Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Earthquake series cause uplift variations at continental margins

18.10.2016

A new mechanism may explain how great earthquakes with magnitudes larger than M7 are linked to coastal uplift in many regions worldwide. This has important implications for the seismic hazard and the tsunami risk along the shores of many countries. The mechanism is proposed by an international team of scientists led by Vasiliki Mouslopoulou of the GFZ German Research Centre for Geosciences in the journal Tectonics. The idea is that series of severe earthquakes within a geologically short period of time cause the rising of the land where one tectonic plate slips beneath another slab of the Earth's crust in a process called subduction.

To test their hypothesis, the scientists investigated ancient coastlines that were preserved over time, so-called paleoshorelines, to determine the rate of uplift over past millennia. Vasiliki Mouslopoulou says: "It is not unlikely that coastlines along active subduction margins with no detectable tectonic uplift over the last 10,000 years will accommodate bigger than M7 earthquakes in the near future."


Flight of marine terraces on the south coastline of Crete, Greece, eastern Mediterranean. The lower prominent paleoshoreline (indicated by the red-line) records tectonic rock uplift during the 365 AD M>8 earthquake. The higher marine terraces (indicated by the yellow-lines) record cumulative uplift over many earthquake-cycles that occurred during the last 125,000 years.

Credit: Vasiliki Mouslopoulou, GFZ

Uplift is common along the coastlines of continents at subduction systems worldwide (e.g., Kamchatka, Japan, New Zealand and Papua New Guinea) with rates of vertical uplift accrued over the last 10,000 years being generally higher - up to ten times more than for time intervals larger than 125,000 years.

This rate variability is odd and requires explanation. The origins and the magnitude of these rate variations were examined by German (GFZ) and New Zealand (University of Canterbury) scientists using a global data set of 282 uplifted paleoshorelines from eight subduction margins globally (Italy, Greece, New Zealand, Japan, Papua New Guinea, Iran-Pakistan, Chile) and 2D numerical models.

Paleoshorelines are a useful tool to constrain the magnitude and mechanisms of this uplift, as they are often spectacularly preserved as wave-cut platforms, benches and sea-notches, providing a geological record of the interplay between sea-level changes and rock uplift.

Data analysis and modelling suggest that varying uplift rates along subduction margins are mainly a short-term phenomenon. For geologists, short term means shorter than 20,000 years. These uplift rates cannot be accounted for by plate-boundary processes, as previously thought. Instead, they reflect a propensity for natural temporal variations in uplift rates where recent (not more than 10,000 years ago) uplift has been greatest due to temporal clustering of large-magnitude (bigger than M7) earthquakes on upper-plate faults.

Given the size and geographical extent of the analyzed dataset the conclusions of this work are likely to have wide applications.

Asked what's new with these findings Vasiliki Mouslopoulou explains: "For the first time temporal clustering of great-earthquakes is shown on active subduction margins, indicating an intense period of strain release due to successive earthquakes, followed by long periods of seismic quiescence." This finding has applications to the seismic hazard of these regions, as it highlights the potential for future damaging earthquakes and tsunamis at active subduction margins with no measurable recent uplift. In such cases, paleoshorelines older than 10,000 years could provide an important constraint for hazard analysis. In other words: To assess the likelihood of future great quakes it will help to look at paleoshorelines.

Further, it alerts scientists that earthquake clustering may not only characterise shallow faulting and smaller-sized earthquakes with magnitudes lower than M7 but it is a property of large subduction earthquakes.

This work presents a conceptual model in which strain is released by temporally clustered great-earthquakes that rupture faults within the upper-plate as opposed to the zone where the tectonic plates meet (plate-interface). Onno Oncken of GFZ comments: "This is an intriguing finding that changes the stereotype view that all or most great subduction earthquakes occur along the active contact, i.e. plate-interface, of the two converging plates. We hope that this new finding will promote the mapping and discovery of such faults along active subduction margins and will also help explain the variability in the recurrence of great-earthquakes encountered on many subductions globally."

###

Mouslopoulou, V., Oncken, O., Hainzl, S., Nicol, A., 2016. Uplift rate transients at subduction margins due to earthquake clustering. Tectonics, doi:10.1002/2016TC004248

Media Contact

Josef Zens
josef.zens@gfz-potsdam.de
49-331-288-1040

 @GFZ_Potsdam

http://www.gfz-potsdam.de 

Josef Zens | EurekAlert!

Further reports about: GFZ Zealand earthquake sea-level changes seismic hazard tectonic uplift

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>