Collapsed homes, destroyed port amenities and 1000’s of victims — on 22 May 1766, an earthquake of roughly 7.5 magnitude items and a subsequent water surge triggered a disaster in Istanbul. The origin of the quake was situated alongside the North Anatolian Fault within the Sea of Marmara. It was the last main earthquake to hit the metropolis on the Bosporus.
Researchers of the GEOMAR Helmholtz Centre for Ocean Research Kiel (Germany), along with colleagues from France and Turkey, have now been capable of display for the first time with direct measurements on the seafloor that considerable tectonic pressure has constructed up once more on the North Anatolian fault beneath the Sea of Marmara.
The North Anatolian fault zone marks the boundary between the Eurasian and Anatolian plates. “Strong earthquakes happen when the fault zone turns into locked. Then tectonic pressure accumulates, and the seismic vitality is launched in an earthquake,” explains Dr. Lange.
Tectonic pressure construct-up alongside fault zones on land has been repeatedly monitored for years utilizing GPS or land surveying strategies. This isn’t doable in seabed fault zones as a result of the low penetration depth of the GPS satellite indicators underneath the water. Nonetheless, the part of the North Anatolian fault that poses the definite menace to the Istanbul metropolitan area is positioned underwater within the Marmara Sea.
To date, it has solely been potential to extrapolate, for instance utilizing land observations, whether or not the plate boundaries there are transferring or locked. Nevertheless, the strategies couldn’t distinguish between a creeping motion and the entire locking of the tectonic plates. The brand new GeoSEA system developed at GEOMAR measuring acoustic distances on the seabed now allows scientists for the first time to straight measure crustal deformation with mm-precision. Over an interval of two and a half years, a complete of ten measuring devices have been put in at a water depth of 800 meters on each side of the fault. Throughout this time, they carried out more than 650,000 distance measurements.