|Fig.40. Earth magnetic field
The upper region of the atmosphere (plasmasphere), about 100 km and higher, contains plenty of ions. The condition of plasma retained by Earth’s magnetic field is determined by the interaction of Earth’s magnetic field with the solar wind, which explains the relationship between terrestrial magnetic storms and solar flares (K. P. Belov, N. G. Bochkarev, 1983).
The magnetic field intensity at Earth’s surface highly depends on the geographical location, being about 0.5 Oe (50 microT ) on average, about 0.34 Oe at the magnetic equator, and 0.66 Oe at the magnetic poles.
This intensity rises sharply near magnetic anomalies, reaching, for example, 2 Oe inside the Kursk Magnetic Anomaly. Periodically, Earth’s magnetic field experiences disturbances called magnetic pulsations, resulting from the excitation of hydromagnetic waves in Earth’s magnetosphere. Pulsation frequency ranges from millihertz to one kilohertz (V. A. Troitskaya, A. V. Guglielmi, 1969).
The geomagnetic field is not so constant and varies from time to time. For instance, some 2500 years ago the strength of the magnetic field was 50% higher than it is today.
The so-called inversions of the geomagnetic field, or geomagnetic reversals, when the positions of the north and south magnetic poles become interchanged, have occurred over and over throughout Earth’s history. Along with inversions of the geomagnetic poles, there are less dramatic shifts of the geomagnetic field, the so-called “excursions,” when the geomagnetic poles migrate rapidly to rather great distances but no geomagnetic reversal takes place. Earth’s history has seen repeated occurrences of “excursions” of the geomagnetic poles when the North geomagnetic pole traveled towards the equator and reversed upon reaching it, returning to its former location.
It is hard to overestimate the importance of the geomagnetic field for the existence and evolution of life on Earth, for the lines of force of the magnetic field create a kind of a magnetic shield around the planet that protects Earth’s surface from cosmic rays pernicious to all living things, and from the influx of charged particles of high energies.
The North geomagnetic pole is now located in the Canadian Arctic and continues to drift northwestwards, while the South geomagnetic pole is located off the coast of Antarctica, south of
Mandea and Dormy (2003), summarizing their ground observations and discussing the movement of the North geomagnetic pole, stated that its velocity “has more than doubled in the last 30 years, reaching the huge velocity of about
According to a forecast by N. Olsen and M. Mandea (2007), the North geomagnetic pole will be closest to the North Geographic Pole (at a distance of
Studying the geomagnetic reversals and sea level fluctuations in the Phanerozoic Era has enabled a number of researchers to conclude that there is a certain correlation between those processes (E. E. Milanovskiy, A. G. Gamburtsev, 1998). The intensity of Earth’s magnetic field in the past has also been subject to significant fluctuations. For instance, a study by G. N. Petrova and A. G. Gamburtsev established the existence of rhythms in the paleointensity of the geomagnetic field, predominated by rhythms with periods of 20-25 ka, 70 ka, 160-170 ka and other, though less distinct, periods (G. N. Petrova, A. G. Gamburtsev, 1998).
Fig. 41. Graph of velocity of North Geomagnetic Pole movement
(N. Olsen and M. Mandea, 2007)
Fig. 41 contains a graph showing the movement of the North geomagnetic pole. As can be seen from the graph, the North geomagnetic pole’s drift rate had increased almost fivefold by the late 1990s as compared to 1980. This fact might point to a substantial change in energy processes within Earth’s core, which form the geomagnetic field of our planet. No doubt the observed phenomenon may be indicative of the beginning of another cycle of surge in Earth’s endogenous activity.
To what further consequences may the vastly accelerated displacement of the North Magnetic Pole lead? Given that a decrease in Earth’s magnetic field intensity accompanies this process, it can be assumed that global climate change will be influenced as well. There are so-called “cusps” in the polar ice cap areas – polar gaps that have increased in size in recent years. Radiation particles from the solar wind and interplanetary space enter Earth’s atmosphere and hit its surface through those cusps, which means that huge amounts of extra matter and energy get into the polar areas resulting in “heating” of polar caps. Naturally, changing of the positions of the geomagnetic poles also causes shifting of the cusps and, consequently, displacement of the areas of high flux of solar energy into Earth’s atmosphere and towards its surface. This process is followed by a redistribution of cyclones and anticyclones across the planet, leading to serious global climate change (V. E. Khain, E. N. Khalilov, 2008, 2009).
5.2. VARIATIONS OF ANGULAR VELOCITY OF EARTH’S ROTATION
Irregularity of Earth’s diurnal rotation rate was found as early as in the beginning of the twentieth century. According to V. M. Kiselev (1980), these variations are mostly expressed in three ways: 1. the rotation axis changes its spatial orientation; 2. the rotation axis changes its position relative to Earth’s surface; 3. the angular velocity of Earth’s rotation is variable relative to the instantaneous axis.
Changes in the spatial position of Earth’s axis are mainly caused by the gravitational influence of the Moon, Sun and Solar system’s planets on Earth. This value can be calculated quite accurately. Much more difficult is the case with the second and third aspects, which manifest themselves in the form of, respectively, movement of the poles relative to Earth’s surface and variations of Earth’s angular velocity (Fig 42). All movements of the poles can be classified into three categories: a motion with a period of 14 months and variable amplitude of
Fig. 42. Earth’s precession and nutation diagram
However, these movement types are not dealt with in this paper; therefore, attention will be focused on the irregularity of Earth’s diurnal rotation rate. There are three main aspects usually singled out as to variations of the length of the 24-hour day: 1) Secular changes of 1-2 ms per 100 years, 2) Seasonal variations with an amplitude of about 0.5 ms, and 3) Irregular yearly changes whose magnitude exceeds secular changes by more than a factor of ten.
Secular changes in the day length are mostly associated with the effect of tide-raising forces resulting from Earth’s gravitational interaction with the Moon and the Sun. Seasonal variations of Earth’s angular velocity are due to the changes in zonal atmospheric circulation during the year and partly due to lunar tides.
Isaac Newton first noticed irregular variations of Earth’s rotation rate in 1875 when he was studying the motion of the Moon. The existence of the irregular changes of Earth’s rotation became evident after the works of de Sitter and Spencer Jones, who found simultaneous changes in the mean motion of the Moon, Sun, Mercury, Venus, Mars, and the satellites of Jupiter, proportional to their mean motions. However, to date there is no general consensus as to what causes the irregular changes of Earth’s angular velocity (V.M. Kiselev, 1980).
Fig. 43 contains a graph of irregular variations of Earth’s day length from 1850 to 2000, smoothed out via 5-year running averages. There have been attempts by various researchers to put forward some concepts to explain the mechanism of irregular changes of Earth’s diurnal rotation.
P. N. Kropotkin, N. N. Pariysky and other researchers attribute the observed variations of Earth’s diurnal rotation rate to possible changes in its radius and shape: P. N. Kropotkin (1984), N. N. Pariysky (1984), V. E. Khain, Sh. F. Mehdiyev, E. N. Khalilov (1984, 1986, 1987, 1988, 1989)
according to data by V. M. Kiselev (1980)
Y is day length variations graph;
γ (ms) axis is changes in day length.
As P. N. Kropotkin pointed out in his work (1984), the periodic changes in Earth’s radius are the original cause of both the cyclicity of tectonic processes’ manifestation and the variations of Earth’s angular velocity (Kropotkin, 1984). The same idea was simultaneously proposed by V. E. Khain, Sh. F. Mehdiyev and E. N. Khalilov (1984) who, similar to P. N. Kropotkin in 1984, drew a conclusion about the periodic changes in Earth’s radius, which is reduced due to intensification of the subduction process and slowing down of the spreading process during the times when Earth is getting compressed, with the opposite process taking place during the periods of Earth’s expansion.
It is noteworthy that P. N. Kropotkin in his work (1984) established a good correlation between the
The theoretical calculations of Earth’s elastic deformation and of respective changes in its moment of inertia, rotation, and surface gravity were made by N. N. Pariysky as early as 1954. Based on his calculations, N. N. Pariysky concluded that neither solar activity effects nor atmospheric phenomena could cause the observed changes in Earth’s angular velocity. In his view, those variations might be the result of Earth’s global deformation processes leading not only to the periodic changes of its radius, but also to the complex change of its shape. Judging from his description of this process, it must be quadrupole in nature, that is, Earth must “change its shape, expanding in the middle and polar regions and shrinking ten times more in the equatorial areas” (N. N. Pariysky, 1984).
Research findings on irregular changes of gravity, cited in a work by D. D. Ivanenko (1984), refer to the situation where the shrinking of Earth at the measuring point would be in line with the overall increase in Earth’s moment of inertia, which is only possible if another part of the globe is expanding. According to V. M. Fedorov, there are some specifics regarding the distribution of catastrophic earthquakes in the diurnal cycle of Earth’s rotation. Those specifics are explained by the cause-and-effect relationship between the distribution of earthquakes and the dynamics of constituent tide-rising forces of the Moon and Sun in connection with Earth’s diurnal rotation.
While studying the correlation between Earth’s global seismic activity and its rotation speed, a group of scientists (Friedmann, Klimenko, Polyachenko, 2005) came to interesting conclusions: 1) the correlation between the frequency of near-surface earthquakes and Earth’s angular acceleration grows monotonically with increasing magnitude, and 2) correlations between the seismic activity and variations of Earth’s angular velocity in subduction zones drawn along the latitude and the meridian are qualitatively different. At the end of their research, the authors conclude: “It is the processes of crustal compression and extension in the direction transverse to the rotation axis that are responsible for the changes in the annual seismic activity and angular velocity of Earth’s rotation.”
The most recent works by N. S. Sidorenkov, a well-known researcher of Earth’s rotation irregularity, contain some interesting conclusions about the relation of Earth’s rotation instability to hydrometeorological processes. Those studies formed the basis for the method of forecasting hydrometeorological characteristics, patented by scientists (N. S. Sidorenkov, P. N. Sidorenkov, 2002). N. S. Sidorenkov mentions the existence of a statistically significant correspondence between the tidal fluctuations of Earth’s rotation speed and changes of weather processes in the atmosphere. Natural synoptic periods coincide with Earth’s rotation modes. Lunar-solar zonal tides cause tidal fluctuations of Earth’s rotation rate. According to those researchers, the evolution of synoptic processes in the atmosphere occurs not only because of the climate system’s internal dynamics, but also under the control of the lunar-solar zonal tides (Sidorenkov, 2004).
The research conducted by a number of scientists (Zharkov, Pasynok, 2004) allowed them to conclude that the variations of Earth’s angular velocity are very complex in nature, with completely different harmonics. When superimposed on each other, those harmonics create a very complex pattern of variation in Earth’s day length. Based on that, V. N. Zharkov and S. L. Pasynok attempted to develop a theory of Earth’s rotation, calling it a new theory of nutation. According to that theory, nutation of Earth’s rotation is conceived as a quite complex though harmonious system that has a specific hierarchy of many superimposing nutational movements of the rotation axis of different degrees.
In our view, the variations of Earth’s diurnal rotation are undoubtedly connected to the deformation processes and mass changes in the core-lithosphere - hydrosphere – atmosphere system. The aforesaid can be confirmed by the changes in the angular velocity of Earth’s rotation and displacement of its axis following the catastrophic earthquakes in Indonesia (Sumatra, 26 December 2004) and Chile (27 February 2010), to name a few. The Indonesian earthquake of Dec. 26, 2004 shifted the position of the Geographic North Pole by
To exemplify the deviations of Earth’s angular velocity from the predicted values, a graph drawn by N. V. Sidorenkov (2009) is given in Fig. 44.
Meanwhile, our comparison of the day length variations graph and solar activity (solar constant) graph yielded interesting results (Fig. 45). From the very start, the observer’s attention is drawn to the presence of common trends in the nature of day length variations and the curve enveloping the peak values of solar constant variations.
The existence of a correlation between solar constant variations and changes in the day length might have a physical explanation. Let us build a logical chain. If solar activity affects geodynamic processes as well as processes in the hydrosphere (e.g. melting of ice, changes in water level in oceans and seas) and the atmosphere, this should lead to the redistribution of masses in these strata of Earth, changing Earth’s moment of inertia and angular velocity. No doubt this issue requires more thorough research.
Fig. 44. Measured (dotted line) and forecast (red line) tidal fluctuations of Earth's
rotation speed from 01 October 2006 to 31 December 2007 (N. S. Sidorenkov, 2009)
On the Y-axis are shown 10^-10 variations of angular velocity of rotation.
To match both scales, a constant 150*10^-10 is added to all measured values.
Fig. 45. Comparison of graphs of changes in Earth’s day length and solar activity
(solar constant), by E. N. Khalilov (2010)
Sa axis is solar constant values;
ms axis is day length variation values (in ms);
Graphs:solar constant variations graph is marked in yellow;
Earth’s day length variations graph is marked in blue;
Graph passing through peak values of solar constant variations is marked in lilac.
5.3. SOLAR-TERRESTRIAL RELATIONS
The sun is the source of the most energetic outer space impact on our planet. Even rough estimates demonstrate that the thermonuclear fuel reserves inside the sun are enough to keep its physical condition unchanged for 1011 years. The sun annually radiates energy equal to 3х1033 cal and is a source of total electromagnetic radiation, an interplanetary plasma cloud, fast electrons, solar cosmic rays, etc. It loses most of its energy in the form of wave radiation (Y. I. Vitinsky, 1972, 1973, 1983; O. G. Shamina, 1981). The total amount of energy emitted into space by the sun can be determined experimentally based on the energy flow per unit area of Earth’s surface; it is called the solar constant and averages 1.95 cal/cm2 ∙ min, or about 1360 W/m2 (E. A. Makarova, 1972); the total flux of radiant energy is 3.8х1026 J/sec.
The appearance of sunspots on the sun’s surface is an indicator of increasing solar activity. In 1908, Hale discovered that sunspots have a magnetic field whose intensity reaches 2000 - 4000 gauss, whereas the strength of the sun’s overall magnetic field is one gauss or less. At the beginning of a solar cycle, the spots appear at latitudes of 300 - 400, then shift towards the equator from the south and north and reaching their maximum at about 100 - 200 latitude, following which the number of spots decreases (V. M. Kiselev, 1980). Research findings indicate that the duration of sunspot drift towards the equator is about 11 years. At the end of each 11-year cycle, the magnetic field near the poles changes its polarity. Thus, the magnetic cycle of the sun is 22 years.
In the middle of the nineteenth century, S. H. Schwabe and R. Wolf established the fact that the number of sunspots changes with a mean periodicity of 11 years.
H. Babcock and R. Leighton (1961) (1969) proposed a model explaining the existence of the 22-year magnetic solar cycle. According to them, the rise of a magnetic flux tube to the photosphere’s surface is accompanied by the appearance of an initial leading sunspot followed by a second one. In adjacent 11-year cycles, the leading sunspots have different polarity.
The relative sunspot number is one of the most common indices of solar activity. R. Wolf suggested that the solar activity index be determined according to the following formula:
W = k (10g + f ) (1)
where W is the Wolf number, g is the number of sunspot groups on the visible solar disk, and f is the number of sunspots (including nuclei and pores) in all groups. The value of the coefficient k depends on many factors: the particular methods of observations, visibility conditions at the time of observation, and the observer’s personal characteristics, to name a few.Another index of solar activity is the total sunspot area corrected for foreshortening, according to the formula:
where S is the area of the first sunspot, θ is arc sin (ri/R), R is the radius of the visible solar disk, and ri is the distance between its center and the sunspot being observed.
There is a statistical relationship between S and W with a correlation coefficient of +0.85 (V. M. Kiselev, 1980). The regression equation of S and W is as follows in equation (3) (Y. I. Vitinskii, 1976):
S = 16.7 W (3)There are several more solar activity indices examined by Y. I. Vitinskii in his work (1973).
Fig. 46. Graph for Wolf numbers variations (W)
Royal Observatory of
Fig. 46 contains a graph for Wolf number variations from 1700 to 2010.
The generally accepted numbering pattern for 11-year solar activity cycles is that the number zero is assigned to the 11-year cycle whose maximum value occurred in 1750. The average length of a 11-year cycle is considered to be 11.1 years. However, the actual duration of an 11-year cycle varies considerably; if determined by the epochs of minimum, the cycle period ranges from 9.0 to 13.6 years, and it is between 7.3 to 17.1 years when determined by the epochs of maximum (Y. I. Vitinskii, 1976).
While many researchers acknowledge the existence of 11-year and 22-year cycles of solar activity, cycles with longer periods are a matter of much debate. This is due to the unreliability of solar activity observation data earlier than 200 years ago.
Based on analysis of the historical records of observations of sunspots and polar auroras, D. Schove provides some data that makes it possible to estimate the changes of solar activity qualitatively over the last 2000 years (Y. I. Vitinskii, 1973). The data by D. Schove prove the reality of the existence of a cycle with a period of 80-90 years in the Wolf numbers variations and allows us to single out a cycle with an average duration of 554 years (Y. I. Vitinskii, 1976).
Fig. 47. Graph for Wolf numbers variations (W) from 2000 to May 2010
An attempt to characterize solar activity in a way not predominated by the 11-year cyclicity was made by A. Stojko and N. Stojko (1969). For that, they used the values of short-lived sunspots’ areas W1, variations between 1900 and 1963 of which were compared with Earth’s diurnal rotation variations. These two phenomena correlate with
К = (+08); (+09).
Fig. 47 shows the solar activity change from 2000 to May 2010.
It has become evident in recent decades that the significance of the solar activity’s impact on terrestrial processes is much broader and deeper than previously thought. In our view, B. M. Vladimirsky in his work (2002) is quite right in his attempt to attribute many highly sensitive physical and chemical processes taking place on Earth to the influence of various components of solar activity. There are given some interesting examples of heliospheric parameters affecting anthropogenic processes.
Efforts to identify the statistical relationship between solar activity and volcanic manifestations have been made by a number of scientists: A. I. Abdurakhmanov (1976); N. K. Bulin (1982); Y. A. Hajiyev (1985); Sh. F. Mehdiyev, E. N. Khalilov (1984, 1985); S. V. Tsirel (2002); and V. E. Khain, E. N. Khalilov (2008, 2009), among others.
For instance, A. I. Abdurakhmanov, P. P. Firstov and V. A. Shirokov suggested a link between volcanic eruptions and the 11-year cyclicity of solar activity. According to the authors, years in the vicinity of maximum solar activity are unfavorable for volcanic eruptions, whereas the years most favorable for eruptions lie near the minimum of solar activity, mostly in the middle and end of solar cycle decline (A. I. Abdurakhmanov, 1976).
A number of researchers (Sh. F. Mehdiyev, E. N. Khalilov, 1987; V. E. Khain, E. N. Khalilov, 2008, 2009) indicate in their works that the effect of solar activity on earthquakes and volcano eruptions occurring in different geodynamic zones (in Earth’s compression and extension zones) is not equal. They have divided all earthquakes and volcanoes according to their association with Earth’s zones of compression (lithospheric plates’ subduction and collision zones) and extension (rift zones). The research findings show that during increased solar activity periods there is generally a rise in the activity of Earth’s compression zone earthquakes and a drop in the activity of Earth’s extension zones. The authors conclude that due to non-simultaneity of the extension and compression processes, Earth experiences periodic deformations and changes in radius, which are reflected in Earth’s angular velocity variations and global sea level fluctuations (V. E. Khain, E. N. Khalilov, 2008, 2009).
Of interest is the initial analysis of a possible correlation between solar activity and Earth’s volcanic activity. We took the solar constant graph as a basic parameter of solar activity. It is this parameter that, in our view, most perfectly reflects the actual influx of solar energy into outer space, including towards Earth.
Fig. 48 provides a comparison of graphs for the solar constant and volcanic eruption numbers, smoothed out over 5-year running averages. Both images are identical, differing only in the graphical style for better perception. One can see a certain correlation between the 11-year solar activity cycles and volcanic activity cycles. The greatest overlap is observed in solar activity cycles #14, 16, 17, 18, 20, 22, and 23
However, the most interesting correlation is, in our opinion, full coincidence in the general type of the straight-line solar and volcanic activity trends. Around 1950, the angle of the straight-line trends in both processes decreased sharply, meaning volcanic activity growth became less intense. This fact may be yet another indication of a possible solar activity impact on Earth’s geodynamic activity.
Fig. 48. Comparison of solar activity (solar constant) graph and volcanic
eruption numbers smoothed out over 5-year running averages (by E. N. Khalilov, 2010)
Solar activity (solar constant) graph is marked in red;
Volcanic eruption numbers graph smoothed with 5-year averages is marked in dark blue and azure;
Lines reflecting general nature of parameter variations in all graphs are marked in green, yellow and white
Determination of a statistical relationship between the timelines of volcanic activity and solar activity suggests the existence of a similar link between solar activity and Earth’s seismicity as well. The precondition for this supposition is the commonly known existence of geodynamic and correlated relations between volcanism and seismicity.
A number of works have been dedicated to studying the statistical relations between the solar and seismic activity parameters: A. D. Sytinskii (1963-1998); P. M. Sychev (1964); John F. Simpson (1968); O. V. Lusmanashvili (1972, 1973); F. A. Makadov (1973); Y. D. Kalinin (1973, 1974); Gribin (1974); G. Y. Vasilyeva (1975); P. Velinov (1975); H. Kanamori (1977); V. D. Talalayev (1980); N. V. Kulanin (1984); Y. D. Boulanger (1984); Sh. F. Mehdiyev, E. N. Khalilov (1984, 1985); Jakubcova and M. Pick (1987); A. D. Sytinskii (1989); R. M. C. Lopes, S. R. C. Malin, A. Mazzarella (1990); O. A. Khachay (1994); L. N. Makarova, Gui-Qing Zhang (1998); A. V. Shirochkov (1999); X. Wu, W. Mao, Y. Huang (2001); I. V. Ananyin, A. O. Fadeev (2002); K. Schulenberg (2006); S. D. Odintsov, G. S. Ivanov-Kholodnyi and K. Georgieva (2007); and V. E. Khain, E. N. Khalilov (2008, 2009), among others.
Based on the study of about 2000 earthquakes in Earth’s different regions for one solar activity cycle period between 1962 and
Elaborating the proposed hypothesis, Y. D. Kalinin in his subsequent work (1974) states that changes in solar activity bring about irregular fluctuations of Earth’s angular velocity, affecting thereby seismic activity.
O. V. Lusmanashvili in his study (1972) mentions the possibility of solar activity impact on the distribution of Caucasian earthquakes. Reviewing earthquakes of the Caucasus between 1900 and 1970, O. V. Lusmanashvili concludes that there is a close link between the seismic activity of the Caucasus and
Other attempts to find a relation between Earth’s seismicity and solar activity were made in a number of works by A. D. Sytinskii (1963 - 1998), as well as by P.M. Sychev (1964) and V. D. Talalayev (1980). They state in particular that Earth’s overall seismicity represented by the total energy of earthquakes and the annual number of catastrophic earthquakes depends on the phases of the 11-year solar cycle. The highest seismic activity coincides with the epochs of maximum and minimum of the 11-year solar cycle. It is also pointed out that most earthquakes occur 2-3 days after the active region crosses the central solar meridian.
A study by A. D. Sytinskii (1973) suggests that the relation between seismicity and solar activity is realized via planetary atmospheric processes. The mechanism of dependence is as follows: due to increased solar activity there is a perturbation of the atmosphere’s quasi-stationary state, leading to global redistribution of the atmospheric mass, i.e. to shifting of the Earth - atmosphere system’s center of gravity and consequently, to distortion of Earth’s figure.
As A. D. Sytinskii (1998) points out, seismicity’s dependence on the 11-year cycle, discovered by him earlier was verified and confirmed by experimental forecasting of Earth’s overall seismicity and that of its specific regions. Earth’s seismic activity maxima were predicted for the period from 1963 to 1995. I. V. Ananyin and A. O. Fadeev in their works (2002) come to the conclusion about the existence of correlation between seismic activity variations, average annual temperatures at Earth’s surface and solar activity. They see this correlation as a possible basis for the solar activity impact on both average annual temperatures and seismic activity.
I. K. Gribin in his work (1974) examines the causes of the devastating 1982
V. M. Lyatkher’s study indicates that the course of changes of the average interval between large earthquakes corresponds to solar cycle length variations. It is pointed out in particular that a quasi-periodic component with a period of about 60-100 years is observed in solar activity variations. The discovered correlation between solar activity and the frequency of large earthquakes suggests that local seismicity characteristics identified on the basis of time-limited statistical material can also vary in time with about the same periodicity as the smoothed solar cycle lengths.
John F. Simpson (1968) considers solar flares to be a trigger for large earthquakes in areas where the mechanical stresses have reached the critical values. However, he points out that solar flares should not be seen as an earthquake-causing factor.
It should be noted that there are also studies that have found no clear relationship between Earth’s seismicity and solar activity. For instance, Van Gils who has analyzed more than 20000 weak earthquakes between 1910 and 1945 declared the absence of any relation between solar activity and low seismicity.
Chinese scientist Gui-Qing Zhang (1998) concluded that earthquakes often occur around the minimum years of solar activity. In the peak years of solar activity, the number of earthquakes is relatively lower than around the peaks.
A study by a group of scientists (S. D. Odintsov, G. S. Ivanov-Kholodnyi and K. Georgieva, 2007) showed that the maximum seismic energy released by earthquakes within the 11-year solar activity cycle is observed during the cycle’s decline phase and before its solar maximum. They found that the maximum in the number of earthquakes directly correlates to the moment of sudden increase in the solar wind velocity.Of certain interest is, in our view, a work by K. Schulenberg (2006, http://theraproject.com/sitebuildercontent/sitebuilderfiles/WPGMpresentation.pdf) taking a non-standard approach to the sun’s possible effect on earthquakes. It reveals quite a convincing statistical relationship between the periods preceding sunrise and following sunset, and large earthquakes in
Fig. 49. Comparison of large earthquake caused fatality numbers graph
(white) with solar activity graph (blue). By E. N. Khalilov, 2010
Fig. 49 shows a comparison of graphs for solar activity (Wolf numbers) and for the number of killed during strong earthquakes from 1900 to May 2010. Even a cursory glance at the graphs reveals a high correlation. The more detailed analysis allows us to notice that, except for solar activity cycles #21 and 23, the remaining cycles correspond to the higher numbers of dead. A very high maximum of 1977 fatality numbers occurred at the beginning of the 21st cycle whose maximum was in 1980 while the maximum number of 2004 deaths falls on the end of 23rd solar activity cycle.
Obviously, the correlation between numbers of dead during large earthquakes and solar activity implies the existence of a similar link between large earthquakes and solar activity.Fig. 50 contains a comparison of graphs for numbers of large magnitude (М>8) earthquakes and solar activity for the period from 1900 to May 2010. The large earthquakes graph is drawn with 5-year running averages. The high correlation between the two graphs can be seen even at primary visual analysis. Of 10 reviewed 11-year solar activity cycles, only two (16th and 17th solar activity cycles) do not coincide with the cycles of increased numbers of large earthquakes.
Fig. 50. Comparison of large (M>8) earthquake numbers graph (red)
with solar activity graph (blue). By E. N. Khalilov, 2010
In some cases, there is a slight misalignment between the solar and seismic activity cycles. For instance, the seismic activity cycle is shifted by 2 years towards the end of the 19th solar activity cycle. Nevertheless, in general, the picture of the high correlation between these two processes is quite impressive.
Fig. 51. Comparison of large tsunami numbers graph (yellow)
with solar activity graph (blue). By E. N. Khalilov, 2010
Large earthquakes are known to be closely associated with tsunamis, which usually result from strong earthquakes in the aquatic environment. Fig. 51 contains a comparison graph for solar activity and large tsunamis. As can be seen from the comparison, most powerful tsunamis have occurred during high solar activity times, that is, during solar activity cycles #16, 18, 19, 21, 22, and 23.
- From 1980 to present, the North Magnetic Pole’s drift velocity has increased by more than 500%. This might indicate the beginning of an increase in Earth’s geodynamic activity since Earth’s magnetic field is formed as a result of complex energy processes in its inner and outer core.
- It has been established that variations of the angular velocity of Earth’s rotation are correlated with the solar constant trend.
- A correlation between the solar and volcanic activity trends has been found.
- A direct correlation has been discovered between solar activity (11-year cycles) and the numbers of large earthquakes, of fatalities during large earthquakes, and of tsunami.
These conclusions are provisional and intended for better understanding of the research findings presented in the following sections.