worms sick
2013-12-02
Microplastics make marine worms sick
Tiny bits of plastic trash could spell big trouble for marine life, starting with the worms, say a team of researchers from Plymouth University and the University of Exeter who report their evidence in a pair of studies in the Cell Press ...
JCI early table of contents for Dec. 2, 2013
2013-12-02
JCI early table of contents for Dec. 2, 2013
Predicting outcome for high-dose IL-2 therapy in cancer patients
One of the most potent forms of immunotherapy for patients with metastatic melanoma and renal cell carcinoma is high-dose (HD) bolus IL-2 therapy. ...
Predicting outcome for high-dose IL-2 therapy in cancer patients
2013-12-02
Predicting outcome for high-dose IL-2 therapy in cancer patients
One of the most potent forms of immunotherapy for patients with metastatic melanoma and renal cell carcinoma is high-dose (HD) bolus IL-2 therapy. Approximately 15% of patients respond to ...
Blocking antioxidants in cancer cells reduces tumor growth in mice
2013-12-02
Blocking antioxidants in cancer cells reduces tumor growth in mice
Many cancers have adapted to cope with high levels of immune system-produced free radicals, also referred to as reactive oxygen species, by overproducing antioxidant proteins. One of these ...
Silent RNAs express themselves in ALS disease
2013-12-02
Silent RNAs express themselves in ALS disease
RNA molecules, used by cells to make proteins, are generally thought to be "silent" when stowed in cytoplasmic granules. But a protein mutated in some ALS patients forms granules that permit translation of ...
First Nations adults have more than double the risk of end-stage kidney disease
2013-12-02
First Nations adults have more than double the risk of end-stage kidney disease
First Nations adults with diabetes have more than double the risk of end-stage kidney disease compared with non–First Nations adults, found a new study in CMAJ (Canadian ...
Johns Hopkins researchers show how a modified pacemaker strengthens failing hearts
2013-12-02
Johns Hopkins researchers show how a modified pacemaker strengthens failing hearts
Findings advance opportunities for a 'pacemaker in a bottle'
Johns Hopkins heart researchers are unraveling the mystery of how a modified pacemaker used to treat many patients ...
LAST 30 PRESS RELEASES:
Heat and heavy metals are changing the way that bees buzz
What’s behind the enormous increase in early-onset gastrointestinal cancers?
Pharmacogenomics expert advances precision medicine for bipolar disorder
Brazilian researcher explores centenarian stem cells for aging insights
Dr. Xuyu Qian's breakthrough analysis of 18 million brain cells advances understanding of human brain development
Gene networks decode human brain architecture from health to glioma
How artificial light at night damages brain health and metabolism
For ultrasound, ultra-strength not always a good thing
Matching your workouts to your personality could make exercising more enjoyable and give you better results
Study shows people perceive biodiversity
Personality type can predict which forms of exercise people enjoy
People can accurately judge biodiversity through sight and sound
People diagnosed with dementia are living longer, global study shows
When domesticated rabbits go feral, new morphologies emerge
Rain events could cause major failure of Waikīkī storm drainage by 2050
Breakthrough in upconversion luminescence research: Uncovering the energy back transfer mechanism
Hidden role of 'cell protector' opens cancer treatment possibilities
How plants build the microbiome they need to survive in a tough environment
Depression due to politics and its quiet danger to democracy addressed in new book 'The Sad Citizen'
International experts and patients unite to help ensure all patients are fully informed before consenting to new surgical procedures
Melting glaciers could trigger more explosive eruptions globally, finds research
Nearly half of U.S. grandchildren live within 10 miles of a grandparent
Study demonstrates low-cost method to remove CO₂ from air using cold temperatures, common materials
Masonic Medical Research Institute (MMRI) welcomes 13 students to prestigious Summer Fellowship program
Mass timber could elevate hospital construction
A nuanced model of soil moisture illuminates plant behavior and climate patterns
$2.6 million NIH grant backs search for genetic cure in deadly heart disease
Pennsylvania’s medical cannabis program changed drastically when anxiety was added as a qualifying condition
1 in 5 overweight adults could be reclassified with obesity according to new framework
Findings of study on how illegally manufactured fentanyl enters U.S. contradict common assumptions, undermining efforts to control supply
[Press-News.org] What drives aftershocks?High-resolution GPS signals provide new insights into the mechanisms of stress transfer in subduction zones