Climate change is increasingly predisposing polar regions to large landslides. Tsunamigenic landslides have occurred recently in Greenland ( Kalaallit Nunaat ), but none have been reported from the eastern fjords. In September 2023, we detected the start of a 9-day-long, global 10.88-millihertz (92-second) monochromatic very-long-period (VLP) seismic signal, originating from East Greenland. In this study, we demonstrate how this event started with a glacial thinning–induced rock-ice avalanche of 25 × 10 ⁶ cubic meters plunging into Dickson Fjord, triggering a 200-meter-high tsunami. Simulations show that the tsunami stabilized into a 7-meter-high long-duration seiche with a frequency (11.45 millihertz) and slow amplitude decay that were nearly identical to the seismic signal. An oscillating, fjord-transverse single force with a maximum amplitude of 5 × 10 ¹¹ newtons reproduced the seismic amplitudes and their radiation pattern relative to the fjord, demonstrating how a seiche directly caused the 9-day-long seismic signal. Our findings highlight how climate change is causing cascading, hazardous feedbacks between the cryosphere, hydrosphere, and lithosphere.

Momentum Conservative Schemes for Shallow Water Flows - Volume 4 Issue 2 - S. R. Pudjaprasetya, I. Magdalena

The Bay of Bengal has been at the heart of human civilisation and trade for many centuries. Accordingly, this oceanic space has seen influx of people from around the world including European traders who plundered natural wealth of this region for many years. Unabated exploitation of natural resources has been the primary reason for deterioration of environment of this part of the world. To add to this, supporting a growing population through unsustainable anthropogenic activities for decades is considered a primary cause for deterioration of marine life, habitats, coastal and marine ecosystems and numerous ocean ecosystem services of this oceanic space. Since the health of the oceanic space is critical for survival of life of Earth, a detailed study of the impacts of a growing population on the coastal environment of the Bay is considered important. Unfortunately, since the anthropogenic activities causing this deterioration are numerous, they cannot be covered in one paper. Hence, only a select few critical anthropogenic activities causing coastal erosion, resource degradation, and marine pollution are being analysed here. The study shows that as a result of increasing population, terrestrial activities such as increasing built up area, industries, land use activities, fisheries and aquaculture, and construction of shore protection structures have resulted in reduced coastal vegetation and increased pollution of the ocean. As a result the coastal landscape is witnessing increased coastal erosion, coastal flooding and inundation, loss of vegetation and faunal communities especially fishes. While local initiatives and projects reflect a positive commitment to address resource degradation and to create resilient coastal ecosystems, these efforts need to be transformed into achievements by dedicated and nuanced involvement of all stakeholders, especially the public, for the desired results.

In this paper, we investigate wave attenuation caused by mangroves as a porous media. A 1-D mathematical model is derived by modifying the shallow water equations (SWEs). Two approaches are used to involve the existing of mangrove: friction term and diffusion term. The model will be solved analytically using the separation of variables method and numerically using a staggered finite volume method. From both methods, wave transmission coefficient will be obtained and used to observe the damping effect induced by the porous media. Several comparisons are shown to examine the accuracy and robustness of the derived numerical scheme. The results show that the friction coefficient, diffusion coefficient and vegetation’s length have a significant effect on the transmission coefficient. Moreover, numerical observation is extended to a 2-D SWEs, where we conduct a numerical simulation over a real bathymetry profile. The results from the 2-D numerical scheme will be validated using the data obtained from the field measurement which took place in Demak, Central Java, Indonesia. The results from this research will be beneficial to determine the characteristics of porous structures used for coastal protection.