Around the world, earthquakes like the one in China are associated with triggered aftershocks that are very large. In 1999, a 7.1 earthquake in Duzce, Turkey, followed a 7.4 magnitude earthquake in Izmit, Turkey. In 2004, an 8.7 magnitude earthquake struck three months after the Sumatra Andaman earthquake of magnitude 9.2. While analysis of the Turkish earthquakes was not timely enough to shed light on the second earthquake there, the researchers believe that information on the Sumatra Andaman earthquake did illuminate the situation.
For the May 12 earthquake, the researchers performed analysis of co-seismic stress transfer onto Sichuan basin faults using broad ranges because at this time, exact values for all the various factors are unknown. The researchers report in today's (July 6) advanced online edition of Nature that "this approach enables rapid mapping of faults with heightened rupture likelihood."
"We knew that the fault was there and we knew it was active," says Eric Kirby, associate professor of geosciences at Penn State. "I had done some previous work in the area, but I do not think anyone would have anticipated the size of this earthquake."
The May earthquake in Sichuan Provence was 7.9 in magnitude and collapsed buildings, destroyed villages and killed thousands of people. The earthquake occurred in the area where the Sichuan basin and the Longmen Mountains meet. This is on the eastern edge of the Tibetan Plateau in an area deformed by the collision of the Indian and Asian tectonic plates. The area is crisscrossed with fault lines.
The researchers, who include Tom Parsons, research geophysicist, U.S. Geological Survey, Chen Ji, assistant professor of Earth sciences, University of California-Santa Barbara, and Kirby, used a model to see how the Sichuan earthquake, which took place on the Beichuan fault, affected other portions of that fault and others in the area. They looked at physical characteristics of the faults including the directions and amounts of movement of the faults – whether and how much they moved up and down and side to side, and the estimates of the frictional resistance to motion along the fault.
"The Sichuan earthquake seemed to rupture on the northern portion of the Beichuan fault," says Kirby. "It does not seem to have involved the southwestern branch."
According to the model, after the May 12 earthquake, stress increased on faults running parallel to the Wenchuan-Maowen fault and the two major faults that are perpendicular and to the north of the fault. Some smaller faults south of the earthquake zone show a decrease in stress. However, according to the model, the majority of the faults in the area are still stressed.
"The occurrence of triggered earthquakes after a major earthquake can be months, years or decades," says Kirby. "Sumatra seems to be a really nice example. Also, the historic record in Turkey shows a series of earthquakes that progress from east to west over 60 years."
The data used in the model consists of ranges rather than actual measurements because of the difficulty of obtaining information from that area of China at the moment. The models always use a range of friction because the movement of the faults changes the friction sometimes in unknown or unexpected ways.
"The model takes what we think we know about the faults in the region and asks what was the change to stress associated with the earthquake," says Kirby. "The model shows where an increase in the potential for failure may occur, but we do not know the trigger point for these faults. The analysis does not say there is going to be an earthquake, just that the potential exists on some of the faults."
Andrea Elyse Messer | EurekAlert!
Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft
How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology