Thermal state of the lithosphere beneath The Laptev Sea: Geodinamic implications from geomagnetic data

The Laptev Sea is a unique region, representing a transition zone from the spreading Gakkel Ridge to the rift system, located on the continental margin of Eurasia. In this study, we construct high-resolution distributions of the depths to the top and bottom of the lithospheric magnetic layer (LML) for the Laptev Sea and adjacent areas using the centroid method and the EMAG2v3 model of the lithospheric magnetic field. Maximum bottom depths of the LML (45–48 km) are observed under the Siberian Platform, in the north of the Verkhoyansk Range, and under the Lena River delta and Buor-Khaya Bay, while the shallowest bottom depths (<34 km) are attributed to the Eurasia Basin and eastern Laptev Sea. Our results indicate that the coldest lithosphere is attributed to the Siberian Platform. The lithospheric heating is observed under the Eurasia Basin and eastern Laptev Sea; the western part of the shelf, Buor-Khaya Bay, and Lena River delta are characterized by the colder lithosphere. The eastern segment of the Khatanga-Lomonosov Fracture is characterized by a local temperature minimum. An area of relatively high temperatures in the east of the shelf passes to the continent through the Yana Bay and covers the Yana-Indigirka lowland. This fact along with the crustal thinning and extension allow us to suggest rifting processes in the considered area.

Распределение глубин нижней границы магнитоактивного слоя литосферы
Источник: Filippova A.I., Filippov S.V., Radziminovich Ya. B. Thermal state of the lithosphere beneath the Laptev Sea: Geodynamic implications from geomagnetic data // Journal of Asian Earth Sciences. 2024. 261. 105970. DOI: 10.1016/j.jseaes.2023.105970

Potential Locations of Strong Earthquakes in Bulgaria and the Neighbouring Regions

Information about potential earthquake sources is a key issue for seismic hazard assessment. This study presents the application of a phenomenological approach based on pattern recognition to determine the possible locations of strong earthquakes in the Bulgarian region. The technique assumes the origin of strong earthquakes in morphostructural nodes formed around the intersections of morphostructural lineaments identified by morphostructural zoning. More“Potential Locations of Strong Earthquakes in Bulgaria and the Neighbouring Regions”

Trigger mechanisms of gas hydrate decomposition, methane emissions and glacier breakup in polar regions as the result of deformation tectonic waves

This paper presents a new revolutionary theory of Academician Leopold Isaevich Lobkovsky on the impact of strong subduction earthquakes on the Earth’s climate and the catastrophic collapse of ice shelves as a trigger effect. A seismogenic-trigger mechanism is proposed for the activation of methane emission on the Arctic shelf in the late 1970s, which caused the onset of a sharp climate warming in the Arctic, as well as the intensive collapse of the ice sheet ice shelves of West Antarctica in the late 20th and early 21st centuries, accompanied by the release of methane from the underlying hydrate-bearing sedimentary rocks and the rapid climate warming in Antarctica.

More“Trigger mechanisms of gas hydrate decomposition, methane emissions and glacier breakup in polar regions as the result of deformation tectonic waves”

Productivity within the epidemic-type seismicity model 

The Geophysical Journal International published an article by Doctor of Physical and Mathematical Sciences G. Molchan and his Italian colleagues, devoted to the theoretical analysis of the productivity of seismic events. The productivity of a magnitude m event can be characterized in term of triggered events of magnitude above m – Δ: it is the number of direct ‘descendants’ νΔ and the number of all ‘descendants’ VΔ. There is evidence in favour of the discrete exponential distribution for both νΔ and VΔ with a dominant initial magnitude m (the case of aftershock cluster). We consider the general Epidemic Type Aftershock Sequence model adapted to any distribution of νΔ. Our first result shows that models with branching aftershock structure do not allow for the coincidence of distribution types of νΔ and VΔ (say, the discrete exponential, as in the scientific literature). The second problem is related to the tail behaviour of the VΔ distribution. We show the fundamental difference in tail behaviour of the VΔ – distributions for general-type clusters and clusters with a dominant initial magnitude: the tail is heavy in the former case and light in the latter. The real data demonstrate the possibilities of this kind.

Source: G. Molchan, E. Varini, A. Peresan Productivity within the epidemic-type seismicity model Geophysical Journal International, Volume 231, Issue 3, December 2022, Pages 1545–1557,DOI: 10.1093/gji/ggac269, Published: 22 July 2022