A sharp bend in the middle is the only blemish. The long-standing explanation for this distinctive feature was a change in direction of the Pacific oceanic plate in its migration over a stationary hotspot – an apparently unmoving volcano deep within the earth.
According to the results of an international research group, of which LMU Munich geophysicist Professor Hans-Peter Bunge was a member, however, the hotspot responsible for the Hawaii-Emperor seamount chain was not fixed. Rather it had been drifting quite distinctly southward. Nearly 50 million years ago, it finally came to rest while the Pacific plate steadily pushed on, the combination of which resulted in the prominent bend. The movements of hotspots are determined by circulations in the earth’s mantel.
“These processes are not of mere academic interest,” Bunge emphasizes. “Mantel circulation models help us understand the forces that act on tectonic plates. This in turn is essential for estimating the magnitude and evolution of stresses on the largest tectonic fault lines, that is the sources of many major earthquakes.”
The characteristic bend in the trail of the 5000 kilometer long Hawaii-Emperor seamount chain is one of the most striking topographical features of the earth, and is an identifying feature in representations of the Pacific Ocean floor. For a long time, textbooks have explained the creation of the Hawaii-Emperor chain as an 80 million year-long migration of the Pacific oceanic plate over a stationary hotspot. Hotspots are volcanoes rooted deep within the bowels of the earth, from which hot material is constantly pushing its way up to the surface. According to this now obsolete scenario, the bend would have come about as the Pacific plate abruptly changed direction.
In the past 30 years, geophysicists had also depended on the apparently unchanging locations of hotspots in the earth's mantel in their definition of a global reference for plate tectonics. More recent investigations, however, suggest that hotspots are less stationary than so far assumed. An international research group, of which Professor Hans-Peter Bunge of the LMU Munich Department of Earth and Environmental Sciences was a member, took a closer look at certain evidence pointing towards substantial inherent motion of the underground volcanoes, and has now confirmed this evidence.
“Paleomagnetic observations suggest that the bend in the Hawaii-Emperor chain is not the result of a change in the relative motion of the Pacific plate,” Bunge states. “On the contrary, it seems the hotspot had been drifting rapidly in a southward direction between 80 and 40 million years ago before it came to a complete halt.” If the trail of the Hawaiian hotspot is corrected to include this drift, the result implies a largely constant movement of the Pacific plate over the last 80 million years. The bend ultimately came about as the hotspot started to slow down.
The driving force behind the migration of the hotspot is the circulation of material under the surface of our planet. “The earth’s interior is in constant motion,” reports Bunge. “Over geological timescales, this motion compares to the weather patterns in our atmosphere. These patterns can easily lead to a change in position of hotspots. Numerical simulations of this global circulation in the earth’s mantel allow us to retrace these motions in unprecedented detail.”
The new data will now be entered into the mantel circulation models presently used. These calculations help explain the driving and resisting forces acting on tectonic plates. “And we need to understand these forces because they are essential for estimating the magnitude and evolution of stresses on the major tectonic fault lines – that is, the sources of many major earthquakes on our planet,” says Bunge. The findings to come from these models will allow scientists to improve their computer models by checking their calculations against observations. (hp/suwe)You will find more information about the calculations at:
Luise Dirscherl | EurekAlert!
Further reports about: > Bent tectonics > Earth's magnetic field > Earthquakes > Environmental Sciences > Hawaii-Emperor seamount chain > LMU > Mantel circulation models > Pacific Ocean > Pacific oceanic plate > Paleomagnetic observations > Science TV > computer model > environmental risk > international research > stationary hotspot > tectonic plate > tectonic plates > undersea volcanoes
Modeling magma to find copper
13.01.2017 | Université de Genève
What makes erionite carcinogenic?
13.01.2017 | Friedrich-Schiller-Universität Jena
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering