Comparative investigation of seismic hazards and approaches to mitigation - Essay Example

?Comparative investigation of seismic hazards and approaches to mitigation Introduction “A seismic hazard at a site is defined as a quantitative estimation of the most possible ground shaking at the site” (Datta, 22) Probabilistic approach or the deterministic approach is considered to obtain it. The possibility of the ground shaking is represented by “peak ground acceleration”, “peak ground velocity”, or “ordinates of the response spectrum”. The devastating earthquakes have been witnessed all around the globe, sometimes with shocking loss of life. The occurrence of earthquake in future is expected. The Asian countries are one of the most earthquake-prone nations in the world. To make sure that the infrastructure of the country and other losses caused by the natural catastrophe is minimized certain mitigation approaches are taken up by the countries. The devastating nature of the earthquake has made many countries carry on extensive research and development programs like hazard assessment and disaster response program. Japan- the seismic hazards and its mitigation approach The Seismologists in Japan are of the opinion that Japan is yet to face a large-scale devastating earthquake, which might strike the region of Kanto, Tokai and Nankai. Intensive efforts are being taken by the country to mitigate the disasters and minimize the economic impact of the earthquakes (Office of technology Assessment Washington Dc, 149). This has resulted into extensive research and development of disaster related programs to combat the earthquake. Japan is an “archipelago” in the Pacific, which is separated by the Sea of Japan from the east coast of Asia. The four main island of the nation are Honshu, Hokkaido, Kyushu and Shikoku. The nation is one of the most crowded and densely populated regions in the world. About 125 million people live in the cities along the coast. The closest neighbors of the nation are Korea, Russia and China. Japan is situated at a region where several continental plates like the Eurasian, the Philippine Sea, the Pacific Ocean and the North American plates converge- an important reason that the country faces frequent earthquakes and volcanoes. The largest earthquakes have occurred in the Philippine Sea and Pacific plates. Japan experienced the most devastating earthquake in the year 1923 on September 1st – the Great Kanto Earthquake. In the span of a minute 1 lakh people were dead and over 3 lakhs buildings were destroyed. The forces were so great that it lifted the southern bay as high as upto 2 m (6.6 ft) and also raised the distant land of Tokyo to 10 cm (4 in) and experienced a horizontal movement of 20cm (8in). The giant waves- tsunami that was generated by the tremor of the earthquake washed away ships inland and it swept people and houses out of the sea. The geographical situation of the country makes it earthquake prone- in one year it witnessed as many as 5000 earthquakes. After the devastating earthquake of 1923, the Japanese government imposed seismic codes based on the performance of certain buildings in Tokyo during that time. And it was after that there came in many advances in the earthquake engineering research, seismic codes and the construction practices of the city. The Japanese designing codes were a two-stage design process that was taken up. The first phase includes an analysis approach and the second phase involved an explicit assessment of the buildings, whether they will be able to withstand the severe ground motions. The construction companies in Japan spend a considerable amount on the research and development work annually including “testing of scaled building models in large in- house laboratories and research into passive and active control technologies” (Office of Technology Assessment Washington Dc, 149). The countermeasures taken up by the country included three important aspects- the making of the city more disaster resistant, strengthening the disaster prevention system of the city like tsunami warning system and raising awareness and finally promoting earthquake predictions. The Disaster Prevention radio communication network was linked to the agencies at federal, prefectural and municipal level. The local level governments were responsible for the adequate supply of water, food and medical aides to the victims. (Office of Technology Assessment Washington Dc, 149; Ikeuchi and Ichago; Fujiwara) Inspite of all this measures taken up by the nation; it was again in 1995 Japan witnessed a devastating earthquake- the Hyogoken - Nandu earthquake in 1995. The Earthquake destroyed 95 percent water front structures in the country. The earthquake made all argue on the inefficiency of the federal mechanism and led the nation take up some significant steps in combating the problem. The waterfront structures, which were typical in nature such as “gravity type quay” wall, were immediately rubble backfilled behind the wall. But filling up with such granular material could cause all the more harm, as they are vulnerable to deformation under “seismic load”. Another destroying impact of earthquake is the liquefaction related damages such as “subsidence” and “lateral spreading”. There have been several measures taken up by Yasuda like substituting the conventional materials with some lightweight granular materials. This can reduce the liquefaction during earthquake and thereby lessen the earthquake induced permanent deformation of the structures. While designing the geotechnical structures, “cost reduction, structural performance and sustainability” and building environment friendly disaster mitigation technique remains the top priority. Therefore the Tire chips were developed from the scrap tires which were “lightweight, elastic, compressible, highly permeable, earthquake resistant, thermally insulating, and durable”, which could be used to backfill the waterfront structures (Hazarika, 454). The technique was named SAFETY (Stability and Flexibility of structures during earthquakes using tyres). In this technique the tire chips were placed behind the structures as cushion to act as a vibration absorber. The cushion helped in reducing the load against the structure owing to its “energy absorption capacity”. This also helped in cutting down the permanent displacement of the structure by using the flexibility of the material. Thus the major principle of the technique lies in giving flexibility to the structure by the cushioning act and thereby provided “stability to the structure by absorbing the energy and restraining excessive structural displacement during earthquakes”. (Hazarika, 455) Indonesia- the seismic hazards and its mitigation approach Indonesia is situated along the equator and surrounded by two continents- Asia and Australia and by two well-known oceans the Indian Ocean and the Pacific Ocean; it is an “archipelagoan” country consisting of about 14,000 islands and an approximate population of 147,500,000. It is known to be one of the seismically active nations in the world and is located on three-earthquake belt. The first belt is the Alpide or Tethys mountain system. Pacific Circumbelt is the second earthquake belt and the third belt is the Australian Circumbelt. The three major active plates of the earth- Eurasian, Indo-Australian and Philippine plates surround it. The country witnesses an average earthquake rate of 350 earthquakes annually, arising not only from the tectonic nature but some of the earthquakes which occurs in the country are volcanic in nature caused due to volcanic activities and some are also caused by landslides occurring in the land as well as in the sea. There exist 127 volcanoes in the country; out of which only 70 are active so earthquakes caused by the volcanic eruptions also affect the country. Some of the devastating earthquakes that occurred in Indonesia are the earthquakes of Aceh Earthquake of 2004 which measured Mw 9.0-9.3 and it was pursued by tsunami, “the 2005 Nias Earthquake measuring 8.7 Mw, the 2009 Tasik Earthquake measuring 7.3 Mw” and the most recent one of “Padang in 2009” which was measured to be 7.6 Mw. The Aceh earthquake had a devastating effect on the country as it destroyed innumerable “engineered and non engineered buildings”, communication systems and public amenities. The “Sundra Strait fault”, the Indian Ocean Subduction fault, the Baribis fault and the Cimandri fault” are the major fault system of the area (Creating Earthquake Preparedness in Schools). The noticeable “Lembang fault” within the “Bandung” makes it more susceptible to great calamity. The soil of the region Bandung is made from the deposits of alluvium soil which is soft making the city all the more vulnerable to the shocks during an earthquake. The negligence from the part of the authority had led to the growth of urban population in the region, which makes it susceptible to devastating outcomes. The infrastructure of that region which includes hospitals and schools are not appropriately constructed to stand the risk of collapse. The initial step to carry out mitigation technique in the city will be to carry out “basic intensity zoning mapping and risk assessment” (Creating Earthquake Preparedness in Schools) The Indonesian Urban disaster Mitigation project (IUDMP) was launched in 1997 under the Asian Urban disaster Mitigation to reduce risk of urban population. The institute’s main focus was to spread proper awareness about earthquake among students and preparing them to take right measures when earthquake strikes. The program also included training the teachers. To reach the population in a better way the institute distributed pamphlets, leaflets, simple manuals and posters among the people residing in those areas. Designing and implementing earthquake resistant school building construction and taking measures in constructions in post earthquake times were initiated. The program also included training of the engineers, local government representatives, small contractors and craftsmen on earthquake resistant techniques. Mitigation of disaster refers to “the measures taken in advance to reduce the impact of a disaster. It includes structural measures and non structural measures such as education, training and technology transfer.”(Creating Earthquake Preparedness in Schools) An effort has been taken by the country to combat the disaster caused by earthquake at the central level and down to the grass root level. The country has established a national Natural disasters Mitigation coordinating agency at the central level, which is being headed by the Minister coordinator of the People’s Welfare. The committee is seconded by three other ministers as well, they are namely the minister of Social welfare, the minister of home affairs, the minister of public works, The committee also consists of 21 members from all the departments including the Search and Rescue Energy and the Indonesian Red Cross. (Alrasjid; Scheper) The organizing units for natural disaster Mitigation have also been established at the province level. The Governor along with representatives from the armed forces chairs the committee as the deputy chairman. The similar organization structure has been also followed in the regency and the Municipality levels and the sub-ordinate level, namely the village level. The main works of the committees were to work on the “preventive measures”, “relief and recovery assistance”, “the phase of rehabilitation”. The preventive measures undertaken by the committee included the relocating of the population from the disaster prone zone to the more secure areas through local settlement activities. The activities like transmigration were taken up where the populaces were moved to either other areas or to other islands. This program involved giving of the agricultural sites to the people which were already prepared with dwellings, and also complementary elements of social, educational, health, roadwork, infrastructure and many more. The relief and recovery assistance carried by the committee mainly involved “search and rescue activities” to extend a helping hand to the people who are affected badly by the disaster. The help was mainly for those people who reside in the remote areas where conventional transportation is not possible. The recovery and relief work also included the assistance of first aid to the victims and supplying them with clothes, food, shelter, medicines, hospitalization and sanitation. This works also included the aid for demolished and ruined buildings, destroyed agricultural plants and equipments, the devastated temples, churches, or mosques. The economic infrastructures like shops and market places were also aided by the recovery and relief work. Aids were also extended for rehabilitation of public utilities like roads and irrigation network. The rehabilitation of government buildings like hospitals, schools, office buildings, government housing was also taken up. People were also provided with funds to repair their demolished agricultural equipments and structures, irrigation system and village roads. The development works like construction of new road, market places were taken up as well. The relief program also provided the people with the provision of credit assistance for economic ventures like the expansion of educational institutes, and providing with social and cultural facilities and also building up means of transportation and the means of production. Priority has been given to the people who are frequently exposed to the natural disasters. Transmigrates are given training before they are relocated to the other place so that they can easily adjust themselves in the new settlement. The populaces of these areas are also provided with the equipments, which are required, by their respective branches of art of living they follow. The transmigration mainly aims at shifting the populace from the over populated area of Bali and Java. (Alrasjid, 402-404) Japan and Indonesia - A Comparison The above analysis shows some dissimilarities and similarities in the mitigation approaches taken up by Japan and Indonesia to combat the seismic hazards. It is evident from the above analysis that both the countries have taken adequate steps to combat the problem of seismic hazards but even then it has faced the catastrophe, which has claimed many lives causing a great loss to the economy. Both Japan and Indonesia has similar approaches in fighting the disaster of earthquake. Both the countries concentrate on the fact that adequate level of awareness has to be spread among the population of the country to minimize the devastating effect of the natural calamity. Owing to their geographical differences, the nature of the calamity is different in the two countries. While Japan faces earthquakes due to the plate tectonic movements and volcanoes, the volcanic eruptions and landslides beside the tectonic movements cause earthquakes in Indonesia. While it is seen that Japan concentrate more in the infrastructural development of the city on accordance to geographical conditions by building houses and other infrastructure with shock absorbing materials like tire chips. Indonesia on the other hand relocates its citizen from the hazard prone zone to the safer zone. The country has taken up the measure of transmigration. But both the countries are keen on spreading awareness among its citizens which they feel will help in reducing the effects of hazards. The prediction of the disaster is an important aspect that is being given importance by both Indonesia and Japan. Recently Japan and Indonesia have joined hands together to come up with more effective ways to fight the ills of the earthquakes, thereby making an effort to save more lives and minimize the damage caused by the earthquakes and volcanic eruptions. The research program named “Multidisciplinary Hazard Reduction from Earthquakes and Volcanoes in Indonesia” is an extended four year project that has been taken up to mitigate the impact of the disasters (SATREPS). The project taken by the countries emphasize on the fact that proper steps should be taken to prepare the country in reducing the hazards and top predict disasters. The project involves the participation of 14 institutes from both Japan and Indonesia, which will have a multidisciplinary approach to deal with the problem. The agency has indicated 17 provinces namely Aceh, West Sumatra, West Java, East java, Bali, West Papua and Papua are at a risk of volcanic eruptions. (Indonesia and Japan join forces on disaster project) Conclusion The analysis of the subject gives evidence of the initiative being taken up by both the countries. The great loss of lives and the economic loss to the economy are great issues of concerns, which the countries are trying to address. While some of the measures taken up by the countries have proved to be efficient in minimizing the devastating effects, some measures are also to be taken to fight natural calamities like earthquakes and volcanic eruptions by both the countries. There are instances where despite taking adequate measures the country has faced devastations. Scopes are to be given to research in these areas so that the effect can be minimized to a greater extent. Appendix: Figure 1: The active volcanoes, plate tectonics and the “Ring of fire” (Active Volcanoes, Plate tectonics and the “Ring of Fire”) Figure 2: average number of earthquake in Japan per year (Japan: Earthquake density map) Figure 3: Number of earthquakes in Indonesia (Novisio USGS Earthquake, 2011) References: 1. Alrasjid, Harun, “ Social and Economic aspects in the mitigation of earthquake disasters”, n.d., April 28, 2011 from: http://desastres.usac.edu.gt/documentos/pdf/eng/doc13426/doc13426-contenido.pdf 2. “Creating Earthquake Preparedness in Schools”, ADPC, August 2004, April 28,2011 from: http://www.adpc.net/AUDMP/library/safer_cities/10.pdf 3. Datta, T.K., Seismic Analysis of structures, United States, John Wiley and Sons, 2010. 4. Office of Technology Assessment Washington Dc, Reducing earthquakes losses, Diane publishing house, 1995. 5. “Indonesia and Japan join forces on disaster project”, Jakarta globe, 2010, April 29,2011 from: http://www.thejakartaglobe.com/nvironment/indonesia-and-japan-join-forces-on-disaster-project/365260 6. Active Volcanoes, Plate tectonics and the “Ring of Fire”, USGS, N.D., April 30, 2011 from: 7. Japan: Earthquake density map, USGS, 2010, April 30, 2011 from: 8. Novisio USGS Earthquake, 2011, April 30, 2011 from: 9. SATREPS, Multidisciplinary Hazard Reduction from Earthquakes and Volcanoes in Indonesia, Japan and Technology Agency, 2009, April 30, 2011 from: http://www.jst.go.jp/global/english/kadai/h2009_indonesia.html 10. Scheper, Elizabeth, Tsunami Evaluation Coalition, Impact of the tsunami response on local and national capacities, 2006, April 30, 2011 from: http://www.alnap.org/pool/files/capacities-indonesia.pdf 11. Fujiwara, Hiroyuki, Japan Seismic Hazard Information Station, April 30, 2011 from: http://cais.gsi.go.jp/UJNR/6th/orally/O43_UJNR.pdf 12. Ikeuchi, Koji and Nobuharu Isago, Earthquake Disaster Mitigation Policy in Japan, PWRI, April 30, 2011 from: http://www.pwri.go.jp/eng/ujnr/joint/39/paper/42ikeuchi.pdf Read More