THE DEVASTATING EARTHQUAKE

ON THE IRAN–IRAQ BORDER

E.A. Rogozhin1, A.L. Sobisevich1, L.E. Sobisevich1, K.Kh. Kanonidi2 

1 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

2 Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation,

Russian Academy of Sciences, Moscow; Troitsk, Russia

Abstract. The process of preparation and development of a catastrophic seismic event that significantly changed the natural environment in the western part of Zagros and affected the earth's crust and upper mantle is analyzed. The macroseismic effect, focal mechanism of the hearth, aftershock sequence, seismotectonic position of the source and other parameters characterizing the features of the zone of this disastrous earthquake that occurred in the border region of Iran–Iraq on November 12, 2017 are described. The magnitude of it was about M = 7.4. In one town (Iraq, Darbandikhan) was recorded macroseismic effect, meets a nine influences on a Modified scale, Mercalli. An area of about 150⋅100 km2 – 7–8 points effects, the intensity 5–6 points covered an extensive area – about 800⋅700 km2, and 4–5 point impact was observed all over Western Iran and Eastern Iraq and appeared in such major cities as Tehran, Baghdad, Kirkuk, Ahmad, Pasht. In the period from 12.11.2017 to 21.01.2018 the 50 aftershocks with mb = 4.2–5.6 magnitude were registered in the epicenter zone of the earthquake according to the Geophysical Survey of RAS data. Their epicentral area stretched out in meridional direction along the border, mostly to the South from the epicenter of the main shock. Its length has reached about 210 km and width is about 60 km. Position of the epicentral field of the aftershocks makes it possible to relate the earthquake 12.11.2017 of fault zone Khanaqin of the meridional strike and dextral strike-slip kinematics. It crosses in the diagonal direction the mountain-folded belt of Zagros near the state border of Iran and Iraq. Given the size of the earthquake, established on the distribution of epicenters of the aftershocks, it covered the fault zone Khanaqin of almost its entire length. Special attention is paid to the identified prognostic effects. The data of observations of seismic observatories hardware complexes reflecting the processes of earthquake preparation and development are given. Before the earthquake on November 12, 2017, information and measuring systems of the North Caucasus geophysical observatory of Schmidt Institute of Physics of the Earth of RAS recorded gravitomagnetic disturbances of ultra-low frequency range. These characteristic prognostic effects appeared a few hours before the main shock. The data of the seismic observatories, reflecting the processes of preparation and development of earthquakes analyzed. In the light of the collected data it becomes clear that the experimental study of a separate class of fundamental problems of gravitomagnetism highlighted by the authors in recent years is becoming the defining problem of geophysics. The gravitomagnetic disturbances in the lithosphere and other geospheres of the Earth recorded at large distances from the focal area can be considered as a short-term harbinger of the time of the main high-magnitude shock. For using of these effects in order to real forecast of the expected magnitude, location and time of the upcoming earthquake, apparently, it is necessary to develop a network of observatory observations, reflecting the stage of formation of the focal structures, and quickly complexing of these forward-looking effects with a the medium-to short-term precursors of a different nature.

Keywords: Zagros, Iran, Iraq, earthquake, focal mechanism solution, seismotectonics, deformation, fold, fault, aftershocks, gravitomagnetic disturbances.

About the authors

ROGOZHIN Evgeny A. – Ph. D. (geol.-min.), professor, head of department, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. Moscow, Russia. Tel.: +7 (499) 254-87-15. E-mail: eurog@ifz.ru

SOBISEVICH Alexey L. – corr. member of RAS, deputy director, head of laboratory, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. Moscow, Russia.

Tel.: +7 (499) 254-90-80. E-mail: alex@ifz.ru

SOBISEVICH Leonid E. – Ph. D. (tech.), professor, principal researcher, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences. Moscow, Russia. Tel.: +7 (499) 254-87-52.

E-mail: sobis@ifz.ru

KANONIDI Konstantin Kh. – leading researcher, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences. Moscow; Troitsk, Russia. Tel.: +7 (495) 334-01-09. E-mail: kanoidi@triniti.ru