Vol.3, No.6, 436-443 (2011) Natural Science
http://dx.doi.org/10.4236/ns.2011.36060
Influences of solar cycles on earthquakes
Marilia Tavares, Anibal Azevedo
1Instituto de Fisica, Universidade Federal Fluminense, Niteroi, Brasil;
2Departamento de Matemática, UNESP Faculdade de Engenharia, Sao Paulo, Brasil
Received 6 February 2011; revised 10 March 2011; accepted 5 April 2011.
ABSTRACT
This paper inspects possible influence of solar
cycles on earthquakes through of statistical
analyses. We also discussed the mechanism
that would drive the occurrence of increasing of
earthquakes during solar maxima. The study
was based on worldwide earthquakes events
during approximately four hundred years (1600-
2010).The increase of earthquakes events fol-
lowed the Maxima of Solar cycle, and also de-
pends on the tectonic plate location. From 1600
until 1645 events increased during the Maxima
in some of the tectonic plates as Pacific, Ara-
bian and South America. The earthquakes ana-
lyzed during two grand solar minima, the
Maunder (1645-1720) and the Dalton (1790-1820)
showed a decrease in the number of earth-
quakes and the solar activity. It was observed
during these minima a significant number of
events at specific geological features. After the
last minima (Dalton) the earthquakes pattern
increased with solar maxima. The calculations
showed that events increasing during solar
maxima most in the Pacific, South America or
Arabian until 1900. Since there were few records
during these three centuries we needed addi-
tional analysis on modern data. We took the last
four solar cycles events (1950-2010) and made
similar calculations. The results agreed with the
former calculations. It might be that the mecha-
nism for the Sun-Earth connection relies on the
solar wind speed. In both records (1600-1900)
and (1950-2010) the results showed a significant
increase in earthquakes events in some of the
tectonic plates linked to solar maxima. The So-
lar wind energy striking the Earth’s magneto-
sphere affects the entire environment because
the pressure on the region increases and the
magnetosphere shrinks sometimes four Earth’s
radii. This sudden compression causes earth-
quakes in specific plates. During the times of
solar minima the pressure from the solar wind
on the earth decreases, then the magnetosphere
expands and earthquakes happen in a different
pattern according to the geological feature on
earth’s surface less frequently. Solar driven
events include coronal mass ejections (CME)
and coronal holes, which are at a maximum
during the descending phase of solar activity.
The tectonic are important because there is he-
terogeneity in the crust and the tectonic stress
depends on each region. The geo-effectiveness
of solar wind from a coronal hole only depends
on the position of the hole relative to the Earth
and for the CMEs an additional factor is their
velocity. The influence of these solar events
could be detected from electromagnetic varia-
tions on the ground prior the earthquakes. The
goal in this research was to show the solar
events influenced the earthquakes and seis-
mologic events following some special display
and also how the Sun’s activity played to make
earthquakes increase. This paper discussed
details of this mechanism, calculations and as-
sociated factors.
Keywords: Solar Cycles; Earthquakes; Currents;
Geomagnetic
1. INTRODUCTION
Sun-Earth connections, are complex and involve, solar
wind, ionosphere and ground. Ritz [1] and Serrano et al.
[2] have investigated the relationship between the solar
activity and earthquakes. The first aim on this paper is to
show a possible connection between sunspots and earth-
quakes. After studying earthquakes in Italy, Mazzarella
et al. [3] thought that seismi city is related to solar activ-
ity and that geomagnetic anomalies are likely to trigger
earthquakes.
Han Yanben, Zengjian, Jinbing and Lihua [4] studied
the relationship between big earthquakes (Ms ≥ 8) and
solar activity that occurred in China and western Mon-
golia. They discovered that the occurrence dates of most
of the big earthquakes in and near faults with west-east
strike are close to the maximum years of sunspot num-

M. Tavares et al. / Natural Science 3 (2011) 436-443 437
bers. According to their paper, the appearance of many
magnetic storms in years of maximum solar activityis
the cause an increased number of earthquakes. Magnetic
storms would result in anomalies of geomagnetic field
and in eddy current in the faults, producing earthquakes
with near west east strike. They supposed that initiation
of an earthquake occurs easily since the eddy currents
heat the rocks in the faults and therefore decrease the
shear resistance and the static friction limit of the rock.
Sobolev et al. [5] and Zolotov et al. [6] were interested
in the same subject. They investigated a supposed rela-
tionship between solar wind, particle radiation and
earthquakes.
Earthquakes have inhomogeneous distribution on the
Earth’s surface. The shallow earthquakes happen in areas
that are transform or divergent tectonic boundaries.
Convergent tectonic boundaries have intermediate, deep
and huge earthquakes. There are several parameters con-
sidered on this study such as tectonics, magnitude, depth,
and the heterogeneity in the Earth’s crust for each plate
considered.
Properties of rocks must be understood in addition to
the of electrical properties of igneous and high—grade
metamorphic rocks which make up the bulk of crust in
the depth range where most earthquakes occur, about 7 -
35 km. Freund and Hermance [7-9], showed different
sources of electrical charges generated by rocks. The
first aim of this research is to find out the possible con-
nections between the sunspot variations and their influ-
ence on the earthquakes. We research, search for the
mechanism that would involve Sun (during the Maxima)
and the intensification of earthquakes. Our theory in-
tends to explain the occurrence of earthquakes during the
solar minima as well.
During the minima of sunspots the earthquake events
are detected more often around specific geological fea-
tures such as slip strike faults or subduction zone.
In 2004 [10,11], a multinational consortium led by the
French government launched a new earthquake detection
satellite called DEMETER (for detection of electro-
magnetic emissions transmitted from earthquake re-
gions). DEMETER’s purpose is to study disturbances in
the ionosphere related to natural geophysical events such
as earthquakes, volcanic eruptions or tsunamis. Infrared
radiation detected by satellites may also prove to be a
warning sign of earthquakes to come. Sensors in
NASA’s Terra Earth Observing System satellite regis-
tered what NASA called a “thermal anomaly” on 21
January 2001in Gujarat, India, just five days before a
7.7-magnitude quake there; the anomaly was gone a few
days after the quake. Earthquake forecasters can also
watch for changes in the ionosphere by monitoring very-
low-frequency (3 to 30 kilohertz) and high-frequency
(3 - 30 megahertz) radio transmissions.
Gousheva et al. [12] also made some analysis with the
ionospheric perturbations related to the seismic activity
using the VLF radio signals collected with the DEME-
TER satellite. They monitored on the days of arrival of
high-speed solar wind. They noted a well-pronounced
maximum in the number of earthquakes seen on the day
of arrival of high-speed solar wind and one day after it.
This paper started the analysis of Sun-Earth events
with records from four centuries ago. After 1600statisti-
cal analysis of the data recorded worldwide was more
reliable, likewise for the sunspots recorded.
This study started before the two minima, Maunder
and Dalton, both occurred after 1600. During these two
periods it was possible to observe the importance that
tectonic plates played in the incidence of events. Our
calculations provided results for the entire period
(1600-1900) what included the maxima and the minima
occurred.
The monitoring of the frequency of sunspots and
earthquakes became accurate worldwide after 1900. This
circumstance allowed us to consider parameters such as
depth, magnitude and, location for earthquakes.
Analyzing in both periods (1600-1900, 1950-2010)
the variations in earthquakes and sunspot maxima or
minima suggested that probably electromagnetic distur-
bances from the outer space affected the ground.
Once an earthquake event starts, there is also a forma-
tion of new electric currents because of friction from the
rocks and material around the epicenter. It would explain
the observations of earthquakes in specific geological
areas such as fault, trench, and at the biggest one in scale
in subduction zones. There is a possibility that earth-
quakes happen in clusters. It means earthquakes in some
areas happen in a chain therefore we can predict them.
One must study the electromagnetic Earth’s circuit in
a system that will include ground, atmosphere, iono-
sphere, and Solar Wind interactions simultaneously. The
detection of ionospheric electromagnetic disturbances
prior to earthquakes is of paramount importance for a
future prediction and better understanding of Earth
events.
2. CALCULATIONS
Our initial calculations focused in the long period
from 950 A.D. until 1600 A.D. However, there was a
lack of information for both types of events (sunspots
and earthquakes) until 1600; it was not possible to make
any conclusions with the few data recorded. Therefore,
we choose to restart at 1600 AD for two reasons: solar
cycle and earthquake data files improved after 1600. All
the data in this study came from the National Geophysi-
cal Data Center (NGDC) there are earthquakes recorded

M. Tavares et al. / Natural Science 3 (2011) 436-443 438
since 2150 B.C. To work with the ancient data (before
1600) were impossible. We abandoned the data before
1600 AD.
Nevertheless, on average the earthquake number
available in the period 1600-1900 supplied enough data
for our first analysis and some results. During this period
1600-1900 there was two grand solar minima. One was
the Maunder minimum (also known as the prolonged
sunspot minimum), the name used for the period roughly
spanning 1645-1720, when sunspots became exceed-
ingly rare, as noted by solar observers of the time. Dur-
ing one 30-year period within the Maunder Minimum,
astronomers observed only 50 sunspots. It was not a lack
of observations, because some astronomers carried out a
systematic program of solar observations. The Dalton
minimum was a period of low solar activity lasting from
about 1790 to 1820.The Dalton minimum coincided with
a period of lower than average global temperatures. The
data recorded in the period 1600-1900 were enough to
preliminary information about the behavior of earth-
quakes and solar cycle evolution.
The earthquake events showed a decrease during the
two minima Maunder and Dalton. During both minima
the earthquakes took place in tectonic plates with special
geological features. It is alike solar cycles influenced
earthquakes variations. Next we show two tables con-
structed within the Maunder and Dalton minima, these
tables identified some events that happened in several
special geological features.
Table 1 shows the main characteristics of the plate
boundaries and tectonics in earthquakes during the
Maunder Minima. Divergent plates had small and shal-
low earthquakes; transform boundaries had large, shal-
low earthquakes; convergent boundaries evolve huge,
intermediate earthquakes, even in subduction zones,
which have the greatest depth earthquakes. Trenches are
subduction zones, such as the Marianna, Japan and Peru-
Chile. The Anatolian plates (Turkey) are a left lateral
transform fault. The Iranian system is important because
there is continent- continent collision and strong intra-
plate earthquakes. Most of those faults lies on shear or
transform boundaries. The largest amounts of late Ce-
nozoic shear are localized in faults in Sistan province, in
the far east of the country. This may mean that the pre-
sent-day rates of slip are highest in Sistan. An uneven
distribution of right-lateral shear across eastern Iran may
explain the initiation of the E-W Dasht-e-Bayaz fault
and the bending along the Doruneh fault to the north - as
more clockwise rotation of these E-W faults be expected
in the Far East. In China earthquakes happened in the
strike slip faults such as Sichuan. Earthquakes events
happened in the Pacific area and Arabian plates. Events
that happened in other plates were not enough and they
did not count on this paper [13,14].
Table 2 contains earthquake events, which ensued
during the Dalton minima. These events showed simi-
larities with the Maunder minimum events. Earthquakes
occurred around special land structures such as strike
slip faults and (or) trenches. For this period with low
solar activity we have compared the estimated value of
the sunspots to the number of earthquakes in this period.
The variations of solar activity and earthquakes both
decreased, which demonstrates that on the time-scales of
the order of three centuries, seismic activity followed the
solar activity. The outcomes obtained for the Maunder
minima corroborated the results for the Dalton mini-
mum.
The characteristics of the earthquakes during the Dal-
ton minimum (Table 2) revealed changes in South Pa-
cific, North Pacific, Arabian and South America plates-
decreased in activity.
Apparently during the Maunder minimum not enough
data were available from North America. However, the
earthquake events in other areas happened more around
specific geological features (strike slip faults, convergent
boundaries). The Dalton minima the events happened
more in strike slip faults around transform boundaries
and trenches for convergent boundaries.
In Eurasia most of the activity was around Italy and
Greece, with 88% of earthquakes in this area during the
Table 1. Characteristics of earthquake events during Maunder (1645-1720) minimum.
Event occurred during the Maunder Minimum
Location (plate) Event occurred vs
Total in each plate (%) Geological feature
South Pacific Phillipines-11/21- ~51% Manilla trench
Indonesia -10/21~47% Sumatran fault-parallel trench with parallel strike slip structure*
South East Pacific Peru-Ecuador-Chile-27/35-~77%Peru-Chile convergent trench
Japan -28/58-~48% Marianna, Japan trench
North Pacific China -24/58`~41% Strike-slip faults in china (Sichuan)
Iran -20/35-~58% Twelfve faults-sinistral, Dextral strike-slip*
Arabian Turkey -14/35-~40% Anatolia fault*
Note*: most faults are strike slip.

M. Tavares et al. / Natural Science 3 (2011) 436-443 439
Table 2. Characteristics of earthquake events during Dalton (1790-1820) minimum.
Event occurred during the Dalton Minimum
Location (plate) Event occurred vs
Total in each plate (%) Geological feature
Phillipines-3/12- ~25% Luzon trench
South Pacific Indonesia -8/12~67% Sumatran fault system*
Japan -12/28-~42% Marianna, Japan trench
North Pacific China -13/28`~46% Longmenshan fault*
Arabian Iran -10/11-~90% 14 fault*
Eurasia Italy -10/11-~50% S’ Angelo
Greece -10/26-~38% Atalanti, Aquae Lulia*
Chile, Peru -10/18-~56% South America fault*
South America Venezuela, Colombia-8/18-44% Strike slip, subduction zones
North America Missouri, Arkansas, California -8/19-42% New Madrid*, Saint Andreas fault Oaxaca fault*
*faults most Strike slip, transform boundaries or subduction zones.
period. Eurasia is a convergent boundary on the border
in Italy and Greece. In the Mediterranean area there is
even a little subduction zone responsible for deeper
earthquakes. Nevertheless, the earthquakes during the
Dalton minima were around the strike slip faults on
those countries. In the North American plate, the activity
was around the Pacific area, Mexico had some intraplate
earthquake in the Oaxaca fault (strike-slip).The activity
in California was in the San Andreas Fault. The earth-
quakes in Missouri and Arkansas were due to the New
Madrid fault, also a strike slip fault. We showed in those
tables the most important areas where the earthquakes
took place during these two periods. The two Tables
showed places and geological structures where most
earthquake events most happened in both minima. The
tables also show the percentage of the total number of
events and the number of earthquakes focalized in each
area during the period.
Figure 1 shows earthquake data (separated by plates)
in the crust during three hundred years.This figure
analyzed the data in five tectonic plates between 1600-
1900.The earthquake events have been influenced by
different processes depending on Earth’s crust. During
solar maxima the events increased most in Pacific,
Arabian and South America observed since 1600. The
same behaviour took place after the last minima consi-
dered and after the Daltonwas an increase in the earth-
quakes events in Pacific and South America plates. The
results showed that solar activity affected earthquakes in
different processes which depended on Earth’s crust.
During the grand minimas, earthquake activity
decreased and events were reported mostly in specific
plates and geological features, for example North and
South Pacific , South American (subduction zones) and
fewer events in Arabianplates (strike slip fault). The plot
shows how the events behaved during three centuries
1600-1900. This time interval included the two deepest
solar minima, the Maunder and Dalton minima as you
see at the Figure 1. There was a clear variation for each
plate considered, during the Maunder and Dalton min-
ima. In some plates the earthquakes almost disappeared.
Between these two minima earthquakes increased in
Eurasia (before Dalton) and in Pacific and Arabian (after
Dalton).The Maunder minimum coincided with the mid-
dle, and coldest part, of Little Ice Age during which the
world was subjected to bitterly cold winters. Qualita-
tively the number of earthquakes (in some of the tectonic
plates) increased and decreased following the same tra-
jectory of the solar cycles (maxima and minima). Quan-
titatively we would need more events detected to com-
pare both.
In order to find out the accuracy of these results, we
took as a sample a modern period (1950-2010) when the
earthquakes and sunspots have a huge amount of data
recorded. Despite of a possible lack of data during the
first period the modern data will validate or not the re-
sults obtained.
Finally, this study calculated statistically the distribu-
tion of earthquakes and solar cycles for the last part of
20th century and part of the 21st century. Figure 2 shows
the earthquake events during the last part of the last
century and part of 21st century. During each of the 5
solar maxima (1958, 1968, 1979, 1991, 2000) there was
a clear maximum of earthquake events for some tectonic
plates. During the last solar maximum (2000), earth-
quake activity increased on the Arabian, Eurasia and
North Pacific plates. Other plates (Caribbean, Africa and
South America) had fewer events. After 2005, in most of
plates, earthquake events decreased, even with better
data acquisition. This coincides with the decreased solar
activity. The increase of earthquakes depended on the
place they occurred, it depends most of heterogeneity in
the crust and also the geological variables such as if the
tectonic plate is transform, convergent, divergent even if

M. Tavares et al. / Natural Science 3 (2011) 436-443 440
Figure 1. Earthquakes shallowdepth in the period 1600-1900. Note the years of the two
minima, Maunder and Dalton, marked by M’s and D’s.
Figure 2. The last part of the 20th century (1950-2009): earthquakes events in Hemi-
spheres, South and North.
there was in a subduction region. The depth of an earth-
quake is an important parameter and it seems to influ-
ence the correlation between plates and events. The
highest correlation (Sun-Earth) is observed for shallow
earthquake events. In the period (1900-2010) there has
been generally higher solar activity with many sunspots
and CME’s.The instrumentation to detect earthquakes
became more sophisticated during this time. However,
some earthquakes may have been cause by underground
nuclear explosions. It was necessary to limit our data set
to some earthquake parameters, magnitude >4.0, inten-
sity >3.0, and by depth 7 - 35 km. In this paper we limit
the events in the crust, where 85% of earthquakes hap-
pen. The North and South Pacific, contain 70% of earth-
quakes observed worldwide, mainly around the subduc-
tion zones. Those locations are known by huge and in-
termediate events, and also the deepest, earthquakes.
Part of South America earthquakes is on the Pacific side
where there is a convergent boundary with subduction
zones. Eurasia which is part a convergent plate and part
transform or divergent, had decreased earthquake activ-
ity in recent years. Some plates did not change earth-
quake activity during most of the century, with very few
events recorded. Antarctica had just three events in the
20th century. The Caribbean plate had gaps of low activ-
ity or none. The South American remained steady.

M. Tavares et al. / Natural Science 3 (2011) 436-443 441
Comparing the events by Hemisphere, Southern is less
activity during the solar maxima than the Northern. An
anomaly behavior was the activity in Indo-Australian
plates where the number of earthquakes is growing even
after the last solar maxima observed. After 2005 most
plates analyzed even showed a decrease in the earth-
quake events. This paper uses data from only eight of the
plates since the other four plates have not had events
recorded continuously or even frequently.
Figure 3 shows the trend-line for earthquake events
during the last 60 years. The activity increased in the
period of sunspot maxima. It is calculated that a regres-
sion that would show a relationship among tectonic
plates. Probably some plates have an interconnection
with one another concerning earthquakes. They are
North Pacific depth 10 - 20 km, 20 - 30 km, Indo Aus-
tralian 10 - 20 km, Arabian 0 - 10km, Eurasia 10 - 20 km.
If plates appear to have correlated earthquake events,
then an earthquake in one of them induces one in another.
The trend line concerns the North Pacific plate and its
relationship with other plates. If an event happens in the
North Pacific plates the possibility is 31% there will be a
next event in other plates.
The connections among events are very complicated
to analyze; some event may possibly attached to another
one without sun correlation. If one event happens in on
plate it correlates other event in the nearby plate. This
point will be clear up with mathematical models that
give us the probability that one event happen in one or
another plate. It is also possible that some Sun storm
events disturb the ground and ignites a first earthquake
followed by a cluster.
At this point more studies are necessary since the
seismological community attention focused on me-
chanical processes as rocks deform as a macroscopic
body, on when and where micro cracks appear, what role
the water plays and intergranular water films when and
how seismic slip may occur. Seismologists need new
tools that can provide information before the rocks reach
the critical point of rupture. It is necessary to study pre-
earthquake events and seismological electromagnetic
waves before and after an earthquake.
3. RESULTS
We found that during solar minima earthquakes oc-
curred mostly along the strike slip faults that had had a
long rest, such as the New Madrid (1811-1812), Loma
Prieta (1989), Haiti (2010), [15,16]. Some major earth-
quakes happened during solar minima such as observed
by Akhoondzadeh et al. [17]. Besides the seismological
characteristics (they occurred in subduction zones or
strike slip faults), it looked connected with the variations
in the speed of solar wind. Let make a briefly analysis in
the New Madrid earthquakes. It happened 1811-1812 in
a chain of earthquakes. It happened in a minimum be-
tween the Cycle 5 and Cycle 6 those had a very few
number of sunspots during the maxima. They were the
two lowest maxima since 1700. We supposed that Solar
wind pressure has been feeble during this time and the
Earth surface released energy in places where the tec-
tonic was compatible with the observations during other
minima.
Finally, for the last half past of the 20th century (1960-
Figure 3. Earthquake events vs.yearscorrelation and regression line.

M. Tavares et al. / Natural Science 3 (2011) 436-443 442
2001) solar events increase agreed with higher occur-
rence of earthquakes in some of tectonic platesanalyzed.
A rough prediction would give us that earthquakes
should happen regularly in China around the Sichuan
fault system. In Iran or Turkey (around the Anatolian
fault), in South America (Peru-Chile trench), in Eurasia
particularly in the fault system in Italy (those earth-
quakes in Eurasia happened after more than ten years in
a sunspot minimum) in the North America trough of
New Madrid. During the sunspot maxima the earthquake
activity increased in different tectonic plates. However
in some tectonic plates events remained steady or did not
happen at all. This means that the increase of sunspots or
disturbances from CME events operate differently prob-
ably due to heterogeneity of Earth’s crust. Overall, in the
last 60 years the number of earthquakes increased in two
plates, North and South Pacific. During the last solar
maximum the number of earthquakes increased in sev-
eral locations such as Arabian, Eurasia and North and
South Pacific. These last five years or more (after the
maxima), events decreased in all tectonic plates com-
pared to the Sunspot maxima (in 2000).
Correlation and the regression factor calculations
during the last cycles (1960-2010) pointed to the possi-
bility the events are in association with each other. It
could happen in a chain or in a cluster of earthquakes in
the same area or different ones. A better mathematical
model is necessary. Particularly, events that happened in
the North Pacific are likely to happen in the South Pa-
cific as well. These results indicated a connection be-
tween events that make complicate the analysis of
earthquakes versus solar cycles. The effect that the tec-
tonic each plate plays on the earthquakes is of para-
mount importance.
4. SUMMARY AND DISCUSSIONS
There was a clear decrease in earthquakes for the two
grand solar minima examined and an increase in the
number of earthquakes for the last half of the 20th cen-
tury. This increase in solar events, called the Modern
Maxima, coincided with the intensification of earth-
quake events in several plates. More data is needed re-
garding the variations of disturbances in the ionosphere
caused by these variations (solar storms) in the solar
cycles and the variation concerning the dynamic pres-
sure. Dynamic pressure (Dp) affects the flux transfer
from the dayside to night side, and the depending of the
tectonic ground is important. Dynamic pressure is a
function of speed and density of the solar wind. Satel-
lites detect electromagnetic disturbances in the iono-
sphere and in regions such as the South Atlantic anomaly.
It is possible that these disturbances affect the ground
under that region. The main sources of high-speed solar
wind are solar coronal holes and coronal mass ejections
(CME’s). Satellite and ground-based instruments regu-
larly monitor them both and could make it able to fore-
cast periods of enhanced seismic risk. To be geoeffective,
the solar wind from a coronal hole or from a CME has to
first arrive at the Earth, so the geoeffectiveness of solar
wind from a coronal hole or from a CME depends on its
position relative to the Earth. For the CMEs an addi-
tional factor is their size and speed. Faster and wider
CMEs are more geoeffective [18,19].
Solar wind speed which causes more dynamic pres-
sure on Earth’s magnetosphere is the physical mecha-
nism which increases the number of earthquakes. Varia-
tionsin solar wind during a Coronal Mass Ejection event
can exert pressure, deforming and shrinking the magne-
tosphere by 4Re (Earth radius). The tension on magnetic
field lines is analogous to the tension on a violin string.
The pressure will affect the Earth surface in different
ways depending of the tectonic of each region; some
areas are more susceptible to release energy in a form of
earthquake or other analogous phenomena (such as vol-
canoes).
Nowadays, we know that earthquakes and volcanism
occur primarily in those zones where one plate is rub-
bing against the “fault lines”. Earth directed Coronal
Mass Ejections (CME) were very frequent during 2000-
2002. There was a continuous impact of huge amount of
energy, changing the Kp indices (planetary indices) and
free electrons in the upper part of the atmosphere. These
changes in Sun-Earth environment induced by the Sun
have changed the geosphere and atmosphere from time
to time.
A similar explanation for earthquakes happening dur-
ing the minima relies in the Solar Wind decreasing speed.
If the solar speed is lower the magnetosphere relax and
expands again, the consequences are that earthquakes
follow different trajectory this time. Earthquakes will
happen more in geological feature such as strike slip
fault or trenches (subduction zones). Finally, earthquakes
do not follow cycles as solar cycles because it depends
from the Earth’s structure and in fact, it happens in a
sequence determined by the plate and the geological
feature of each of them. It is difficult to find out a direct
connection Solar Maxima and ground since earthquakes
perhaps happening in clusters or related to each other. It
makes events less cyclic and interconnected depending
of the Earth structure of each region under surveillance.
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