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 Northern oceans pumped CO2 into the atmosphere
27.03.2017 | CAGE - Center for Arctic Gas Hydrate, Climate and Environment

nachricht Weather extremes: Humans likely influence giant airstreams
27.03.2017 | Potsdam-Institut für Klimafolgenforschung

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>