In the year of the 150th anniversary of the discovery of Franz Josef Land by the expedition of Karl Weyprecht and Julius Payer, scientists will assess the seismic hazard of the island of Alexandra Land and conduct research to obtain the climatic characteristics of the northernmost archipelago of our country. The first stage of the complex expedition of the Russian Geographical Society to the Franz Josef Land archipelago started from Severomorsk on May 15.
On August 30, 1873, the sailing-steam schooner Admiral Tegetthoff, jammed with ice, washed up on the shore of an unfamiliar land. Members of the expedition led by Karl Weyprecht and Julius Payer named it after the Austro-Hungarian Emperor Franz Joseph I.
In the year of the 150th anniversary of the geographical discovery, a complex expedition of the Russian Geographical Society set off to this remote archipelago, hidden in the ice of the Arctic Ocean. The first stage of research will take place on the island of Alexandra Land. The expedition includes specialists from the Russian Geographical Society and the Russian Arctic National Park, scientists representing the most advanced branches of science, employees of the Institute of Physics of the Earth named after A.I. O. Yu. Schmidt Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation N. V. Pushkov (IZMIRAN) and the Arctic and Antarctic Research Institute (AARI).
— The main work will be aimed at studying the seismicity of the Arctic, – says the scientific leader of the expedition, senior researcher at the IPE RAS, Candidate of Physical and Mathematical Sciences Ruslan Zhostkov. — It is believed that this is an aseismic region where earthquakes do not occur, but the results of our research in the framework of earlier expeditions of the Russian Geographical Society and the Northern Fleet show that earthquakes with an intensity of up to 9 points have occurred in the past in the Arctic. Therefore, one of our tasks will be to search for traces of ancient earthquakes, those that took place in the era of pre-instrumental observations and were not documented.
Scientists will analyze the relief using geomorphological analysis and geophysical methods of deep research: microseismic sounding and georadar survey. In particular, ground penetrating radar research will make it possible to determine near-surface geological disturbances – if some seismic event occurred in the past, then the geological layers will be broken or deformed. Also, according to the results of measurements, one can judge the near-surface structure of the region under study.
According to IZMIRAN researcher Igor Prokopovich, the use of low-frequency antennas with a length of 3 m will allow using GPR to survey the upper part of the geological section to a depth of several tens of meters for low-resistance deposits in permafrost conditions. With the gradual movement of the receiving and transmitting equipment of the georadar along the surface of the earth, scientists will build a radargram, which is also called a georadar profile.
— The radar method also makes it possible to fairly accurately estimate the depth of geological layers or local objects.c, – explains Igor Prokopovich. — Such data should help in mapping faults, determining their age, which will be used together with other results of the expedition to assess the tectonic activity of the region.
During the expedition, an ice survey will be carried out on fast ice – this is ice that is close to the coast and stands motionless. According to Anna Timofeeva, a researcher at the AARI Ice Regime and Forecasts Department, sea ice thickness is an important characteristic, and its fluctuations are a sensitive indicator of climate change. Currently, scientists estimate the thickness mainly using satellite remote sensing and numerical modeling. But any remote measurements require verification – comparison with the values obtained by the contact method.
— Other measurements of various ice characteristics will be made, including temperature and salinity profiles.– adds Anna Timofeeva. — It is also planned to take ice cores to take samples to measure the amount of chlorophyll.
Scientists will conduct fundamental research on the propagation of geoacoustic waves in the system: seabed – sea – ice cover, using the technology developed at the IPE RAS. This will make it possible to remotely determine the thickness and strength of ice, which is necessary for researching the ice situation in the Arctic and navigation.
“If our technology is scaled to lower frequencies, by placing sensors on the ice, it is possible not only to study the structure of the ice cover, but also to probe the seabed to search for minerals, — says Ruslan Zhostkov. — For the first time in the Arctic, we applied this technology in 2021 to identify deep fault zones. At that time, polar bears prevented the operation of several sensors, but even such powerful predators could not cause any damage to domestic devices developed jointly by the IPE RAS, MIPT and the Gidropribor concern. Therefore, this year we are going to complete the work we have begun, as well as conduct a new high-frequency experiment with a seismic streamer. If earlier we were interested in the structure of the bottom and we worked at low frequencies, now we will study the structure of ice using frequencies above 5 Hz.
Specialists will also conduct more detailed studies using additional methods, including using a seismic microarray (a highly sensitive antenna assembled from several seismic sensors).
