Description: Our analysis of new bathymetric data reveals six submarine landslides at the eastern Sunda margin between central Java and Sumba Island, Indonesia. Their volumes range between 1 km³ in the Java fore-arc basin up to 20 km³ at the trench off Sumba and Sumbawa. We estimate the potential hazard of each event by modeling the corresponding tsunami and its run-up on nearby coasts. Four slides are situated remarkably close to the epicenter of the 1977 tsunamigenic Sumba M w = 8.3 earthquake. However, comparison of documented tsunami run-up heights and arrival times with our modeling results neither allows us to confirm nor can we falsify the hypothesis that the earthquake triggered these submarine landslides.

Description: Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While early warning systems are frequently used to predict the magnitude, location and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services or financial loss. Complementing early warning systems with impact forecasts has a two‐fold advantage: it would provide decision makers with richer information to take informed decisions about emergency measures, and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multi‐hazard early warning systems. This review discusses the state‐of‐the‐art in impact forecasting for a wide range of natural hazards. We outline the added value of impact‐based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe. Plain language summary Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While such systems are frequently used to predict the magnitude, location and timing of potentially damaging events, they rarely provide impact estimates, such as the expected physical damage, human consequences, disruption of services or financial loss. Extending hazard forecast systems to include impact estimates promises many benefits for the emergency phase, for instance, for organising evacuations. We review and compare the state‐of‐the‐art of impact forcasting across a wide range of natural hazards, and outline opportunities and key challenges for research and development of impact forecasting.

Description: Controls on the deformation pattern (shortening mode and tectonic style) of orogenic forelands during lithospheric shortening remain poorly understood. Here, we use high-resolution 2D thermomechanical models to demonstrate that orogenic crustal thickness and foreland lithospheric thickness significantly control the shortening mode in the foreland. Pure-shear shortening occurs when the orogenic crust is not thicker than the foreland crust or thick, but the foreland lithosphere is thin (〈70–80 km, as in the Puna foreland case). Conversely, simple-shear shortening, characterized by foreland underthrusting beneath the orogen, arises when the orogenic crust is much thicker. This thickened crust results in high gravitational potential energy in the orogen, which triggers the migration of deformation to the foreland under further shortening. Our models present fully thick-skinned, fully thin-skinned, and intermediate tectonic styles in the foreland. The first tectonics forms in a pure-shear shortening mode whereas the others require a simple-shear mode and the presence of thick (〉∼4 km) sediments that are mechanically weak (friction coefficient 〈∼0.05) or weakened rapidly during deformation. The formation of fully thin-skinned tectonics in thick and weak foreland sediments, as in the Subandean Ranges, requires the strength of the orogenic upper lithosphere to be less than one-third as strong as that of the foreland upper lithosphere. Our models successfully reproduce foreland deformation patterns in the Central and Southern Andes and the Laramide province.

Description: Extreme climatic and geophysical events pose a threat to societies and have the capacity to cause significant damage and losses whenever they occur, both in their immediate aftermath and in the medium- to long-term. Their consequences can be amplified even further when more than one event affects the same geographical areas within a short time. Be it cascading hazards, in which one event triggers the next, or simply hazards that happen to occur simultaneously (“compounding” hazards), estimation of their cumulative consequences is challenging because the action of one event affects the exposure and vulnerability to the next one. While the efforts from the research community to develop multi-hazard perspectives have increased considerably in recent years, multiple remaining challenges require strongly-coordinated efforts across different disciplines and areas of expertise to tackle them with the most appropriate tools. With a multidisciplinary team of scientists from four different Helmholtz research centres in Germany, we have started working on the CASCO project (2022-2024), in which we will develop an integrated risk workflow for CAScading and COmpounding hazards in COastal urban areas by focusing on a series of events occurring around Mount Etna (Italy). The case-scenario starts with a strong earthquake that triggers a submarine collapse at the eastern flank of Mount Etna, an area already known to be unstable, and both the earthquake and the landslide trigger a tsunami that hits the coasts of Sicily and Calabria. Almost concomitantly, a heatwave or heavy rainfall happens to affect the same regions, further stressing the population that had been affected by the combined effects of the earthquake and tsunami. The project will be directed towards the modelling of the cascading earthquake, landslide and tsunami events, the compounding heatwave and rainfall, as well as their immediate impacts in terms of cumulative damage and casualties. Moreover, the medium- to long-term response in urban dynamics and the effect of these extreme events on the economic development of the affected populations will be explored. By focusing on a tangible scenario, CASCO will not only tackle the challenges associated with bringing together the whole risk chain (which will be valid beyond our case-study) but also produce outcomes that help increase awareness of such extreme events and the need for societies to develop suitable strategies to strengthen their resilience and improve their disaster response.