This paper discusses the relations between the impacts of volcanic eruptions at multiple-scales and the related-issues of disaster-risk reduction (DRR). The review is structured around local and global impacts of volcanic eruptions, which have not been widely discussed in the literature, in terms of DRR issues. We classify the impacts at local scale on four different geographical features: impacts on the drainage system, on the structural morphology, on the water bodies, and the impact on societies and the environment. It has been demonstrated that information on local impacts can be integrated into four phases of the DRR, i.e., monitoring, mapping, emergency, and recovery. In contrast, information on the global impacts (e.g., global disruption on climate and air traffic) only fits the first DRR phase. We have emphasized the fact that global impacts are almost forgotten in the DRR programs. For this review, we have extracted case studies from Indonesia, and compared them to those of other regions, because Indonesia is home to >130 volcanoes and experienced several latest volcanic eruptions with VEI > 5.

In the last 20 years, Kuwaru coastal area has been under constant threat from both physical and non-physical processes. Such threat is exacerbated by...

Coastal regions are one of the most vulnerable areas to the effects of global warming, which is accompanied by an increase in mean sea level and changing shoreline configurations. In Indonesia, the socioeconomic importance of coastal regions where the most populated cities are located is high. However, shoreline changes in Indonesia are relatively understudied. In particular, detailed monitoring with remote sensing data is lacking despite the abundance of datasets and the availability of easily accessible cloud computing platforms such as the Google Earth Engine that are able to perform multi-temporal and multi-sensor mapping. Our study aimed to assess shoreline changes in East Java Province Indonesia from 2000 to 2019 using variables derived from a multi-sensor combination of optical remote sensing data (Landsat-7 ETM and Landsat-8 OLI) and radar data (ALOS Palsar and Sentinel-1 data). Random forest and GMO maximum entropy (GMO-Maxent) accuracy was assessed for the classification of land and water, and the land polygons from the best algorithm were used for deriving shorelines. In addition, shoreline changes were quantified using Digital Shoreline Analysis System (DSAS). Our results showed that coastal accretion is more profound than coastal erosion in East Java Province with average rates of change of +4.12 (end point rate, EPR) and +4.26 m/year (weighted linear rate, WLR) from 2000 to 2019. In addition, some parts of the shorelines in the study area experienced massive changes, especially in the deltas of the Bengawan Solo and Brantas/Porong river with rates of change (EPR) between −87.44 to +89.65 and −18.98 to +111.75 m/year, respectively. In the study areas, coastal erosion happened mostly in the mangrove and aquaculture areas, while the accreted areas were used mostly as aquaculture and mangrove areas. The massive shoreline changes in this area require better monitoring to mitigate the potential risks of coastal erosion and to better manage coastal sedimentation.

A landslide is one of natural hazards that affect humans and their livelihood especially in the mountainous area. The increasing landslide risk due to global climate change and demographic pressure demands integration between disaster risk reduction and sustainability management, for instance, the recently increasing people's awareness of the landslide and its impacts. Landslides occur in particular location regarding both physical and non-physical features of an area, comprising geomorphology, geology, geomorphometry, human activities, earthquake probability, rainfall occurrence, and etc. This research aims to understand the characteristics of the specific land surface that bears susceptibility to landslides using a geomorphometric approach and to analyze the relationship between geomorphometric characteristics and landslide events. The Tinalah watershed is located in Menoreh Mountains, one of mountainous areas in Java where highly frequent landslides occur. Geomorphometric characteristics, derived from DEMs with 2x2-m2 grid resolution, consist of elevation, slope gradient, aspect, profile curvature, plan curvature, and general curvature. The inventory of landslide events, consisting of the location, time, area, perimeter, typology, and activity, is derived from the field maps, local government's report analysis, and interviews with local people. In this research, landslide distribution is mapped using the multi-temporal records of landslide events during 2006-2010. A raster-based spatial analysis reveals the relationship between landslide events and geomorphometric characteristics. Each variable shows the quantitative information of landslide distribution in the Tinalah watershed. As a result, geomorphometric characteristics have the most significant relationship with the landslide distribution in this study area