It may be necessary to carry out a study about risk analysis of building vulnerability to tsunami hazard in order to identify and develop potential tsunami risk in a coastal community. The objective of this study is  to develop a risk analysis of building vulnerability to tsunami hazard in Parupuk Tabing, Padang. The study aims to: (1) identify and develop the building vulnerability of various building types to tsunami hazard; (2) simulate the tsunami propagation; and (3) develop risk analysis of building vulnerability to tsunami hazard in Padang.  Risk level is determined by relative vulnerabilty index score of each building to a tsunami. The buildings were classified in five classes (very low risk, low, medium, high and very high). The method used to analize pattern of various types of building and tsunami inundation is by applying formulas in the field and simulating an earthquake with TUNAMI N3 Imamura method respectively. Clearly, the relative vulnerability index ranges of the building samples in Parupuk Tabing are from 3 to 5 (medium, high and very high risk). This study shows that risk components for building protection are around 30 to 40%, whereas water inundation is 33.33%, followed by building vulnerability of 22.67-33.67%. It can be estimated that, the condition can be very vulnerable, if the level of water is  more than 2 m around a building and the vulnerability of water is around 33%. The results of this study contribute to the development of risk management strategies in designing of building and construction standards as well as plan for vertical evacuation and land use zones in order to mitigate the impact of tsunami disaster in coastal communities of Padang.

Padang was destroyed by tsunamis generated by the earthquakes in the history of Padang. As an area located in a coastal region, its buildings in Padang face major vulnerability against a tsunami. The objectives of this study are to develop the potential impact model of building vulnerability toward tsunami hazard and to compare the building damage levels based on water inundation, internal, and external factors in Ulak Karang and Pasir Jambak sub-districts. The objective of this research is also to give recommendation to government in making planning strategies for reducing and managing the tsunami risk on building vulnerability. There are three stages of modeling; first stage in this study is simulating an eartquake model for two study areas to estimate the maximum inundation. The second stage of modeling is implementing the spatial analysis of building vulnerability based on the field surveys and GIS. The third stage to conlude is developing the Relative Vulnerability Index (RVI) scores of buildings by mapping the building vulnerability toward tsunami hazard and giving several alternatives to develop a risk management plan in a coastal community. The result shows that Ulak Karang sub-district is determined to be more vulnerable than Pasir Jambak sub-district because many buildings near the coastline of Ulak Karang sub-district are made of timber and are arranged close to each other. Moreover, many buildings in Ulak Karang sub-district, especially along the river, are made of traditional brick. Although near Pasir Jambak coastline many buildings are made of timber, but the buildings are not close to each other. There are several alternatives to increase resilience of buildings in a coastal zone, namely: 1) regulation for buildings that have RVI: 4 and 5; 2) building codes; 3) vertical evacuation structures; 4) land use zones; 5)  sea walls along the coastlines; 6) natural barriers and 7)  early warning system.

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Tsunami hazard is an adverse event, which causes damage to properties and loss of life. The study on the effects of tsunami hazard on building vulnerability can help establish and improve the resilience of the building. The problem in assessing the building vulnerability towards tsunami hazard is significant whereby available models for assessing the risk are not applicable for buildings in Padang, Indonesia. The study developed a new Relative Vulnerability Index (RVI) model to estimate building vulnerability for assessment the risk. Literature review was carried out with regards to model development. The model was grouped in two categories of vulnerability, namely the Water Inundation (WI) and the Building Vulnerability (BV). The water inundation comprises tsunami inundation factor. Then, the building bulnerability consists of both internal and external factors. Contribution of each factor is 1/3 or 33.33% of the overall weighting of the new RVI scores. The new RVI model has applied a formula of 1/3 water (tsunami) inundation factor + 1/3 internal factor + 1/3 external factor. The total value of all weights put together should be equal to 100. To use the model, it is necessary to investigate two internal and external factors based on the characteristics of a building and specific geographichal feature of an area. In conclusion, this study has successfully developed a new RVI model for building vulnerability towards tsunamis. In comparison to other approaches, the model offers an adaptable methodology for the characteristics of the buildings and spesific geographical features of the area.

Sebagian besar peta rawan tsunami Indonesia, khususnya kota Padang baru mulai dirancang setelah kejadian bencana tsunami Aceh tahun 2004. Peta rawan tsunami yang tersedia sekarang memiliki sumber dan kajian yang berbeda‐beda. Tujuan dari penelitian ini adalah menganalisis perbedaan peta inundasi hasil pemodelan dengan TUNAMI N3 dan peta inundasi tsunami berdasarkan peta topografi. Untuk penelitian ini, peta inundasi tsunami diambil dalam skala besar (1:5.000) agar dapat memberikan informasi yang lebih terperinci karena dibuat dengan ukuran grid 90 meter. Daerah tinjauan dipilih di daerah Ulak Karang, Kecamatan Padang Utara, Kota Padang, karena merupakan wilayah padat penduduk dan termasuk sebagai pusat perekonomian. Hasil elevasi tsunami maksimum pemodelan tsunami dari sumber blok Pagai dan blok Sipora adalah 6,22 m dan 2,15 m. Keberadaan Kepulauan Mentawai berperan dalam meredam energi tsunami yang bersumber dari blok Sipora menghasilkan fluktuasi elevasi gelombang tsunami di blok Sipora lebih kecil daripada blok Pagai. Perbandingan luasan terdampak inundasi blok Pagai, blok Sipora dan berdasarkan topografi adalah 48%, 22% dan 38% dari seluruh luasan daerah tinjauan. Luasan wilayah terdampak inundasi berbanding lurus dengan nilai elevasi gelombang tsunami maksimum yang dihasilkan. Peta inundasi berdasar topografi memiliki kelemahan karena menganggap tinggi elevasi tsunami pada setiap grid di bibir pantai adalah sama dengan asumsi 5 meter. Berbeda dengan peta inundasi hasil pemodelan yang memiliki data elevasi tsunami yang telah mempertimbangkan kondisi profil pantai yang terintegrasi sebagai data batimetri dalam set up pemodelan.