Excess Topography Research Articles

Study of Earthquake Landslide Hazard by Defining Potential Landslide Thickness Using Excess Topography: A Case Study of the 2014 Ludian Earthquake Area, China

Influenced by the combined effects of crustal uplift and river downcutting, rivers with significant potential energy are often found in high mountain and canyon areas. Due to the active tectonic movements that these areas have experienced or are currently experiencing, geological hazards frequently occur on the mountains flanking the rivers. Therefore, evaluating the susceptibility and risk of earthquake landslides in river segments of these high mountain and canyon areas is of great importance for disaster prevention and mitigation, as well as for the safe construction and operation of hydropower stations. Currently, a major challenge in the study of landslide susceptibility and hazard is determining the thickness of potential landslide bodies. The presence of excess topography reflects the instability of the disrupted slopes, which is also a fundamental cause of landslides. This study takes the example of the Ludian earthquake in 2014, focusing on the IX and VIII intensity zones, to extract the excess topography in the study area and analyze its correlation with seismic landslides. The correlation between the critical acceleration value and the excess topography was validated using the Spearman’s rank correlation coefficient, resulting in a correlation coefficient of −0.771. This indicates a strong negative correlation between the excess topography and critical acceleration, with significant relevance. The landslide susceptibility distribution obtained by setting the potential landslide thickness based on the excess topography and proportion coefficient showed an ROC curve analysis AUC value of 0.829. This is higher than the AUC value of 0.755 for the landslide susceptibility result using a uniform potential landslide thickness of 3 m, indicating the higher model evaluation accuracy of this approach. Earthquake landslide hazard predictions for rapid post-earthquake assessments and earthquake landslide hazard zoning for pre-earthquake planning were made using actual seismic ground motion and a 2% exceedance probability in 50 years, respectively. Comparing these with the 10,559 coseismic landslides triggered by the Ludian earthquake and evaluating the seismic landslide development rate, the results were found to be consistent with reality. The improved model better reflects the control of excess topography and rock mechanics properties on the development of earthquake landslide hazards on high steep slopes. Identifying high-risk seismic landslide areas through this method and taking corresponding preventive and protective measures can help plan and construct safer hydropower and other infrastructure, thereby enhancing their disaster resistance.

Excess topography and outburst flood: Geomorphic imprint of October 2023 extreme flood event in the Teesta catchment of Eastern Himalayas

The 2023 South-Lohnak Lake outburst flood event across the upstream Teesta catchment triggered short-lived, high-magnitude flooding and substantial socioeconomic disruption downstream. We performed landscape analysis across the Teesta catchment using topographic metrics to understand the geomorphic response to this extreme flood event. We estimated the various topographic metrics such as ksn anomaly (normalized channel steepness index) (∼500–2500 m0.9), SL-index (stream-length gradient index) (∼5000–7000 m), and KsnQ (channel steepness-weighted discharge) along the trunk channel draining through the South-Lohnak Lake, which shows high magnitude in flooded regions and numerous spikes in their longitudinal profiles across mass-wasting regions downstream. We used the KsnQ metric as an event characteristic to investigate the changes in the channel morphology due to high-magnitude flooding. There was a sudden increase in the magnitude of the KsnQ metric when the river traversed through the Chungthang dam over the high ranges of excess topography (∼0–1700 m). This shows that the downstream channel morphology changes rapidly during this flood event, and KsnQ is a significant indicator of geomorphic change. To understand the spatial relationship between the physical drivers that trigger this outburst flood, we quantified the causal relationship between glacial-hydrological drivers over the upstream Zemu-sub catchment. Our observations suggest that precipitation intensity and surface temperature had a significant direct causal influence on snowmelt and snow depth (in terms of water equivalent) over the event duration with a 5-day and 1-day lag composite. Through the inclusion of lagged composites and causal linkages, the drivers across the glaciated landscape serve as event anomalies, which trigger the glacier hillslope failure and subsequent high-magnitude outburst flooding. Therefore, we suggest that the interaction of topographic discontinuity with hydrological extremes and their causal interdependencies influences this outburst event in the upper reaches, followed by high-magnitude flooding in the downstream reaches of the Teesta River. However, the long-term geomorphic consequences of such events on the evolution of the regional landscape remain unclear.

Geomorphic effect of landslide dam on the Jinsha River

As an extreme surface process, landslide dam affects the long-term change of river landform, especially the change of channel and hillslope. The Jinsha River is located on the eastern edge of the Qinghai-Tibet Plateau, the structural geology is active, developed more landslide geological disaster. Based on the 30 m SRTM DEM, we automatically extracted the river longitudinal profile, steepness index, river knickpoint and excess topography using TopoToolbox. Through interpretation of remote sensing imagery and field work, we identified 660 landslide dams, more than 90% are located in the excess topography with a threshold hillslope of 30. Our analysis reveals that there are 481 river knickpoints were extracted with heights above 30 m, Among them, 70 river knickpoints have good spatial correlation with the landslide dam, landslide dam has an impact can form knickpoints of up to 478m. In the densely distributed river channel of the landslide dam, the steepness index with the relatively high values. Therefore, landslide dams may have a significant inf1uence on the channel and hillslope, we should pay attention to the role of landslide dam in the evolution of river landscape.

Analysis of Quantified Hillslope Erosion by Excess Topography in the Hengduan Mountain

Analysis of Quantified Hillslope Erosion by Excess Topography in the Hengduan Mountain

Analysis of the Controlling Effect of Excess Topography on the Distribution of Coseismic Landslides during the Iburi Earthquake, Japan, on 6 September 2018

Coseismic landslides cause changes in the hillside material, and this erosion process plays an important role in the evolution of the topography. Previous studies seldom involved research on the influence of excess topography on the occurrences of coseismic landslides. The Iburi earthquake, which occurred in Japan on 6 September 2018 and triggered a large number of landslides, provided a research example to explore the relationship between coseismic landslides and excess topography. We used the average slope of the lithology as the threshold slope of the corresponding stratum to calculate the excess topography of the different lithological units. Based on the advanced spaceborne thermal emission and reflection radiometer (ASTER) digital elevation model (DEM) with a resolution of 30 m, a quantitative analysis was conducted on the excess topography in the study area. The results indicate that the excess topography in the study area was mainly distributed in the valleys on both sides of the river, and the thickness of the excess topography on the high and steep ridges was generally greater than that at the foot of the slope, which has a relatively flat topography or a low elevation. In the area affected by the earthquake, approximately 94.66% of the coseismic landslides (with an area of approximately 28.23 m2) developed in the excess topography area, indicating that the distribution of the excess topography had a strong controlling influence on the spatial distribution of the coseismic landslides. The Iburi earthquake mainly induced shallow landslides, but the thickness of the landslide body was much smaller than the excess topography height in the landslides-affected area. This may imply that the excess topography was not completely removed by the coseismic landslides, and the areas where the earthquake landslides occurred still have the possibility of producing landslides in the future.

Indicative Effect of Excess Topography on Potential Risk Location of Giant Ancient Landslides—A Case Study in Lengqu River Section

In order to identify giant ancient landslides more effectively and to quantify the risk of giant ancient landslides, this study takes a Lengqu River section located on the Qinghai–Tibet Plateau as an example and then uses the red relief image map (RRIM) method to enhance the digital elevation model (DEM) for topographic 2D visualization to identify giant ancient landslides. Then, the relationships between giant ancient landslides (GALs), resurgent GALs, the deposition of inactive GALs and the excess topography of hillslopes under 30° threshold are analyzed separately. A total of 54 GALs are identified at last by using the RRIM method; 77.75% of GALs are still located on excess topography, 68.38% of resurgent GALs occurred on excess topography, and 62.21% of the deposition of inactive GALs are on non-excess topography. The RRIM method provides a new way to identify giant ancient landslides. The excess topography provides an indication of the risk of new landslides through the destructive effect of GALs on the threshold hillslope, and the preliminary investigation of the quantitative relationship between the resurrection of GALs and excess topography also shows that there is a certain pattern between the resurrection of GALs and the excess topography under the natural state, so the excess topography has a certain indication of the generation of new landslides and secondary resurrection at the original GAL positions.

Debris flow susceptibility based on the connectivity of potential material sources in the Dadu River Basin

The Dadu River Basin (DRB) is an important economic corridor on the Chuanxi Plateau. The DRB is located in the highly changeable terrain of the eastern Qinghai-Tibet Plateau and is often threatened by debris flows. To mitigate the damage of debris flow disasters to the construction and operation of large infrastructures such as railways, roads and hydropower stations in the DRB, it is necessary to evaluate debris flow susceptibility. The connectivity of potential material sources (CPMS), which proxies the possibility of potential material transfer from the source to the outlet, was calculated using an improved index of connectivity, excess topography and brittle fracture index to identify and quantify debris flow susceptibility. The results show that the IC and the gully scale have a Logartihmic function in the DRB, in which IC decreases as the catchment area increases. In 3967 gullies of the Dadu River and its tributaries, the total connectivity of potential material sources (TCPMS) could be used to distinguish between debris flow gullies and non-debris flow gullies (AUC = 0.748). The TCPMS and average connectivity of potential material sources (ACPMS) were used to classify the scale and activity intensity of the 2398 debris flow gullies into four levels. The moderate- and high-activity intensity and large- and extra large-scale debris flows are mainly distributed in Danba, Luding and Kangding. The results of this study provide reference and evidence for the identification and evaluation of debris flow susceptibility.

Residence Time of Over‐Steepened Rock Masses in an Active Mountain Range

AbstractIn uplifting mountains, hillslopes steepen toward a threshold angle set by substrate material strength. Hillslopes beyond the threshold angle, referred to as excess topography, are mechanically unstable. The residence time scale of rock masses in excess topography (Tex) is critical for understanding time scales of surface processes and landscape evolution in steep mountains. However, Tex remains loosely constrained for varying slopes and lithologies. Here, we calculate Tex in the eastern Tibetan mountains by quantifying excess topography across lithologies, long‐term landslide erosion rates caused by seismicity and climate, and exhumation rates. Tex increases with local slope angles and is of the same order of magnitude across different lithologies but slightly longer for metamorphic rocks. Range‐scale Tex is estimated as ∼61–157 kyr, ∼3–9% of the relief‐rejuvenation timespan of threshold topography. Similar Tex regardless of lithologies and methods suggest steady‐state construction and erosion of excess topography over thousand to million years time scales in this orogen.

30-year record of Himalaya mass-wasting reveals landscape perturbations by extreme events

In mountainous environments, quantifying the drivers of mass-wasting is fundamental for understanding landscape evolution and improving hazard management. Here, we quantify the magnitudes of mass-wasting caused by the Asia Summer Monsoon, extreme rainfall, and earthquakes in the Nepal Himalaya. Using a newly compiled 30-year mass-wasting inventory, we establish empirical relationships between monsoon-triggered mass-wasting and monsoon precipitation, before quantifying how other mass-wasting drivers perturb this relationship. We find that perturbations up to 5 times greater than that expected from the monsoon alone are caused by rainfall events with 5-to-30-year return periods and short-term (< 2 year) earthquake-induced landscape preconditioning. In 2015, the landscape preconditioning is strongly controlled by the topographic signature of the Gorkha earthquake, whereby high Peak Ground Accelerations coincident with high excess topography (rock volume above a landscape threshold angle) amplifies landscape damage. Furthermore, earlier earthquakes in 1934, 1988 and 2011 are not found to influence 2015 mass-wasting.

Dynamic topography and the nature of deep thick plumes

Deep mantle plumes imaged by seismic tomography have much larger radii (∼400 km) than predicted by conventional geodynamic models (∼100 km). Plume buoyancy fluxes estimated from surface topography concur with narrow plumes with low viscosities expected from their high temperatures. If plumes are thick as imaged by tomography, buoyancy flux estimates may require very viscous or thermochemical plumes. Here we assess the dynamical plausibility of an alternative model, a ponding plume, which has been suggested to explain thick plumes as well as buoyancy fluxes estimated from surface topography. In the ponding plume model, a thick conduit in the lower mantle narrows significantly after passing through the mantle transition zone, below which excess material from the thick lower-mantle plume, which cannot be accommodated by the narrow upper-mantle plume, spreads laterally. Such excess material in the mid-mantle, however, should still manifest itself in surface topography, the amplitude of which can be quantified via topography kernels. We find that the ponding of a purely thermal plume would lead to unrealistic excess topography, with the scale of ponding material large enough to be detected by seismic tomography. If mantle plumes are as thick as indicated by seismic tomography, it appears to be necessary to deviate from either conventional temperature-dependent viscosity or the assumption of purely thermal origins.

A field investigation on debris flows in the incised Tongde sedimentary basin on the northeastern edge of the Tibetan Plateau

An investigation on 152 gullies along the Daheba River in the Tongde sedimentary basin was performed. Debris flows develop in gullies with an excess topography ZE, which represents the sediment availability, above a critical threshold value. Debris flows in the Daheba watershed are supply-unlimited, i.e sediment is abundantly available from the steep erodible gully banks. Debris flows consist of a head and a body. The body propagates faster than the head and constantly supplies it with sediment. The body and head propagate in an intermittent way through the transient storage of sediment on the riverbed and its subsequent remobilization. Although the main sediment supply is provided by bank collapse, debris-flow events also incise the gully bed. The growth and incision of debris-flow gullies in supply-unlimited watersheds is mainly controlled by the frequency of occurrence of debris flows, which is closely related to ZE. With growth of the gully drainage area, ZE and the debris-flow frequency initially increase, until they reach maximum values in gullies with a drainage area of intermediate size, which are assumed to be the morphologically most active gullies. With further growth of the gully drainage area, ZE and the debris-flow frequency decrease, which opposes the development of debris flows and leads to a more stable gully morphology.

Analysis of Hillslope Erosion Based on Excess Topography in Southeastern Tibet

The southeastern Tibetan Plateau has been deeply dissected by major rivers and their tributaries into high-relief topography with deep gorges. In this region, most hillslope gradients in the high-relief areas approach a threshold value, and landslides are the dominant surface erosion process. For this work, we analyzed the hillslope erosion process by determining the excess topography from the threshold hillslope. Slope analysis found a similar normal distribution of slope values for six large drainage basins with different lithology, precipitation, and tectonic settings. Overall, 82% of the slopes in our study area were 30 ± 5°, so this was taken as a reasonable range of threshold hillslope angles. We determined that the excess topography calculated for different threshold values all occur along major fluvial inner gorges. We found a linear relationship between excess topography and the mean erosion rate in drainage basins, which indicates that hillslope erosion, especially landslides, is the main erosion process. In contrast, the correlation between excess topography and the slope is only found for low-relief topography. This suggests that excess topography is a better metric than the slope to reflect the spatial distribution of erosion rates in the southeastern Tibetan Plateau. In addition, for a threshold value of 30°, we collected data from 4,430 landslides and found that 71% of these landslides had occurred in an area of excess topography. This implies that most recent landslides did not reduce the slope below the threshold value. As a result, the potential for future landslides remains high in areas where landslides have recently occurred.

The gravity field and interior structure of Dione

During its mission in the Saturn system, Cassini performed five close flybys of Dione. During three of them, radio tracking data were collected during the closest approach, allowing estimation of the full degree-2 gravity field by precise spacecraft orbit determination.The gravity field of Dione is dominated by J2 and C22, for which our best estimates are J2 × 106 = 1496 ± 11 and C22 × 106 = 364.8 ± 1.8 (unnormalized coefficients, 1-σ uncertainty). Their ratio is J2/C22 = 4.102 ± 0.044, showing a significative departure (about 17-σ) from the theoretical value of 10/3, predicted for a relaxed body in slow, synchronous rotation around a planet. Therefore, it is not possible to retrieve the moment of inertia directly from the measured gravitational field.The interior structure of Dione is investigated by a combined analysis of its gravity and topography, which exhibits an even larger deviation from hydrostatic equilibrium, suggesting some degree of compensation. The gravity of Dione is far from the expectation for an undifferentiated hydrostatic body, so we built a series of three-layer models, and considered both Airy and Pratt compensation mechanisms. The interpretation is non-unique, but Dione's excess topography may suggest some degree of Airy-type isostasy, meaning that the outer ice shell is underlain by a higher density, lower viscosity layer, such as a subsurface liquid water ocean. The data permit a broad range of possibilities, but the best fitting models tend towards large shell thicknesses and small ocean thicknesses.

Designing a Supramolecular Process for Post-STI CMP Cleaning

Chemical mechanical planarization (CMP) is a critical process step used in the fabrication of integrated circuits (ICs) and has ultimately led to the extension of Moore’s Law. Through a synergistic balance of a colloidal dispersion and mechanical downforce, excess topography is removed to achieve angstrom-level uniformity. Upon the completion of the CMP process, removal of unwanted particle residue/organic contaminants is achieved using oxidation/reduction reactions, etching, or encapsulation chemistry coupled with ultrasonic methods or polyvinyl alcohol (PVA) brush cleaning. The nature of the current cleaning techniques has been known to provide insufficient cleaning capacity for next generation devices. This work focuses on employing supramolecular chemistries as a means to improve overall post-STI CMP cleaning efficiency under low mechanical stress conditions, ultimately reducing defectivity. More specifically, the development of a supramolecular brush comprised of biomimetic polymers, such as β-cyclodextrin, was synthesized with excellent pore size tunability, which in turn is correlated to swellability, durability, and efficiency of particle removal.

Development of “Soft” Cleaning Chemistries for Enhanced STI Post-CMP Cleaning

Due to the emergence of sub-10 nm technologies, limiting device defects has become of utmost importance in maintaining high performing integrated circuits. Shallow trench isolation (STI) chemical mechanical planarization (CMP) uses a synergistic balance of ceria (CeO2) nanoparticles and functional chemistry to modulate critical surface adsorption interactions necessary to remove excess topography. Literature has identified that the surface redox state of the CeO2 nanoparticle (Ce3+/4+) is a critical factor in controlling CMP performance. More specifically, controlling the oxygen vacancies has been shown to directly impact removal rate (Ce3+ state), as well as post-CMP cleaning efficiency (Ce4+ state). Current post-CMP cleaning processes utilize oxidation/reduction reactions, etching, encapsulation, and ultrasonic methods as a means of undercutting the particle from the substrate surface. These methods have proven to be highly effective at particle removal but have shown to potentially induce further defectivity due to the aggressive cleaning conditions. This work aims to develop a post-CMP cleaning chemistry that enhances particle removal via soft encapsulation of undesirable nanoparticle/slurry chemistry non-covalent complexes on the wafer surface. By employing a polyelectrolyte/surfactant (PES) matrix, a surface adsorbing/charge-flipping encapsulation process is proposed as a vehicle to remove slurry contamination at low friction. Investigation into the synergy between slurry chemistry and PES cleaning chemistry, with respect to defect aggregate formation, was correlated to the cleaning efficiency as well as friction. Techniques were developed to study real-time properties such as the defect aggregate formation mechanism via in-line dynamic light scattering (DLS), coefficient of friction (COF), particle removal, and scratch defectivity to draw a correlation between cleaning chemistry structure and post-CMP performance.

Pressure Responsive Multi-Layered Composite Nanoparticles for through Silicon Via (TSV) Chemical Mechanical Planarization (CMP) Applications

Through silicon vias (TSV) have gained much attention due to the emergence of the vertical alignment necessary to produce 3D integrated circuit devices. Due to the large overburden caused by the electroplating process in TSV, high removal rate of copper (Cu) is essential for producing highly planar and defect free substrates. Therefore, focus has shifted to the development of processes and chemistries that produce highly planar and defect free Cu surfaces. In order to obtain this planarity, a process known as chemical mechanical planarization (CMP) is implemented in which a silica nanoparticle dispersion coupled with a mechanical force synergistically removes excess topography. The demands on TSV CMP have become stringent in order to meet the following criteria: very high removal rates, low dishing, high selectivity to nitride after barrier clear, low defectivity, and uniform surface topography. This work focuses on the development of a pressure responsive, multi-layer composite nanoparticle to provide a process driven synergy with the slurry formulation. These composites can be held together either covalently or non-covalently to the nanoparticle core using additives with amine, amino acid, and surfactant functionalities. The additives respond to an applied force and shear at the slurry-pad interface, resulting in controlled release of the slurry chemistry. Initial results show that at downforces ranging between 2.5-5 psi removal rates are at an excess of 1 micron per minute, while at below 1 psi removal rates are below 0.2 micron per minute and produce uniform surface quality at low surface roughness.

Development of “Soft” Cleaning Chemistries for Enhanced STI Post-CMP Cleaning

With the rapid miniaturization of advanced technologies, limiting device defects has become of utmost importance in maintaining high performing integrated circuits. Shallow trench isolation (STI) chemical mechanical planarization (CMP) uses a synergistic balance of ceria (CeO2) nanoparticles and functional chemistry to modulate surface adsorption interactions necessary to remove excess topography. This work aims to develop a post-CMP cleaning chemistry that enhances nanoparticle removal via “soft” encapsulation by employing a polyelectrolyte/surfactant (PES) matrix. A surface adsorbing/charge flipping encapsulation process is proposed as a vehicle to remove slurry contamination at low friction. Investigation into the synergy between slurry chemistry and PES cleaning chemistry, with respect to defect aggregate formation, was correlated to the cleaning efficiency as well as friction. Using a suite of techniques to study the real-time defect aggregate formation mechanism it was determined that the supramolecular structure is critical to balance defect forming events with enhanced cleaning efficiency.

Sediment-starved trenches and rough subducting plates are conducive to tsunami earthquakes

Tsunami earthquakes generate large tsunamis but only moderate ground shaking. The discrepancy between the magnitude of the surface wave and the resulting tsunami height makes them a serious threat to coastal communities and a problem for tsunami early warning. Although at least 13 tsunami earthquakes took place since 1896, there is little consent on what controls their genesis. It remains unclear if they are tied to distinct subduction-zone structures or geometries or if they can occur along all active margins. To help shed light on the genesis of these unusual earthquakes, I combine marine acoustic data from subduction-zone segments that experienced tsunami earthquakes in order to search for structural similarities in the nature of the subducting oceanic plate. The structural comparison indicates that tsunami earthquakes preferentially occur in regions where the subducting plate is characterized by excess topography which is not blanketed by trench sediment. While subducted, the topographic obstacles likely cause fracturing along their track. This contributes to the development of a thick, structurally and lithological complex, and fragmented plate-boundary shear-zone, which may be prone to fail at a low velocity during a tsunami earthquake. The results suggest that when assessing the risk of a tsunami earthquake, special focus should be placed on the combination of lower-plate topography and trench sediment thickness.

Large landslides lie low: Excess topography in the Himalaya-Karakoram ranges

Mass wasting is an important process for denuding hillslopes and lowering ridge crests in active mountain belts such as the Himalaya-Karakoram ranges (HKR). Such a high-relief landscape is likely to be at its mechanical threshold, maintained by competing rapid rock uplift, river incision, and pervasive slope failure. We introduce excess topography, Z E , for quantifying potentially unstable rock-mass volumes inclined at angles greater than a specified threshold angle. We find that Z E peaks along major fluvial and glacial inner gorges, which is also where the majority of 492 large (>0.1 km 2 ) rock-slope failures occur in the Himalaya9s largest cluster of documented Pleistocene to Holocene bedrock landslides. Our data reveal that bedrock landslides in the HKR chiefly detached from near or below the median elevation, whereas glaciers and rock glaciers occupy higher-elevation bands almost exclusively. Less than 10% of the area of the HKR is upslope of glaciers, such that possible censoring of evidence of large bedrock landslides above the permanent snow line barely affects this finding. Bedrock landslides appear to preferentially undermine topographic relief in response to fluvial and glacial incision along inner gorges, unless more frequent and smaller undetected failures, or rigorous (peri-)glacial erosion, compensate for this role at higher elevation. Either way, the distinct patterns of excess topography and large bedrock landsliding in the HKR juxtapose two stacked domains of landslide and (peri-)glacial erosion that may respond to different time scales of perturbation. Our findings call for more detailed analysis of vertical erosional domains and their geomorphic coupling in active mountain belts.

Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust

AbstractUnderstanding the causes of rock and surface uplift is important because they control the location of mountain building, depocenters, and drainage characteristics and can influence climate. Here we combine previous thermochronological data with field observations to determine the amount of exhumation, rock, and surface uplift that occurs in the upper plate of Central and South American subduction zones during the collision, accretion, and subduction of oceanic plateaus and aseismic ridges. The collision of buoyant and topographically prominent oceanic plateaus and ridges can drive at least 5 km of rock uplift within 2 Ma. Uplift appears to be an immediate response to collision and is generally independent of the slab dip. The amount of rock uplift is controlled mainly by excess topography associated with the ridge (ultimately linked to buoyancy) and erosion, while it is also influenced by the strength of the subduction interface related to the presence of volcanic asperities and overpressured sediments in the subduction channel. The quantity of exhumation is strongly dependant on climate‐induced erosion and the lifespan over which the topography is uplifted and supported. Sediment draining into the trench may leave the elevated ridge axis sediment starved, increasing the shear stresses at the ridge subduction interface, leading to positive feedback between ridge subduction, rock uplift, and exhumation. Trench‐parallel variations in exhumation have a direct impact on exploration paradigms for porphyry‐related metalliferous deposits, and it is likely that porphyry systems are completely eroded by the impingement of plateaus and aseismic ridges within temperate and tropical climates.