The first stage of the expedition of the Russian Geographical Society to Franz Josef Land has ended. The main purpose the expedition was to continue the research started during the expedition of the Russian Geographical Society and the Northern Fleet in 2021. In search of traces of ancient earthquakes, the scientists expanded the picture of the seismotectonic situation of the island, measured the thickness of fast ice, and also recorded earthquakes on Svalbard and on the island of Vanuatu in the Pacific Ocean. We will tell about this and other details of the expedition in our article.
The expedition to the island of Alexandra Land was attended by the specialists from the Russian Geographical Society and Russian Arctic National Park, employees at the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS), the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), and the Arctic and Antarctic Research Institute (AARI).
2img_7990.jpg
The start was scheduled for May 15 from Severomorsk, but due to weather conditions, the flight was postponed for a day. By the evening of May 16, an AN-26 military transport plane delivered the scientists to Nagurskoye Airfield on the island of Alexandra Land, from where the researchers reached the “Omega” base of the Russian Arctic National Park, where they were going to live and work.
“There are almost no roads in the usual sense on the island, it is a tunnel dug in the snow,” says the lead scientist of the expedition, senior researcher at the IPE RAS, Candidate of Physical and Mathematical Sciences Ruslan Zhostkov. “The jeep we drove to the base was an off-road truck for Moscow roads, but by local standards it was a weak car that could only drive where a bulldozer had cleared something like a road.”
The base of Russian Arctic National Park, which sheltered the expedition participants, is located almost on the shore of Severnaya Bay and resembles a solid two-storey country cottage. The first floor windows are protected by bars in case a polar bear tries to get inside. However, during the expedition, the researchers didn’t see any of them, which they were very happy about, since meeting with such a dangerous beast immediately stops all field work.
3img_7991.jpg
“ ‘Omega’, a research station, which was opened back in the Soviet Union, is a unique place – the northernmost station, where you can conduct research at any level and in almost all fields,” said the head of the expedition Sergey Chechulin. “And we want to return to it the high level of importance for academic science that it had in Soviet times. So that it would be a year-round operating base where scientists could conduct long-term research in various research fields.”
Alexandra Land met the expedition with beautiful weather by Arctic standards – sunny and windless. The temperature did not drop below -15 °C.
“Usually the Arctic is associated with snow, ice, and icebergs, but I have seen different Arctic, including flowers and butterflies,” Ruslan Zhostkov shares. “I associate the Arctic with difficulties. Otto Yulievich Schmidt said that real people were drawn to places where it was difficult. The Arctic is difficult to get to, the transportation is difficult, little infrastructure is developed, it is very difficult to work there.”
4img_7994.jpg
And the difficulties were not long in coming – the snowmobiles did not start. The lack of transport made serious adjustments, but did not stop the work of the scientists. On the same evening, as the polar day was in full swing on Alexandra Land, the researchers, divided into two groups, went to install seismic equipment and conduct research.
The employees from the national park made every effort not to disrupt the work of the scientists, and lent them a tracked vehicle. The next day, the builders lent them a Trecol, an all-terrain vehicle with low-pressure wheels, that can move through the snow without falling through and leaving virtually no traces. But for safety reasons, neither the tracked vehicle nor the Trecol could go out on the ice, to move across which a snowmobile was needed.
6img_7996.jpg
“We conducted an ice survey, although from the very beginning nothing went according to plan,” says Anna Timofeeva, a researcher at the Department of Ice Regime and Forecasts of AARI. “As a result, the first time we were taken by car on the road to the location closest to the shore, from where, carrying heavy equipment in backpacks and in our hands, we walked about half a kilometer on stones and sinking in the snow, and then the same amount directly along the fast ice. With the second ice survey, in another place, we were a little more lucky, because, at least, they took us to the shore on the Trecol, but then we walked half a kilometer on the ice ourselves. In total, we went out on ice twice, each time conducting profile measurements. These two profiles were conveniently located around the place used as an ice berth for unloading ships.”
The length of the first profile was about 100 m, the second – 120 m, ice was drilled every 10 m, thickness and other standard morphometric characteristics of ice were measured. The average thickness of the ice in the first profile was 90 cm, in the second – 100 cm.
Knowing where, what, and at what time of the year the thickness of the ice is is important for navigation. Such monitoring should be conducted regularly, but for these places it was conducted for the first time.
7img_7989.jpg
“In 2021, the research team worked here in 10 areas,” Sergey Chechulin notes. “After studying the reports, we realized that the most promising in this region is research in the field of seismology and oceanology. This is important because Alexandra Land is the only island in the archipelago where people are actively working, and we need to understand what is happening here, how earthquake-prone this zone is.”
According to Ruslan Zhostkov, this year the seismologists focused their efforts on the instrumental study of the sea ice cover, which required short-period instruments that register short elastic waves. Knowing from the experience of the last expedition that polar bears can destroy the equipment, special strong boxes were made to protect fragile and expensive devices for recording geoacoustic signals.
Sensors were installed in several more places on land, since anomalies were detected in the data of 2021 and they needed to be clarified.
For the high-frequency experiment, the scientists deployed a seismic streamer on the ice – 24 geophones (sensors measuring high-frequency vibrations), placed every 5 m and connected to a monitor. The devices were installed in recesses in the snow with snow sprinkled on top of them to avoid wind-related interference.
8img_7993.jpg
“We used the seismic streamer to determine the main characteristics of the ice,” explains Ruslan Zhostkov. “The IPE RAS has been developing methods of seismic monitoring in the conditions of ice-covered sea for a long time, using non-invasive (non-destructive) control. The RGS’s expedition became an opportunity to conduct a number of experiments to test them. By installing seismic sensors on the ice, we will be able to judge its thickness and other parameters. In particular, the characteristics of geoacoustic waves propagating through the ice determine its thickness and elastic parameters. This method is convenient to use, for example, to control the condition of winter roads.”
The members of the expedition also placed seismic stations on the island to register earthquakes occurring on the planet. If a meter layer of dense snow held a person, then the tracked vehicles, on which the researchers moved, periodically fell through and got stuck, creating additional problems and slowing down the work. To install the devices, the scientists had to break through a layer of snow with the help of a fishing ice drill. A seismic station, broadband or three-component high-frequency for a microgroup, was placed on permafrost. A microgroup is several stations located at a great distance from each other. Having placed them, the geophysicists got an antenna capable of detecting even a weak earthquake. After making sure that the equipment was working, it was covered with snow to provide thermal insulation and protect it from the wind, since otherwise the fluctuations of the device under the influence of wind, and not the earth's surface, would be recorded.
According to the scientists, in Arctic conditions, temporary seismic stations are more convenient to install either at the end of winter, when there is a lot of snow, or at the end of summer, when the top layer of permafrost (about 50 cm) thaws and it can be excavated to install a sensor. If you put the equipment in the off-season, then it is very difficult to break through the ground frozen like concrete and it will not be possible to hide it from the wind.
To determine the deep geological structure, the researchers conducted microseismic sounding using seismic stations, and to create an orthophoto and identify terrain features – aerial photography at Cape Dvoynoy in the west of Severnaya Bay.
9img_7988.jpg
After analyzing satellite images of the island, they identified several faults through which they carried out measurements using ground-penetrating radar (GPR) to detect disturbances in the upper geological layers. A ground-penetrating radar is two antennas in the form of three-meter conductive webs. Ground-penetrating radar measurements are convenient to carry out in frosty weather due to the greater depth of penetration of radio waves into a frozen environment; besides it is more convenient to work on snow. The geophysicists promptly covered four profiles (profile – passage back and forth about 250 m). The recording process looks like this: one person pulls the antennas from the front, the second goes with the registration unit connected to the receiving antenna and captures, step by step, the signals reflected from the geological layers when moving the ground-penetrating radar.
“The first analysis of GPR profiles taken in the areas of supposed tectonic faults revealed signs of ruptures in the structure of geological deposits, which is a sign of seismic activity,” notes IZMIRAN researcher Igor Prokopovich. “These results will be further systematized and processed within the framework of the large IZMIRAN project on deep GPR, supported by a grant from the Russian Science Foundation.”
174a9553ushanov_zfi_.jpg
It also turned out that at the location of the ice survey, the ice was as if submerged in water. According to Anna Timofeeva, an interesting effect was observed: outwardly it was not visible that the ice was immersed in water, but as soon as the hole was drilled, water poured out of it almost like from a fountain. This phenomenon can occur when a significant amount of snow falls.
“Under the influence of tidal currents, cracks can form in the fast ice, through which sea water flows out onto the ice and freezes, forming layers,” explains Anna Timofeeva. “Actually, a crack near the shore was just observed. In principle, this effect and the fact that the fast ice has a peculiar layering were confirmed when measuring the vertical salinity profile of the ice core. In total, three ice cores were selected, their temperature profiles (immediately after extraction) and salinity (after melting) were measured. To do this, the cores were sawed into pieces of 10 cm, picked up from the ice, melted in a warm room.”
To obtain samples for chlorophyll, the water obtained from the core was filtered using a special technique using a manual compressor and a portable filtration unit, as well as water taken from the same well into a separate sample. After that, the samples were frozen. In frozen form, they were delivered to St. Petersburg, where they will be analyzed in laboratory conditions.
“Measurements using a microgroup, microseismic sounding, GPR, and aerial photography are necessary for making a long-term seismic forecast,” Ruslan Zhostkov emphasizes. “Exploring the seismotectonics of the island of Alexandra Land, we are looking for traces of ancient earthquakes in order to understand whether they occurred in the past or not, and if they did happen, what they were like and approximately when they may happen again in the future. In the Arctic, no one has solved such problems with instrumental methods before us. We cannot definitively say that there will be an earthquake here or there in a certain amount of years, we raise questions. We are saying that things are complicated here in the Arctic. There are signs that seismic events took place here, which means that they cannot be ignored. It is necessary to equip new expeditions and conduct more detailed research. We are creating a fundamental basis, a basis for further research.”
0m8a5097.jpg
During their work on the island, the scientists have installed four broadband stations for microseismic sounding, seven high-frequency three-component seismic stations, 24 geophones (as part of a seismic streamer), covered five profiles of GPR survey and two profiles of ice survey.
During this period, the seismic stations recorded an earthquake on Svalbard with a magnitude of 4.74 and on the island of Vanuatu in the Pacific Ocean with a magnitude of 7.69. There were no seismic events on Alexandra Land during the expedition, but this means that the researchers simply did not get there at right time and the right hour – in principle, an earthquake can happen at any moment.
“Our research team thanks the RGS for the opportunity to conduct scientific research in such a remote area of the Arctic and personally the head of the expedition Sergey Chechulin,” Ruslan Zhostkov added.
Marina Kruglyakova