Devastating earthquake in Kazakhstan both distant and imminent: Cambridge Professor09 сентября 2014, 14:22
Almaty city in southern Kazakhstan should study active seismic faults to be better prepared for a new devastating earthquake that is "more likely to happen than not", Cambridge University Professor James Jackson who came to Almaty to establish cooperation with local scientists is quoted by Tengrinews as saying.
The earthquake threat has always been a problem for Almaty. The 1.5-million-people city is located in the area where an 8-magnitude earthquake that can leave tens of thousands dead and hundreds of thousands injured and homeless is a dreadful but realistic scenario. So both people and authorities are eager to find our what ease can be done to minimise the aftermath of an earthquake like that.
Dr. James Jackson, 59, FRS, is Professor of Active Tectonics and Head of Bullard Laboratories, Department of Earth Sciences, Cambridge University. He made his name in geophysics, using earthquake source seismology to examine how continents are deformed. His central research focus is to observe the active processes shaping our continents.
Professor Jackson came to Kazakhstan to lecture in Almaty-based Satpayev Kazakh National Technical University on September 3-4 as part of Cambridge University's Earthquakes Without Frontiers project. Its goal is to collect the knowledge and expedience of scientists from all over the world and use it to minimise the aftermath of strong earthquakes.
The five-year study that commenced 3 years ago targets the Alpine-Himalayan belt stretching from Italy, Greece and Turkey, across the Middle East, Iran and Central Asia, to China. Kazakhstan's south is part of this belt.
The southern seismic active zone of Kazakhstan is a part of the North Tian-Shan ridge system. And Zailiyskiy Alatau mountains are located 15 minutes drive from Almaty, Kazakhstan's most populated city.
Earthquakes of small magnitude are fairly frequent in the area. And the maximum magnitudes of expected earthquakes range from 6.0 to 8.3.
Almaty city was destroyed by devastating earthquakes several times. In recorded history catastrophic earthquakes in Almaty took place in 1770, 1807, 1865, 1887, 1889 and 1911. In each of these earthquakes the city was heavily destroyed but was rebuilt every time.
Dr. James Jackson explained that earthquakes mostly occur in places of faults. Fault zones are areas of crustal stress where tension within the Earth stretches the crust to form a basin, or range, with fault-blocked mountains flanking the basin, or where compression squeezes the crust together as one block of land slides over another, forming overthrust mountains.
90% of earthquakes on the Earth are caused by deformations resulting from interaction of plates and are confined to narrow belts. These belts define the boundaries of the plates. The interiors of the plates themselves are largely free of large earthquakes, that is, they are aseismic.
However, active deformation is observed in the Tian Shan mountains that are located far from plate boundaries. As you can see on the map above, Kazakhstan and the Tian Shan range that has been causing the earthquakes in Almaty are located inside the large Eurasian Plate. So, according to the theory of tectonic plates no series of strong earthquakes like those recorded in 1770, 1807, 1865, 1887, 1889 and 1911 were supposed to happen in the area.
The theory or not, in practice this area in Central Asia is a seismically and tectonically active intracontinental spot that is developing between Tarim and Kazakh Platforms. And this contradiction of plate tectonic theory makes the Tian Shan a key place to study the dynamics of intracontinental deformation.
Earthquakes Without Frontiers project focuses mostly on three regions: Central Asia and Iran, Northeast China and Himalayan foothills because these are the areas of a large number of active faults that are causing strong earthquakes.
"There are no (tectonic) plate boundaries in Asia that is why earthquakes here affect large territories and are generated by a large number of faults," Professor Jackson said.
According to the Cambridge University Professor there are around 10 significant faults near Almaty city, and 2 of them were being studied as part of the Earthquakes Without Frontiers project to learn the processes going on under the Earth's crust, identify their role in the earthquakes taking place in the area and determine the magnitude of earthquakes they are capable of causing in the future.
Professor James Jackson said that it was impossible to predict earthquakes or prevent them, but it was possible to study the faults and use the data in city planning and architectural designs to minimise the damages and losses of human lives in the earthquakes that would happen.
When asked whether more devastating earthquakes had to be expected in Almaty, he said that another "earthquake in Almaty is more likely than not, and people have to be ready for it as much as possible".
Construction of earthquake-resistant buildings, raising awareness of the population and training of all the city's services to act correctly during earthquakes is the key to saving lives, he said.
"We have completed one of the field seasons in Kazakhstan and Kyrgyzstan" where we studied the aftermath of the 1911 earthquake and the faults it activated.
The two faults that the Professor was talking about have been the subjects of scrupulous scientific research and mapping for decades, because of their lengths and depth, and because they are active and pose a threat of new devastating earthquakes. They are both located along the Chon-Kemin-Chilik fault zone at the intersection between the Kazakh Platform and the Tien Shan fold belt.
European INCO-Copernicus program re-examined the area in 2001 and released the following two maps.
The first fault zone - Kemin Fault - is located around 50 km south of Almaty city in Kyrgyzstan. It was the one that caused the most remembered destructive earthquake that left Almaty in ruins in 1911, according to Professor Jackson.
The second fault zone - Chilik Fault - is located further off to the east along the same fault line. It was the source of another powerful earthquake that took place in 1889 near Chilik village nearly 150 km from Almaty.
The fault zones like this one (the Chon-Kemin-Chilik fault line) are formed as a result of infrequent but very strong earthquakes. And the probability of new earthquakes in the fault zones is high, Professor Jackson said.
For example, the 8.2 earthquake of 1911 created a network of surface raptures nearly 190 km long and activated six sections of the fault zone. The earthquake affected a total area of over 10,000 square km - a streak 200 km long and 70 km wide.
The 1911 earthquake killed 452 and injured 740 people. The number of casualties was relatively small for such a strong earthquake because it affected mostly unpopulated mountainous area. It leveled Almaty city to the ground, too, but the houses were mostly wooden at that time and only a little over 100 buildings were made of stone. This also reduced the casualties.
Since then the city has become larger, and high-rise stone, glass and metal buildings have replaced the 2-3 storey wooden structures. Almaty is the largest city of Kazakhstan with a population of nearly 1.5 million people now.
The city's authorities are well aware that it is located in an earthquake prone zone ranging from 8 to 10 magnitude, so a lot of attention is given to safety of the buildings and use of appropriate technologies in construction.
The last strong earthquake - the strongest in the last 50 years - occurred in the area on August 19, 1992. It was a 7.3 magnitude earthquake that originated from the same fault zone, but since the epicentre was around 130 km away from Almaty it was felt in the city as a 5-6 magnitude earthquake and caused no casualties or destruction.
An array of seismically active fault lines cross the city, mostly from the west to the east. This makes the city and its people an even more likely target for a devastating earthquake.
You can see the fault lines (in light blue) on the Almaty city planning map bellow:
Public awareness of the fault lines running below the city is high in Almaty, but according to Professor James Jackson many in Kazakhstan do not realise that the fault zone running south of the city in the mountains is no less important and probably more dangerous. So he recommended placing it's research and monitoring higher on the country's scientific agenda.
"High-rise buildings are sensitive to earthquakes that originate far away, even when low-rise building remain unaffected. But it also matters how the shock technically moves through the earth. Generally speaking, modern cities will tall buildings are more vulnerable to distant earthquakes than they were in the old days when buildings were low-rise," the Cambridge professor explained. "Almaty is as likely to be affected by an earthquake originating from a fault located in immediate proximity from the city or inside the city, as from a large fault located a distance away," he said.
"Some faults are easier to locate and study than others. It is easier to study faults in the mountains where the terrain is not build up with houses and other structures. We begin with the simplest ones to gain experience and better understanding, and to train the personnel to do the scientific work. We know there are faults in Almaty, but they are covered with buildings and are very difficult to study. Of course we would like to study them, we know they are dangerous, but they are not the only faults that matter. Almaty is vulnerable to the faults located far away, too. And we should use the opportunity and study what we can," Mr. Jackson said.
He pointed out that aftermath of earthquakes of similar magnitude varied from country to country. For instance, the 6.8 magnitude earthquake in Los Angeles, California in 1994 resulted in the death of 50 people, while the death toll of the 6.6 magnitude earthquake Bam, an oasis city in southeastern Iran in 2003 made 40 thousand people.
"Certainly, the main reason for such difference is the quality of housing construction,” Mr. Jackson said. “But there are also other factors, such as better understanding of the earthquake threat and study of faults, communication and exchange of knowledge in this field between scientists from different countries and higher awareness of the society," he continued, adding that countries like the United States, Chile, New Zealand and Japan were better prepared for earthquakes than countries like Iran, China, India, Turkey and Pakistan where death tolls of earthquakes have often reached tens of thousands.
"We should take a global approach to the problem of earthquakes. Central Asian countries have now also joined the project and we will be able to put together a world map of seismological zones that have already been studied. We hope that Kazakhstani scientists will also join our research. We want your students to become active participants of the project. Young people are very sociable and are good at finding common ground. There are no boundaries for science," the Cambridge professor said addressing the students and faculty in the Almaty technical university.
Studying the processes causing earthquakes takes both satellite data and field survey. Chile, the United State and Japan have been monitoring faults for decades to identify the patterns. But it is important that the monitoring is done in all the seismically prone regions, the British scientist said.
During his meeting with Almaty Mayor (Akim) Akhmetzhan Yessimov on September 3, Professor James Jackson said: "We would like to cooperate with Kazakhstan scientists in analysing the nature of earthquakes. Besides traditional seismology we have a large database of geological surveys made with the use of space technologies. Besides, we would like to train a young generation of scientists in Kazakhstan to exchange experience and information in the future. I am sure that Kazakhstan can become one of the leaders in seismological studies."
He offered the city administration to host a global conference on seismology under the aegis of Cambridge and Oxford universities and UNESCO in 2015. The Almaty Mayor supported the initiative and welcomed the expansion of ties between Kazakhstani and international seismology experts.
Almaty city is already cooparating with UNESCO in the field of seismology. A UNESCO-spearheaded seismology conference and workshop were held in Almaty in May this year for the first time in the post-Soviet space.
Earthquakes without Frontiers brings together the scientists from Cambridge, Durham, Leeds, Northumbria and Oxford Universities, the Overseas Development Institute and the British Geological Survey as well as researchers from Nepal, India, China, Kazakhstan, Kyrgyzstan, Iran, Italy, Greece and Turkey.
The project is funded by the UK’s Natural Environment Research Council and the Economic and Social Research Council.
By Tatyana Kuzmina (Assel Satubaldina contributed to the story)