TwinSat Workshop ISTC, Moscow, February 16-17, 2011 Earthquake pre-curser models and the requirements as regards the TwinSat experiments V.M. Sorokin and V.M. Chmyrev Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences (IZMIRAN), 142190 Troitsk, Moscow region, Russian Federation Schmidt Institute of Physics of the Earth (IPE), Russian Academy of Sciences, 10, B. Gruzinskaya Str., 123995 Moscow, Russian Federation This report presents a summary of experimental data on the lithosphere-atmosphere-ionosphere coupling and a brief description of the formation mechanisms of electromagnetic and plasma disturbances in near Earth space at the preparatory phases of earthquakes. On this basis we suggest the proposals on further development of theoretical modeling and experimental studies of atmospheric and ionospheric earthquake precursors using the correlated twin-satellite and ground-based observation.

Basic experimental results Enhancement of seismic activity and typhoons produce DC electric field disturbances in the ionosphere with magnitudes up to 10 mV/m. These disturbances occupy an area of the order of several hundred km in diameter over earthquake region. DC electric field enhancements arise in the ionosphere from hours to 10 days before earthquakes. Chmyrev et al., Phys. Earth Planet. Inter. 1989; Sorokin et al., J. Atmos. Solar-Terr. Phys. 2005; Gousheva et al., Nat. Haz. Earth Syst. Sci. 2008, 2009. Magnitudes of ULF geomagnetic field oscillations detected in seismically disturbed ionosphere before earthquakes lie in the range from 0.2 to 3 nT. Chmyrev et al., Phys. Earth Planet. Inter. 1989; Bilichenko et al., Doklady 1990; Bhattacharya et al., Indian J. Radio & Space Phys. 2007. Small-scale (4-10 km) irregularities of plasma density with relative amplitudes up to 10 - 30 % and correlated electromagnetic ELF emissions with amplitudes 3-10 pT at frequencies ~450 and ~140 Hz correspondingly are excited within geomagnetic field tubes (3-4 deg. in latitudes) connected to epicenter region several days before earthquake. Blecki et al. (2009, 2010) have observed such ELF emissions well correlated in time and space with the thermal anomaly observed by NOAA18 satellite. Serebryakova et al., G. R .L. 1992; Chmyrev et al., J. Atmos. Solar-Terr. Phys. 1997; Blecki, Parrot and Wronovski, Int. J. Remote Sensing 2009, J. Asian Earth Science 2010; Zhang, Zeren, Parrot et al., Adv. Space Res. 2010.

Basic experimental results (continuation) Quasi-stationary electric field on the Earth surface in earthquake epicenter area does not exceed the value ~100 V/m. Vershinin et al., Atmos. Ionosph. Elect.-Magn. Phenom., 1999 Pre-earthquake VHF electromagnetic radiation is generated in the atmosphere at altitudes 1 to 10 km over the quake zone. Vallianatos and Nomicos, 1998; Ruzhin et al., 2000; Ruzhin and Nomicos, 2007. Seismic related disturbances in the troposphere create the conditions for over-horizon propagation of signals from ground-based VHF transmitters on the routes passing through the earthquake area. Fukumoto, Hayakawa, Yasuda, Seismo - Electromagnetics 2002; Fujiwara et al., G. R. L. 2004; Ohno et al., Seismo - Electromagnetics 2005. Seismic related disturbances of the lower ionosphere produce anomalous effect in Schumann resonance phenomena including unusual enhancement of the fourth harmonic and shift in frequency ~ 1Hz from conventional value at this harmonic. Hayakawa et al., Seismo - Electromagnetics 2005; Nikolaenko et al., Seismo - Electromagnetics 2005. Detection of seismic related phase and amplitude disturbances of VLF/LF transmitter signals in the Earth-ionosphere waveguide day to week before earthquake give an evidence of the lower ionosphere modification by earthquake preparation processes. Gokhberg et al., Phys. Earth Planet. Inter. 1989; Gufeld et al., Phys. Solid Earth 1992; Rozhnoi et al., Phys. Chem. Earth 2004; Rozhnoi et al., Nat. Haz. Earth Syst. Sci. 2009. .

Basic experimental results (continuation) Outgoing long wave (8-12 μm) radiation anomalies in the atmosphere (10-12 km) with the thermal flux intensity from 4 to 80 Watts per square meter have been observed in the zones ~2.5 degrees in latitude and longitude over earthquake region weeks to month before large earthquake. Ouzounov et al., Tectonophysics 2007. Alterations in the total water vapor column and changes in aerosol parameters and ozone concentration in connection with large earthquakes have been reported. Dey et al., Adv. Space Res. 2004; Okada, Mukai, Singh, Adv. Space Res. 2004; Tronin, Seismo-Electromagnetics 2002; Tronin, Remote Sensing 2010. Concentration of charged soil aerosols in the atmosphere in seismic region increases by one to two orders of magnitude days to week before earthquakes. Similar effect was observed in intense radon (Rn222) and other radioactive substances outbursts on the eve of large earthquakes. Alekseev, Alekseeva, Nucl. Geophys. 1992; Virk and Singh, Geophys. Res. Lett. 1994; Heinke et al., Geophys. Res. Lett. 1994; Pulinets et al., Adv. Space Res. 1997; Yasuoka et al., Appl. Geochem. 2006; Omori et al., NHESS 2007. 4

Model of DC electric field penetration from the lithosphere into the ionosphere This model assumes that the field source is situated in the lithosphere and the field is transferred through the atmospheric layer with altitude dependent electric conductivity. The layer is a part of the closed global atmosphere-ionosphere electric circuit at given electric field on the ground. Pulinets et al., 2003; Grimalsky et al., 2003; Ampferer et al. 2010; This model gives maximum magnitude of the electric field in the ionosphere not exceeding 0.001 mV/m when the ground field value is ~100 V/m and therefore seems to be impracticable. 1. Earth surface 2. Conductive layer of the ionosphere 3. Lithosphere source of electric field. 4. Electric field on the ground. 5. DC electric field in the ionosphere 6. Atmosphere – ionosphere electric circuit. Electric field in the ionosphere

The key role in seismo-ionospheric interaction belongs to electromotive force (EMF) in the lower atmosphere. The external current of EMF is excited in a process of vertical atmospheric convection and gravitational sedimentation of charged aerosols. Aerosols are injected into the atmosphere due to intensified soil gas elevation in the lithosphere during the enhancement of seismic activity. Sorokin et al., 2001 1. Atmospheric convection and turbulent diffusion. 2. Gravitational sedimentation. 3. Atmospheric radioactivity. 4. Soil gases. 5. Conduction electric current. 6. Electromotive force.

Model of DC electric field generation in the ionosphere by seismic related Electro Motive Force (EMF) in the lower atmosphere Inclusion of EMF into the atmosphere – ionosphere electric circuit leads to DC electric field growth up to 10 mV/m in the lower ionosphere. Sorokin et al., 2001; 2005; 2007; Sorokin and Chmyrev 2010 1. Earth surface 2. Conductive layer of the ionosphere 3. External electric current in the lower atmosphere 4. Conductivity electric current in the atmosphere – ionosphere circuit 5. DC electric field in the ionosphere 6. Field - aligned electric current 7. Charged aerosols injected into the atmosphere by soil gases Electric field in the ionosphere

The source of ionization determining the conductivity level in the near ground atmospheric layer Radioactive elements such as radon, radium, thorium, actinium and their decay products enter the atmosphere together with soil gas. Sorokin et al., 2001; Sorokin et al., 2007 The vertical distribution of ion production rate as a result of absorption in the atmosphere of the gamma radiation and the alpha particles from the decay of radioactive elements being constituents of the atmospheric radioactivity. Curves 1,2 and 3 correspond to different level of atmospheric radioactivity growing from 1 to 3.

The ionization-recombination processes Equilibrium values of ion number densities are determined by the recombination process and the adhesion to aerosols in the atmosphere. The light single-charged ions and the heavy ions are produced as a result of light ions adhesion to aerosols in the atmosphere near the Earth’s surface. Sorokin et al., 2007 EMF electric current and charge densities:

The self-consistent system of nonlinear equations for the calculation of spatial distribution of external current, atmosphere conductivity and DC electric field in the Earth – ionosphere circuit at given intensity of aerosols injection and the atmosphere radioactivity (the feedback effect is taken into account):

Altitude profiles calculated for the atmosphere conductivity over the center of disturbed area Conductivity depends on both the level of atmospheric radioactivity and the number density of aerosols. Left panel shows the conductivity profiles at different levels of atmospheric radioactivity. Right panel presents the conductivity profiles at different number density of charged aerosols near the Earth’s surface.

The altitude dependences of external electric current over the center of disturbed region External current is formed as a result of: convective transfer and turbulent diffusion of charged aerosols, ionization of the lower atmosphere by radioactive sources, adhesion of electrons to molecules, interaction of charged ions with charged aerosols

Spatial distributions of DC electric field calculated for axially symmetric external electric current Sorokin et al., 2006 Upper panel: Horizontal component of DC electric field in the ionosphere. Inclination of the magnetic field is Lower panel: Vertical component of DC electric field on the ground.

Spatial distribution of horizontal electric field in the ionosphere and vertical electric field near the Earth surface over the ellipsoidal fault Sorokin et al., 2005

An example of large magnitude DC electric field distribution in the lower atmosphere normalized to the breakdown electric field Sorokin et al., 2011 At definite conditions the seismic related DC electric field can reach the breakdown value in some region of the atmosphere (marked out by red in the figure below).

Pre-earthquake DC electric field reaching the breakdown value initiates numerous chaotic electrical discharges and related phenomena in the lower atmosphere Chaotic electric discharges. Heating of atmosphere in the discharge region and the generation of outgoing long wave (8-12 μm) radiation. Broadband electromagnetic VHF emission. Airglow in visible range of wavelengths. Refraction and scattering of VHF radio waves in the troposphere providing the over-horizon reception of ground-based VHF transmitter signals.

Generation of VHF electromagnetic emissions in the atmosphere Sorokin et al., 2011 Coordinates used for the calculation of electromagnetic radiation parameters Maxwell equations:

Frequency spectrum of electromagnetic radiation generated by random electric discharges Green function: Power spectrum of the electromagnetic waves radiated by random discharges during the time interval T: Frequency spectrum of the radiation electric field:

Calculated spectrum of VHF electromagnetic radiation at distance 300 km from the epicenter of disturbed area The radiation source is modeled by the disk-like random discharges region with radius 40 km and thickness 1 km located at 6 km altitude in the atmosphere. Two vertical lines on the curve in figure show the spectral densities observed in experiment (Ruzhin and Nomicos, 2007). Sorokin et al., 2011

Vallianatos and Nomicos (1998), Ruzhin et al. (2000), Hayakawa et al Vallianatos and Nomicos (1998), Ruzhin et al. (2000), Hayakawa et al. (2006), Ruzhin and Nomicos (2007) have shown that the seismic related VHF emissions are observed during several days before earthquakes and the source region lies in the atmosphere at the altitudes about several km above the earthquake center that gives a possibility for over-horizon observation of these emissions.

Acoustic Gravity Wave (AGW) instability related to DC electric field enhancement in the lower ionosphere The formation of large enough DC electric field in the ionosphere exceeding definite threshold value ( ) leads to instability of acoustic-gravity waves and generation of periodic or localized ionospheric structures in a form of solitary dipole vortices or vortex chains and associated plasma density and electric conductivity disturbances in the ionosphere. Sorokin et al., 1998; Chmyrev and Sorokin, 2010 The frequency dependence of the refraction index and the absorption coefficient of acoustic-gravity wave in the ionosphere in the presence of an external electric field. Vortex formation.

Formation of field-aligned currents, plasma irregularities and ELF electromagnetic emissions in the upper ionosphere The excitation of horizontal spatial structure of conductivity in the lower ionosphere results in the formation of magnetic field- aligned currents and plasma layers stretched along the geomagnetic field. Sorokin et al., 1998 Irregularities of the ionosphere conductivity. DC electric field in the ionosphere. Field – aligned electric current. Plasma layers stretched along geomagnetic field. Thunderstorms. Lightning electromagnetic emission. ELF electromagnetic radiation.

Examples of satellite observations of ULF magnetic field oscillations, electron number density fluctuations and ELF electromagnetic emissions caused by the formation of the ionosphere conductivity irregularities Chmyrev et al., 1989; Chmyrev et al., 1997 1. Earthquake. 2. Irregularities of the ionosphere conductivity. 3. Field-aligned currents and irregularities of electron number density. 4. Satellite trajectory crossing the disturbed region. ULF magnetic field. Electron number density fluctuations. ELF electromagnetic emissions

Excitation of horizontal small-scale irregularities of electric conductivity in the lower ionosphere is a key factor for the generation mechanism of electromagnetic ELF wave precursors to earthquakes. These waves are generated in the interaction process of thunderstorm related EM radiation with small-scale plasma irregularities excited in the lower ionosphere before earthquakes. These EM pulses radiated by lightning discharges and propagated in sub-ionospheric wave guide with small attenuation are scattered by the irregularities and re-emitted into the upper ionosphere. Borisov et al., 2001

Other applications of the model for periodic disturbances of electric conductivity in the lower ionosphere: Generation of the narrow-band gyrotropic waves and associated magnetic field oscillations on the Earth surface through the interaction of background electromagnetic noise with periodic inhomogeneities of electric conductivity in the ionosphere over seismic region. Sorokin and Hayakawa, 2008 Interpretation in terms of gyrotropic waves of Schumann-resonance-like anomalous line emissions observed before earthquakes. Hayakawa et al., 2010

Model for electron number density distribution in the ionosphic E - region disturbed by the electric current flowing into the ionosphere from the atmosphere. Sorokin et al., 2006 Self-consistent system of non-linear equations for ion number density and electric field in the lower ionosphere:

Model for electron number density distribution in the D layer of the ionosphere disturbed by the electric current flowing from the atmosphere to the ionosphere Laptukhov et al., 2009 Self-consistent system of non-linear equations for electron and ion number density, temperature and the electric field: (Biagi et al., 2004).

The scheme of processes responsible for the atmosphere – ionosphere coupling

It is expected that further development of the earthquake precursor generation models will broaden a list of the precursor signals to be used for the forecasting purposes and therefore enhance an accuracy and viability of forecast. We suggest the following tasks to be included in a program of work within the TwinSat project: Development of the numerical methods for finding 3D-distribution of DC electric field in closed atmosphere-ionosphere electric circuit, which is generated by external electric current excited in the lower atmosphere; Development of the theoretical model for the disturbances of D-, E- and F- layers of the ionosphere connected with the generation of external electric current. Development of the theory of internal/acoustic-gravity wave instability in the ionosphere under influence of DC electric field taking into account the relative movement of ionized and neutral plasma components and various inclinations of the magnetic field. Development of the theory of nonlinear vortex structures and related disturbances in the ionosphere influenced by the electric field and some other factors caused by earthquake activity. Investigation of the “splitting” mechanism, which is expected to produce the transformation of relatively large-scale current and plasma disturbances into small-scale filamentary structures through the instability of Drift-Alfven Waves (DAW). This instability arises at definite plasma and current density gradients excited by the internal gravity wave vortices and leads to the formation of self-organized nonlinear DAW structures – solitary vortices and vortex chains detectable from satellites. Analyses of the electric discharges formation mechanism by the electric field, reaching the breakdown value; development of the models for electromagnetic and optical radiation, atmosphere heating and the scattering of radio waves in the discharge region. Special attention will be paid to the runaway breakdown effects and associated phenomena in the atmosphere and the ionosphere of the Earth. Development of self-consistent electrodynamic model of the precursors and the proposals for its implementation to improve a quality and reliability of short-term earthquake forecast.

The TwinSat project requirements Objectives: Validation of current experimental findings and theoretical models regarding the short-term earthquake precursors through specialized coordinated twin-satellite and ground based observations; Search for new precursory signals and estimation of their potential for accuracy improvement of forecasting the time and position of impending earthquakes; Development of comprehensive theoretical model describing the formation and interconnection of the precursor signals. Two-level structure of observations includes: The space segment consisting of two mother/daughter platforms - the micro satellite TwinSat-1M and the nano satellite TwinSat-1N, operated at the controllable separation. The inter-satellite radio link provides transmission of scientific information from TwinSat-1N to TwinSat-1M for the data collection in high capacity onboard memory of micro satellite and subsequent delivery of whole data set from two satellites to appropriate ground telemetry station. The ground segment consisting of the network of geophysical stations situated in several zones of high earthquake and volcano activity. Two satellites will be in a fast operation mode on the passages over these zones, where supporting ground-based measurements of relevant electromagnetic field and the atmosphere parameters should be performed. Comparison of the ground-based and two-satellite observation results with seismic data will allow us to define the existence (or absence) of correlation between the measured parameters and their cause-sequence links with seismic activity.

(Continuation) Why two satellites are needed: To enable synchronous measurements of the precursor signals in separated points along the orbit to determine their spatial structure and the dynamic characteristics such as the propagation velocity, temporal/spatial variations, etc. To develop and test the scheme of joint operation and information exchange on the orbit of two very small platforms as a prototype of future cost effective satellite constellation for monitoring of large-scale natural disasters. Parameters to be measured on TwinSat-1M: Vector of DC electric field, +/- 250 mV/m, resolution 0.5 mV/m; Spectral and wave characteristics of 6 electromagnetic field components in ULF/ELF range (0.5 – 350 Hz); Spectrum of wave electric field in ULF/ELF and VLF/LF (3-300 kHz) ranges; amplitude and phase variations of ground based VLF/LF transmitter signals. Spectrum of wave magnetic field in VHF range (26 – 48 MHz); Variations of thermal and super thermal (0.3 - 20 eV) plasma parameters; Energy distributions of electron and ion fluxes with energies 0.3 – 300 eV for two directions; Lightning activity in sub-satellite regions (optical measurements).

(Continuation) Parameters to be measured on TwinSat-1N: Variations of thermal and super thermal (0.3 – 20 eV) plasma parameters; Energy distributions of electron and ion fluxes with energies 0.3 – 300 eV for two directions; Wave form of ULF/ELF magnetic field oscillations (0.5 – 350 Hz), one or two components. Data from other satellites to be requested: Outgoing long wave (8-12 μm) radiation intensity and thermal images of seismically active zones. Ground-based measurements: Atmospheric gas composition; Radon emission and variations of radioactivity; Dynamics of aerosol injection; Atmospheric DC electric field and current variations; Spectral and wave characteristics of ULF/ELF/VHF electromagnetic emissions including the arrival direction finding and locating the radiation sources; Remote sensing of the ionosphere disturbances through the registration of amplitude and phase variations of VLF/LF signals from ground based transmitters at appropriate propagation routes; Seismic and magnetic field oscillations.

(Continuation) Where to deploy the ground stations: The most attractive is the deployment of multi-discipline ground network in the Kamchatka/Kuril region, which is characterized by the strongest earthquake and volcano activities over the world. 29 active Kamchatka volcanoes annually produce 3 to 4 eruptions of explosive type. Taking into account the highest occurrence rate of eruptions in the selected area we can expect the formation of unique set of data on the precursory signals obtained from coordinated ground and twin-satellite observations. We could make use of the existing networks in Greece, Italy and Iceland after corresponding adaptation for the TwinSat experiments. Orbit requirements: Sun - synchronous orbit with altitude ~ 800 km, inclination ~ 98.6 deg and period ~100 min; Separation between the satellites lies in the range from 1 to 400 km; Micro satellite requirements: Attitude control: 3-axis with accuracy ~ 10 angular minutes; Timing and positioning accuracy: 0.1 ms/30 m; Data transmission rate: ~2 Mbit/s; Onboard memory: ~1 Gbyte.

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