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Glacial ripping involves glaciotectonic disintegration of rock hills and extensive removal of rock at the ice-sheet bed, triggered by hydraulic jacking caused by fluctuating water pressures. Evidence from eastern Sweden shows that glacial ripping caused significant subglacial erosion during the final deglaciation of the Fennoscandian ice sheet, distinct from abrasion and plucking (quarrying). Here we analyse the ice drag forces exerted onto rock obstacles at the base of an ice sheet, and the resisting forces of such rock obstacles: glaciotectonic disintegration requires that ice drag forces exceed the resisting forces of the rock obstacle. We consider rock obstacles of different sizes, shapes and fracture patterns, informed by natural examples from eastern Sweden. Our analysis shows that limited overpressure events, unfavourable fracture patterns, low-transmissivity fractures, slow ice and streamlined rock hamper rock hill disintegration. Conversely, under fast ice flow and fluctuating water pressures, disintegration is possible if the rock hill contains subhorizontal, transmissive fractures. Rock steps on previously smooth, abraded surfaces, caused by hydraulic jacking, also enhance drag forces and can cause disintegration of a rock hill. Glacial ripping is a physically plausible erosion mechanism, under realistic glaciological conditions prevalent near ice margins.

Interpretation: This satellite image interpretation map shows the combined landslide maps produced by the British Geological Survey. The scale of mapping was between 1:5,000 and 1:10,000 and the satellite image resolution is between ~2 m and ~5 m. Five new landslides have been mapped (by the publication date). Geolocation of landslide might not be accurate. Framework: International Charter Disaster Activation 797/798. This inventory was prepared in rapid mapping mode using a combination of automatic satellite image mapping and expert interpretation (from the ALMEO project run by the British Geological Survey). ALMEO Is part of the BGS International NC programme ‘Geoscience to tackle Global Environmental Challenges’, NERC reference NE/X006255/1.

Glacial ripping involves glaciotectonic disintegration of rock hills and extensive removal of rock at the ice-sheet bed, triggered by hydraulic jacking caused by fluctuating water pressures. Evidence from eastern Sweden shows that glacial ripping caused significant subglacial erosion during the final deglaciation of the Fennoscandian ice sheet, distinct from abrasion and plucking (quarrying). Here we analyse the ice drag forces exerted onto rock obstacles at the base of an ice sheet, and the resisting forces of such rock obstacles: glaciotectonic disintegration requires that ice drag forces exceed the resisting forces of the rock obstacle. We consider rock obstacles of different sizes, shapes and fracture patterns, informed by natural examples from eastern Sweden. Our analysis shows that limited overpressure events, unfavourable fracture patterns, low-transmissivity fractures, slow ice and streamlined rock hamper rock hill disintegration. Conversely, under fast ice flow and fluctuating water pressures, disintegration is possible if the rock hill contains subhorizontal, transmissive fractures. Rock steps on previously smooth, abraded surfaces, caused by hydraulic jacking, also enhance drag forces and can cause disintegration of a rock hill. Glacial ripping is a physically plausible erosion mechanism, under realistic glaciological conditions prevalent near ice margins.

The Science for Humanitarian Emergencies and Resilience (SHEAR) programme supports world-leading research to enhance the quality, availability and use of risk and forecast information. Forecasting rainfall-induced landslides is a difficult yet important task that can provide time to take action to save lives, reduce economic losses and help to mitigate the impacts of landslides. The type, quality and accessibility of data directly constrain the choice of approach used for the landslide forecasting and its skill. However, in many landslide-prone countries, limited resources, and lack of investment lead to limited data availability and/or insufficient quality data for informed forecasts. This paper collates understanding from SHEAR consortium members on key considerations for developing territorial (‘regional-scale’) landslide forecasts, particularly in developing country contexts.

Tropics make up about 40% of the earth’s surface area and are home to approximately 40% of the world’s population [1]. Significant and variable depths of residual soils occur across tropical regions for instance Southern India, South-West China, Malaysia, Africa, Taiwan, Hong Kong, Singapore, Sri Lanka, the Philippines, and Northern Brazil. Rapid development in these countries, coupled with changing climate, results in an increasing number of landslides affecting people, property, and livelihoods. Step changes in landslide risk management can be achieved through landslide susceptibility mapping in conjunction with the determination of thresholds at which landslides might be initiated. The landslide trigger thresholds can be defined as a condition that when overcome can cause a change in the state of a system or landscape resulting in one or more landslides [2]. These thresholds can be developed at different spatial scales using approaches such as process-based, conceptual, empirical, statistical, or probabilistic methods [3]. The existing review of studies on trigger thresholds by [2] highlights the challenges of limited landslide inventories, quality of datasets, need for objectivity and reproducibility, and validation. The landslide trigger threshold in tropical countries mostly uses empirical or data-driven methods, which are usually based on incomplete and/or impact-biased landslide inventories. The incomplete or limited landslide inventory further limits the development of the threshold considering the regional or domain-specific ground-based information such as geology, geomorphology, climate, and hydrology. Therefore, the resulting trigger thresholds at regional-scale in a tropical setting are less reliable for landslide forecasting-based applications. The landslides in tropical residual soils may not always directly correlate to rainfall amount or rainfall intensity owing to the importance of soil properties [4], derived from the underlying geology and anthr

Indonesia encompasses one of the most active tectonic regions on Earth. Geological hazards in the country are a potent threat to a large and vulnerable population. It is therefore important that decisions made by disaster managers are informed by the best available earth science. However, large areas remain unstudied, with limited knowledge of past behaviour impacting understanding of future hazards and risks. To understand the challenges and research opportunities related to natural hazards in Indonesia, the Resilience Development Initiative (RDI) and British Geological Survey (BGS) organised a collaborative workshop over two days in January 2022. The workshop provided an opportunity to bring together key stakeholders in disaster risk science and management in Indonesia. The workshop aimed to discuss and offer a forum to explore research needs in terms of understanding, measuring, mitigating, and modelling geological hazards in Indonesia, with a specific focus on earthquakes, landslides, volcanoes and tsunamis. The main findings from this exercise are summarised below. Fundamental hazard assessment. A common theme across the four geological hazards discussed was the need to improve fundamental hazard assessments. For earthquakes, this involves improving the understanding of crustal faults at the local level and feeding this into national hazard assessment exercises. For landslides, a significant challenge raised was the resolution of susceptibility maps. There is a need to produce local hazard assessments considering local geological and environmental conditions. For volcanoes, the challenges were around understanding how past activity can be used to inform understanding of future hazards. However, participants agreed that it is difficult to understand the potential range of activity at infrequently active volcanoes, making hazard assessment more challenging. The main challenge for tsunamis was understanding the relative importance of various tsunami mechanisms. Ea

Landslide Early Warning Systems are described in numerous articles, and research works around the world. But what actually is this (and what is it not) and what are the components of it? In order to deal with these questions, first it has to be explained what landslides are and what early warning systems are. Thus, the first part of the talk will deal with landslides in general, looking at classifications, like Cruden & Varnes (1991). Then the general description of Early Warning Systems will be discussed by looking at the definitions from the UNISDR and UNDRR and the component of people-centred early-warning systems as described during the Early-Warning Conference III (EWC III). Based on these definition and explanations, the third part of the talk will focus on landslide early warning systems. The different components of early-warning systems relevant from a landslide perspective will be described. In conclusion: - Landslide are complex natural phenomena and we do not really know when and where they will definitely occur. But, there might be indicators and the analysis of these indicators might help to identify more landslide prone areas. - Landslide Early Warning Systems, should include the same components of any Early Warning Systems, as defined by UNISDR and UNDRR. - Unfortunately many publications and research works deal just with parts of the whole chain but still call it Early Warning Systems.

The benefits of urban green and blue infrastructure (UGI) are widely discussed, but rarely take into account local conditions or contexts. Although assessments increasingly consider the demand for the ecosystem services that UGI provides, they tend to only map the spatial pattern of pressures such as heat, or air pollution, and lack a wider understanding of where the beneficiaries are located and who will benefit most. We assess UGI in five cities from four continents with contrasting climate, socio-political context, and size. For three example services (air pollution removal, heat mitigation, accessible greenspace), we run an assessment that takes into account spatial patterns in the socio-economic demand for ecosystem services and develops metrics that reflect local context, drawing on the principles of vulnerability assessment. Despite similar overall levels of UGI (from 35 to 50% of urban footprint), the amount of service provided differs substantially between cities. Aggregate cooling ranged from 0.44 °C (Leicester) to 0.98 °C (Medellin), while pollution removal ranged from 488 kg PM2.5/yr (Zomba) to 48,400 kg PM2.5/yr (Dhaka). Percentage population with access to nearby greenspace ranged from 82% (Dhaka) to 100% (Zomba). The spatial patterns of pressure, of ecosystem service, and of maximum benefit within a city do not necessarily match, and this has implications for planning optimum locations for UGI in cities.

Dense networks of dilated fractures occur locally in the upper 5–15 m of bedrock in basement gneisses in eastern Sweden. Near Forsmark, pre-existing sub-horizontal fractures have been jacked open and filled with water-lain sediment, likely during the latest Weichselian glaciation. Despite extensive previous research, it is uncertain whether subglacial hydraulic jacking led to the generation of new fractures, in addition to reactivation of pre-existing ones. Re-analysis of historic photos from excavations near the Forsmark power plant indicates formation of two types of new fracture. Firstly, rock fragments were broken off the main fracture surfaces as existing fractures were jacked open. Secondly, fracture analysis shows that whilst few subvertical fractures occur above tight sub-horizontal fractures, a higher density of vertical fractures occurs above dilated sub-horizontal fractures, suggesting new formation. We apply a model of beam failure theory, borrowed from structural engineering, to constrain potential new fracture generation, using assumptions based on measured water pressure fluctuations from beneath the Greenland Ice Sheet. This modelling shows that beam failure is a plausible mechanism for the generation of new vertical fractures during a subglacial water fluctuation cycle under a range of realistic glaciological conditions. This implies that hydraulic jacking can result in further in situ disruption and brecciation of the shallow rock mass, decreasing the rock mass strength and increasing its hydraulic conductivity. Altogether, hydraulic jacking of existing fractures and the formation of new vertical fractures results in effective subglacial mechanical weathering of the shallow rock mass.

Understanding the impact of fracture networks on rock mass properties is an essential part of a wide range of applications in geosciences from understanding permeability of groundwater aquifers and hydrocarbon reservoirs to erodibility properties and slope stability of rock masses for geotechnical engineering. However, gathering high-quality, oriented-fracture datasets in the field can be difficult and time-consuming, for example, due to constraints on field work time or access (e.g. cliffs). Therefore, a method for obtaining accurate, quantitative fracture data from photographs is a significant benefit. In this paper we describe a method for generating a series of digital fracture traces in a geographic information system (GIS) environment, in which spatial analysis of a fracture network can be carried out. The method is not meant to replace the gathering of data in the field but to be used in conjunction with it, and it is well suited when field work time is limited or when the section cannot be accessed directly. The basis of the method is the generation of the vector dataset (shapefile) of a fracture network from a georeferenced photograph of an outcrop in a GIS environment. From that shapefile, key parameters such as fracture density and orientation can be calculated. Furthermore, in the GIS environment more complex spatial calculations and graphical plots can be carried out such as heat maps of fracture density. Advantages and limitations compared to other fracture network capture methods are discussed.