Earthquakes on the Chamman and Chiltan Fault Lines in Quetta Pakistan Specifically in 1935 - Research Paper Example

? Earthquakes on the Chamman and Chiltan Fault Lines in Quetta Pakistan Specifically in 1935 Earthquakes on the Chamman and Chiltan Fault Lines in Quetta Pakistan Specifically in 1935 ? The twentieth century has bought a series of deformations that are earthquake related and lie in the western region of British India, now Baluchistan in Pakistan. Although there are still several catalogs of earthquakes that exist, the early events were in particular due to some errors, location biasness and incompleteness. Using original sources, it has been confirmed that more than a thousand earthquakes were macro-seismic locations and have assigned the MS magnitudes to the earthquakes since 1892. There have been 34 important earthquakes recorded in this reason of which one of the most significant one took place on 31st May 1935 (Erduran? et al., 2012). This earthquake took place at 3am in the middle of the night. It was known as the deadliest earthquake in South Asia. This was the most seismic region of Pakistan at the top of the Chamman and Chiltan fault lines. The earthquake lasted for three minutes but had several immense aftershocks. The tremors of the earthquake were felt a long distance away and the destruction was caused in all the towns near Quetta, the main city, including the city itself. The earthquake had killed 30,000 to 60,000 people in the region. The aftershocks, however, did not cause much damage in Quetta but in the surrounding regions. The scientists have found out the main causes of the earthquakes in Baluchistan from 1892 to 2001 and have analyzed the issues as a wide topic. Most of the research was based on the 1935 earthquake as it is marked as a few of the deadliest ones in the 20th century. The significance of this topic in the lives of the Pakistanis and Asians can be seen through various consequences and analyses made by the scientists. To develop the topic and introduce the issues, it is important to see what type of an earthquake it was actually. The earthquake was, as recorded in the new instruments, 7.7 MW while the previous instruments had recorded 8.1 MW which was a wrongly calculated amount. The epicenter of the earthquake was recorded to be 4.0 km from Ali Jaan, a town in Quetta. The focal depth of the earthquake was 17kms ?(Ambraseys & Bilham, 2003). ? According to the scientists these earthquakes took place in Baluchistan because of the fault lines in the region. It happened due to the two blocks of earth suddenly colliding past one another. The earthquake of 1935 is recorded to have no foreshocks which are the movements felt before the earthquake happened. Records show that there were no such claims. However, it is true that scientists cannot tell whether it is a foreshock before the main earthquake happens, but after the earthquake occurred in 1935, it was held that there were no foreshocks experienced. Even though there were no foreshocks, the earthquake had some unusual events recorded prior to the earthquake. It is true that scientists have not yet found a way in which the earthquakes can be predicted, yet they can analyze how and when they are most likely to occur in future. Quetta is said to be hit by the 1935 quake again in the near future however, the time can never be accurately told. The unusual events that scientists recorded before the earthquake were unusual bright lights, flashes of lights in the mountains, landslides, dust clouds and rock falls. Unusual events seem to be unjustified even after many years of research as the scientists say that earthquakes have very less to do with the weather changes. They cannot be predicted by any machines or instruments. They shake the earth’s surface because of the collision of faults. The Quetta earthquake was also a sudden event where hundreds of people were buried under the rubble because it was 3am in the morning and most of them were not awake to assess the emergency. The significance and further details of the earthquake are discussed later. However, this earthquake holds immense significance as it records one of the most severe consequences ever seen or experienced. These earthquakes had geological reasons that will be unfolded later but the scientists have plotted reports of the future assessments of earthquakes in the region. The reports of the previous earthquakes prove to be very helpful for the future analysts. The importance of predicting future assessments is because of the cultural and economical importance that the city holds. Quetta is a trading hub for Afghanistan and Pakistan as most routes go through Quetta. As the city is located at the main seismic zone and earthquakes are very closely recorded in the city and, moreover, there is immense cultural and economical importance that has to be protected, there is a keen need to assess the future reliability of the city (Ambraseys & Bilham, 2003). Through previous data collected by the scientists, the future analysts can make proper assessments and work on them to save the structure of the city. Quetta had been regarded as the targeted city of the earthquake risk and loss assessment. The main aim of this risk assessment in the city was to assess the damage and losses that can be seen in the potential future earthquakes so that the authorities and the public could be informed prior to the risk that they could face. It is important for an earthquake risk assessment to be reliable and so that it identifies the vulnerable buildings typologies. Scientists believe that the risk assessment of the past and the future earthquakes is the main reason why this topic is given much importance throughout the country. With the help of the information, data, and consequences and aftereffects, the scientists analyze and report the impacts of the possible severe earthquakes that could take place in the city affecting the cultural, social and economic grounds. Through that information, they predict the risks to the continuing activities of the city. It is true that past information gives a very clear view for assessing the risks to the scientists who tend to work for the betterment of the economic and cultural sustainability of a city. With the help of the data collected by the scientists, it could be analyzed where the geographical constraints of the earthquakes lied. The scientists were much concerned about the high magnitude earthquakes that happened in quite a while and how they affected the whole city and the functions. Thus, reports were made on the experiences before and after the earthquake that were recorded through many sources. Regarding the main earthquake in 1935, scientists found out that there were no foreshocks before the main shock, but the largest aftershock was 5.8 MW and it occurred in June 1935. That had caused much of the extra damage to surrounding towns such as Mastung, Maguchar and Kalat. Uptill October 1935, many smaller magnitude aftershocks were felt. This information was important in the future analysis and in the risk assessment necessary to make ?(Ambraseys & Bilham, 2003). In respect of the main shocks, the scientists had managed to collect information through the locals that the intensity was the most at the small region in the epicenter but it spread across the distant regions too. This was the primary information collected from primary sources which would help in the critical analysis and research methods of geographical and environmental reasons. The observations included the liquefaction in the northwest valley and mud volcanoes that erupted in this area. The latter mud volcanic eruption lasted for nine hours. The earthquake’s affects were felt stretching from the north to the south. In the present day Pakistan, it spread to Karachi, Dera Ismail Khan, Chagai, and as far as India and Afghanistan. Most of the risk assessments in the area for the future are made in regard to the three deadliest scenarios ever seen. These were the 1935 earthquake of 7.7 MW, four years earlier 6.8 MW in Sharigh and 7.3 MW in March the same year. However, these were incomparable to the 1935 one. Thus, all the risks and potential damages have been recorded or predicted under these three earthquake scenarios recorded by the scientists. The first scenario was recorded to show no damage to the buildings and population of the city. But its features are recorded and used for analyzing the risk and potential damage that could have been caused. The second and third were, however, much more severe and they led to similar damages and casualties. In these two, New Hazara Town in Quetta was the one to suffer the most damage and this was because it was the closest to the epicenter of the earthquakes leading to a higher ground notion; it had unfavorable soil conditions and the most vulnerable typology; the adobe buildings were prominent in this district (Erduran? et al., 2012). In a broader view, the macro-seismic information collected by the scientists showed the physical features of the region at the time of the earthquake. This region was inaccessible and it lacked large urban centers. The area had a low literacy level, and was responsible for a poor documented history that mentioned the earthquakes in the nineteenth century. The history of earthquakes before 1870 in Baluchistan has been vague and almost of no use, yet they did confirm that these events confirmed the seismic activity of the region. Some of the important details about the earthquakes were available after Quetta had been established as the military center, the railroads were built, and the geodetic surveys started in this region in the 1880s. The history of the events gave the identification to the seismic region after studying the moderate shocks in the early twentieth century. The scientists have been successful in noting the moderate and the large earthquakes, even though they have not been fully identified. However, for the moderate ones the epicenter was considered to be the focal point that was identified but for the ones that were deadly before the 1950s, the analysis and identification were made through the magnitude of the earthquake. These magnitudes are understandable for the tele-seismic locations. However, when the macro-seismic information was not available to determine the epicenters, the scientists located the epicenters through the location errors. There were several methods used by the scientists to determine and examine the earthquakes in Baluchistan. Firstly, they had used various techniques of primary research to identify the earthquake and its experiences. A series of surveys were carried out to understand the physical features of the earthquake that could be later related to the geographical constraints and the actions going on in the region. The surveys were carried out to record the first look of the earthquake witnessed by the locals and those who were present there. This information was collected through a number of places other than just Quetta, especially in the 1935 scenario, because the affects were felt till a long distance (Gunn, 2008). This information seemed reasonable for the scientists because on the basis of that they were able to make the risk assessments and the future analysis. For a detailed scientific research on the consequences and causes of the earthquake, many other methods were used. However, at times these methods are criticized because they were merely low quality techniques and tools used before 1950. In the present day analysis, the scientists may be able to find much of the information on these earthquakes in a fraction of a second. But for that time period, some of the best methods that the scientists could come up with were applied. As mentioned earlier, the macro-seismic information that was collected by the scientists needed formal methods to test the completeness. However, the best method for them was to test their implications. For this, the statistical techniques were not appropriate. This was because the statistical techniques stick to the inter-related events recorded, but this set of data included both the geophysical process information and the process of the events while being recorded. The previous data being from the 100 years long datasets, it is impossible to overlook the possibilities of the region and much of the records would be from the active period in the seismic activities. In case of the macro-seismic information not available through the test of completeness, the epicenter locations are determined from the location errors. These were available, after 1899, from the records of the international agencies which were the British Association for the Advancement of Science (BAAS), International Seismological Summary (ISS), International Seismological Centre (ISC) and U.S. Geological Survey (USGS). BAAS published the number of epicenters of the larger shocks for which the macro-seismic information used to determine approximate positions and times. The ISS determinations begun in 1918 and they usually varied in their accuracy and were supposed to be used with caution. These locations were categorized into three sections, the epicenters of which were properly calculated, the adopted epicenters which were adopted positions from old locations on assumptions of having the same origins, and the epicenters which were determined from the macro-seismic locations. The second and third categories may not be reliable and can be showing errors (Reitherman, 2012). The scientists have managed to use plenty of sources and methods to determine the location and the magnitudes of the earthquakes. These included the primary methods and the international methods as well. These methods changed immensely as the time changed and in the end some of the best scientists had assessed the reality of these earthquakes. It was important ,however, to not only go into the scientific details but also into the practical approach which was analyzed through the experiences of many. People were interviewed, surveys were held and many other techniques were used to gather the sets of primary data. In the same way, the ISS and BAAS along with other authorities have put together the datasets available from the analysis of this data and then they come to the conclusions ?(Ambraseys & Bilham, 2003). ? It has been analyzed that the macro-seismic information is the most reliable to determine the locations and the epicenters. The result of determining the epicenter will be the risk assessment that the scientists have to make in order to look into the future. The data sets of the previous earthquakes were found and it was concluded that Baluchistan has a ground notion where the earthquakes may be formed. This is a totally geographical aspect to the formation of the earthquakes. The research on the region also signifies the seismic movement and the depth to which it is occurred. These earthquakes were determined to be ruptured till a depth of 37km (Coburn, 2003). Furthermore, the results and the conclusions made by the scientists can be understood from the analysis and statements made by a well known scientist after the study of the information and events that took place in Quetta in 1935 and earlier. He has analyzed the present day situation of Baluchistan considering the previous quakes and is noted to have said that the machine records assessed that an earthquake of magnitude similar than the one in 1935 will attack Quetta in 2012. He confirmed that the GPS machines that are installed in areas such as Chaman, Shahrag, Kalat, Sorab and others have indicated the notion that the mountainous areas are in a continuous eight-millimeter annual movement towards the south. Due to this movement, great stress is being gathered under the soil. This would most likely cause the severe earthquake of a 7.5 magnitude. The scientist believes that these geographical reasons were the ones that hit Quetta with an earthquake in 1935. Even though now there are machines that indicate the symptoms, previously there were no such machines. According to one of the reports published on the conclusions drawn of the earthquakes, it was assessed and identified that Pakistan, Kashmir, India and Afghanistan were in the zones of high seismic activities. Earthquakes would occur in these regions because of the very active fault system in this wide region. But the more precise conclusion was drawn when it was found that the earthquakes in Pakistan were the direct result of the Indian region moving towards the north and having a collision with the Eurasian continent at a high rate of about 40 mm/yr. This is the major tectonic collision that is causing the uplift and produces the highest peaks of the mountains in the world including the Himalayan, the Karakoram and the Hindu Kush ranges. When the Indian plate moves towards the north, it becomes pushed by the Eurasian plate and beneath it. Much of this compression and motion in between these two plates and their collisions have been the reason of the major thrust faults present in the Earth’s surface and the mountain foothills that dip towards the north beneath the ranges, and it will continue to be this way. These thrusts are the Main Frontal thrust, the Main Central thrust, Main boundary thrust and the Main Mantle Thrust. These have a severe impact as the arc across the foothills in the northern India and enter in the northern Pakistan. References Ambraseys, N., & Bilham, R. (2003). Earthquakes and associated deformation in Northern Baluchistan 1892-2001. Bulletin of the Seismological Society of America, 93 (4), 1573–1605 Coburn, A. (2003). Earthquake protection. NY: John Wiley & Sons. Erduran, E., Magsi, M.A., Gill, M.A., & Lindholm, C. (2012). Earthquake hazard and risk assessment in Pakistan: Earthquake risk assessment of Quetta. NOSRAD report no 12/2. Gunn, A. (2008). Encyclopedia of disasters: Environmental catastrophes and human tragedies. London: Greenwood Publishing Group. Reitherman, R. (2012). Earthquakes and engineers: An international history. Texas: ASCE Publications. Read More