Crater Field Research Articles

Iron projectile fractionation processes in siliceous glass from small impact craters

Detection of extra-terrestrial geochemical components in melt generated during meteorite impact provides diagnostic evidence that can be used to confirm a hypervelocity impact event, and in some cases, classify the projectile. However, projectile contamination is often present at sub-percent levels, and can be difficult to detect. In contrast, meteoritic abundances in glass from small impact craters (<1 km diameter) formed by iron meteorites can be anomalously high, which has been attributed to glass originating from the projectile-target interface. Emulsion textures, immiscible liquids, metal spherules, and non-meteoritic siderophile element ratios have been cited as evidence that the projectile component is typically fractionated in impact glass. Here we present compositional data for impact glass from the Henbury crater field in Australia, where the largest crater is 145 m in diameter and the subgreywacke target rock and IIIAB iron projectile are geochemically distinct. Mixing models (Fe-Si, Ni-Co, Cr-Ir) and high platinum group element abundances indicate average projectile contributions ranging from 3 to 13 % in Henbury glass, comparable to ranges reported in glass from the Kamil (Egypt) and Wabar (Saudi Arabia) impact craters. However meteoritic siderophile element ratios (Fe:Ni, Fe:Co, Ni:Co) in Henbury glass appear nearly unfractionated, whereas Wabar and Kamil glasses have more fractionated ratios. Observed variations are attributed to fractionation of meteoritic Ni by formation of immiscible Ni-rich spherules during oxidation of meteoritic iron, and subsequent separation of Ni-rich spherules from glass during ejection. The Henbury glass sample analyzed is interpreted as an example of an interface melt that quenched prior to extensive oxidation and phase separation, and thus may represent one of the least fractionated samples of melt from the projectile-target interface described thus far, whereas Wabar and Kamil glasses record more evidence of fractionation processes. These results further highlight the influence of metal spherule formation on the composition of ejected glass from small impact structures formed by iron meteorites and provide new insights that explain textural features observed in natural impact glasses.

Jake Seller Draw impact structure, Bighorn Basin, Wyoming, USA: The deepest known buried impact structure on Earth and its possible relation to the Wyoming crater field

We provide evidence demonstrating the impact origin of a structure, here named the Jake Seller Draw impact structure, which is buried below the Jake Seller Draw drainage basin, in the Bighorn Basin of Wyoming, western United States. The 4.3-km-diameter structure was first recognized as a seismic disturbance at a depth of ∼6.5 km in two- and three-dimensional seismic profiles. Microstructural analysis of drill cuttings situated in the center and outside of Jake Seller Draw revealed the presence of multiple sets of planar deformation features and planar fractures in nine quartz grains, thereby confirming the hypervelocity impact origin of the structure. The seismic data show that Jake Seller Draw is a complex impact structure containing a 1-km-wide central uplift. The geologic and seismic data suggest that Jake Seller Draw is the most deeply buried impact structure known on Earth to date. The stratigraphic framework suggests that the crater was formed in a nearshore environment at the Pennsylvanian−Permian boundary, ∼280 m.y. ago. This age coincides with the age of the Wyoming crater field 300 km southeast of Jake Seller Draw and may suggest a common origin.

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

Secondary cratering on Earth: The Wyoming impact crater field

Abstract A large number of small impact structures have been discovered in Wyoming, USA, and we raise the question of how this accumulation occurred. We document 31 crater structures of 10–70 m diameter with corresponding shock features but missing meteorite relics. All craters occur along the outcrops of the uppermost Permo-Pennsylvanian Casper Sandstone Formation and are ~280 m.y. old. Their spatial arrangement shows clusters and ray-like alignments. Several craters have elliptical crater morphologies that allow the reconstruction of impact trajectories. The radial arrangement of the trajectories indicates that the craters are secondary craters formed by ejecta from a primary crater whose likely position and size are reconstructed. Modeling ballistic trajectories and secondary crater formation indicates that impacts occurred at around 700–1000 m/s and caused small shock volumes with respect to crater volumes. This is the first field of secondary craters found on Earth, and we disentangle its formation conditions.

Comprehensive Geophysical Study at Wabar Crater, Rub Al‐Khali Desert, Saudi Arabia

AbstractInterest in impact craters on the earth's surface has increased worldwide and is being investigated by using remote sensing, geological, boreholes, geophysical, and laboratory measurements. These measurements are used to build dynamic models to study crater formation. In this work, the near‐crater sediments at the young Wabar crater field in Saudi Arabia have been investigated using magnetic, transient electromagnetic (TEM), seismic, and ground‐penetrating radar (GPR) methods. The main objectives of this research were to (a) explore the possibility of any remnant major pieces of the meteorite, (b) investigate the meteoroid direction, and (c) map the deformational structures associated with the meteorite impact. Our results show five different magnetic anomaly types and three layers in the subsurface. The maximum depth of deformation due to the impact of the meteorite is about 25 m as shown by the seismic travel time tomogram, the quasi‐2D TEM, and the 3D GPR model. TEM survey confirmed the geometrical characteristics of the major crater and located another small crater (known as Philby‐A). The magnetic survey shows no evidence of any remnant major pieces of the meteorite; however, it was used to trace ejecta material containing highly dilute magnetic material. The magnetic carrier is most likely spheres of metal incorporated in the black/green glasses. During the expedition, many small pieces of the meteoroid were found and collected for further geochemical analysis. Based on the geophysical findings, the meteorite direction was found to be from north to south.

Investigating the subsurface structure of the main crater of the proposed Sirente meteorite crater field (Central Italy): new clues from reflection seismics

The Sirente crater field (Central Italy) consists of a main, ≈130 m wide, droplet-shaped in plan view depression with a prominently elevated rim, and 30 smaller depressions in its close vicinity. It was discovered in 2002 and proposed to be of meteorite impact origin based on its geological and geomorphological similarities to known crater fields. It is developed in non-lithified lake sediments (i.e. carbonate mud). Given the age of formation in the 3rd to 5th centuries A.D., the inferred catastrophic origin was, in the media, soon related to the celestial sign (“Chi Rho”) said to have been seen by Emperor Constantine in 312 A.D. and suggested to have changed the course of both Roman and Christian history. However, the meteoritic origin is not yet confirmed and has been contested. This work presents new geophysical data on the subsurface structure of the main crater, which provides further clues around the controversy of its origin. Two roughly transversal seismic reflection profiles across the main crater reveal a deep (53 m on average), rootless, bowl-shaped structure with a poorly developed, deep-seated central mound, as well as different seismic facies representing a crater infill of disturbed material resembling the breccia lens in craters formed in rock. This survey also allowed the recognition of possible compaction-fissures and upturned strata below the rim, similar to what is known from explosion craters in porous, unconsolidated targets. Some of these structures had already been noted in published resistivity surveys (ERT). The structural features noted in this geophysical survey are consistent with the impact hypothesis and do not support other proposed mechanisms of formation such as karst or mud volcano.

Introduction to the special issue

This special issue is the result of efforts by the Planetary Crater Consortium to engage the crater and broader planetary science community regarding the state of knowledge about impact craters. Impact craters are the most abundant landform on almost all solid surfaces in the solar system, observed on all bodies imaged closely to date except Jupiter's moon Io. Crater populations form the only known metric for modeling the surface ages of planetary bodies, and they are used to inform the underlying dynamics of the objects that generate them and the physics of the impacts themselves. Individual craters are used to understand local geology and geophysics, the environment in which they exist, and other important processes on the bodies upon which they form. In May 2015, the first-of-its-kind “Workshop on Issues in Crater Studies and the Dating of Planetary Surfaces” was convened at The Johns Hopkins University's Applied Physics Lab, where 50 community members presented talks and participated in discussions about the history of impact crater studies, where the field currently stands, and the most pressing questions and issues that are critical to advancing the field. This special issue arose from that conference. In this volume are 14 papers that span a wide range of topics. There are three review papers describing the state of knowledge of secondary impact craters, how large a counting surface needs to be for adequate crater statistics, and a survey of techniques and results of crater depth measurements for the last >50 years on solar system bodies. There are also new science papers, detailing crater morphometry and new methods and recommendations to measure them, terrestrial crater field work, models for types of craters and related features on the Moon and Mars, and implications of crater studies to Martian climate. Finally, there are three papers that describe new techniques and methods to analyze craters: a fast and robust way to determine crater saturation, a method to determine secondary crater clusters from those produced by atmospheric fragmentation, and a re-examination of classic size-frequency distribution techniques with new recommendations on how to display and analyze crater populations. Readers and editors alike thank the contributing authors and reviewers for their hard work on this valuable volume on impact craters. The editors and authors hope that the work in this volume will help pave the way for future research and studies into impact craters for many years to come.

Revised recommended methods for analyzing crater size‐frequency distributions

AbstractImpact crater populations help us to understand solar system dynamics, planetary surface histories, and surface modification processes. A single previous effort to standardize how crater data are displayed in graphs, tables, and archives was in a 1978 NASA report by the Crater Analysis Techniques Working Group, published in 1979 in Icarus. The report had a significant lasting effect, but later decades brought major advances in statistical and computer sciences while the crater field has remained fairly stagnant. In this new work, we revisit the fundamental techniques for displaying and analyzing crater population data and demonstrate better statistical methods that can be used. Specifically, we address (1) how crater size‐frequency distributions (SFDs) are constructed, (2) how error bars are assigned to SFDs, and (3) how SFDs are fit to power‐laws and other models. We show how the new methods yield results similar to those of previous techniques in that the SFDs have familiar shapes but better account for multiple sources of uncertainty. We also recommend graphic, display, and archiving methods that reflect computers’ capabilities and fulfill NASA's current requirements for Data Management Plans.

Morphology of the Morasko crater field (western Poland): Influences of pre-impact topography, meteoroid impact processes, and post-impact alterations

Small impact craters (<1km) developed in unconsolidated sediments are expected to be relatively common on Earth; however, only a few tens of them have been documented thus far. Among the reasons for this small number of documented craters are the post-impact erosion and sedimentation processes that modify craters and the lack of universal identification criteria to allow the differentiation of impact structures from landforms of other origins. Here, we focus on the well-preserved impact craters on the Morasko Hill push moraine in western Poland. These craters were formed by iron meteoroid impacts in unconsolidated sediments of glacial and fluvial origins ca. 5000–6000years ago. We provide a new high-resolution topographic model of the crater field to identify the influences of the pre-impact topography, impact processes, and post-impact modifications on the final morphology of the craters. The topographic model obtained from airborne LiDAR data and total station surveying consists of DEMs related to the recent and reconstructed pre-impact topographies. Parameterization of recent topography in terms of slope gradients, slope curvatures, and roughness allowed us to delimit the boundaries of the craters and to calculate their Feret diameters, ellipticities, slope gradients, crater depths, and volumes. The novelty of our study lies in the estimation of the last two parameters based on the reconstructed pre-impact topography and modelled paraboloids related to each crater. The obtained results show that the studied craters are circular, bowl-shaped features displaying different cross-sectional asymmetries that resulted from the interplay between the trajectories of the bombarding projectiles and the topographies of the primary pre-impact glacial and post-glacial landforms. The oblique impacts likely influenced the asymmetric distribution of ejecta during the excavation of the craters and are considered as factors conditioning mass movements during the post-impact modification of the craters. The compilation of the existing data on terrestrial small-impact craters reveals that they are susceptible to post-impact geometry modification (shallowing and widening) and that many craters have depth/diameter ratios lower than are typical for simple impact craters.

Grazing Impacts Upon Earth’s Surface: Towards an Understanding of the Rio Cuarto Crater Field

The origin of the Rio Cuarto crater field, Argentina has been widely debated since the early 1990s when it was first brought to public attention. In a binary on–off sense, however, the craters are either of a terrestrial origin or they formed via a large asteroid impact. While there are distinct arguments in favour of the former option being the correct interpretation, it is the latter possibility that is principally investigated here, and five distinct impact formation models are described. Of the impact scenarios it is found that the most workable model, although based upon a set of fine-tuned initial conditions, is that in which a large, 100–150-m initial diameter asteroid, entered Earth’s atmosphere on a shallow angle path that resulted in temporary capture. In this specific situation a multiple-thousand kilometer long flight path enables the asteroid to survive atmospheric passage, without suffering significant fragmentation, and to impact the ground as a largely coherent mass. Although the odds against such an impact occurring are extremely small, the crater field may nonetheless be interpreted as having potentially formed via a very low-angle, smaller than 5° to the horizon, impact with a ground contact speed of order 5 km/s. Under this scenario, as originally suggested by Schultz and Lianza (Nature 355:234, 1992), the largest of the craters (crater A) in the Rio Cuarto structure was produced in the initial ground impact, and the additional, smaller craters are interpreted as being formed through the down-range transport of decapitated impactor material and crater A ejecta.

Investigation on Impact Resistance Foamed Concrete Reinforced by Polypropylene Fibre

Foamed Concrete (FC) needs high strength to prevent dynamic loading, thus it is important to enhance the ductility. Usage the Polypropylene Fibre (PF) examined its contribution in strength of FC on impact resistance. Microstructures were observed that air voids in matrix of FC produce micro-porous that reduce interfacial bonding into matrix and generate micro-crack that may propagation crack growth. Presence of PF in admixture results fibrillation and reduces micro-cracks. Tensile test was investigated that PF delays crack growth in matrix. In this investigation impact test were conducted using an instrumented drop-weight impact tower. When impactor hits the target surface in free surface condition causes compressive plastic wave transform to be tensile wave. It was affected by tensile strength therefore local effect has not found spalling in crater field. In addition influence of porous in matrix FC has ability to absorb the energy and it was not found distal crack around surface area. Penetration depth results showed FC with PF subjected to impact loading was lower than without FC. Presence of PF increases FC strength and local effect results there was not impression of fragments around distal surface due to brittle crushing.

Investigation on Energy Absorption of Slab Foamed Concrete Reinforced by Polypropylene Fibre Subjected to Impact Loading

Polypropylene Fibre (PF) as reinforcement has contributed to the intensity of Foamed Concrete (FC) slab when subjected to impact loading. The presence of PF in the admixture reduces the micro-porosity that generates the micro-crack of the slab. However, the fibrillation of PF in the admixture enhances the bonding mechanism system between PF and the FC matrix. The impact test conducted uses an instrumented drop-weight impact tower. Results show that FC without PF produces a distinct radial crack and clear fragments within the crater field unlike FC with PF. However, both slab materials did not generate spalling nor scabbing upon impact and the influence of porosity produces only local damage due to the mechanism of brittle crushing effect of porous walls. In this study, the energy absorption between FC with and without PF was investigated and from observation produces only minor differences. Results also verify that FC with PF did not loss its ability to absorb energy upon impact.

Ages of large lunar impact craters and implications for bombardment during the Moon’s middle age

Standard lunar chronologies, based on combining lunar sample radiometric ages with impact crater densities of inferred associated units, have lately been questioned about the robustness of their interpretations of the temporal dependance of the lunar impact flux. In particular, there has been increasing focus on the “middle age” of lunar bombardment, from the end of the Late Heavy Bombardment (∼3.8Ga) until comparatively recent times (∼1Ga). To gain a better understanding of impact flux in this time period, we determined and analyzed the cratering ages of selected terrains on the Moon. We required distinct terrains with random locations and areas large enough to achieve good statistics for the small, superposed crater size–frequency distributions to be compiled. Therefore, we selected 40 lunar craters with diameter ∼90km and determined the model ages of their floors by measuring the density of superposed craters using the Lunar Reconnaissance Orbiter Wide Angle Camera mosaic. Absolute model ages were computed using the Model Production Function of Marchi et al. (Marchi, S., Mottola, S., Cremonese, G., Massironi, M., Martellato, E. [2009]. Astron. J. 137, 4936–4948). We find that a majority (36 of 40) of our superposed crater size–frequency distributions are consistent with the Model Production Function. A histogram of the original crater floor model ages indicates the bombardment rate decreased gradually from ∼3.8Ga until ∼3.0Ga, implying an extended tail to the Late Heavy Bombardment. For large craters, it also preliminarily suggests that between ∼3.0 and 1.0Ga bombardment may be characterized by long periods (>600Myr) of relatively few impacts (“lulls”) broken by a short duration (∼200Myr) of relatively more impacts (“spike”). While measuring superposed craters, we also noted if they were part of a cluster or chain (named “obvious secondary”), and analyzed these craters separately. Interestingly, we observe a wide variety of slopes to the differential size–frequency power-law, which demonstrates that there can be considerable variation in individual secondary crater field size–frequency distributions. Finally, four of the small, superposed crater size–frequency distributions are found to be inconsistent with the Model Production Function; possible reasons are: resurfacing has modified these distributions, unrecognized secondary craters, and/or the Model Production Function has incorrect inputs (such as the scaling law for the target terrain). The degraded appearance of the superposed craters and indications of resurfacing suggest that the first cause is the most likely.

Geological and geophysical investigation of Kamil crater, Egypt

Abstract– We detail the Kamil crater (Egypt) structure and refine the impact scenario, based on the geological and geophysical data collected during our first expedition in February 2010. Kamil Crater is a model for terrestrial small‐scale hypervelocity impact craters. It is an exceptionally well‐preserved, simple crater with a diameter of 45 m, depth of 10 m, and rayed pattern of bright ejecta. It occurs in a simple geological context: flat, rocky desert surface, and target rocks comprising subhorizontally layered sandstones. The high depth‐to‐diameter ratio of the transient crater, its concave, yet asymmetric, bottom, and the fact that Kamil Crater is not part of a crater field confirm that it formed by the impact of a single iron mass (or a tight cluster of fragments) that fragmented upon hypervelocity impact with the ground. The circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the NW and an impact angle of approximately 30 to 45°. Newly identified asymmetries, including the off‐center bottom of the transient crater floor downrange, maximum overturning of target rocks along the impact direction, and lower crater rim elevation downrange, may be diagnostic of oblique impacts in well‐preserved craters. Geomagnetic data reveal no buried individual impactor masses &gt;100 kg and suggest that the total mass of the buried shrapnel &gt;100 g is approximately 1050–1700 kg. Based on this mass value plus that of shrapnel &gt;10 g identified earlier on the surface during systematic search, the new estimate of the minimum projectile mass is approximately 5 t.

Ablation spherules in the Sikhote Alin meteorite and their genesis

Practically all of the examined spherules extracted in 1948–1949 from soil at the crater field of the 1947 Sikhote Alin meteorite shower are ablation spherules produced during this meteorite fall. The spherules can classified into two textural types: (i) fine-grained, which consist of Ni-bearing magnetite (3–6 wt % NiO) dendrites, sometimes with minor amounts of interstitial P- and Fe-rich material, and (ii) coarse-grained, which also consist of Ni-bearing magnetite dendrites or grains, sometimes with wuestite, an interstitial material, which resembles that in type (i) or has a silicate composition. The texture, mineralogy, and chemistry (presence of P and Si) of these spherules differ from those of iron cosmic spherules (type I) that occur in the background flux of micrometeorites. The spherules are thought to were produced by the ablation of meteoritic material at elevations of about 12 km (in the region where disintegration starts) and below, at maximum temperatures of 1600–2180°C and oxygen fugacity of 10−14 to 10−1 atm. Conceivably, the ablated material was enriched in silicates compared to the fallen material.

Tooting crater: Geology and geomorphology of the archetype large, fresh, impact crater on Mars

The 27.2km diameter Tooting crater is the best preserved young impact crater of its size on Mars. It offers an unprecedented opportunity to study impact-related phenomena as well the geology of the crust in the Amazonis Planitia region of Mars. For example, the nearly pristine condition enables the partial reconstruction of the sequence of events for crater formation, as well as facilitates a comparison to deposits seen at the Ries crater in Germany. High-resolution images taken by the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) on the Mars Reconnaissance Orbiter spacecraft have revealed a wealth of information on the distribution of features within the crater and beyond the rim: a large central peak, pitted material on the floor and terrace blocks, lobate flows interpreted to be sediment flows, impact melt sheets, four discrete layers of ejecta, and an asymmetric secondary crater field. Topographic data derived from the Mars Orbiter Laser Altimeter (MOLA) and stereo HiRISE and CTX images show that the central peak is ∼1100m high, the lowest point of the crater floor is 1274m below the highest part of the rim, and the crater rim has ∼600m of variability around its perimeter. Layering within the cavity walls indicates ∼260m of structural uplift of the target material, which constitutes ∼35% of the total relief of the rim. Abundant evidence is found for water flowing down the cavity walls, and on the surface of the ejecta layers, both of which took place sometime after the impact event. Thickness measurements of the ejecta layers reveal that the continuous blanket is remarkably thin (∼3–5m) in some places, and that the distal ramparts may be ∼60m high. Crater counts made on the ejecta layers indicate a model age of <3Ma for the formation of Tooting crater, and that the target rocks have a model age of ∼240–375Ma. It is therefore possible that this may be the source of certain basaltic shergottite meteorites ejected at ∼2.8Ma that have crystallization ages which are comparable to those of the basaltic lava flows that formed the target materials for this impact event. The geology and geomorphology of Tooting crater may help in the interpretation of older large impact craters on Mars, as well as the potential role of target volatiles in the impact cratering process.

Secondary crater fields from 24 large primary craters on Mars: Insights into nearby secondary crater production

[1] Crater statistics are used across a wide variety of applications on planetary surfaces, one of the most notable being estimating relative and absolute ages of those surfaces. This requires an assumed cratering rate over time and that craters be randomly distributed. Secondary craters - craters that form from the ejecta of an impact event - belie this assumption by creating greater crater density in a local area at a single time, significantly affecting crater statistics. There has been substantial debate over the relative importance of secondary craters, and our findings in this Mars study indicate that these events can be very significant and cannot be ignored when age-dating surfaces. We have analyzed secondary crater fields found close to 24 primary craters on Mars. Among other findings such as terrain control over secondary crater field characteristics, we conclude that a single large impact event (>100 km) can significantly affect crater statistics at the ∼1–5-km-diameter level over a non-trivial fraction of a planetary surface (minimum secondary crater diameters examined were ∼0.9 km; the minimum primary crater diameter was ∼20 km). We also suggest a potential way to avoid significant contamination by the majority of secondary craters that occur close to the primary impact event without the need to manually classify every crater as primary or secondary. Our findings are specific to Mars, but further work may show the patterns are applicable to other solid bodies.

Comparison of four meteorite penetration funnels in the Campo del Cielo crater field, Argentina

Abstract– More craters may be discovered in the future, but as it is currently known, the Campo del Cielo crater field is 18 km long by 4 km at its widest point. Such a distribution of craters suggests that the parent meteoroid entered and traversed the atmosphere at a very low angle relative to horizontal. The crater field contains at least 20 small craters produced by the larger fragments of the parent meteoroid. Four of these are explosion analog craters and the rest are penetration funnels. During four field seasons, we have constructed topographic and magnetic maps of four of the penetration funnels as found, and then dug trenches across them to learn their original structures and recover meteorites preserved within them. Structures of these penetration funnels indicate very low angles of impact, i.e., 9–16° relative to horizontal. This supports the idea that the parent meteoroid traversed the atmosphere at a low angle. Data given here for the four penetration funnels include projectile masses, lengths, widths, depths, and estimates of impact angles and azimuths. One of the penetration funnels described here (No. 6) can almost be classified as an explosion analog crater.

The Kaali crater field and other geosites of Saaremaa Island (Estonia): the perspectives for a geopark

The Kaali crater field and other geosites of Saaremaa Island (Estonia): the perspectives for a geoparkThe Island of Saaremaa in Estonia offers highly spectacular geological features that belong to the most interesting in the Baltic Sea area. A unique geological monument on the island is the Kaali meteorite-crater field, formed by nine meteorite impacts. There are also attractive coastal cliffs, huge erratics, alvars (limestone areas covered by a very thin soil) and well-developed glacial and marine landforms. Limestone cliffs and shingle beaches abound with Silurian fossils and offer great opportunities to fossil collectors. The island is a prospective geopark. During the past few years, the geology of the island has become an intensely studied object of Estonian and Polish geologists.

The “Sirente crater field,” Italy, revisited

A scientific debate has developed in the last few years as to whether a 130 m diameter sag pond surrounded by a saddle‐shaped rim and neighboring smaller sags from the Sirente Plain (Abruzzi, Italy) represent the only known Italian meteoritic crater field, a mud volcano, or an anthropogenic feature. To decipher the nature of the Sirente landforms, we carried out geophysical and geochemical investigations. Geoelectric profiles document two karstified shelf carbonate ridges lying at 10–40 m depth below calcareous lacustrine silts (and deeper more conductive sediments, likely soils/tephra) filling the plain. The smaller sags lie just above the ridges, implying a karstic origin, whereas the main sag (also resting above a carbonate ridge) shows no roots in excess of 10–20 m depth, in contrast to the “crater” interpretation. High‐resolution magnetic surveys reveal negative/positive anomaly stripes in correspondence with the buried ridges/valleys, respectively. The smaller sags, as well as the main crater are located in the domain of negative residuals. The positive long‐wavelength magnetic signature is likely due to the strongly susceptive soils/tephra filling the buried valleys. Magnetic modeling shows that the field observed over the crater is incompatible with the field generated by a buried meteorite with realistic characteristics. The smaller sags are characterized by small magnetic anomaly couplets, perfectly reproducible considering the susceptibility contrast between the fill‐in soil and the surrounding silts. Our data show that the Sirente crater and the minor depressions are simply the results of human activity and karstic processes, respectively.