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Multiring basins dominate the crustal structure, tectonics, and stratigraphy of the Moon. Understanding how these basins form is crucial for understanding the evolution of ancient planetary crusts. To understand how preimpact thermal structure and crustal thickness affect the formation of multiring basins, we simulate the formation of lunar basins and their rings under a range of target and impactor conditions. We find that ring locations, spacing, and offsets are sensitive to lunar thermal gradient (strength of the lithosphere), temperature of the deep lunar mantle (strength of the asthenosphere), and preimpact crustal thickness. We also explore the effect of impactor size on the formation of basin rings and reproduce the observed transition from peak‐ring basins to multiring basins and reproduced many observed aspects of ring spacing and location. Our results are in broad agreement with the ring tectonic theory for the formation of basin rings and also suggest that ring tectonic theory applies to the rim scarp of smaller peak‐ring basins. The largest impact craters on the Moon are multiring basins that exhibit three or more topographic rings. Great volumes of material were ejected and redistributed during the formation of these 1,000‐km‐scale basins. Formation of these basins is the predominant process driving change of the lunar crust, the outermost layer of the Moon. Why large basins have multiple topographic rings and what they might tell us about the Moon remain poorly understood. Here we simulate the formation of these basins and their rings during an asteroid impact. We explore how thickness of the lunar crust, size of the impacting body, and interior temperature of the Moon affect the formation of basins and their rings. With well‐persevered multiring basins and an abundance of high‐quality gravity and topography data, the Moon is an ideal location to explore the formation of multiring basins. A better understanding of the formation of these basins will help us understand how similar basins may have affected the crusts of the Earth, Mars, Mercury, and Venus. We simulate the formation of multiring basins exploring the effect of impactor size, target thermal structure, and crustal thicknessOur simulations reproduce observed trends in ring spacing including the transition from peak‐ring to multiring structuresOur results show that basin ring formation is quite sensitive to target thermal structure in general agreement with ring tectonic theory

The 4 April 2010 Mw7.2 El Mayor‐Cucapah (EMC) earthquake in Baja, California, and Sonora, Mexico, had primarily right‐lateral strike‐slip motion and a minor normal‐slip component. The surface rupture extended about 120 km in a NW‐SE direction, west of the Cerro Prieto fault. Here we use geodetic measurements including near‐ to far‐field GPS, interferometric synthetic aperture radar (InSAR), and subpixel offset measurements of radar and optical images to characterize the fault slip during the EMC event. We use dislocation inversion methods and determine an optimal nine‐segment fault geometry, as well as a subfault slip distribution from the geodetic measurements. With systematic perturbation of the fault dip angles, randomly removing one geodetic data constraint, or different data combinations, we are able to explore the robustness of the inferred slip distribution along fault strike and depth. The model fitting residuals imply contributions of early postseismic deformation to the InSAR measurements as well as lateral heterogeneity in the crustal elastic structure between the Peninsular Ranges and the Salton Trough. We also find that with incorporation of near‐field geodetic data and finer fault patch size, the shallow slip deficit is reduced in the EMC event by reductions in the level of smoothing. These results show that the outcomes of coseismic inversions can vary greatly depending on model parameterization and methodology. Complete study of El Mayor‐Cucapah coseismic displacement, fault geometry, and slip distributionWe investigate consistency of inferred slip on the faults by varying Earth structure and choice of geodetic constraintsApparent shallow slip deficits can be related to fault geometry discretization, smoothing, and geodetic constraints

We investigate 3‐D local earthquake tomography for high‐quality travel time arrivals from aftershocks following the 2010 M7.0 Haiti earthquake on the Léogâne fault. The data were recorded by 35 stations, including 19 ocean bottom seismometers, from which we selected 595 events to simultaneously invert for hypocenter location and 3‐D Vpand Vsvelocity structures in southern Haiti. We performed several resolution tests and concluded that clear features can be recovered to a depth of 15 km. At 5 km depth we distinguish a broad low‐velocity zone in the Vpand Vsstructure offshore near Gonave Island, which correlate with layers of marine sediments. Results show a pronounced low‐velocity zone in the upper 5 km across the city of Léogâne, which is consistent with the sedimentary basin location from geologic map. At 10 km depth, we detect a low‐velocity anomaly offshore near the Trois Baies fault and a NW‐SE directed low‐velocity zone onshore across Petit‐Goâve and Jacmel, which is consistent with a suspected fault from a previous study and that we refer to it in our study as the Petit‐Goâve‐Jacmel fault. These observations suggest that low‐velocity structures delineate fault structures and the sedimentary basins across the southern peninsula, which is extremely useful for seismic hazard assessment in Haiti. Local tomography in Haiti3‐D P and S velocity inversionsAftershock relocations

Recent analysis of New Horizons data revealed an ∼1,000‐km‐diameter region of large‐scale lineations antipodal to Sputnik Planitia, the 1,200 × 2,000 km elliptical impact basin on Pluto's anti‐Charon hemisphere. At the available resolution, these lineations are similar to antipodal terrains associated with large impact basins elsewhere in the Solar System. Here, we simulate the Sputnik Planitia‐forming impact and track stress waves through a Pluto‐like target body to the antipode. We find that the Sputnik Planitia‐forming impact is capable of producing significant antipodal terrains and the observed lineations may be extensional graben. The extent and mode of deformation at the antipode, however, is sensitive to ocean thickness and core composition. Simulations that best reproduce the observed terrains imply that Pluto may have hosted a >150‐km‐thick ocean and a hydrated core at the time of impact. Pluto's interior structure remains largely a mystery, including the composition of the core and the existence and extent of a subsurface ocean. Though seismological study is not yet possible on Pluto, the reaction of a planet's interior structure to stress waves produced by large impacts can be used to indirectly probe the planet's interior—seismology by impact. We use impact modeling to simulate the formation of Sputnik Planitia, Pluto's massive impact basin, to determine how the dwarf planet's interior controls transmission of stress waves to the opposite hemisphere. Our results suggest that a large subsurface ocean beneath the ice shell, as well as a core that has experienced substantial alteration from interactions with an ocean above, are critical to match the size of the lineated terrain observed antipodal to Sputnik Planitia. We model the formation of Pluto's Sputnik Planitia basin from an impact origin to assess the dwarf planet's interior structureOur simulations illustrate the Sputnik Planitia‐forming impact is capable of producing significant antipodal terrains on PlutoThe extent and mode of deformation at the antipode is most consistent with a thick (>150‐km) ocean and a hydrated core We model the formation of Pluto's Sputnik Planitia basin from an impact origin to assess the dwarf planet's interior structure Our simulations illustrate the Sputnik Planitia‐forming impact is capable of producing significant antipodal terrains on Pluto The extent and mode of deformation at the antipode is most consistent with a thick (>150‐km) ocean and a hydrated core

We simulate the formation of the large elliptical impact basin associated with Pluto's Sputnik Planum (SP; informal name). The location of SP suggests that it represents a large positive mass anomaly. To find the conditions necessary for SP to have a positive mass anomaly, we consider impacts into targets with a range of thermal states and ocean thicknesses. Assuming the basin evolves to its current‐day configuration, we calculate the mass and gravity anomalies associated with SP. We find that SP can only achieve a large positive mass anomaly if Pluto has a more than 100 km thick salty ocean. This conclusion may help us better understand the composition and thermal evolution of Pluto. Furthermore, our work supports the hypothesis that SP basin has an impact origin. We model the formation of Pluto's Sputnik Planum (SP) basinThe mass anomaly associated with SP provides constraints on a subsurface oceanPluto must have a greater than 100 km thick briny ocean if SP has a large positive mass anomaly