Uplift Rates Research Articles

Surface exposure ages of middle–late Pleistocene marine and fluvial terraces along the northern and southern Sanriku coasts, Northeast Japan

To estimate long-term rates of coastal uplift along the northern Pacific coast of Northeast Japan, we determined the surface exposure ages of marine and fluvial terraces based on terrestrial in situ cosmogenic radionuclide dating of exposed bedrock surfaces. Based on reinterpretation of marine and fluvial terraces, we collected samples from the northern and southern Sanriku coast. The surface exposure ages from 10Be concentrations in quartz calculated from the measured 10Be/9Be ratios commonly suggest MIS 5 and MIS 7 for the marine and fluvial terraces and averaged coastal uplift rates of ca. 0.25 ± 0.15 and 0.4 mm/yr along the northern and southern Sanriku coast at intermediate timescales. The results may demonstrate different styles of crustal strain accommodation in the northern Northeast Japan arc above the subducting Pacific plate.

Seismic risk mitigation at Campi Flegrei in volcanic unrest

Campi Flegrei is a densely populated volcanic area in Italy. Its inner caldera periodically experiences uplift and subsidence, known as bradyseism, also accompanied by seismic activity. In the last decade, with uplift rates up to 2 cm/month, about nine-thousand earthquakes were recorded. Upon request of the local administration, the most updated data were collected and analyzed to evaluate the risk management strategy consisting of structural retrofitting according to the building code. Here it is shown that the reference moment magnitude is in the range 4.4, 5.1, based on fault mapping, geomorphological inference, earthquake relocation, stress-drop analysis, and ground motion modelling. Earthquake forecasting enabled computing the exceedance probabilities of these magnitudes. Earthquake engineering showed that the minimum magnitudes expected to cause exceedance of design ground motion, are larger than the reference magnitudes. Finally, the risk reduction implied by the safety levels of new constructions was assessed for reinforced concrete buildings.

Holocene fringing reef along southern Andaman and Swaraj Dweep shoreline

The Andaman and Nicobar Islands are rimmed by discontinuous fringing reef that is in general wider on western margin vs the eastern margin. This study characterizes the facies updip from the modern fringing reefs to the present shoreline of south Andaman and Swaraj Dweep, and describes in detail the coral terraces/carpets within and above the inter-tidal zone representing the Holocene Fringing reef. Field studies, satellite, and drone datasets have been utilized to map different facies, that include: coralgal boundstone, biodetrital-grainstone, beachrock, and coralgal rudstone. Multiple exposed microatolls as well as coral terraces (coral carpets) of Acropora and Porites (dated 8.7-8.4 ka BP) have been identified within the intertidal zone (Radhanagar Beach, Swaraj Dweep) indicating that Holocene fringing reef have down-stepped offshore to the current location of modern fringing reefs owing to either tectonics or eustasy. The eustatic sea-level fluctuations are relatively well established for the Holocene and we compute the tectonic uplift rates utilizing the stream-power-incision and linear-inversion model. A tectonic uplift rate of ~ 0.05 mm/yr (for Swaraj Dweep) during the past 100 ka is estimated, while taking into account a wide range of erodibility indexes and response time intervals. It is identified that the computed uplift rate is an amalgamation of the coseismic deformation along with the interseismic and aseismic surface deformation. Thus, not all exposed coral terraces/microatolls are exposed due to coseismic deformation (for example uplift in parts of Andaman due to earthquake in 2004). The average long-term uplift rates are a magnitude lower than the eustatic sea-level fall rates during Holocene, thus, we suggest that most of the Holocene fringing reefs are exposed due to eustatic sea-level fall and down-stepped to the current location of the modern fringing reefs. This would entail that the eustatic sea-level change rates would play a significant role in determining future of the modern fringing reef (catch-up vs keep up vs give up), and the coastal morphology of south Andaman and Swaraj Dweep, with implications for coastal inundation and stability in the scenario of climate change.

Quaternary deflection of the Macuma River as it crosses the actively growing Cutucú antiformal culmination in southeastern Ecuador

Models of fold growth involve simple mechanisms of tip propagation or an increase in amplitude and breadth by maintaining the tip fixed. Whatever the growth mechanism, the drainage network adapts to the newly created tectonic slopes. Lithological resistance to erosion, as well as climate and uplift rates, exerts a control on bedrock incision rates and, therefore, on whether a transverse river maintains its course or finally is deflected. In southeastern Ecuador, the northernmost end of the Cutucú Uplift corresponds to the Macuma anticline, a north-plunging periclinal fold that encroaches into the Amazonian plain. The east-flowing Macuma River exhibits a pronounced narrow curvature entrenched within the anticline structure. Morphometric analysis including river profiling, across-valley geometry, hypsometric-integral data, and small-scale saddle features such as wind gaps, evidence an antecedent east-flowing straight water gap in the initial stages of fold growth. Nevertheless, the gradual exposure of a rock-resistant core has deflected the Macuma River but only in its middle course while the general west-east trend is maintained. Consequently, the landscape resulted in a linked pair of elongated inner ridges bound by a horseshoe morphostructure. Through detailed geomorphic analysis, a complex history of lateral propagation has been established for the Macuma anticline. Thus, behind the frontal nose, an actively propagating core tip attained a point where it became fixed while the anticline began to grow in amplitude and breadth. Finally, a renewed phase of tip propagation encroached into the adjacent northern Amazonian plain and constructed a narrow anticlinal nose which is currently preserved as a pristine non-dissected surface.

Retraction Note: Increasing uplift rate since ~10 Ma in the eastern Tibetan Plateau from river profile inversion

Retraction Note: Increasing uplift rate since ~10 Ma in the eastern Tibetan Plateau from river profile inversion

Flat-Slab Mechanics Transforming Double-Arc Expressions Along the Middle America Trench

The southeast–northwest variation in the trench–volcano distance along the Middle America subduction zone is widely recognised to be due to the horizontal (flat) geometry of the descending Cocos plate (slab) in its northwestern part. In the topographic and gravitational expressions, the southeastern segment forms doubled low–high (i.e. trench–continental shelf edge–oceanic basin–volcanic arc) belts, whereas the northwestern segment forms wide doubled low–high belts. To define their attribution, the surface uplift rates were computed from a two-dimensional dislocation-based subduction model with hypocentre-based plate interface geometries. The trench-perpendicular plate-interface profiles exhibited similar curvature compositions, which were reflected in three (shallow, moderate depth and deep) convexities (downward bends) and one concavity (upward bend) between the moderate-depth and deep convex sections. The steady subduction along the first and second positive curvatures (shallow and moderate-depth convexities) in the southeastern and northwestern segments could serve as mechanical sources of short-wavelength double-arc formation. The latter two (negative and third positive) curvatures (concavity and deep convexity) in the northwestern segment produced distinct features including the narrow continental shelf, large trench–volcanic-arc distance and relevant long-wavelength double arcs. This was attributed to the direct contact of the flat elastic slab with the overriding plate.

Short Communication: Numerically simulated time to steady state is not a reliable measure of landscape response time

Abstract. Quantifying the timescales over which landscapes evolve is critical for understanding past and future environmental change. Computational landscape evolution models are one tool among many that have been used in this pursuit. We compare numerically modeled times to reach steady state for a landscape adjusting to an increase in rock uplift rate. We use three different numerical modeling libraries and explore the impact of time step, grid type, numerical method for solving the erosion equation, and metric for quantifying the time to steady state. We find that modeled time to steady state is impacted by all of these variables. Time to steady state varies inconsistently with time step length, both within a single model and among different models. In some cases, drainage rearrangement extends the time to reach steady state, but this is not consistent in all models or grid types. The two sets of experiments operating on Voronoi grids have the most consistent times to steady state when comparing across time step and metrics. On a raster grid, if we force the drainage network to remain stable, time to steady state varies much less with computational time step. In all cases we find that many measures of modeled time to steady state are longer than that predicted by an analytical equation for bedrock river response time. Our results show that the predicted time to steady state from a numerical model is, in many cases, more reflective of drainage rearrangement and numerical artifacts than the time for an uplift wave to propagate through a fixed drainage network.

Fault Interaction and Strain Partitioning Deduced From Deformed Fluvial Terraces of the Eastern North Qilian Foreland, NE Tibetan Plateau

AbstractFaulting and folding of basement rocks together accommodate convergence within continental orogens, forming complex zones of intraplate deformation shaped by the fault interaction. Here we use the river terraces along the Dongda river to examine the tectonic deformation patterns of the hinterland and the foreland of the eastern North Qilian Shan, a zone of crustal shortening located at the northeast margin of the Tibetan Plateau. Five Late Pleistocene–Holocene terraces of Dongda river are displaced by three major reverse faults: Minle‐Damaying fault, Huangcheng‐Ta'erzhuang fault, and Fengle fault, from south to north. Based on displaced terrace treads, we estimated vertical slip rates along the Minle‐Damaying fault as 0.7–0.8 mm/a, and along the Fengle fault as 0.5–0.7 mm/a. Deformed terraces suggest an additional uplift of ∼0.2 mm/a through the folding of the Dahuang Shan anticline. Inhomogeneous uplift of the intermontane basins between the Minle‐Damaying fault and the Dahuang Shan anticline indicates a 0.9 ± 0.2 mm/a uplift rate along the Huangcheng‐Ta'erzhuang fault. Kinematic modeling of this thrust system shows that deformation propagated northward toward the foreland along a south‐dipping 10° décollement rooted into the Haiyuan fault at the depth of ∼20 km. This system accommodates 2.7–3.4 mm/a total crustal shortening rate. We suggest this broad thrust belt and the relatively high rate of shortening within this part of the eastern Qilian Shan is a result of the oblique convergence along a restraining bend of Haiyuan fault system. The elevated shortening rate within this area indicates high potential seismic hazard.

Multi-stage ecological pond and reservoir system to enhance river water quality: demonstration study on Periurban River

ABSTRACT Pollution of urban rivers not only destroys the river ecology but also adversely affects the health of residents and urban landscape. In this regard, we selected a certain river in Wuhan for research. In this paper, we utilize the modified bypass multi-stage ecological pond reservoir system, set up the front parthenogenetic pond, aeration and oxygenation pond, ecological purification pond and other processes, supplemented with aeration–bacteriophage coupling, filler-type ecological floating island and other technologies to improve the water quality of the river. Results show that 4 months after the operation of the system, the rate of enhancement in water transparency reached 550%, and with a dissolved oxygen (DO) uplift rate of 322%, in addition, this system achieved 77.98, 77.78 and 74.41% removal of the ammonia nitrogen (NH3-N), total phosphorus (TP), chemical oxygen demand (COD) respectively, and the effluent water quality meets the target water quality standard. The process not only has a good pollutant removal effect, low cost and other characteristics but also can enhance the river landscape and improve biodiversity. It can provide a reference for similar river pollution water quality improvement.

The Application of Amino Acid Racemization Geochronology of <i>Tubipora</i> sp. in Marine Terraces of Manokwari Region, West Papua, Indonesia

The active neotectonics of northern West Papuan coastlines allow the formation of emergent marine terraces associated with Quaternary sea-level high stands. These terraces contain fossils from the coral assemblage, which are useful for geochronological assessments and further estimating uplift rates. Here, we report the applicability of amino acid racemization (AAR) of Tubipora sp. to discriminate different ages associated with stages of sea-level high stand, constrained by previous uranium-thorium (U/Th) series dating. The results from amino acid dating of three samples reveal two distinct extents of racemization corresponding to terraces developed during Marine Isotope Stage (MIS) 5 sensu lato and 1. However, AAR analysis could not further discriminate interstadial MIS 5a and 5c as determined by published radiometric dating. This indicates the low resolving power of amino acid dating to distinguish sub-sequences beyond the interglacial period. Nevertheless, the cost-effective and rapid analysis of AAR dating of Tubipora sp. can be used as preliminary results related to marine terraces formed in different interglacial events.

A new technique mapping submerged beachrocks using low-altitude UAV photogrammetry, the Altınova region, northern coast of the Sea of Marmara (NW Türkiye)

High-resolution aerial imagery captured from low altitudes enables the detailed reconstruction of the geomorphological features of submerged beachrocks and the quantification of their topographic complexity. These coastal deposits serve as vital indicators for estimating past sea-level positions and deformation, contributing to our understanding of climate and tectonic processes across various temporal and spatial scales. This study focuses on submerged beachrocks identified in the nearshore coastal area of Tekirdağ city (Altınova), and the existing knowledge regarding such geological formations is limited.Situated in the tectonically active western Marmara region, the coastal zone of The Tekirdağ-Altınova is influenced by the North Anatolian Fault Zone (NAFZ), which has significantly shaped the coastline over time. Utilizing unmanned aerial vehicle (UAV) data, we successfully isolated submerged beachrocks from other coastal deposits, identifying them at depths of 2 m below current sea level and extending approximately 5 km along the coast. This identification was facilitated by integrating high-resolution aerial imagery with morphological analysis techniques, specifically employing structure-from-motion photogrammetry to generate a dense point cloud for bathymetric mapping.The utilization of cost-effective UAV imagery facilitated the efficient monitoring of beachrocks. Geographic information systems (GIS) and the TerraceM application were employed to analyze the high-resolution bathymetry data (with a 5 cm resolution), enabling the precise estimation of shoreline angles and associated errors. These shoreline angles, which correspond to the past sea levels high stand, were mapped using swath profiles oriented perpendicular to the isobaths. Our findings reveal that the majority of submerged beachrocks exhibit shoreline angles between ∼ −0.7 m and −1.1 m. This study presents innovative methodologies for mapping the height and spatial distribution of beachrocks, as well as for reliably estimating reliable uplift rates in the nearshore area of Tekirdağ-Altınova.

Tectonic Activity Analysis of the Laji-Jishi Shan Fault Zone: Insights from Geomorphic Indices and Crustal Deformation Data

Fault segmentation plays a critical role in assessing seismic hazards, particularly in tectonically complex regions. The Laji-Jishi Shan Fault Zone (LJSFZ), located on the northeastern margin of the Tibetan Plateau, is a key structure that accommodates regional tectonic stress. This study integrates geomorphic indices, cross-fault deformation rate profiles, and 3D crustal electrical structure data to analyze the varying levels of tectonic activity across different segments of the LJSFZ. We extracted 160 drainage basins along the strike of the LJSFZ from a 30 m resolution digital elevation model and calculated geomorphic indices, including the hypsometric integral (HI), stream length-gradient index (SL), and channel steepness index (ksn), to assess the variations in tectonic activity intensity along the strike of the LJSFZ. The basins were categorized based on river flow directions to capture potential differences across the fault zone. Our results show that the eastern basins of the LJSFZ exhibit the strongest tectonic activity, demonstrated by significantly higher SL and ksn values compared to other regions. A detailed segmentation analysis along the northern Laji Shan Fault and eastern Jishi Shan Fault identified distinct fault segments characterized by variations in SL and ksn indices. Segments with high SL values (>500) correspond to higher crustal uplift rates (~3 mm/year), while segments with lower SL values exhibit lower uplift rates (~2 mm/year), as confirmed by cross-fault deformation profiles derived from GNSS and InSAR data. This correlation demonstrates that geomorphic indices effectively reflect fault activity intensity. Additionally, 3D crustal electrical structure data further indicate that highly conductive mid- to lower-crustal materials originating from the interior of the Tibetan Plateau are obstructed at segment L3 of the LJSFZ. This obstruction leads to localized intense uplift and enhanced fault activity. These findings suggest that while the regional stress–strain pattern of the northeastern Tibetan Plateau is the primary driver of the segmented activity along the Laji-Jishi Shan belt, the direction of localized crustal flow is a critical factor influencing fault activity segmentation.

Pulsed uplift of the South Tianshan since the Late Miocene indicated by the linear inversion on river longitudinal profiles

The early Cenozoic collision and subsequent continuous convergence between the Indian and Eurasian plates reactivated the Tianshan orogen in the Central Asia and caused multistage uplift of the mountain range. The modern Tianshan, with high mountain peaks of >7000 m, forms very prominent topography that profoundly affects the regional tectonics and climate. However, the late Cenozoic uplift process and topography growth of the South Tianshan remain controversial. River longitudinal profile inversion provides a distinctive way to reveal rock uplift history since the late Cenozoic. In this study, we presented linear inversion on river longitudinal profiles of four drainage basins originating from high mountains in the South Tianshan. The inversion results from two basins in the northern flank show fast and continuous increases in the uplift rates from about 0.1–0.2 mm/a to 0.6–1.0 mm/a since 4 Ma. While in the southern flank, the uplift rates of the two basins increased gradually from about 0.1 mm/a to 0.2 mm/a before 10 Ma and from 0.2 mm/a to 0.4 mm/a around 10 Ma and 6 Ma, respectively. Our results combined with recently published chronological data in this region indicate that the South Tianshan experienced a pulsed tectonic uplift process since the Late Miocene. Moreover, the pulsed tectonic uplift should lead to an elevated South Tianshan during 6–4 Ma, coinciding well with the ∼5.3 Ma extreme aridification in the Tarim Basin, thus supporting that the rain shadow effect caused by high topography of South Tianshan is a critical reason for aridification.

Estimation of Denudation Parameters and River Capture Events From Neural Network Inverse Modeling of River Profiles and Thermo‐ and Geochronology Data

AbstractEarth's topography represents the cumulative effects of tectonics and surface processes modulated by climate and lithology. These factors shape landscapes through time. River profiles can be inverted to estimate the rock uplift histories or lithology‐specific erodibilities. However, river systems are dynamic and evolve in response to spatial and temporal internal dynamics, such as river capture events. Here, we present a modeling framework to infer denudation rates from the inversion of river profiles and thermo‐ and geochronology data. We achieve this by coupling a landscape evolution model and an efficient inverse modeling scheme to infer poorly resolved erosional and tectonic parameters. An application of the approach is presented for the Neckar catchment, southwest Germany, characterized by stark lateral variation in bedrock erodibility and rock uplift, and that have demonstrably undergone multiple river capture events. Different end‐member scenarios are explored in the simulations. First, we test uniform and spatial variability in rock uplift rate and bedrock erodibility, and second, temporal variations in rock uplift rate and base level. Finally, we simulate river capture events by adding upstream sections (drainage area) at specific times and locations within the fluvial network. We find that spatial variation in rock uplift rate is necessary to reproduce the Neckar's river profile while honoring analytical observations. Simulations integrating river captures allow improved river profile predictions of specific tributaries of the Neckar catchment, leading to potentially more realistic erodibility and rock uplift history estimates. The time and location of the capture events determined from the modeling agree with previous estimations from geological evidence.

Recent uplift of Chomolungma enhanced by river drainage piracy

The Himalayas, which host glaciers, modulate the Indian Monsoon and create an arid Tibetan Plateau, play a vital role in distributing freshwater resources to the world’s most populous regions. The Himalayas formed under prolonged crustal thickening and erosion by glaciers and rivers. Chomolungma (8,849 m)—also known as Mount Everest or Sagarmāthā—is higher than surrounding peaks, and GPS measurements suggest a higher uplift rate in recent years than the long-term trend. Here we analyse the potential contribution of a river capture event in the Kosi River drainage basin on the renewed surface uplift of Chomolungma. We numerically reconstruct the capture process using a simple stream power model combined with nonlinear inverse methods constrained by modern river profiles. Our best-fit model suggests the capture event occurred approximately 89 thousand years ago and caused acceleration of downstream incision rates. Flexural models estimate this non-steady erosion triggers isostatic response and surface uplift over a broad geographical area. We suggest that part of Chomolungma’s anomalous elevation (~15–50 m) can be explained as the isostatic response to capture-triggered river incision, highlighting the complex interplay between geological dynamics and the formation of topographic features.

Characterization of the active fault deformation zone of the Chegualin Fault in the alluvial plain of southwestern Taiwan

The activity of a creeping active fault poses significant challenges to engineering structures due to surface deformation. Therefore, quantifying the strain concentration caused by an active fault, delineating the extent and location of the Active Fault Deformation Zone (AFDZ), estimating long-term deformation trends, and predicting future deformations are crucial in the field of engineering geology.This study comprehensively integrates multi-timescale analytical methods by incorporating detailed geodetic data, rupture surveys, morphotectonic analysis, geological borehole data, biochronological data, radiocarbon dating, and Holocene uplift rate analysis to identify or confirm the locations of active faults and the long-term evolution trends of active deformation zones. Based on our findings, three active fault planes are identified, with one possibly being the main fault with the highest activity. Furthermore, by comparing long-term deformation rates derived from isochrone lines with short-term deformation rates obtained from leveling, we observe a risk of slip rate deficit. These findings have significant implications for engineering geology. As a general contribution, our study can serve as a site screening strategy for similar locations. Regarding the infrastructure we targeted, we provide critical input parameters for further numerical models (such as the trishear model) to simulate surface deformation, and offer essential design parameters for structures. Considering potential coseismic deformation on the investigated fault, these results are fundamental for future investigations or mitigation plans.

The Miocene Acceleration of Strike-Slip Deformation in the Northern Tian Shan, Central Asia

Abstract The Tian Shan has been deformed during the Cenozoic as a far-field response to the India–Eurasia collision. This contribution reports new apatite fission-track (AFT) and apatite (U-Th)/He data from the northern Tian Shan, including areas along the southern margin of the Junggar Basin and adjacent to the western segment of the Bolokenu-Aqikekuduk Fault (BAF). Thermal history modeling of the presented data suggests that the Cenozoic exhumation along the basin margin started >20 Ma, and the oblique-slip BAF could have been active since at least ~10 Ma with a total exhumation magnitude of ~2 km during the late Cenozoic. Since then, the mean exhumation rate on southern wall of the BAF is comparable to the Quaternary uplift rate previously measured on the same segment of the fault. To examine the extent of the Miocene acceleration of the transpressional deformation pattern, an exhumation model since 50 Ma was established by inverse modeling >1000 published and new AFT and (U-Th)/He ages from the Tian Shan and the northeastern Tibetan Plateau. The model suggests that after the initial unroofing, a significant acceleration in exhumation occurred during 15–10 Ma, in regions including the interiors of northern and southwestern Tian Shan near major strike-slip structures. This change coincided with the northward propagation of the Pamir and the eastward expansion of the northeastern Tibetan Plateau along the west and south margins of the Tarim Basin, respectively.

The Miocene Acceleration of Strike-Slip Deformation in the Northern Tian Shan, Central Asia

Abstract The Tian Shan has been deformed during the Cenozoic as a far-field response to the India–Eurasia collision. This contribution reports new apatite fission-track (AFT) and apatite (U-Th)/He data from the northern Tian Shan, including areas along the southern margin of the Junggar Basin and adjacent to the western segment of the Bolokenu-Aqikekuduk Fault (BAF). Thermal history modeling of the presented data suggests that the Cenozoic exhumation along the basin margin started >20 Ma, and the oblique-slip BAF could have been active since at least ~10 Ma with a total exhumation magnitude of ~2 km during the late Cenozoic. Since then, the mean exhumation rate on southern wall of the BAF is comparable to the Quaternary uplift rate previously measured on the same segment of the fault. To examine the extent of the Miocene acceleration of the transpressional deformation pattern, an exhumation model since 50 Ma was established by inverse modeling >1000 published and new AFT and (U-Th)/He ages from the Tian Shan and the northeastern Tibetan Plateau. The model suggests that after the initial unroofing, a significant acceleration in exhumation occurred during 15–10 Ma, in regions including the interiors of northern and southwestern Tian Shan near major strike-slip structures. This change coincided with the northward propagation of the Pamir and the eastward expansion of the northeastern Tibetan Plateau along the west and south margins of the Tarim Basin, respectively.

Laminar burning velocity, cellular instability, and the superadiabatic flame temperature phenomenon for NH3/syngas/air premixed flames

The laminar burning velocity (LBV) and cellular instability of ammonia/syngas/air were investigated using the spherically expanding flame method at an initial pressure of 3 atm and temperatures of 298–448 K. The impacts of equivalence ratio, temperature, and hydrogen ratio on LBV were scrutinized. The results demonstrate that the LBV varies non-monotonically with the equivalence ratio and increases with increasing temperature and hydrogen ratio. Flame instability was analyzed using flame uplift rate, Lewis number, thermal expansion ratio, flame thickness, critical radius, critical Peclet number and logarithmic growth rate of perturbation in combination with the schlieren images. Of these, the flame uplift rate is used to quantify buoyancy instability, a flame instability that has received little attention. At high pressures, lower LBV makes the flame susceptible to buoyancy instability. The flame uplift rate increases with increasing flame radius, suggesting that the buoyancy instability becomes increasingly significant as the spherical flame expands. The diffusional-thermal instability is weaker at the fuel-rich side and enhanced at the leaner side. As the hydrogen ratio increases, the flame instability increases. Hydrodynamic instability is not susceptible to temperature, which is only slightly weakened with increasing temperature. Additionally, the phenomenon of superadiabatic flame temperature (SAFT) in ammonia/syngas/air flames was first found and analyzed its temperature dependence. Increasing the initial temperature suppresses SAFT occurrence.

When Does the Concavity Index Constrain Stream Power Parameters?

AbstractBy defining the attributes of river networks, we can quantitatively extract records of climatic and tectonic changes from them. The stream power incision model (SPIM) provides a framework within which this can be achieved, as it facilitates the calculation of the relative rock uplift from river characteristics. One parameter that has been widely employed in tectonic and fluvial geomorphology is the channel steepness index, a metric that can represent the normalized rock uplift rate experienced by a river. However, to accurately infer the channel steepness index, we must accurately estimate m/n, the ratio between the two positive exponents of the SPIM. Present methodologies to constrain m/n rely on an assumption that rock uplift and erodibility are spatially invariant. These conditions are rarely present on Earth. In this study, we use a synthetic example and examples from the Siwalik Hills and Olympic Mountains to demonstrate how existing methodologies to constrain m/n produce systematic errors when there is spatial variation, and particularly spatial gradients, in the processes driving landscape evolution. To solve this problem, we present a methodology to estimate m/n based on a large river network inversion that accounts for spatial variation in landscapes. After demonstrating that the methodology can accurately recover m/n in our synthetic landscape, we show that our methodology can reconcile contrasting observations in the Siwaliks, and is critical to inferring accurate values of channel steepness index in the Olympic Mountains. This highlights the utility of large topographic inversions for investigating landscape dynamics.