The Late Pliocene-Quaternary Outer Thrust System of the Apennine-Maghrebides fold-and-thrust belt extends ~2000 km from northern Italy to Sicily.Its northernmost arc is seismically active and represents a test case to study geometries and seismogenesis of slowly deforming megathrusts developed within the continental lithosphere.Two distinct SW-dipping reverse shear zones (T1 and T2) in the Outer Thrust System of eastern Central Italy have been recently unveiled thanks to geological and integrated seismological information.These shear zones penetrate the Adria continental lithosphere to a maximum depth of ~60 km, with an outward convex shape associated with an outwarddiverging radial pattern.This paper presents new constraints on the megathrusts' geometry in light of a novel microseismic catalog (from 2009-2022) specifically focused on the compressional volume.Further details in the reconstruction of T1 and T2 are derived from a recent compressional seismic sequence (November 2022, M W 5.5) located in the Adriatic offshore.It activated the outermost T1 upper crustal segment with pure compressional kinematics and illuminated T2 at lower crustal depths.We integrate geological sections, seismic lines, serial hypocentral cross sections, and focal mechanisms to build a detailed nonplanar 3-D model of the thrusts involved.In addition, we build Coulomb stress scenarios for analyzing the possibility of the static interplay between the upper crust T1 segment activated by the 2022 sequence and the underlying T2 crust segment.The overall results may be relevant for assessing seismic hazards in areas with multi-depth active structures and for gaining insights into plate tectonic dynamics.

River deltas occupy only ~0.65% of Earth's land surface, but collectively house ~4.5% of the global population and account for more than 6% of the global GDP.Because of ongoing human interventions in the past century (river diversions, groundwater and petroleum extraction, and urbanization), deltas are coming under additional and intense threat from climate change and the impending sea-level rise.Many highlatitude and tropical deltas where population pressure is low and human modification is minimal face less peril for the foreseeable future, but densely populated deltas, especially those in Asia with extreme urbanization and environmental pressures, will be more susceptible to land loss and drowning.Here we consider six key deltas-Mississippi, Yangtze, Niger, Bengal, Nile, and Indus-emphasizing recent findings and consensus as to their health and how human activities have brought these vulnerable ecosystems perilously close to or beyond the point of no return.

The growing concerns about the ethics of geologic sampling are relevant to teaching, research, and our geoheritage (Chan and Mogk, 2022) . This paper examines our current culture and attitudes on ethics from sample collection to archiving, based on a community survey across multiple professional societies and geoscience disciplines, as well as a Geological Society of America (GSA) Connects 2022 Noontime Lecture Town Hall. Many helpful comments and suggestions from the geoscience community have helped move this process forward toward a consensus on the need for developing standards for ethical geologic sampling. The topic of sampling is complex and exposes values in conflict, with individual examples intimately tied to a particular question being asked; thus, one size does not fit all. Professional societies can provide a valuable service by having clearly stated guidelines for professional practice (e.g., as a requisite for publication), and by developing resources about sampling that can be easily accessed and imported into curricula for training future generations of geoscientists. A survey made up of 46 questions was beta tested and refined prior to its release to multiple listservs of co-sponsor societies in August 2022, administered by GSA staff. We collected results (n = 810) over a threeweek open period for responses. All anonymous survey data (see Supplemental Material 1 ) were aggregated so that no individuals could be identified. Nearly all questions had a full spectrum of choices, many with optional comment boxes. The results are briefly summarized in the six categories (A-F) below and served as a springboard for discussion at the GSA Connects 2022 Noontime Lecture Town Hall in Denver,

Recent field-based studies indicate that the northern margin of North America is best interpreted as a tectonic boundary that experienced a long, complex history of strike-slip displacement. Structures juxtaposing the Pearya and Arctic Alaska terranes with North America are linked and define the Canadian Arctic transform system (CATS) that accommodated Paleozoic terrane translation, truncation of the Caledonian orogen, and shortening within the transpressional Ellesmerian orogen. The structure was reactivated during Mesozoic translational opening of the Canada Basin. Land-based evidence supporting translation along the Canadian Arctic margin is consistent with transform structures defined by marine geophysical data, thereby providing a robust alternative to the current consensus model for rotational opening of the Canada Basin.