Mosses diversity from Simeulue Island, Sumatera, Indonesia

Simeulue is an oceanic islands located in the western coast of Sumatera, just offshore of the southwestern coast of Aceh Province, Indonesia. The diversity of mosses in the island was unknown. Unfortunately, the island was largely devastated by the 2004 tsunami, which also affected the flora of the island, including the moss flora. In order to conserve the present day mosses flora, the current study is conducted covering several types of habitats. 83 samples of mosses from 41 species have been collected and identified. Three species are apparently new records to both Simeulue and Sumatera; Hyophila javanica (Nees) Brid., Taxithelium kerianum (Broth.) M. Fleisch., and Taxithelium ramicola Broth. Neckeropsis gracilenta (Sande Lac.) M. Fleisch. is the dominant species.

Current condition of coastal protection structures of Meulaboh, Westcoast of Sumatra Island, Indonesia

Meulaboh is coastal city that has tourism potential. The city has been facing coastal erosion hazard since a long time from high energy wave activity coming from Indian Ocean. To protect the coast from the erosion hazard, a coastal defence structures were built along the city’s coast overlooking the Indian Ocean. Before the 2004 tsunami, hard structures built on the coast that open to waves from the Indian Ocean were damaged by daily wave activity. This study assess effectiveness of the current coastal protection structures protect coastline in the three coastal segments of the city, namely the Padang Seurahet, Ujung Karang and Kampung Pasir, in order to find out if the construction of the structures is the right choice. Related to the tourism potential of Meulaboh City also studied the possibility to expand the function of the structures. The coastal protection structures data for this study were mainly obtained from field observations in June 2021. Effectiveness of the structures protecting coastline were analysed based on technical criteria. Meanwhile, possibility to expand the function of the structures were analysed according to environmental condition of the coastal segments and types of tourism activity. The results of this study show that the hard structure that now exists on Meulaboh coast can protect the city’s coast from the hazard of erosion without negatively impacting the surrounding coastline. In addition, the structure is considered to be expandable to support the development of tourism potential of Meulaboh City. Thus it can be conclude that the choice of hard structure for coastal protection in most of Meulaboh coastline is appropriate.

Evaluation of coastal pollution in Banda Aceh based on BOD5 and DO approach

The demand for preserving the aquatic environment is a top priority for the Indonesian government. The Banda Aceh coast has experienced anthropogenic developments since the 2004 tsunami hit. During the preliminary investigation in 2017, it indicated that the Banda Aceh coast had been contaminated. Here, we investigated water quality in Banda Aceh coast has been conducted during 2018-2019. We employed the Winkler titration for determining Biological Oxygen Demand (BOD5) and Dissolved Oxygen (DO). Furthermore, we generated spatial analysis to show the distribution of BOD5 and DO around the Banda Aceh coast. As a result, BOD5 has been decreased with the value of 1.33 mg/L. Interestingly, the increased DO value of 1.48 mg/L indicated the presence of autotroph biota producing an oxygen atom during 2018-2019. A contrary influence of BOD5 and DO on NO3- was identified, which approximately 50% concentration of nutrient determined by oxygen availability in 2018, while it was less than 5% for the 2019 survey. In conclusion, we suspect that the Banda Aceh coast is categorized as polluted waters for marine biota and tourism.

Communal space patterns in tsunami aid housing for creating public open space after COVID-19 (case study: Gampong Tibang, Banda Aceh, Indonesia)

After the 2004 tsunami disaster, many aid housing developments were carried out, including housing in Gampong Tibang (Tibang Village), Banda Aceh City, with the pattern of building in the initial plot, with low building density. The local community has developed their housing according to their needs. When the COVID-19 pandemic broke out, requiring everyone to be in their respective homes, causing open space in the housing environment to become important as a village communal space, which has social and health functions for residents. This research emphasizes how people use communal open spaces for various activities, which are adaptive to the COVID-19 health protocol. The study approach uses field research quickly, the data is obtained by observing the type of housing open space that has the public function (communal open space) and the behavior of the community in using the space. The analysis was carried out in an analytical descriptive manner, looking at the pattern of activities associated with the COVID-19 health protocol. The results showed that there were 9 communal spaces spread over 4 types: a) field with a bale (an open design building of wood), which was used by men; b) the space around the kiosk that provides seating on an open terrace for all residents; c) open space around the intersection for children to play dynamically (cycling, running, sitting); d) the terrace of the residents’ house which is more for the passive activities of women. That four types of spaces according to the COVID-19 health protocol are very familiar with a natural atmosphere (enough air circulation and sufficient exposure to sunlight). The conclusion of the study shows that the need for socio-cultural space is still needed by the community during the COVID-19 pandemic which can actually make residents healthy.

What Is Tsunami Earthquake?

A tsunami earthquake is defined as an earthquake which induces abnormally strong tsunami waves compared with its seismic magnitude (Kanamori 1972; Kanamori and Anderson 1975; Tanioka and Seno 2001). We investigate the possibility that the surface waves (Rayleigh, Love, and tsunami waves) in tsunami earthquakes are amplified by secondly submarine landslides, induced by the liquefaction of the sea floor due to the strong vibrations of the earthquakes. As pointed by Kanamori (2004), tsunami earthquakes are significantly stronger in longer waves than 100 s and low in radiation efficiencies of seismic waves by one or two order of magnitudes. These natures are in favor of a significant contribution of landslides. The landslides can generate seismic waves with longer period with lower efficiency than the tectonic fault motions (Kanamori et al 1980; Eissler and Kanamori 1987; Hasegawa and Kanamori 1987). We further investigate the distribution of the tsunami earthquakes and found that most of their epicenters are located at the steep slopes in the landward side of the trenches or around volcanic islands, where the soft sediments layers from the landmass are nearly critical against slope failures. This distribution suggests that the secondly landslides may contribute to the tsunami earthquakes. In the present paper, we will investigate the rapture processes determined by the inversion analysis of seismic surface waves of tsunami earthquakes can be explained by massive landslides, simultaneously triggered by earthquakes in the tsunami earthquakes which took place near the trenches.

GIS Based Tsunami Risk Assessment

Tsunami is a coastal hazard which occur due to undersea earthquakes, Meteorite falls, volcanic eruptions or even nuclear weapon operations. The tsunami hazard which occurred in December 2004 was generated due to an undersea earthquake 400m west of northern Sumatra and it inundated coastal areas of Indonesia, Sri Lanka, Thailand and India. This hazard became one of the worst disasters in the history resulting in over thirty thousand fatalities and over seventy thousand house damage in Sri Lanka. This study is focused towards creation of GIS based Tsunami risk map for Galle city which was badly hit by the 2004 Tsunami. Tsunami vulnerability was assessed using weighted overlay spatial method with input parameters of population density, sex ratio, age ratio, disability ratio and damaged building ratio. Tsunami hazard map was developed based on tsunami inundation map which was published by Coastal research and design, costal conservation and resource management department with assistant from Disaster management centre using the Cornell Multigrid Coupled Tsunami Model (COMCOT). Vulnerable and hazard maps were analysed and incorporated to develop final risk map using GIS tool. Keywords GIS; Tsunami Inundation Map; Tsunami Risk Map; Vulnerability; Disaster

The Values of Dark Heritage Post-disaster: A Study of Tsunami Cases in Banda Aceh

The 2004 tsunami disaster that hit Banda Aceh, one city in Indonesia as the worst affected area, has left various relics that need to be considered for their preservation. Nevertheless, it is still a debate so far because heritage preservation refers to the ordinary heritage with positive values from dark heritage after a disaster. It is important to know the significance of values in preserving relics post-disaster as commemoration and learning. In literature, there is still a lack of research about dark heritage values because of natural disasters. The purpose of this research is to explore the community's dark heritage values in encouraging post-disaster area conservation planning. Thus, the purpose of this research is to reveal and explain post-disaster area planning through the approach of dark heritage values. This research was conducted from December 2019 to April 2020 in the post-tsunami area of Banda Aceh as the most affected area with in-depth interviews with 36 informants from the local community, survivors, tourists, experts, and government to know their values. This study uses an interpretative approach because it seeks to construct the existence of dark heritage values in people's perception of seeing a post-disaster area as a heritage. The study results provide new insights that understanding a historic area is not always seen from values with a positive side. Still, dark side values also become a reference that needs to be considered to be preserved for the area's sustainability. The results showed that communities have memory, symbolic, narrative, religious, and scientific values in the post-disaster landscape.