Land Use Change Detection and Urban Sprawl Monitoring in Metropolitan Area of Jakarta (Jabodetabek) from 2001 to 2015

Being 13th largest city in the world makes Jakarta as a fascinating city in South East Asia. Its surrounding regions are included in a particular metropolitan area called “Jabodetabek”. Population growth in this metropolitan area about 10 million only in 15 years from 2000 to 2015. Consequently, loss of vegetation and agricultural land, less water resources, increasing demand for housing and transportation infrastructure as the effect of this ever-growing population take place. This phenomenon can be detected using Landsat satellites images. The settlement or urban area in Jabodetabek shows a huge increase in percentage from 2001 to 2015, so much that the urban area is the dominant land cover and reaches up to 61 percent of Jabodetabek in year 2015. Moreover settlement density in Jabodetabek (ring zones 25 to 45 km from central city) shows an increase of more than 20% urban areas in year 2015. Furthermore, the result of compactness reveals that this urban expansion in Jabodetabek was spread out from 2001 to 2008 and became more compacted by 2015

Identification and ranking of subaerial volcanic tsunami hazard sources in Southeast Asia

Tsunamis caused by large volcanic eruptions and flanks collapsing into the sea are major hazards for nearby coastal regions. They often occur with little precursory activity and are thus challenging to detect in a timely manner. This makes the pre-emptive identification of volcanoes prone to causing tsunamis particularly important, as it allows for better hazard assessment and denser monitoring in these areas. Here, we present a catalogue of potentially tsunamigenic volcanoes in Southeast Asia and rank these volcanoes by their tsunami hazard. The ranking is based on a multicriteria decision analysis (MCDA) composed of five individually weighted factors impacting flank stability and tsunami hazard. The data are sourced from geological databases, remote sensing data, historical volcano-induced tsunami records, and our topographic analyses, mainly considering the eruptive and tsunami history, elevation relative to the distance from the sea, flank steepness, hydrothermal alteration, and vegetation coverage. Out of 131 analysed volcanoes, we found 19 with particularly high tsunamigenic hazard potential in Indonesia (Anak Krakatau, Batu Tara, Iliwerung, Gamalama, Sangeang Api, Karangetang, Sirung, Wetar, Nila, Ruang, Serua) and Papua New Guinea (Kadovar, Ritter Island, Rabaul, Manam, Langila, Ulawun, Bam) but also in the Philippines (Didicas). While some of these volcanoes, such as Anak Krakatau, are well known for their deadly tsunamis, many others on this list are lesser known and monitored. We further performed tsunami travel time modelling on these high-hazard volcanoes, which indicates that future events could affect large coastal areas in a short time. This highlights the importance of individual tsunami hazard assessment for these volcanoes, the importance of dedicated volcanological monitoring, and the need for increased preparedness on the potentially affected coasts

Identification and Analysis of Tsunamigenic Volcanoes in Indonesia using Satellite-Based Earth Observation Data

Geographically, geologically, hydrologically, and demographically, Indonesia is a disasterprone area because it is located on an active Earth's crust where there are five faults of the Earth's plates that meet, collide, and cause dynamic movements of the earth. Many of the major earthquakes and volcanic activity in Indonesia were in shallow regions, which trigger a tsunami that can kill thousands of people. To identify these tsunamigenic volcanoes, a multi-criteria analysis based on criteria from previous studies and historical tsunamigenic volcanic events is used. Using the value of the weights in calculating the potential level, the volcanoes that have a high potential to cause a tsunami are Banda Api, Batu Tara, Wetar Volcano, Iliwerung, Iya, Anak Krakatau, Rokatenda, Ruang, Serua/Legatala, Wurlali, and Pusukbukit. As a follow-up to this study, in-depth research needs a dataset that is more accurate on high potential volcanoes to define risk that can occur on the site. Besides that, data verification on site is needed to clarify the accuracy of this analysis. For areas close to settlement/population area, volcano monitoring is essential to minimize the risks that may occur in the surrounded area