An Enhanced Earthquake Risk Assessment Methodology using H3 Spatial Indexing (Case Study: Sorong City)
Atik Nurul Aini (a,b*), Dewa Putu Adikarma Mandala (a), Mizan Bustanul Fuady Bisri (a,c)

a) Cerdas Antisipasi Risiko bencana (CARI! bencana)
Jalan Sepak Bola 5, Bandung 40293, Indonesia
*atiknurulaini[at]students.itb.ac.id
b) Faculty of Earth Sciences and Technology, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
c) GSICS, Kobe University, Kobe, Japan
2-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

Risk assessment is the first step in disaster risk reduction in general and becomes even more important for types of disasters with potentially significant impacts such as earthquakes. Besides the direct impact of very devastating shocks, earthquakes can also trigger disasters that are no less damaging such as landslides, liquefaction, and tsunamis. This study aims to apply the H3 spatial indexing system to improve earthquake risk assessment using Sorong City as a case study, and compare the result of risk assessment using H3 and the usual risk assessment in Indonesia. On September 24, 2015, Sorong City was rocked by an earthquake that left dozens of victims injured and hundreds of houses damaged.

H3 is a geospatial indexing system developed and open sourced by Uber. It uses hexagons in its indexing in its calculation and visualization, which are hierarchical and global. In a hexagon, all neighbors are equidistant and have the property of expanding neighboring rings that are close to a circle, also filling space optimally. On average, a polygon can be filled with hexagon tiles with a smaller margin of error than square tiles. The H3 spatial index is used in earthquake hazard, vulnerability, capacity, and risk assessment systems. The value of each parameter is entered into each hexagon so that in the end each hexagon has its risk index value.

The study shows that the use of H3 in earthquake risk assessment can provide a more detailed level of analysis and indirectly does not depend on regional administrative boundaries. Technically, this advantage provides a more efficient calculation method and is also easier to modify partially both spatially and in terms of the parameters used. Based on the performance evaluation results on the spatial join aspect, H3 provides much faster performance compared to traditional indexing systems. Hence, the H3 spatial index will be very useful to meet the need for an earthquake risk assessment on a larger scale with a higher level of resolution.

Keywords: h3 spatial index- risk assessment- earthquake

Topic: Interdisciplinary Geosciences