Seismometers under the Marmara Sea to help pinpoint fault activity
By Summit Voice
SUMMIT COUNTY — German and Turkish scientists are trying to get a better handle on seismic activity in Earthquake-prone Turkey, where the 13 million residents of Istanbul are at risk for a major quake, perhaps as strong as 7.4 on the Richter Scale.
The new seismic monitoring network on the Marmara Sea near Istanbul won’t be able to predict a specific quake, but should help scientists better understand what’s happing with the faults in the region.
“An earthquake prediction is not the goal of the project ,”said GFZ researcher Professor Marco Bohnhoff, director of the project. “Earthquake prediction is still not possible. But the data gathered in our project of the seismic activity before, during and after the expected strong quake will mean a great advance in the study of earthquakes.”
The team this week started drilling to place seismic sensors in eight boreholes on the outskirts of Istanbul and around the eastern Marmara Sea, where they will gather more precise data than has been available to date.
The seismometers will be permanently install at various depths and will be able to detect barely perceptible earthquakes of a very small magnitudes at a high resolution — thus providing information on the earthquake rupture processes associated causing the quakes.
The project is being set up under the auspices of the GFZ German Research Centre for Geosciences.
“Istanbul, with more than 13 million inhabitants, is located in a region that is extremely vulnerable to earthquakes. A high probability of a strong earthquake of magnitude up to 7.4 is assumed for the region,”said GFZ Professor Georg Dresen. “The data of small earthquakes in the region that are measured in the borehole can provide important information about the processes before a major earthquake.”
The monitoring is particularly challenging because the earthquake zon lies under the seabed of the Marmara Sea, about 20 kilometers off the coast of Istanbul. Placing the seismometers in the deep boreholes reduces the noise level and helps ensure precise measurements.
“This means we have to get as close as possible to the quake source region,” Bohnhoff said. “With our new, specially developed borehole seismometers, the ratio of signal-to-background noise can be improved by at least a factor of 10, and therefore achieve a much higher resolution.”
The project involves close cooperation with the Disaster and Emergency Management Presidency of Turkey (AFAD). The drilling is implemented as part of the International Continental Scientific Drilling Program ICDP. Engineers and scientists at the GFZ supervise the construction and installation activities.
Upon successful completion and handover of the fully equipped pilot bore hole on the peninsula Tuzla just off Istanbul a first test phase will commence before the remaining seven wells will be drilled.