Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Micro-earthquakes preceding a 4.2 earthquake near Istanbul as early warning signs?

01.11.2018

One of the high-risk geological structures lies near Istanbul, a megacity of 15 million people. The North Anatolian fault, separating the Eurasian and Anatolian tectonic plates, is a 1.200 kilometer-long fault zone running between eastern Turkey and the northern Aegean Sea. Since the beginning of the 20th century its seismic activity has caused more than 20.000 deaths. A large (Mw > 7) earthquake is overdue in the Marmara section of the fault, just south of Istanbul.

In a new study, led by Peter Malin and Marco Bohnhoff of the GFZ German Research Center for Geosciences, the authors report on the observation of foreshocks that, if analyzed accordingly and in real-time, may possibly increase the early-warning time before a large earthquake from just a few seconds up to several hours.


Istanbul and the Prince Islands in the background, on which the borehole observatory GONAF is located.

(photo: M.Bohnhoff, GFZ)

However, the authors caution: „The results are so far based on only one - yet encouraging - field example for an ,earthquake preparation sequence' typically known from repeated rock-deformation laboratory experiments under controlled conditions", says Marco Bohnhoff.

The study from Peter Malin and Marco Bohnhoff, together with colleagues from the AFAD Disaster and Emergency Management Presidency in Turkey, uses waveform data from the recently implemented GONAF borehole seismic network. GONAF operates at low-magnitude detection. It allowed identifying a series of micro-earthquakes prior to an earthquake of magnitude 4.2 which occurred in June 2016 south of Istanbul and which was the largest event in the region in several years.

In the latest issue of Scientific Reports, seismic data from the GONAF network, set up by GFZ in collaboration with AFAD along the Marmara Sea near Istanbul, is processed and analyzed with novel processing techniques. The high resolution borehole seismic array allowed for the detection of tens of seismic events prior to the mainshock. These small events would have been below the detection threshold of most seismic networks worldwide.

By means of the new processing technique, clustering and similarity of the seismic signals was shown to substantially increase in the hours prior to the Mw 4.2 earthquake. If this so-called emergent failure process would be a persistent feature of seismicity there, implementing real-time processing of the novel technique could extend the warning time for future earthquakes in the Istanbul region and lead to a major improvement in the early-warning system for the densely populated area of the Turkish megacity.

"Our study shows a substantial increase in self-similarity of the micro-quakes during the hours before the mainshock," says Professor Bohnhoff of the GFZ; "while the current early-warning system in place in Istanbul relies on the arrival times of seismic waves emitted from the hypocentre to the city and is therefore restricted to a couple of seconds at maximum".

While similar precursory activity has been detected for recent large earthquakes in Japan (2011 Mw9 Tohoku-Oki) and Chile (2014 Mw8.1 Iquique), this is at present by no means a ubiquitous observation and needs further testing before its implementation.

###

Original study: Malin, E.P., Bohnhoff, M., Blümle, F., Dresen, G., Martínez-Garzón, P., Nurlu, M., Ceken, U., Kadirioglu, F.T., Kartal, R.F., Kilic, T., Yanik, K., 2018. Microearthquakes preceding a M4.2 Earthquake Offshore Istanbul. Nature Scientific Reports. DOI: 10.1038/s41598-018-34563-9

Figures:

BU_de: Istanbul und im Hintergrund die Prinzeninseln, auf denen sich das Bohrlochobservatorium GONAF befindet (Foto: M. Bohnhoff, GFZ).

BU_en: Istanbul and the Prince Islands in the background, on which the borehole observatory GONAF is located (photo: M. Bohnhoff, GFZ).

Link: https://media.gfz-potsdam.de/gfz/wv/pm/18/10809_Istanbul_M-Bohnhoff-GFZ.jpg

BU_de:

Darstellung der Nordanatolischen Verwerfungszone (CCBY 3.0: Bohnhoff et.al., Scientific Drilling, 5, 1-10, 2017, doi:10.5194/sd-5-1-2017)

BU_en:

Illustration of the North Anatolian fault zone (CCBY 3.0: Bohnhoff et.al., Scientific Drilling, 5, 1-10, 2017, doi:10.5194/sd-5-1-2017).

Link: https://media.gfz-potsdam.de/gfz/wv/pm/18/10810_ScientificDrilling-GONAF_Bohnhoff-et-al.jpg

Media Contact

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

 @GFZ_Potsdam

http://www.gfz-potsdam.de 

Josef Zens | EurekAlert!
Further information:
http://dx.doi.org/10.1038/s41598-018-34563-9

More articles from Earth Sciences:

nachricht Turbulence creates ice in clouds
08.11.2019 | Leibniz-Institut für Troposphärenforschung e. V.

nachricht Manganese nodules: project on environmental impact during deep sea mining
08.11.2019 | Jacobs University Bremen gGmbH

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

Im Focus: A new quantum data classification protocol brings us nearer to a future 'quantum internet'

The algorithm represents a first step in the automated learning of quantum information networks

Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...

Im Focus: Distorted Atoms

In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.

An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...

Im Focus: A Memory Effect at Single-Atom Level

An international research group has observed new quantum properties on an artificial giant atom and has now published its results in the high-ranking journal Nature Physics. The quantum system under investigation apparently has a memory - a new finding that could be used to build a quantum computer.

The research group, consisting of German, Swedish and Indian scientists, has investigated an artificial quantum system and found new properties.

Im Focus: Shedding new light on the charging of lithium-ion batteries

Exposing cathodes to light decreases charge time by a factor of two in lithium-ion batteries.

Researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory have reported a new mechanism to speed up the charging of lithium-ion...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

Smart lasers open up new applications and are the “tool of choice” in digitalization

30.10.2019 | Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

 
Latest News

Magnets for the second dimension

12.11.2019 | Machine Engineering

New efficiency world record for organic solar modules

12.11.2019 | Power and Electrical Engineering

Non-volatile control of magnetic anisotropy through change of electric polarization

12.11.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>