The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is the first geologic study of the underwater subduction zone faults that give rise to the massive earthquakes known to seismologists as mega-thrust earthquakes.
"The fundamental goal is to sample and monitor this major earthquake-generating zone in order to understand the basic mechanics of faulting, the basic physics and friction," says Harold Tobin, University of Wisconsin-Madison geologist and co-chief scientist of the project.
Tobin will present results from the first stage of the project Sunday, Feb. 15, at the 2009 American Association for the Advancement of Science meeting in Chicago.
Subduction zone faults extend miles below the seafloor and the active earthquake-producing regions — the seismogenic zones — are buried deep in the Earth's crust. The NanTroSEIZE project, an international collaboration overseen by the Integrated Ocean Drilling Program, is using cutting-edge deep-water drilling technology to reach these fault zones for the first time.
"If we want to understand the physics of how the faults really work, we have to go to those faults in the ocean," Tobin explains. "Scientific drilling is the main way we know anything at all about the geology of the two-thirds of the Earth that is submerged."
The decade-long project, to be completed in four stages, will use boreholes, rock samples, and long-term in situ monitoring of a fault in the Nankai Trough, an earthquake zone off the coast of Japan with a history of powerful temblors, to understand the basic fault properties that lead to earthquakes and tsunamis. The project is currently is its second year.
Subduction zone faults angle upward as one of the giant tectonic plates comprising Earth's surface slides below another. Tremendous friction between the plates builds until the system faults and the accumulated energy drives the upper plate forward, creating powerful seismic waves that make the crust shake and can produce a tsunami. But although both shallow and deep parts of the fault slip, only the deep regions produce earthquakes.
During the first stage of the project, the team found evidence of extensive rock deformation and a highly concentrated slip zone even in shallow regions that do not generate earthquakes. One rock core from a shallow part of the fault contains a narrow band of finely ground "rock flour" revealing a fault zone between the upper and lower plates that is only about two millimeters thick — roughly the thickness of a quarter.
Above deeper portions of the fault, the team discovered layers of displaced rock and evidence of prolonged seismic activity that suggest a region known as the megasplay fault is likely responsible for the largest tsunami-generating plate slips.
"A fundamental goal was to understand how the faults at depth connect up toward the Earth's surface, and we feel that we've discovered the fault zone that's the main culprit," Tobin says.
The next stage of drilling will commence this May, with plans to drill additional boreholes into the plate above deep regions of the fault zone. In addition to collecting cores for comparison to those from shallower parts of the fault, the scientists will install sensors in these holes to set up a deep-sea observatory monitoring physical stresses, movement, temperature and pressure.
Harold Tobin | EurekAlert!
Further reports about: > Deep-sea drilling > Deep-sea observatory > Earthquake > NanTroSEIZE > active earthquake zones > cutting-edge deep-water drilling technology > earthquake-generating zone > geophysical fault > major earthquake fault > mega-thrust earthquakes > monitoring physical stresses > movement > tectonic plate > temperature > tsunami-generating plate slips > tsunamis > underwater subduction zone faults > world's largest earthquakes
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering