186 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 A Preliminary Study on Tsunami Disaster in Yogyakarta: Identification of Vulnerability Order and Components Lina Wahyuni1*, Muh. Aris Marfai2, M. Pramono Hadi2 1Doctoral Program of Regional Development Study Program, Faculty of Geography, Gadjah Mada University, Jl. Kaliurang, Sekip Utara, Bulaksumur, Yogyakarta, 55281, Indonesia 2 Regional Development Study Program, Faculty of Geography, Gadjah Mada University, Jl. Kaliurang, Sekip Utara, Bulaksumur, Yogyakarta, 55281, Indonesia *Corresponding Author : linawahyuniananda@gmail.com Received 10 March 2020/ Revised 14 May 2020 / Accepted 23 May 2020/ Available Online 2 June 2020 Abstract A tsunami is a disaster that can be hardly estimated. It is a significant concern UN since more than 60% of the world's population lives in coastal areas prone to tsunamis, including Indonesia. The county community with complex and dynamic plate requires mastering of mitigation strategies as a tsunami preventive effort. Understanding the vulnerable elements in risky areas is critical. However, the magnitude of potential disasters cannot be minimized. This study analyzes the tsunami vulnerability in Bantul, Special Region of Yogyakarta (DIY). The analysis was based on a description of assessment parameters such as land use, the physical condition of the area, social conditions, and availability of infrastructure. The results show that social vulnerability had the most significant impact. Keywords: Vulnerability, Tsunami, Bantul, DIY 1. Introduction A tsunami refers to waves that are faster, taller, and stronger than wind or storm surge (Chen & Cheng, 2016; Rangel-Buitrago et al., 2020). It has frequently occurred in the last decade, damaging coastal structures (Nandasena et al., 2012). Its incidencet on a large scale is relatively less frequent compared to hydrometeorological disasters.The associated waves are unpredictable because they are caused by sudden significant volcanic displacements, initially triggered by earthquakes, landslides, volcanic eruptions, or meteors (Al-Faesly et al., 2012). On December 26, 2004, a tsunami disaster was triggered by the magnitude of an Earthquake with a strength of 9.1 Ritcher Scale (SR) in the Indian Ocean. The maximum height of the waves was 30 meters, causing more than 200,000 deaths and massive GEOSFERA INDONESIA p-ISSN 2598-9723, e-ISSN 2614-8528 Vol.5 No. 2 (2020), 186-195, August, 2020 https://jurnal.unej.ac.id/index.php/GEOSI DOI : 10.19184/geosi.v5i2.17006 Accredited by the Ministry of Research , Technology , and Higher Education of the Republic of Indonesia, No. 30/E/KPT/2019. mailto:linawahyuniananda@gmail.com https://jurnal.unej.ac.id/index.php/GEOSI https://drive.google.com/file/d/1rSnVAs6cuHOwHl5BJ87CL2L6K5DQz7s6/view 187 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 destruction of property in more than ten countries bordering the Indian Ocean (Grilli 2007, Leonard & Lucinda, 2014; Iverson & Prasad, 2007; Roshan et al., 2016). On February 27, 2010, a tsunami disaster was triggered by an 8.8 magnitude earthquake of the coast of Chile. The waves reached local run-ups of 29 meters high on coastal cliffs (Fritz, 2010). On March 11, 2011, a magnitude 9.0 earthquake stroked near the coast of northeastern Japan and swept along the coast, penetrating the land with a maximum height of 40 meters (Yeh et al., 2013). On September 16, 2015, an 8.3 magnitude earthquake occurred off Chile's central coast and triggered a tsunami with a maximum runoff height of 13 meters (Contreras-Lopez et al., 2016). In Thailand, the dock plates at the port of Khao Lak and the fishing port of the Ban Nam Kem deck were severely damaged by the uplifted pressure due to the Indian Ocean tsunami of 2004 (Ghobarah et al., 2006). The same incident occurred in Japan and damaged the Sendai port in the Tohoku region during the 2011 tsunami (Suppasri, 2012). Based on the risk analysis conducted by the National Disaster Management Agency (BNPB) in 2012, four major areas have high risk and probability of tsunami, including Mentawai, Sunda Strait, and southern part of Java, Megathrust south of Bali and Nusa Tenggara, and northern Papua Region. Of the four areas, the South Java Coast or Pansela, has the largest population (BNPB, 2012). Due to a large number of residents in this region, the spatial planning along the South Coast of Java should be based on coastal area disaster mitigation. The coastal area of the Bantul Regency is prone to tsunami because it is a low lying area designed as one of the National Strategic Tourism Area (Hadipour et al., 2019; McGuire, 2020). The existence of South Cross Road (JJLS) increase the strategic value of the coastal areas. It connects the southern coast of Java Island to the coast of Bantul Regency. Also, the new airport development plan in the coastal area of the Kulonprogo Regency is next to the Regency, which is integrated with National Tourism Strategic Area (KSPN) Borobudur and road along JJLS. Generally, airports are encouraged to support the development of KSPN Borobudur and surrounding areas. This is stated in the National Tourism Development Master Plan 2010-2025. Figure 1 shows the DIY Southern Coast Strategic Region. The implementation of spatial planning should be carried out comprehensively, holistically, well-coordinated, integrated, effective, and efficient, focusing on political, economic, social, culture, defense, security, and environmental sustainability (Ibrahim & Hegazy, 2013). Spatial planning needs to be based on the system approach, main function, 188 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 administration, activity, and strategic value areas, taking into account the disaster factor (Muta'ali, 2014). Figure 1. KSPN Pansela Yogyakarta Area. Source: Government Regulation Number 50 the Year 2011 Concerning Master Plan of National Tourism Development Year 2010 - 2025. The development plan of the southern coastal region, including the Bantul area, has encouraged unity in the spatial planning following the risk of the tsunami disaster (Balasundareshwaran et al., 2020). This study analyzes the tsunami vulnerability orderbased on the assessment parameters, including land use, the physical condition, social state,and infrastructure availability. 189 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 2. Methods The identification of dangerous elements in the disaster-prone area is part of mitigation. This aspect was investigated by Tanaka, (2008); Tanaka et al., (2010); Liyanage & Lee, (2012); Freire et al., (2012); & Shibayama et al., (2012). In this research, the risky component was considered a significant factor in mitigation since the magnitude of the disaster cannot be reduced. The assessment of the damage was conducted by identifying and calculating the vulnerability order, including land use, the physical and social condition of the area, availability of infrastructure, and economic. The unit of analysis was the village administration. Theidentification of elements at risk within the tsunami danger zone, including physical, social, and economic elements, is a significant step in determining vulnerability order. The parameters used are based on the National Disaster Management Agency (BNPB) Regulation No. 2 of 2012 and several previous studies. The research flows as follows. Figure 2. Research Flow 3. Results and Discussion Indonesia is a country prone to the tsunamis, especially in the coastal area that directly faces the meeting layer of Eurasia Plate, Indo-Australia, and the Pacific, including the western part of Sumatra Island, the southern part of Java Island, Nusa Tenggara, the northern part of Papua, Sulawesi, Maluku, and the eastern part of Kalimantan Island (BMKG, 190 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 2012; McGuire, 2020).The common disaster occurringis a close-range tsunami of around 200 km from the earthquake epicenter. Local tsunamis can be caused by earthquakes,slide, and volcanic eruptions (BMKG, 2012). Table 2.1 depicts the tsunami history occurring in Indonesia. Table 1. Significant Tsunami Event in Indonesia No Year Location Magnitude Total Victims 1 1883 Krakatau Volcano - 36,000 2 1833 West Sumatera, Bengkulu, and Lampung 8.8 unreported 3 1938 Kal Island, Bangka 8.5 unreported 4 1967 Tinambung - 58 5 1968 Tambu, Southeast Sulawesi 6.0 200 6 1977 Sumbawa 6.1 161 7 1992 Flores 6.8 2,080 8 1994 Banyuwangi 7.2 377 9 1996 Toli Toli 7.0 9 10 1996 Biak 8.2 166 11 2000 Banggal 7.3 50 12 2004 Nangro Aceh Darussalam 9.0 250,000 13 2006 Pangandaraan 7.2 >600 14 2010 Mentawai 7.7 >400 Source : Mardiatno (2008 ) The greatest tsunami in the history of Indonesia occurred in Aceh on December 26, 2004. It started by the earthquake magnitude of 9.3 SR, which caused a strong shock and fault, stretching from Aceh to Andaman. The tsunami was attributed to the earthquake with huge losses and 250,000 deaths (Mardiatno, 2008). Almost all of the tsunami disasters led to material losses and claimed many lives. According to Table 2.1, the most recent tsunami occurred in October 25th 2010 in Mentawai Island, West Sumatra. It started with an earthquake of magnitude 7.7 SR, followed by tsunami waves of 3-10 meters. This caused destruction of 77 villages and more than 400 deaths (Mardiatno, 2008). Bantul Regency has ahigh vulnerability because it directly faces the Indian Ocean. Additionally, the coastal typology tends to be flat (Trihatmoko, 2017; McGuire, 2020). When a tsunami strikes, it is likely to damage the physical and social aspects, as well as the existing infrastructure. Social vulnerability should be the first concern since it relates to the number of people affected (Koroglu et al., 2019; Liu et al., 2020; Malherbe et al., 2020). The readiness of every resident in the face of disasters significantly affects vulnerability. In case the community is ready to face any disaster, the severity can be reduced. 191 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 Social vulnerability is the ability to recover from the impact of natural disasters based on age and sex group of the populations (Dawyer, 2004. in Zulkarnaen, 2012). It is based on the understanding of the disaster and the resulting conditions. This includes the ability to evaluate when it occurs and the recovery process. The population of women, children, and the elderly is considered the most vulnerable (Subarkah, 2009). Based on the Law of the Republic of Indonesia Number 24, 2007 on Disaster Countermeasure, the vulnerable groups include infants, toddlers, and children of pregnant and lactating mothers, the disabled and the elderly. According to Subarkah. (2009), the components used in calculating social vulnerability include age and sex groups. The vulnerability is assessed based on an understanding of current and post-disaster conditions based on the evacuation capability. In this assessment, the population of women, children, and the elderly are targeted. Table 2 shows the population in Bantul Regency, which can be potentially affected in case the tsunami strikes. This data includes the number of people living in the district directly facing the Indian Ocean. Population density also affects the vulnerability of a region. Table 2 shows the Pandak District has the highest population and density. Table 2. Population and Population Density based on District which directly facing the Indian Ocean in Bantul Regency District Population Population Density Srandakan 29,130 1,590 Sanden 30,114 1,300 Kretek 30,111 1,125 Pundong 32,321 1,365 Bambang Lipuro 38,206 1,684 Pandak 48,950 2,014 Source : Statistics of Bantul Regency (2016) Economic vulnerability is the risk of damage, negative impact, or external shock resistance due to unexpected events (Koroglu et al., 2019; Liu et al., 2020). The calculation losses can be a good indicator of the economy (Gulllaumom, 1999, in Zulkarnain 2012). Physical vulnerability is the last aspect describing the extent of damage to physical infrastructures exposed to hazards, such as residential buildings (Ishtiaque et al., 2019). It affects the local community's structural readiness and the condition of structures (Prasstiya, 192 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 2013). The main Physical vulnerability in Bantul Regency include JJLS and the existence of Airport . The most important thing to do in adjusting the development of risk management strategies is to assess vulnerability to potential tsunami damage in the proper order (Lantz et al., 2020). However, vulnerability assessment has never been formulated in an appropriate legal document. Building vulnerability means calculating thestructures' capacity in the horizontal pressure of tsunami flows and its susceptibility to water (Dall'Osso et al., 2009; Koroglu et al., 2019). 4. Conclusion In this study, the ranking of the element at risk involves social, economic, and physical vulnerabilities. Social vulnerability is considered to be the most powerful aspect associated with detailed and varied subcomponents. The economic vulnerability comes second in terms of the economic conditions of a society. It is closely related tocommunities’specific capacity to survive. Physical vulnerability is rated last since rebuilding of infrastructures is easier than social or economic development. Conflict of Interest The authors declare that there is no conflict of interest with any financial, personal, or other relationships with other people or organizations related to the material discussed in the article. References Al-Faesly, T., Palermo, D., Nistor, I., and A. Cornett, A. (2012). Experimental Modeling of Extreme Hydrodynamic Forces on Structural Models. Int. J. Protect. Struct, vol. 3 (4), pp. 477–506. Balasundareshwaran, A., Kumaraswamy, K., Balasubramani, K. (2020). Multi-Hazard Zonation For Effective Management of Disasters in Tamil Nadu. Geosfera Indonesia, vol. 5(1), DOI: https://doi.org/10.19184/geosi.v5i1.16710. BMKG. (2012). Pedoman Pelayanan Peringatan Dini Tsunami. InaTEWs. Edisi kedua. BNPB. (2012). Indeks Risiko Bencana Indonesia. Badan Nasional Penanggulangan Bencana. Jakarta. https://doi.org/10.19184/geosi.v5i1.16710 193 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 Chen & Cheng. (2016). Experimental Study of Uplift Loads Due to Tsunami Bore Impact on a Wharf Model. International Journal of Coastal Engineering, vol. 117 (2016), pp. 126–137. Contreras-Lopez, M., Winckler, P., Sepúlveda, I, Andaur-Álvarez, A, Cortés-Molina, F., Guerrero, C. J., Mizobe, C.E., Igualt, F., Breuer, W., Beyá, Vergara, H., Figueroa- Sterquel, R. (2016). Field Survey Of The 2015 Chile Tsunami With Emphasis On Coastal Wetland And Conservation Areas. Pure Appl. Geophys. Vol. 173 (2), pp. 349- 367. Dall’Osso, F.M., Gabbianelli, G., Withycombe, G., Goff, J., Dominey-Howes, D.A. (2009). Revised (PTVA) Model For Assesing the Vulnerability of Building To Tsunami Damage. Natural Hazard Earth Science. 9:1557-1565. Freire, S., Aubrecht, C., Wegscheider , S. (2012). Advancing tsunami risk assessment by improving spatio-temporal population exposure and evacuation Modeling. Natural Hazards 68:1311-1324. Fritz, H.M. (2010). Field Survey of the 27 February 2010 Chile tsunami. Pure Appl. Geophys, vol. 168 (11), pp. 1989–2010. Ghobarah, A., Saatcioglu, M., Nistor, I. (2006). The impact of the 26 December 2004 earthquake and tsunami on structures and infrastructure. Eng. Struct, vol. 28 (2), pp. 312–326. Government Regulation Number 50. (2011) Concerning Master Plan of National Tourism Development Year 2010 - 2025. Jakarta : President of the Republic of Indonesia Grilli, S.T. (2007). “Source Constraints and Model Simulation of the December 26, 2004, Indian Ocean Tsunami”. Port Coast. Ocean Eng., vol. 133 (6), pp. 414–428. Haipour, V., Vafaie, F., Kerle, N. (2019). An indicator-based approach to assess social vulnerability of coastal areas to sea-level rise and flooding: A case study of Bandar Abbas city, Iran. Ocean & Coastal Management, vol 188., 105077. Ibrahim, H.S., Hegazy, I. (2013). Decentralization in the Egyptian Coastal Management. Journal of Coastal Zone Management, vol 16(2), pp. 102-113. Ishtiaque, A., Eakin, H., Chhetri, N., Myint, S.W., Dewan, A., Kamruzzam, M. (2019). Examination of coastal vulnerability framings at multiple levels of governance using spatial MCDA approach. Ocean & Coastal Management, vol. 171, pp. 66-79. Iverson, L.R., & Prasad, A.M. (2007). Using Landscape Analysis to Assess and Model Tsunami Damage in Aceh Province, Sumatra. Landscape Ecol, vol. 22, pp. 323–331. Koroglu, A., Ranasinghe, R., Jimenez, J.A., Dastgheib, A. (2019). Comparison of Coastal Vulnerability Index applications for Barcelona Province. Ocean & Coastal Management, vol. 178, 104799. 194 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 Lantz, T.C., Moffat, N.D., Jones, B.M., Chen, Q., Tweedie, C.E. (2020). Mapping Exposure to Flooding in Three Coastal Communities on the North Slope of Alaska Using Airborne LiDAR. Coastal Management, vol. 48(2), pp. 96-117. Leonard, L. & Lucinda (2014). Tsunami hazard assessment of Canada. Nat Hazards, vol. 70, pp. 237–274, 2014. Liu, R., Pu, L., Zhu, M., Huang, S., Jiang, Y. (2020). Coastal resource-environmental carrying capacity assessment: A comprehensive and trade-off analysis of the case study in Jiangsu coastal zone, eastern China. Ocean & Coastal Management, vol. 186, 105092. Liyanage, A.N. & Lee, H. (2012). A Schematic Approach for GIS Application for Tsunami Disaster Management. ASEA/DRBC, CCIS 340, pp. 395-400. Marherbe, W., Sauer, W., Aswani, S. (2020). Social capital reduces vulnerability in rural coastal communities of Solomon Islands. Ocean & Coastal Management, vol. 191, 105186. Mardiatno, D. (2008) Risiko Tsunami di Pantai Selatan Jawa: Belajar Dari Kejadian Tsunami di Banyuwangi pada tahun 1994 dan di Pengandaran pada tahun 2006. Jurnal Kebencanaan Indonesia, vol. 6 (2), pp. 15-32 McGuire, C.J. (2020). Coastal Resiliency through Value Capture and Transfer: A Framework Proposal. Coastal Management, vol. 48(2), pp. 57-76. Muta’ali, L. (2014). Development Planning based on Disaster Risk Reduction, (in Bahasa Perencanaan Pengembangan Wilayah Berbasis Pengurangan Risiko Bencana). Badan Penerbit Fakultas Geografi, Universitas Gadjah Mada, Yogyakarta. Nandasena, N., Sasaki, Y., Tanaka, N. (2012). “Modeling field observations of the 2011 great east Japan tsunami: efficacy of artificial and natural structures on tsunami mitigation. Coast. Eng, vo. 67, pp. 1–13. Prasstiya, R.T. (2013). Manajemen Risiko Tsunami di Pulau-pulau Kecil (GiliTrawangan) Kecamatan Pemenang Kabupaten Lombok Utara. Master Thesis.Universitas Gadjah Mada, 2013. Rangel-Buitrago, N., Neal, W.J., Bonetti, J., Anfuso, G., de Jonge, V.N. (2020). Vulnerability assessments as a tool for the coastal and marine hazards management: An overview. Ocean & Coastal Management, vol. 189, 105134. Roshan, A.D., Basu, P.C., Jangi, R.S. (2016). Tsunami Hazard Assessment of Indian Coast. Nat Hazards, vol. 82, pp. 733–762. Shibayama, T., Esteban, M., Nistor, I., Takagi,H., Thao, N.D., Matsumaru, R., Mikami, T., Aranguiz, R., Jayaratne, R., Ohira K. (2012). Classification of Tsunami and Evacuation Areas. Natural Hazards 67:365-386. Statistic of Bantul Regency. (2016). Bantul Dalam Angka. Bantul: BPS. 195 Lina Wahyuni et al / GEOSI Vol 5 No 2 (2020) 186-195 Subarkah. (2009). Spatial multi criteria evaluation for tsunamis vulnerability: Case study of coastal area Parangtritis, Yogyakarta, Indonesia. Master Thesis, Universitas Gadjah Mada, Yogyakarta. Suppasri, A. (2012). Damage Characteristic and Field Survey of The 2011 Great East Japan Tsunami in Miyagi Prefecture. Coast. Eng. J., vol. 54 (01). Tanaka, N. (2008). Vegetation bioshields for tsunami mitigation: review of effectiveness, limitations, construction, and sustainable management. Landscape Ecol Eng 5:71-79. Tanaka, N., Jinadasa, K. B. S. N., Mowjood, M.I.M., Fasly, M.S.M. (2010). Coastal vegetation planting projects for tsunami disaster mitigation: effectiveness evaluation of new establishments. Landscape Ecol Eng 7:127-135. Trihatmoko, E. (2017). Proses dan Dampak Dinamika Wilayah Kepesisiran Jawa Tengah dan Daerah Istimewa Yogyakarta. Master Thesis. Universitas Gadjah Mada, Yogykarta. Yeh, H., Sato, S., Tajima, Y. (2013). The 11 March 2011 East Japan Earthquake and Tsunami: Tsunami Effects on Coastal Infrastructure and Buildings. Pure Appl. Geophys, vol. 170 (6–8), pp. 1019–1031. Zulkarnain, M. W. D.(2012). Evaluasi Multi-Kriteria Keruangan Untuk Penilaian Risiko Total Tsunami di Pacitan. Master Thesis. Universitas Gadjah Mada, Yogyakarta.