Muzaffarabad Earthquake: Causes, Effects and Preventions

Earthquake is a natural disaster associated with the tectonic movements in the Earth’s crust, which are the major cause of earthquakes. As plates move in different directions with one another by tectonic forces, stress builds up in the interior of the earth. When the potential energy exceeds the kinetic energy, the rocks fracture and energy is released. Released energy in the form of seismic waves will then spread out from a point originated called focus, causing the ground to shake. This is an example of earthquake causes and effects essays which delves into the factors that trigger thus natural disaster, the profound impacts  and what measures should be taken for future preventions. 

The collapse of buildings and damages to infrastructures are common harmful impacts of earthquakes causing serious deaths and problems. Overall, death tolls in earthquakes can be attributed to three main causes: structural collapses, non-structural causes, and subsequent disasters. Among all, structural collapses account for 75% of deaths. The impact of building collapse is serious. During earthquakes, tremors of the ground lead to building collapse. The inner structure in buildings will be destroyed. People are often killed directly or being trapped. 

Case Study: Buildings Collapse in Muzaffarabad

Muzaffarabad, the capital in Azad Kashmir of Pakistan, is vulnerable to frequent earthquakes because it is located on the Alpine-Himalayan Belt. About 31% of the world's earthquakes occur in this region. Earthquakes are the most destructive natural disaster in Muzaffarabad. In 2018, Muzaffarabad occurs 12 times of earthquakes of magnitude from 3.6 to 5.8. Frequent earthquakes with high magnitudes cause severe destruction. The building collapse and damages to infrastructures require a longer time and high cost to recover from every occurrence. There will be more loss of life and property. People lost their homes and were displaced. Other earthquakes may occur before the damages caused by the previous earthquake are recovered. 

Muzaffarabad is less developed and the design of houses and buildings in urban and rural areas is often simple. Frequent earthquakes may weaken the building structure. Cracks occur easily in concrete during shaking. When the steel reinforcing bars are exposed to water and oxygen, they will be corroded, leading to the failure of the structure. Concrete that is subjected to long-duration forces is prone to creep as well. A total of 132,420 buildings were damaged in Muzaffarabad in Kashmir Earthquake, while over 115,000 were fully damaged. The damage of buildings is especially severe in this place. This causes a huge loss of life and affects the lives of citizens since most of their homes are destroyed. Large sums of money for reconstruction is necessary. Thus, it is important to find solutions to reduce the damages of frequent earthquakes that seriously affected the lives of residents and caused giant economic losses. Otherwise, people can barely alleviate pain about their loss and the displaced population may encounter difficulties.

Proposed Solutions: EDCC and Bio-Concrete

The two possible solutions to minimize damages caused by the collapse of buildings in earthquakes are the implementation of Eco-friendly Ductile Cementitious Composite (EDCC) and Bio-concrete. These two methods help strengthen buildings so that buildings will not collapse easily. However, they have different usages and materials.

EDCC is invented by Nemkumar Banthia and his research group at the University of British Columbia, Canada. It is a new type of concrete composed of fly ash, cement with polymer-based fiber and other industrial additives. Polymer-based fiber acts like steel in concrete but is more durable. PET fiber is a kind of polymer-based fiber added to EDCC. It consists of covalent bond which requires a lot of strength to break down. PET fiber possesses important characteristics of resistance to water and high strength-to-weight ratio. The tensile strength of PET fibers is 72.4 MPa, which is 18 times of concrete. These properties indicate the high toughness of PET. It has been tested when a 10-mm-thick layer of EDCC is sprayed onto exterior walls, the walls can withstand an earthquake of magnitude 9.0, similar to the quake that hit Tohoku, Japan in 2011. This shows that the fiber-reinforced design can prevent the concrete from fracture. While proneness to corrosion of reinforcing steel impairs the durability and longevity of concrete. Displaced by earthquakes, reaction of reinforcing steel with water and oxygen results in structural failure, causing damages to buildings. In regards to the use of EDCC, there is no need to rebuild the builds. It is sprayable on the exterior wall of the buildings and prevents buildings from collapse during earthquakes. EDCC helps strengthen buildings via enhancing the resistance of most walls against violent vibration. 

As a Preventative and Recovery Measure

Bio-concrete is a self-healing form of concrete that can repair its own cracks. The bio-concrete is mixed like regular concrete but with an extra ingredient acting as a healing agent. Bacteria are used to mix with the nutrients and matrix. By setting the bacteria and calcium lactate into capsules, once the cracks emerge in concrete and water gets in, bacteria will then germinate, multiply and feed on the lactate. They combine the calcium with carbonate ions to form calcite, or limestone, which closes up the cracks. It will return to the resting state after the cracks are completely filled. The processes are repeated under the same environmental conditions. Bio-concrete can be used when people build houses. Bacteria consume oxygen which prevents internal corrosion of reinforced concrete. This helps reduce the risks of buildings collapse during earthquakes. The durability of the concrete structure is increased by the self-healing effect. The number of fully damaged buildings can be reduced and thus the casualties. People have a higher chance of survival. They are protected from being killed easily because of building collapse. 

Apart from prevention, bio-concrete can be applied in rebuilding partially damaged buildings after earthquakes. The self-healing effect shortens the recovery time. Despite a long time for reconstruction as regular concrete, bio-concrete is more effective in reducing the damages to buildings in earthquakes. In addition, using bacteria that can survive the harsh environment of concrete maximizes the self-healing effect. One example is to use Bacillus bacteria because they are active in alkaline conditions and remain dormant in concrete for up to 200 years. Therefore, the response of bio-concrete is rapid and the effect is long-lasting towards the collapse of buildings in earthquakes. 

Comparison between EDCC and Bio-concrete

The proposed solutions are evaluated with a set of criteria to compare their advantages and disadvantages before their implementation. As both solutions help prevent the problem of building collapse, the effectiveness of protecting buildings during earthquakes is a major factor. The final solution should have higher effectiveness in strengthening buildings. The cost of the solutions should also be considered to determine which solution has a more reasonable cost for implementation.

A measure of effectiveness may be considered as the performance of each method to prevent building collapse and minimizes damages of buildings. The method that can strengthen buildings with fewer limitations may be deemed more effective for implementation. A study conducted to investigate the durability of EDCC indicated that fiber addition to the matrix helps increase the shrinkage resistance. With exposure to a harsh and hot extreme for 24 hours, no cracks were observed for EDCC fiber mixes while cracks up to 0.3mm were identified on the surface of plain mortar without fiber. On the contrary, bio-concrete can only seal cracks up to any length with a width less than 0.8mm. Though bio-concrete is useful in repairing cracks and shortening recovery time after earthquakes, the collapse of buildings is inevitable under violent vibrations and it costs a lot of time for reconstruction. However, a 10mm thickness of EDCC can simply be sprayed on the walls of buildings which would be enough to keep the wall intact for a major earthquake. Moreover, limestone-producing bacteria that grow in concrete are harmful to the environment because large amount of carbon dioxide is released but for EDCC, replacement of 70% cement with fly ash can reduce global greenhouse gas emissions from cement industry.

If thinking about the cost EDCC is cheaper than bio-concrete. Fly ash used in EDCC is a waste product of coal-fired power plants. It is half of the cost of standard retrofit. However, the  current cost of bio-concrete is high. A cubic-metre of the material will cost around €160 (approximately $A236) to produce while a cubic-metre for standard concrete costs €80 (approximately $A118). Although Bio-concrete can obtain payback by significantly lowering concrete maintenance and repair costs, the production cost is 2 times of standard concrete.

Also, large-scale reconstruction cannot be afforded by residents in Muzaffarabad. Cost-effectiveness is lowered by the use of bio-concrete. Bio-concrete involves the use of bacteria, so more scientific researches and endurance tests under various external conditions will be carried out, requiring more capitals. The low cost of EDCC as compared to both standard concrete and bio-concrete is prominent.

Evaluation and Final Recommendation: EDCC

Comparing the overall results, EDCC is more effective in preventing the collapse of buildings. It is convenient to use and the effect is significant that can reinforce the walls of buildings against shocks in strong earthquakes. The fiber used in EDCC is also more durable than reinforcing steels. In contrast, bio-concrete is only able to prevent the complete collapse of buildings. It is mainly used for recovery of damaged buildings but there are limitations regarding the negative effect to environment and the intensity of earthquakes. The damages of buildings could hardly be minimized overall. The cost of bio-concrete is too high for citizens. With greater positive effects and lowest price residents in Muzaffarabad can afford, EDCC is a more suitable solution than bio-concrete.

Earthquakes in Muzaffarabad brings constant harmful impacts to citizens. Many people die because of the collapse of buildings. Occurrence of earthquakes cannot be eliminated. Frequent earthquakes only bring more casualties and pain to ppl. In order to minimize serious consequences caused by natural disasters in the unknown future, prevention is needed. Also, repairing the damage could be costly but more importantly, lives will be at risk. Therefore, the city should use EDCC which can be afforded by ppl in construction to effectively strengthen buildings so that buildings would not collapse easily during earthquakes.

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