STUDY OF METHANE CONCENTRATION VARIABILITY IN THE SURFACE LAYER OF THE SEA OF JAPAN IN THE CONTEXT OF SEISMIC EVENTS (BASED ON THE RESULTS OF EXPEDITION STUDIES IN 2017–2018)

A spatial distribution of methane dissolved in sea water is a critical but poorly understood factor in the context of seismic activity. Based on the results of the RV AKADEMIK OPARIN integrated geological-geophysical expedition (September 21 – October 31, 2017), this paper deals with the regularities of methane concentration variability in the surface layer of the Sea of Japan: the average growth and the average growth period were 70 % and 10 h, respectively, after each earthquake whereas a decrease in methane concentration in the sea water was 10–30 % 2–4 h before a seismic event. A decrease in methane concentration occurs irrespectively of the depth of an earthquake. The results obtained show good agreement with the published data and gaseous-geochemical monitoring materials, thus making it possible to associate seismic-related gaseous-geochemical regime not only with gas-saturated sediments but also with the water column of the Japan Basin (Sea of Japan)

ИССЛЕДОВАНИЕ ИЗМЕНЧИВОСТИ КОНЦЕНТРАЦИЙ МЕТАНА В ПОВЕРХНОСТНОМ СЛОЕ ВОД ЯПОНСКОГО МОРЯ В КОНТЕКСТЕ СЕЙСМИЧЕСКИХ СОБЫТИЙ (ПО РЕЗУЛЬТАТАМ ЭКСПЕДИЦИОННЫХ ИССЛЕДОВАНИЙ 2017–2018 гг.)

A spatial distribution of methane dissolved in sea water is a critical but poorly understood factor in the context of seismic activity. Based on the results of the RV AKADEMIK OPARIN integrated geological-geophysical expedition (September 21 – October 31, 2017), this paper deals with the regularities of methane concentration variability in the surface layer of the Sea of Japan: the average growth and the average growth period were 70 % and 10 h, respectively, after each earthquake whereas a decrease in methane concentration in the sea water was 10–30 % 2–4 h before a seismic event. A decrease in methane concentration occurs irrespectively of the depth of an earthquake. The results obtained show good agreement with the published data and gaseous-geochemical monitoring materials, thus making it possible to associate seismic-related gaseous-geochemical regime not only with gas-saturated sediments but also with the water column of the Japan Basin (Sea of Japan).Пространственное распределение метана, растворенного в морской воде, во взаимосвязи с сейсмической активностью играет исключительно важную, но недостаточно исследованную роль. В работе на примере результатов комплексной геолого-геофизической экспедиции на НИС «Академик Опарин» (21 сентября – 31 октября 2017 г.) установлена закономерность изменчивости концентрации метана в поверхностном слое морской воды: после каждого землетрясения средний показатель роста составил 70 %, средний период роста 10 ч; падение уровня концентрации метана в морской воде достигало 10–30 % за 2–4 ч до сейсмического события. Снижение концентраций метана происходит независимо от глубины землетрясения. Полученные результаты согласуются с литературными данными, а также материалами газогеохимического мониторинга и позволяют обсуждать наличие сейсмозависимого газогеохимического режима не только газонасыщенных осадков, но и толщи вод Японского моря

Non-uniformly scaled buckling modes of reinforcing elements in fiber reinforced plastic

© 2017, Allerton Press, Inc. We consider a problem about non-uniformly scaled buckling modes of isolated fiber (without accounting of interaction with the surrounding epoxy) or bundle of fibers, which are structural elements of fiber reinforced plastics under the transverse tension (compression) and shear stresses in prebuckling state. Such initial state is formed in fibers and bundles of fibers at tension-compression tests of flat specimens from cross ply composites with unidirectional fibers. For problem statement we use equations recently constructed by reduction of consistent version of geometrically nonlinear equations of theory of elasticity to one dimensional equations of rectilinear beams. Equations are based on refined shear S. P. Timoshenko model with accounting of tension-compression stresses in transverse directions. We give theoretical explanation of developed phenomenon as reducing shear modulus of elasticity of fiber reinforced plastic during the increasing of shear strains. We show that under the loading process of specimens under review uninterruptedly structure reconstruction of composite trough implementation and uninterruptedly changing of internal buckling modes at changing wave parameter is feasible

Non-uniformly scaled buckling modes of reinforcing elements in fiber reinforced plastic

© 2017, Allerton Press, Inc. We consider a problem about non-uniformly scaled buckling modes of isolated fiber (without accounting of interaction with the surrounding epoxy) or bundle of fibers, which are structural elements of fiber reinforced plastics under the transverse tension (compression) and shear stresses in prebuckling state. Such initial state is formed in fibers and bundles of fibers at tension-compression tests of flat specimens from cross ply composites with unidirectional fibers. For problem statement we use equations recently constructed by reduction of consistent version of geometrically nonlinear equations of theory of elasticity to one dimensional equations of rectilinear beams. Equations are based on refined shear S. P. Timoshenko model with accounting of tension-compression stresses in transverse directions. We give theoretical explanation of developed phenomenon as reducing shear modulus of elasticity of fiber reinforced plastic during the increasing of shear strains. We show that under the loading process of specimens under review uninterruptedly structure reconstruction of composite trough implementation and uninterruptedly changing of internal buckling modes at changing wave parameter is feasible