HR: 1340h
AN: OS33B-0592    [Abstracts]
TI: The Lithosphere-Ocean-Atmosphere Seismo-Electromagnetic Transformer and Applications for the Seaquake Monitoring
AU: * Novik, O
EM: onovik@online.ru
AF: Inst. for Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) of Russian Acad. Sci., 117246, Moscow, Russia, Moscow, 117246 Russian Federation
AU: Ershov, S
AF: Keldysh Institute for Appl. Math. Russian Acad. Sci., Moscow, Russia, Moscow, 125047 Russian Federation
AU: Mikhaylovskaya, I
EM: onovik@online.ru
AF: Moscow State University, Moscow, Russia, Moscow, RUS 119899 Russian Federation
AU: Ruzhin, Y
EM: ruzhin@izmiran.rssi.ru
AF: Inst. for Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) of Russian Acad. Sci., 117246, Moscow, Russia, Moscow, 117246 Russian Federation
AB: To clear the physical nature of seismic electromagnetic (EM) signals observed in near sea regions a mathematical model of seismo-hydro-EM interaction in a lithosphere-ocean-atmosphere domain is formulated on the basis of principles of electrodynamics of moving continuous media. Generation and propagation of seismic, EM, temperature, and hydrodynamic waves caused by elastic displacements (main frequencies 0.1 to 1 Hz and amplitude and duration of the order of a few cm and sec respectively) in the upper mantle under the seafloor are traced numerically up to the low boundary of the ionosphere. The first measurable (50 pT) signal of the described seismic excitation (SE) of the ocean lithosphere arises in the form of ULF oscillations, in the frequency range of the SE, of the horizontal component of the magnetic field at the sea bottom's surface 3.5 sec after the beginning (t = 0) of the seaquake (the axes of polarization of the SE is approximately vertical). The seismic P wave caused by the SE arrives at the bottom a few sec later (depends on the focal depth). Let us note that the computed diffusive EM signal arises (t = 7 sec) at the sea surface together with the hydro-acoustic wave propagating upward from the sea bottom deformed by the seismic P wave. By runs with different reasonable geophysical characteristics of the medium and weak precursory SEs (see above), the magnetic signal amplitude is of the order of a few hundreds of pT at the sea surface and a of the order of a few tens of pT near the lower boundary of ionosphere, t=10 sec. The signal amplitude increases in proportion to the amplitude of a SE. So, the lithosphere-ocean-atmosphere system may be regarded as a seismo-EM transformer. The computed long (150 km) tsunami wave's amplitude far from a shore is about 15 cm only and EM signals (propagating in the atmosphere above the ocean with the light velocity) must be recorded. Basing on these and other numerical results (computed amplitudes, frequencies and velocities of elastic, EM, temperature and hydrodynamic waves are of the orders observed) the authors develop the project of the Lithosphere-Ocean-Atmosphere Multilevel Multidisciplinary Observatory (LOAMMO) including, among others: a bottom station (seismometry, magnetometry, thermometry, sounding), a moored ocean surface buoy (oceanography, satellite link) and an observation balloon (multidisciplinary gradient measurements, a long receiving antenna, the ionosphere sounding). We hope that the LOAMMO and multidisciplinary computations (above) will provide a stable detection of ionosphere Pc pulsations and EM signals of lithosphere origination as well as checking satellite prognostic data regarding earthquakes and seaquakes. The ocean lithosphere seismicity must be investigated and monitored not only because of earthquakes in near sea regions (especially Pacific segment of the Earth) and tsunamis but, as well, in view of increasing interest to global changes and, therefore, to powerful geodynamic processes under the Ocean floor covering about 75% of the Earth surface.
DE: 4263 Ocean prediction
DE: 4500 OCEANOGRAPHY: PHYSICAL
DE: 3210 Modeling
DE: 0619 Electromagnetic theory
DE: 0694 Instrumentation and techniques
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting