2.1. GLOBAL CHANGES OF EARTH’S SEISMIC ACTIVITY
Fig.6 contains a graph showing the alarming dynamics of deaths caused by strong earthquakes.
Thus, the substantial increase in the number of victims of strong earthquakes in the last decade has become evident and this tendency continues to grow.
Neftegorsk, Russia, devastated by an earthquake, 27.05.1995
(Photo by Igor Mikhalev, STF, http://visualrian.ru/images/item/8769)
Earthquakes are among the most dangerous natural disasters on our planet. This is due primarily to the fact that they occur suddenly and cause massive destruction within tens of seconds, resulting in huge death tolls. The destruction of buildings and other structures created by people is the main cause of fatalities during earthquakes.
Over 90% of the world’s earthquakes take place at the boundaries of large and medium lithospheric plates and microplates. The most powerful earthquakes occur at the edges of plates subjected to subduction, active collision, or transform faults. A classic transform fault example is San Andreas, a gigantic fissure about 1300 kilometers (810 miles) long running across the western part of California in the United States and forming the tectonic boundary between the Pacific and North American plates.
Fig. 7 has a world map showing the epicenters of earthquakes that occurred from 1963 to 1998.
Fig. 7. Epicenter map for world earthquakes from 1963 to 1998
In fact, the global earthquake epicenter map reflects the lithospheric plate boundaries and is taken as a basis when mapping the tectonics of lithospheric plates.
Fig. 8 contains a graph showing the dynamics of the numbers of catastrophic earthquakes with magnitude greater than 8.
The graph clearly demonstrates that for 110 years, two periods of an abnormally high occurrence rate of catastrophic earthquakes stand out, the first of which covers the period from 1945 to 1948, and the second of which covers 2003 to 2010, with the second peak being higher than the first one by 33%. The trend characterizing the general tendency of dynamics of catastrophic earthquakes also indicates their significant intensification in the last decade.
Note, however, that devastating earthquakes with magnitude greater than 8 are rare enough, while 6.5 to 8 magnitude earthquakes hit the Earth quite frequently.
The number of people killed during strong earthquakes often amounts to tens and even hundreds of thousands of people. Here are examples of some major earthquakes in recent years: Eastern Iran (Bam), 2003 – 31,000 dead; Sumatra island, 2004 – 227,898 dead; Pakistan, 2005 – 86,000 dead; China (Sichuan), 2008 – 87,587 dead; Haiti, 2010 - 222,570 dead.
Fig. 8. Graph for M>8 earthquakes
(by E. Khalilov, 2010, according to USGS data)Annual number of earthquakes graph is marked in bluePolynomial trend of sixth degree is marked in red
Experts identify two primary factors responsible for the high casualty rate:
- Seismically unstable buildings and structures that collapse causing numerous casualties;
- Lack of predictive information about potential strong earthquakes, catching public services and people unaware when an earthquake strikes, leading to them being unable to make quick, correct decisions to reduce the number of casualties and economic damage.
Generally, it is the high cost of earthquake resistant construction technologies that hampers earthquake engineering. In many densely populated countries located in seismically hazardous regions, most people do not have enough funds to build or buy expensive seismic-resistant houses. The governments, in their turn, are too short of economic resources to construct seismic-resistant buildings for social, medical, educational, and administrative institutions.
The growing number of earthquake casualties directly correlates to the increased number of strong earthquakes with a magnitude greater than 6.5. A magnitude 6.5–7 earthquake in underdeveloped countries could cause much more damage and more casualties than a similar one hitting industrialized countries. For instance, the 2003 Eastern Iran magnitude 6.6 earthquake claimed the lives of 31,000 people.
Strong earthquake, Beichuan, Sichuan Province, China, 10 June 2008
However, a magnitude 7.2 earthquake struck the northern part of the Japanese island of Honshu on 13.06.2008, resulting in two people being killed and 100 injured. The consequences of these two earthquakes are incomparable. So, what is the reason why there were so many victims in Iran and only a small number of casualties in Japan? It is the difference in the construction technologies. In Japan, they use seismic resistant building construction technologies while in Iran, the vast majority of houses are built of bricks or building blocks made of a mixture of natural clay and hay, and are easily destroyed by earthquakes with a magnitude over 6.0.
Of course, catastrophic earthquakes with a magnitude over 8 may entail a huge death toll even in industrialized countries like the U.S., Japan, Canada, etc.
One of the worst natural disasters in the history of humankind is a catastrophic earthquake of enormous energy with a magnitude 9.1-9.3 that occurred 26 December 2004, with an epicenter off the west coast of Sumatra (the Sumatra-Andaman earthquake).
The subduction-caused earthquake triggered a series of devastating tsunamis along the entire Indian Ocean coast. The earthquake and tsunamis killed more than 230,000 people in 14 countries. The height of the waves in the coastal areas reached 15 meters (50 feet). This earthquake’s duration was longer than any other ever witnessed by man, lasting between 8.3 and 10 minutes.
Earthquake and tsunami aftermath, Sumatra, Indonesia, 26 December 2004 http://www.nomad4ever.com/2007/11/23/psychic-predicts-devastating-sumatra-earthquake-for-23122007/
The main earthquake’s hypocenter was located in the Indian Ocean, about 160 km (100 miles) north of the Simeulue Island, off the western coast of northern Sumatra, at a depth of 30 km (19 miles) below the mean sea level. The Sumatra-Andaman earthquake was the largest earthquake since 1964, and the second strongest since the Kamchatka earthquake of October 16, 1737. Since 1900, only one other earthquake has had greater energy, the 1960 Great Chilean Earthquake (magnitude 9.5).
The major magnitude 7.1 earthquake that hit Haiti on 12 January 2010 was one of the most devastating in the history of humankind. The earthquake resulted in an enormous death toll, killing 222,570 and injuring 311,000 people. The estimated material damage suffered is 5.6 billion Euros (Wikipedia). On the day of the earthquake, Haiti’s capital Port-au-Prince saw destruction of thousands of residences and almost all of the hospitals. About 3 million people became homeless.
The major reason for the huge number of victims is seismically unstable, mostly brick, houses.
Aftermath of Haiti earthquake of Jan. 12, 2010
Photo © AFP from Vesti.kz archive (http://vesti.kz/crash/37197/)
The catastrophic Haiti earthquake indicates a direct dependence of the number of earthquake casualties on the quality and seismic resistance of buildings and structures. Once again, the vivid example described above comes to mind; that is, a similar magnitude (M7.2) earthquake in the northern part of the Japanese island of Honshu in June 2008, which killed only 2 people.
A very powerful magnitude 8.8 earthquake occurred on 27 February 2010 off the coast of Maule (Chile). Six regions of Chile that are home to 80% of the country’s population felt tremors from the earthquake. Although this earthquake’s energy was much higher than that of the Haitian earthquake, it killed far fewer people.
Fig. 9 shows a graph reflecting the dynamics of the monthly number of earthquakes with a magnitude over 6.5.
Fig.9. Graph showing monthly number of M>6.5 earthquakes
from January 01, 1977 to April 30, 2010
(by E. Khalilov, 2010, according to USGS data)
Monthly number of earthquakes graph is marked in yellow;
Straight-line trend is marked in blue;
Trend enveloping extreme values of earthquake numbers is marked in lilac;
Blue dots designate peak values of earthquake numbers in cycles, starting from value 10.
The straight-line trend clearly indicates the increase in the number of earthquakes from 1977 to 30 April 2010. Meanwhile, the trend enveloping the extreme values of numbers of earthquakes for different months points to the exponential nature of the tendency observed, thereby greatly aggravating the situation.
Thus, the statistical analysis of the dynamics of the monthly number of earthquakes with a magnitude over 6.5 indicates a persistent tendency of growth in the number of strong earthquakes from 1977 to May 2010.
2.2. GLOBAL CHANGES OF EARTH’S VOLCANIC ACTIVITY
Sarychev Volcano eruption (Kuril Islands) of 12 June 2009
Volcanoes are one of the most formidable, yet most interesting and mysterious formations on our planet. The word “Volcano” was derived from Vulcan, the name of a “god of fire.” Volcanic eruptions and earthquakes are different forms of manifestation of the same process, which is the Earth’s geodynamics. They are unique indicators of rises and falls in our planet’s tectonic activity.
Similar to earthquake dynamics, the dynamics of volcanic eruptions is subject to certain cyclicity. Analysis of the volcanic eruption rate evolution shows that from 1900 to June 2010, a tendency for the number of volcanic eruptions to grow has been observed. This is explicitly seen in the graph of the annual volcano eruption rate, shown in Fig. 10. Three deep minimums stand out in the volcanic activity: 1916-1918, 1941-1942, and 1997-1998. These minimums are limiters for volcanic activity cycles. The current cycle of volcanic activity began in 1999.
Fig. 10. Graph of the world’s volcano eruptions from 1900 to June 2010
(by E. Khalilov, 2010, according to Global Volcanism Program data)
Annual number of volcanic eruptions is marked in yellow;
Trend based on 7-year running averages is marked in blue.
At the same time, as shown in Fig. 11, the straight-line trend characterizing the general tendency of the evolution of volcanic eruption numbers also indicates an increase in the number of volcanic eruptions from year to year.
Analysis of the distribution of world volcanoes shows that they are situated mainly in the Earth’s narrow, tectonically active zones, as shown on the map in Fig. 12. The vast majority of the world’s volcanoes, as well as earthquakes, are located along tectonic plate boundaries. Accordingly, volcanoes are divided into two basic types: subduction zone volcanoes and rift zone volcanoes.
Fig. 12. Map of global volcano distribution
Subduction zone volcanism is a mixed explosive-effusive volcanism, of basic to acidic but mainly of neutral composition. All volcanoes of the western edge of the American continent and of the eastern edge of the Asian continent, as well as those in adjacent island arcs, the Mediterranean Sea region, Indonesia, Aleutian Islands, Japan, Kamchatka, etc. are all examples of this type of volcanism.
The second type comprises volcanoes of mid-ocean ridges and continental rift zones. For the most part, it is tholeiitic effusive submarine volcanism of mid-ocean ridges and volcanic islands seated upon them, such as Iceland or the Azores. Continental volcanoes located, for example, in the Red Sea, East Africa, etc. are also rift zone volcanoes.
In addition to those mentioned above, there is another type of magma volcano that is an oceanic intraplate volcano. These are located in the interior parts of plates, for example, the volcanoes of Comoros and Hawaii.
There is another, though less common, type of volcano that is a mud volcano with breccia as the eruption product. This type of volcano is discussed in the next section.
Volcanoes are active, dormant, or extinct. Extinct volcanoes are those that have retained their shape but there is just no information as to their ability to erupt. However, local earthquakes continue to occur beneath them, indicating thereby that they may awaken any time.
Many modern volcanism areas coincide with high seismic activity zones, which is quite natural. A volcanic earthquake can be identified by the concurrence of the earthquake’s focus with the volcano’s location, and a relatively low magnitude.
The earthquake that accompanied the 1988 Bandai-San eruption in Japan is an example of a volcanic earthquake. After the earthquake, a powerful volcanic gas explosion shattered a whole andesite mountain 670 meters high. Another volcanic earthquake accompanied the 1914 Saku Yama volcano eruption, also in Japan.
The same year’s volcanic earthquake at the Italian volcano of Ipomoea ruined a small town of Casamicciola. There are numerous volcanic earthquakes in Kamchatka related to the volcanic activity of Klyuchevskaya Sopka, Shiveluch and other volcanoes. Manifestations of volcanic earthquakes are almost indistinguishable from the phenomena observed during tectonic earthquakes, but their scope and energy are much smaller.
As a rule, magma volcano eruptions are preceded by a series of small earthquakes with power increasing as the eruption approaches. Preparations for a volcanic eruption and its duration can last for a few years to centuries. The movement of high-temperature magma during eruptions causes numerous strokes and fissures in the crust, manifesting themselves in the form of medium-size and sometimes strong earthquakes.
The history of humankind has seen many strong volcanic eruptions that have claimed thousands of lives. But perhaps the most tragic of them is the eruption of Mount Vesuvius on Aug. 24, 79 AD, which lasted for about one and a half days. The eruption was accompanied by a vast ejection of rock and ash through the volcano vent, which rose several kilometers into the air, subsequently covering huge areas. Violent tremors accompanied the event and air ionization reached its critical value, causing powerful lightning discharges and thunderclaps. Many took it for the end of the world.
Most affected was the beautiful nearby seaport of Pompeii, a major trading center. Within just one day the city of Pompeii was buried under 6-7 meters of volcanic ash and huge pieces of pumice, together with thousands of locals who were trying to escape in their residences and basements. The city fell into complete oblivion and rested under a huge layer of ash for one and a half thousand years until discovered during archaeological excavations.
Unlike earthquakes, catastrophic volcanic eruptions are capable of causing planet-wide climate change. This is exemplified by the monstrous eruption of Krakatoa.
A very powerful volcanic earthquake accompanied the Indonesian Krakatoa volcano eruption of Aug. 26, 1883. A colossal explosion blasted the volcanic cones – the Danan and Perboewatan mountains – to pieces. The sound of the explosion was heard in Australia, at a distance of some 3,600 km, and even on the remote Indian Ocean island of Rodrigues almost 5,000 km away. It is estimated that over 18 cubic kilometers of rock was raised into the air. Ash fell on 827,000 square km. In Jakarta, the major city of the island of Java, volcanic ash completely eclipsed the sun, causing pitch darkness. The finest dust reached the stratosphere where it spread across the entire planet, causing unusually bright sunsets and twilights in all countries. It took years before the fine dust from the upper layers of the atmosphere settled on the land once again. As a result of the partial screening of solar radiation, average annual temperature over large areas of the Earth dropped by several degrees.
Krakatoa eruption, Indonesia
The tremendous explosion caused not just a huge air shock wave but also a gigantic tidal wave – a tsunami up to 40 meters high that devastated many islands and coasts within its reach.
The explosion destroyed half of the volcano itself, and the subsequent tremors caused fierce earthquakes that ruined towns located on the islands of Sumatra, Java, and Borneo. The entire island’s population was killed, and the resulting tsunami swept away every living thing from the low-lying islands of the Sunda Strait. In total, more than 36,000 people died during that eruption.
One of the parameters for monitoring volcanic areas’ conditions is seismic observations. In addition to all other manifestations of volcanic activity, micro-earthquakes make it possible, on the computer screen, to track and model magma movement in the volcano interior, and to establish its structure. Catastrophic earthquakes are often accompanied by increased volcano activity (as in Chile and Japan), but the beginning of major eruptions can also be accompanied by strong earthquakes (for example, Pompeii during the Mount Vesuvius eruption).
Icelandic volcanic syndrome or global international training
The beginning of 2010 coincided with a series of very powerful earthquakes and volcanic eruptions. The most symbolic events were devastating earthquakes in Haiti on January 12, 2010 and in Chile on February 27, 2010, as well as the eruption of the Icelandic volcano of Eyjafjallajokull on March 20, 2010.
Geologically, the island of Iceland is very young. Having emerged in the Tertiary period, it is of volcanic origin and located on the Mid-Atlantic Ridge.
The eruption began on the night of March 20, 2010 and went through several stages. This eruption cannot be called a common eruption, for it marked the beginning of activation of the spreading process along the boundary between the North American and Eurasian lithospheric plates. This is evidenced by the fact that after the volcano had become active again on 1 to 4 April 2010, a strong magnitude 7.2 earthquake occurred on 4 April 2010 at the point where the southern coast of California meets the northern coast of Mexico.
Eruption of Eyjafjallajokull in Iceland, 13 April 2010
On March 25, due to melted glacier water that had found its way to the volcanic crater, there was a steam explosion in the crater, after which the eruption entered a more stable phase. On March 31, around 19:00 pm (Icelandic time), a new, 0.3 km long crack opened approximately 200 meters to the north-east of the first one.
On April 13, a new eruption started at the south edge of the central caldera. A column of ash went as high as 8 km into the air. About 700 people were evacuated. During the day, the meltwater flooded a highway and some destruction followed.
According to experts, the emission of massive amounts of volcanic ash to immense heights in the atmosphere threatened air traffic and caused suspension of airports’ activity in many European countries. All of that caused a large amount of damage to transport companies, airports, tourist companies, etc.
Meanwhile, according to several authoritative organizations, the actions of many European countries’ governments were uncoordinated and inadequate to the situation, indicative of disarray both at the national level in different countries and at the EU level as a whole.
According to Director General of the EU Transport Organization Matthias Ruth, untested computer software that simulates volcanic ash distribution caused the ban on flights. He called on EU leaders to consider adopting safety regulations similar to those in force in the U.S.
As ICAO head Giovanni Bisignani stated, “European governments made a decision without asking anyone for advice or adequately assessing the risk level. It is based on theoretical calculations and not on facts.”According to Alexander Neradko, head of the Russian Federal Air Transport Agency, there was an element of panic during the Icelandic volcano eruption related to the suspension of flights
Thus, the world gained its first experience as to possible development of events in case of a global natural disaster by the example of the Icelandic volcano eruption. However, humanity can hardly be deemed to have successfully passed the test which nature has put to it. It has become evident that lack of necessary international laws and coordinating centers in case of global-scale emergencies may lead to making inadequate and uncoordinated decisions, as well as to panic and chaos.
Given that the world that humankind inhabits is entering a high geodynamic and climatic activity phase, it is necessary to deeply analyze the development of the situation related to the emission of ashes by the Icelandic volcano, and to learn lessons from this experience.
2.3. MUD VOLCANOES
In terms of size and eruption energy, mud volcanoes are considerably inferior to magma volcanoes. This type of volcanism has attracted scientists’ attention for a long time. Mud volcanoes are located in tectonically active regions of our planet. It is noteworthy that Azerbaijan is home to over 300 mud volcanoes, about half of all the world’s mud volcanoes. Many of these volcanoes are genetically associated with hydrocarbon gases of Azerbaijan oil deposits.
As described by eyewitnesses, their eruption begins suddenly, with a subterranean rumble or thunderous roar. After a while, there is a release of mud volcanic breccia consisting of clayish mass with fragments of rocks of different stratigraphic ages. In most cases, hydrocarbon gas accompanying the eruption ignites spontaneously to form a pillar of flame a few hundred meters high (from 200-300 to 1000 m).
Studies conducted by Sh. F. Mehdiyev and E. N. Khalilov (1990) found that more than 90% of the Earth’s mud volcanoes are situated in subduction zones. This is seen on the map in Fig. 13.
Fig. 13. Location map of the world’s mud volcano zones and subduction zones
(by Sh. F. Mehdiyev and E.N. Khalilov, 1987)
1 – mud volcanoes location zones;
2 – subduction zones ; 3 – transform faults.
Mud volcano in Indonesia
The study of eruption dynamics of the world’s mud volcanoes has shown that over the last two hundred years the eruption activity of mud volcanoes has increased (Sh. F. Mehdiyev, E. N. Khalilov, 1984; Sh. F. Mehdiyev, V. E. Khain, T. A. Ismayil-zadeh, E. N. Khalilov, 1987; V. E. Khain, E. N. Khalilov, 2008, 2009)
Fig. 14. World’s mud volcanoes activity diagram
(by V. E. Khain, E. N. Khalilov, 2002)
Annual mud volcano eruption rate graph smoothed with 11-year averages is marked in black;
Straight-line trend is marked in red.
Along with the annual volcanic eruption rates curve reflecting the existence of cyclicity, a straight-line trend is shown on the diagram to characterize a stable increase in the activity of mud volcanoes from1800 to 2000 (Fig.14).
Brief overview and statistical analysis of a number of key indicators of the Earth’s geodynamic activity and its impact on humankind lead to a conclusion that there has been a significant increase in seismic and volcanic activity across the world, especially in the last decade. Analysis of trends in the numbers of strong earthquakes, volcanic eruptions, and fatalities during strong earthquakes allows us to conclude that all these indicators have soared since 2000.
At the same time, statistics for the first five months of 2010 show that this year marks the beginning of another unusually high volcanic and seismic activity cycle whose negative effects for humanity may be catastrophic.
Humankind has already gained its first experience in dealing with global consequences of a moderate-scale volcanic eruption in Iceland. Meanwhile, disproportionately large economic losses, and moral-psychological and social damage suffered by many countries are indicative of poor coordination of actions and lack of international laws and mechanisms ensuring effective governance during global emergencies of international significance.