The vulnerability of coastal environments to sea-level rise varies spatially, particularly due to local land subsidence. However, high-resolution observations and models of coastal subsidence are scarce, hindering an accurate vulnerability assessment. We use satellite data from 2007 to 2020 to create high-resolution map of subsidence rate at mm-level accuracy for different land covers along the ~3,500 km long US Atlantic coast. Here, we show that subsidence rate exceeding 3 mm per year affects most coastal areas, including wetlands, forests, agricultural areas, and developed regions. Coastal marshes represent the dominant land cover type along the US Atlantic coast and are particularly vulnerable to subsidence. We estimate that 58 to 100% of coastal marshes are losing elevation relative to sea level and show that previous studies substantially underestimate marsh vulnerability by not fully accounting for subsidence.

One of the fundamental problems in continental rift segmentation and propagation is how strain is accommodated along large rift-bounding faults (border faults) since the segmentation of propagating border faults control the expression of rift zones, syn-rift depo-centers, and long-term basin evolution. In the Southern Malawi Rift, where previous studies on the early-stage rifting only assessed border fault structure from surficial and topographic expression, we integrate surface and subsurface data to investigate border fault segmentation, linkage, and growth as proxies for strain accommodation along the Bilila-Mtakataka Fault (BMF) System. We used 30 m-resolution topographic relief maps, electrical resistivity tomography (ERT), and high-resolution aeromagnetic data to characterize the detailed fault geometry and provide a more robust estimate of along-fault displacement distribution. Our results reveal a discrepancy between sub-aerial segmentation of the BMF geometry (six segments), scarp height (five segments) reflecting the most recent episodes of fault offset, and cumulative throw (three composite segments) reflecting the long-term fault offset. We also observe that although the BMF exhibits continuity of sub-aerial scarps along its length, the throw distribution shows a higher estimate at the Northern-to-Central segment relay zone (423 m absolute, 364 m moving median) compared to the Central-to-Southern segment relay zone (371 m absolute, 297 m moving median). The ERT profiles across the relay zones suggest a shallower basement and a possible canyon-mouth alluvial fan stratigraphy at the Central-to-Southern segment relay zone, contrasting the deeper basement and “simpler” electrical stratigraphy at the Northern-to-Central relay. The results suggest a more complex long-term evolution of the BMF than was assumed in previous studies. A comparison of BMF’s maximum displacement-vs-length with those of other Malawi Rift border faults and global normal fault populations suggest that although the BMF has possibly reached its maximum length, it remains largely under-displaced as its 580–837 m maximum displacement is significantly lower than that of faults of equivalent length. We suggest that the BMF may continue to accrue significant strain as tectonic extension progresses in the Southern Malawi Rift, thus posing a major seismic hazard in the region.

An electrical resistivity tomography survey was conducted to assess the subsurface conditions associated with the coseismic liquefaction phenomenon in the epicentral region following the M w 5.8 Mirpur earthquake (Pakistan) on 24 September 2019. The Mirpur earthquake produced extensive coseismic liquefaction-induced surface deformations, including: sand blows, ground failure and lateral spreading along the Upper Jhelum Canal and in the nearby villages. Electrical resistivity data were acquired along three profiles and calibrated with available borehole data. The inverted electrical resistivity tomography profiles reveal three regional geoelectric layers, which consist of an upper 2--5-m-thick discontinuous zones of medium resistivity values ranging from 25 m to 60 m, underlain by a 7-8-m-thick zone of low resistivity (<10 m) and a basal layer of high resistivity (> 100 m). Based on geological and geophysical data, we infer that. (1) disrupted geoelectric layers in the shallow subsurface and spatially extended low electrical resistivity (<8 m) layers document the elevated groundwater table due to sudden increase in pore-water pressure triggered by the Mirpur earthquake. These lenses of high conductivity may represent potential hazards in the case of future earthquakes in the study area. (2) Fracture azimuths vary between 120°± 15°and 335°-45°(subparallel and orthogonal to the strike of the Himalayan Frontal Thrust. (3) Common coseismic deformational features (e.g., sand blow and ground fracture) are located within the zone of maximum-recorded ground shaking (intensity of VI) and underlain by Quaternary alluvial sediments. (4) Mega fractures (1.60 m wide and up to 187 m long) oriented parallel to the canal resulted from lateral spreading. We conclude that high resistivity structures extending from depth to the shallow subsurface resulted from either intrusion of air or eruption of sands from layer three. We suggest that high-resolution geoelectrical imaging

Every year incidents of building collapse claim many lives and cause enormous financial losses around the world, which are often blamed on low‐quality materials, non‐compliance with standards, lack of oversight, and failure to enforce building codes. Here, we highlight the role of land subsidence in triggering unprecedented collapses in the city of Lagos, Nigeria, which has reported over 200 casualties during 152 building failures since 2005. We used acquisitions from radar satellites for 2018–2021 and provided data that link subsidence to foundation damage and high building failure risk in the region. We estimate that an area of 5–81 km2 and 255–4,000 buildings are exposed to a high to very high risk of collapse for short‐term (10 years) to long‐term (75 years) periods. Differential land subsidence can trigger building collapse, and the data presented here will enable authorities to create adequate building codes and standards and devise mitigation strategies.

Iron mineral transformations occurring in hydrocarbon‐contaminated sites are linked to the biodegradation of the hydrocarbons. At a hydrocarbon‐contaminated site near Bemidji, Minnesota, USA, measurements of magnetic susceptibility (MS) are useful for monitoring the natural attenuation of hydrocarbons related to iron cycling. However, a transient MS, previously observed at the site, remains poorly understood and the iron mineral phases acting as reactants and products associated with this MS perturbation remain largely unknown. To address these unknowns, we acquired mineral magnetism measurements, including hysteresis loops, backfield curves, and isothermal remanent magnetizations on sediment core samples retrieved from the site and magnetite‐filled mineral packets installed within the aquifer. Our data show that the core samples and magnetite packs display decreasing magnetization with time and that this loss in magnetization is accompanied by increasing bulk coercivity consistent with decreased average grain size and/or partial oxidation. Low‐temperature magnetometry on all samples displayed behavior consistent with magnetite, but samples within the plume also show evidence of maghemitization. This interpretation is supported by the occurrence of shrinkage cracks on the surface of the grains imaged via scanning electron microscopy. Magnetite transformation to maghemite typically occurs under oxic conditions, here, we propose that maghemitization occurs within the anoxic portions of the plume via microbially mediated anaerobic oxidation. Mineral dissolution also occurs within the plume. Microorganisms capable of such anaerobic oxidation have been identified within other areas at the Bemidji site, but additional microbiological studies are needed to link specific anaerobic iron oxidizers with this loss of magnetization.

One of the fundamental problems in continental rift segmentation and propagation is how strain is accommodated along large rift-bounding faults (border faults) since the segmentation of propagating border faults control the expression of rift zones, syn-rift depo-centers, and long-term basin evolution. In the Southern Malawi Rift, where previous studies on the earlystage rifting only assessed border fault structure from surficial and topographic expression, we integrate surface and subsurface data to investigate border fault segmentation, linkage, and growth as proxies for strain accommodation along the Bilila-Mtakataka Fault (BMF) System. We used 30 m-resolution topographic relief maps, electrical resistivity tomography (ERT), and high-resolution aeromagnetic data to characterize the detailed fault geometry and provide a more robust estimate of along-fault displacement distribution. Our results reveal a discrepancy between sub-aerial segmentation of the BMF geometry (six segments), scarp height (five segments) reflecting the most recent episodes of fault offset, and cumulative throw (three composite segments) reflecting the long-term fault offset. We also observe that although the BMF exhibits continuity of sub-aerial scarps along its length, the throw distribution shows a higher estimate at the Northern-to-Central segment relay zone (423 m absolute, 364 m moving median) compared to the Central-to-Southern segment relay zone (371 m absolute, 297 m moving median). The ERT profiles across the relay zones suggest a shallower basement and a possible canyon-mouth alluvial fan stratigraphy at the Central-to-Southern segment relay zone, contrasting the deeper basement and "simpler" electrical stratigraphy at the Northern-to-Central relay. The results suggest a more complex long-term evolution of the BMF than was assumed in previous studies. A comparison of BMF's maximum displacement-vs-length with those of other Malawi Rift border faults and global normal fault populations suggest that although the BMF has possibly reached its maximum length, it remains largely under-displaced as its 580-837 m maximum displacement is significantly lower than that of faults of equivalent length. We suggest that the BMF may continue to accrue significant strain as tectonic extension progresses in the Southern Malawi Rift, thus posing a major seismic hazard in the region.

No abstract

&lt;p&gt;The coastline of the African Gulf of Guinea hosts large river deltas, coastal wetlands and mangrove ecosystems. It is in places densely populated, with many capital megacities with millions of inhabitants such as Lagos, Abidjan and Accra situated at the coast. And population projections for these cities suggest a continued staggering increase in the coming decades. Also, many of the economic activities are located along the coastline. For example, Nigerian coastal areas are home to 85% of the nation industry and to more than 100 million people. On the other hand, the coastland retains pristine transitional environments formed during the Holocene, well recognized for the great biological richness and the high level of endemism. These pressures and foreseen growth make these lowly elevated coastal areas particularly vulnerable to relative sea-level rise (SLR).&lt;/p&gt;&lt;p&gt;Regional or local impact studies of climate-change induced global sea-level rise are scarce and, when available, do not account for vertical land motion, i.e. land subsidence. Coastal land subsidence is critically under-quantified at global scale and the Gulf of Guinea region is no exception to this. Meanwhile, examples elsewhere in the World show coastal economic development and population growth can accelerate land subsidence to rates that are magnitudes larger than global SLR. With the fast-paced developments taking place along the Gulf of Guinea&amp;#8217;s coastline, land subsidence poses an unknown but potentially large hazard to this region.&lt;/p&gt;&lt;p&gt;Here, we present the first findings in our work to assess coastal subsidence in this fast-changing region of the World, through regional and local case studies and satellite assessments. By building on the recent advancements in global elevation data, we aim to update coastal elevation estimates and identify low lying hotspots with high vulnerability to relative SLR. Ultimately, we aim to project coastal elevation change for this important region and, in case of human-induced land subsidence, show how much relative SLR can potentially be avoided by changing to sustainable use of natural resources. Hence, we may be able to alter the fate of deltas, wetlands and coastal cities by quantifying and addressing land subsidence as early as in this fast growing region of the world.&lt;/p&gt;