Elastic Thickness Research Articles

The Effective Elastic Thickness of the Lithosphere Reveals Tectonic Process and Lithospheric Rheology of the Eurasian Basin

ABSTRACTWe obtained the effective elastic thickness of the lithosphere (Te) in the Eurasian Basin using the fan‐shaped wavelet method. For ultraslow spreading ridges, the magmatic heat input is insufficient to form continuous quasisteady‐state magma lenses along the axis, resulting in significant variability in the rheological strength of the lithosphere. We suggested that the tectonic inheritance resulted in the different lithospheric rheology of WVZ and SMZ, consequently leading to distinct tectonic‐magmatic activities. The SMZ with less magmatic activity has a weaker lithosphere than that of the EVZ with extensive magmatism. We propose that the lithospheric rheology and thermal structure of ultraslow spreading ridge may be influenced not by the amount of magma supply but by the mode of magma emplacement.

Gravity anomalies and deep structure of the northeastern Tibetan Plateau and adjacent areas

The northeastern Tibetan Plateau is a region having experienced subduction, collision, and intracontinental extension. In this study, a gravity model (SGG-UGM-2) was used to investigate the distribution of gravity anomalies, Moho depth, and lithospheric effective elastic thickness in the northeastern Tibetan Plateau and adjacent areas. The results were compared with the regional heat flow, crustal magnetic anomalies, and seismicity. The Bouguer gravity anomalies correlate with the surrounding stable blocks (i.e., the Tarim Basin, Alxa Block, Ordos Basin, and Sichuan Basin) and lateral crustal extrusion of the Tibetan Plateau. The isostatic gravity anomalies, Moho depth, and lithospheric effective elastic thickness are –80 to 80 mGal, 35–70 km, and 5–105 km, respectively. Isostatic disequilibrium occurs mainly near boundaries between blocks and is associated with seismic activity. The distribution of Bouguer gravity anomalies and the Moho surface record the northeastward expansion of the Tibetan Plateau. The lithospheric effective elastic thickness decreases gradually from west to east in the Bayan Har Block, reaching its lowest values (<10 km) in the Longmenshan tectonic belt, which confirms the eastward extrusion along the block. The lithospheric effective elastic thickness in the Qaidam Basin is higher than that in the Bayan Har Block and Qilian orogenic belt, which reflects underthrusting of the East Asian lithosphere beneath the Qilian orogenic belt and the fact that extrusion from the Qiangtang Block is blocked by the Qaidam Basin.

Variations of Heat Flux and Elastic Thickness of Mercury From 3‐D Thermal Evolution Modeling

AbstractMercury's low obliquity and 3:2 spin‐orbit resonance create a surface temperature distribution with large latitudinal and longitudinal variations. These propagate via thermal conduction through the thin silicate shell influencing the interior temperature distribution. We use 3‐D thermal evolution models to investigate the effects of lateral variations of surface temperature and crustal thickness on the surface and core‐mantle boundary (CMB) heat fluxes, and elastic thickness distribution. Surface temperature variations cause a long‐wavelength perturbation of the heat fluxes, as well as of the elastic lithosphere thickness, while variations in crustal thickness affect these quantities at small spatial scales. Like the surface temperature, the present‐day CMB heat flux pattern is characterized primarily by spherical harmonics of degrees two and four, which could affect dynamo generation. Placing robust constraints on the thermal evolution based on the available estimates of the age and thickness of the elastic lithosphere remains challenging due to their large uncertainties.

The effective elastic thickness along the Emperor Seamount Chain and its tectonic implications

SUMMARY The Hawaiian–Emperor Seamount Chain, a pre-eminent example of a hotspot-generated intraplate seamount chain, provides key constraints not only on the kinematics of plates but also on their rigidity. Previous studies have shown that the effective elastic thickness, Te, a proxy for the long-term strength of the lithosphere, changes abruptly at the Hawaiian–Emperor ‘bend’ from low values (∼16 km) at the Emperor Seamounts to high values (∼27 km) at the Hawaiian Ridge. To better constrain Te along the poorly explored Emperor Seamounts we have used a free-air gravity anomaly and bathymetry gridded data set, together with fully 3-D elastic plate (flexure) models, to estimate the continuity of Te and volcano load and infill densities along 1000 profiles spaced 2 km apart of the chain. Results show that Te generally decreases northwards along the chain. The decrease is most systematic between Ojin and Jimmu guyots where Te depends on the age of the lithosphere at the time of volcano loading and is controlled by the 340 and 400 °C oceanic isotherms. The largest variation from these isotherms occurs at the northern and southern ends of the chain where Te is smaller than expected suggesting the influence of pre-existing, older, loads. We use these results to constrain the subsidence, flexural tilt, rheological properties and tectonic setting along the seamount chain. We found an excess subsidence in the range 1.2–2.4 km, a tilt as large as 2–3°, oceanic lithosphere that is weaker than it is seawards of the weak zone at subduction zones, and a tectonic setting at Detroit and Koko seamounts that, despite their forming an integral part of the hotspot generated seamount chain, retains a memory of their proximity to earlier loads associated with plume influenced mid-oceanic ridges.

The Crust-Mantle Interaction of the Qiangtang Terrane: New evidence from the Effective Elastic Thickness of the Lithosphere

The crust-mantle interaction in the Qiangtang terrane is significant to study continental rheology and evolution. Its mechanism remains a subject of considerable debate for the reason of lack of sufficient geophysical evidence. The effective elastic thickness (Te) of the lithosphere can provide important constraints on this issue because it is sensitive to the state of mechanical coupling between the crust and the lithospheric mantle. We present new high-resolution Te of the Qiangtang terrane by using the multitaper admittance method with fusion of different window, based on satellite gravity and topographical data. Thus, a detailed study of the lithosphere is conducted, for the first time to utilize the spatial variations of Te and associated parameters, including thermal structures of the lithosphere, uppermost mantle seismic Pn-velocity, and crustal deformation. The results indicate that crust-mantle interaction in the Qiangtang terrane primarily occurs in the middle Qiangtang terrane (87°E ∼ 95°E, 32°N ∼ 34°N), where Te values are lower. In the eastern and western Qiangtang terrane, Te values are higher, implying weaker late-stage modification. Due to Rayleigh-Taylor instability, lithospheric delamination occurred beneath the south Qiangtang terrane. Based on the extent of these low Te values (Te < 50 km), we conclude that the delaminated lithospheric slab sinking into the mantle is ∼400 km in length and elongated in shape. The delamination induces the upwelling of mantle material, upward stress, volcanic activity, extensional faults, and hot springs in the Qiangtang terrane.

Spatial variations in the effective elastic thickness of the Indian Ocean lithosphere

The Indian Ocean lithosphere is a complex assemblage of large igneous provinces, seamounts, plateaus and ridges of different loading ages and tectono-thermal evolution. As a proxy for the strength of tectonic plates, effective elastic thickness (Te) illustrates the relationship between surface deformation and lithospheric rheology of the diverse provinces in response to long-term tectonic processes. Mapping the spatial variations in lithospheric rheology can aid in understanding the detailed tectono-thermal history of the Indian Ocean. In this paper, we perform an assessment of the spatial variation of Te for the Indian Ocean from the inversion of the real free-air admittance between free-air gravity anomalies and bathymetry corrected for the effect of density variations within sediments using a continuous wavelet spectral analysis. Incorporating the effect of sediments substantially reduces Te estimates and better corresponds with the tectonic units in the study region. The results show low overall Te over the Indian Ocean attributed to magmatism and temperature during a multistage opening process. We further demonstrate that temperature controls the strength of warm and young oceanic lithosphere, evidenced by the positive correlation between Te and geothermal proxies. Finally, moderately low Te values at the Southwest Indian Ridge suggest a relatively cold ultraslow lithosphere with sparse magmatism compared to typical mid-ocean ridges.

Surface Uplift Due To Time‐Varying Elastic Thickness in Continental Interiors

AbstractIf, as previously hypothesized, the effective elastic response of the lithosphere is sensitive to the imposed stress regime, then it may vary in time and produce distinctive geomorphic responses. Such effects will be at their most crucial in landscapes of low relief. Motivated by the existence of numerous small endorheic (internally‐drained) basins in central Australia, we examine the influence of changing elastic response in the presence of large embedded loads in the lithosphere underlying stable continental interiors. Focusing on the western Lake Eyre Basin and adjoining Lake Lewis basin—an area with a close correlation between drainage pattern and extreme Bouguer gravity anomalies—we devise a set of numerical simulations that incorporate the flexural response to time‐transient horizontal stresses. The simulations demonstrate that transient changes in the effective elastic thickness can drive topographic changes in low‐relief landscapes, including drainage capture and the development of endorheic basins, consistent with field observations.

Quantitative estimation of the effective elastic thickness around the Burma Plate and correlation analysis of its influencing factors

The Burma Plate is a microplate that extends along the boundary between the Indian and Eurasian plates. It is characterized by an extraordinarily complex lithospheric tectonic setting, resulting from the continental collision in the north, the oceanic crustal subduction in the south, and the large amount of sediment from the Tibetan Plateau. The lithospheric strength is a key to understanding the tectonic evolution of the Burma Plate. In this study, we use topography and gravity disturbance data to estimate the spatial distribution of effective elastic thickness Te, which is a measure of lithospheric strength. The Tevalues range from ∼10 km to 80 km, with higher values in the Indian Plate than those in the other regions. The non-isostatic flexural effects of sediment loading and subducting slab pull can bias the Te estimation, with maximum reductions of ∼50 km and ∼10 km, respectively. The consistent distributions of the Te and the shear wave velocity anomaly ΔVsat 100 km depth suggest that the lithospheric strength is generally controlled by the thermal structure of the upper mantle. Meanwhile, the Te variations are highly related to the geometry of the subducting Indian Plate along the collision and subduction zones, indicating that the plate tectonics play a dominant role in determining the lithospheric strength of the Burma Plate.

Weakened continental lithosphere beneath the northern Red Sea inferred from elastic thickness

The northern Red Sea (NRS) is considered an extended continental region that has resulted in a rift system. Gravity and bathymetry data were used to estimate the Moho depth and the elastic thickness Te of the lithosphere beneath the NRS region to characterize its flexural rigidity and understand its mechanical behavior. Focusing on the Mabahiss Deep in NRS, we analyzed the lithosphere's flexural rigidity. The observed long-wavelength positive Bouguer anomaly is attributed to crustal thinning and lithospheric mantle uplift. The crustal thickness varies from 28 km in coastal areas to 24 km beneath the axial rift, supporting a regional compensation model over the Airy model. Forward modeling suggests that the optimal model explaining the regional Bouguer anomaly is a flexural model with Te equal to 7 km, indicating a weak and irregular continental crust. The primary factor contributing to this weakness is heating activity. Given the weakened state of the crust and the ongoing extension in the region, the NRS rift could evolve into a rupture, potentially leading to the formation of oceanic crust.

Spatial variations in effective elastic thickness and loading ratio in the Indo-Burma subduction zone based on the joint inversion of Bouguer coherence and admittance

Our knowledge of the mechanical structure and geodynamic evolution of the Indo-Burma Subduction (IBS) Zone is currently limited. The effective elastic thickness (Te) reflect the thermo-rheological characteristics of the subduction zone that aid in understanding the long-term deformation and geodynamic evolution. In the present study, we employed joint inversion of wavelet admittance and coherence to obtain the spatial variation in Te and the loading structure (F) over IBS based on satellite gravity and topography data. The spatial pattern of Te and F exhibit a remarkable correlation with the tectonic features of IBS. The Indo-Burma ranges (IBR) and the Central Myanmar basins (CMB) in the Burma Terrain (BT) are characterized by high lithospheric strength (Te = 35–40 km). In comparison, low lithospheric strength (Te = 15–20 km) prevails over the Shan Plateau (SP). High F (0.6–0.8) values over the Bay of Bengal and the SP indicate the dominance of the internal loading, while medium F (0.5–0.6) values over the CMB suggest mixed loading, probably related to the combined effect of thick sediments and dense downgoing slabs. Comparative analysis of Te with shear wave velocity and curie point depth indicates that the thermal state is crucial in controlling the lithosphere strength. Further, the absence of modern interplate seismic activity over the strong coupling zones characterized by high Te in BT suggests that the Indo-Burma megathrust is locked.

Neogene to modern foreland basin development in the Sub-Andean zone of southern Bolivia and northern Argentina, 21−23°S

The Sub-Andean retroarc region is a unique example of an active continental-scale retroarc foreland basin system. Heavily targeted for hydrocarbon exploration, the region hosts a large volume of subsurface data coupled to surface studies dedicated to refining its evolution in time and space. This paper presents a regional correlation of stratigraphic markers from seismic reflection and well logs across the Sub-Andean foothills at 23−21°S in southern Bolivia and northern Argentina, which reveals the contrasting along-strike history of Mesozoic to Cenozoic tectonics that preceded the foreland basin setting. Supported by published geochronological data and new zircon U-Pb maximum depositional ages, we describe the depositional transition from pre-Andean to Andean stratigraphy and discrete episodes of foreland basin subsidence and shortening. Based on interpreted stratigraphic breaks, we define the extent and stepwise evolution of this foreland basin, which was characterized by the progressive eastward migration of foreland basin depozones. Based on restored thickness profiles, we present flexural models of basin subsidence for the Sub-Andean foothills region. The modeling of discrete episodes of foreland basin subsidence refines the widely accepted bimodal elastic strength in the foreland basin at 21−23°S, which is weaker in the western ranges (∼20 km effective elastic thickness) and stronger eastward (&amp;gt;40 km). Modeling results also reveal minimum values of subsidence rates (up to 1.2 mm/yr) in the sequential foredeep depozones and suggest that the modeled tectonic load migration—as constrained by the record of syntectonic strata—probably increased over time through the incorporation of Sub-Andean rocks into the orogenic wedge.

Evolution of Impact Basin Gravity Signatures on the Lunar Farside: A Long‐Term Alteration Process

AbstractLunar impact basins are critical markers to understand the early bombardment history. This study focuses on isostatic compensation processes at 16 lunar farside basins, exploring how long‐term alteration processes affect estimates of impactor sizes and timing. Using a lithospheric flexure model, we analyze the isostatically compensated gravity signature of these basins. Our approach is based on previously published basin formation models using the iSALE‐2D shock physics code. Here we investigate how isostatic compensation processes alter the gravity signature using models of basin formation as initial conditions. We compare our results with the present day observed gravity data. We assume that isostatic compensation is the result of flexural deformation of the crust‐mantle boundary with varying lithospheric elastic thicknesses. Our results indicate that the effect of isostatic compensation on the gravity signature varies depending on the thermal conditions at the time of impact. We find that despite this variability, the overall influence of isostatic compensation on the gravity signature is generally moderate to minor. Additionally, our analysis is consistent with previous studies that have shown that the elastic thickness varies across the Moon. Our findings contribute to our understanding of the relationship between basin formation and the thermal evolution of the Moon. The variations in elastic thickness found provide nuanced insights into lunar geological processes and improve our understanding of the early history of the Moon.

Evidence of crustal flexure induced by fluvial incisions

Fluvial erosion of the Earth's crust creates valleys ranging from hundreds of meters to a few kilometers wide. The resulting unloading is supported by the flexural rigidity of the continental lithosphere. As a result, the bending of the lithosphere around individual river valleys is usually imperceptible in the landscape, specially in tectonically quiescent environments. However, in the Recôncavo-Tucano-Jatobá (RTJ) basins, an elongated Cretaceous rift located in northeastern Brazil, there is evidence of upward bending of sedimentary strata at the edges of the river valleys, where parts of the syn- and post-rift Late Cretaceous sedimentary layers were eroded. To assess whether the flexural response of the lithosphere due to fluvial erosion is able to explain the observed bending along the RTJ basins, we conducted a series of numerical experiments to evaluate the amplitude and wavelength of the lithospheric flexure achieved in the thermomechanical scenarios for the lithosphere, while imposing the observed amount of denudation derived from field data. We conclude that the wavelength and amplitude of the flexural behavior of the lithosphere obtained in the numerical scenarios are consistent with the observed bending only when the upper crust is partially decoupled from the lithospheric mantle, a configuration observed when the lower crust has a low effective viscosity. We propose that a combination of thermal and lithological factors contributed to induce the lithospheric decoupling, including heating of the lower crust due to magmatic underplating and the blanket effect created by the thick sedimentary layer preserved along the rift. Additionally, we propose that the flexural response of the lithosphere to individual river incisions is only noticeable in the continental lithosphere when the flexural rigidity of the lithosphere is low, with an effective elastic thickness (Te) ≲5 km.

The Ancient Lithospheric Parameters of Impact Basins on the Far Side of the Moon Based on the Mantle and Mare Basalt Load Model

AbstractResearch on the lithospheric elastic thickness (Te) of lunar mascon basins can provide a deeper understanding of heterogeneous thermal activity. In this study, we focused on four basins (Moscoviense, Freundlich‐Sharonov, Hertzsprung, and Apollo) located on the far side of the Moon. These basins exhibit a significant variation in admittance and correlation spectra, making it challenging to develop precise fitted models. Based on the global lunar crustal thickness model and mare basalt thickness, we developed a mantle and mare basalt load model to estimate the Te. This small Te (10.1 km) suggests a double impact process or extreme thermal activity caused by volcanism during the formation of the Moscoviense. For the typical highland basins, that is, Freundlich‐Sharonov and Hertzsprung, the Te (∼20 km) corresponds to a minimum heat flux of 34 mW m−2. Considering the additional energy introduced by the impact, this heat flux can be considered as the upper limit for the heat flux of the highland itself during the formation of a mascon basin. For the Apollo basin within the South Pole‐Aitken (SPA) terrane, the Te is 30.7 km. The crust beneath the SPA region is thinned, allowing a greater contribution of stiffer mantle material to the lithosphere, perhaps explaining the higher effective Te. Furthermore, the disparity between the highland and SPA terranes can give rise to their distinct basin formation processes. Impact basins formed within the SPA terrane may have experienced a faster cooling process compared to those formed on the highland terrane following the impact event, leading to a higher Te.

Discussion of the W-Sn-REE Metallogenic Background in the Nanling Region of South China: Evidence from Satellite Gravity and Magnetic Data

The Nanling region is located at the intersection of the Yangtze Block and Cathaysia Block and is characterized by complex geological and tectonic processes, as well as distinct W-Sn-REE mineralization. Despite extensive research on the mineralization of W-Sn and REE deposits in the Nanling region, the factors impacting the distribution pattern of eastern tungsten and western tin deposits, as well as the mechanism of REE enrichment in the parent rocks, remain uncertain. Deep structural and tectonic variability plays a crucial role in the formation of mineral deposits in the upper crust. Information on deep structural and tectonic variability is contained in the Moho depth, Curie depth, effective elastic thickness, lithospheric density, and thermal structure derived from the processing and inversion of satellite gravity and magnetic data. In this paper, we comprehensively analyse satellite gravity and magnetic data from the Nanling region, integrating the processing and inversion results with the tectonic evolution of this region and relevant geological information. It is hypothesized that the Chenzhou–Linwu fault serves as a channel for mineral and thermal transfer in the Sn ore aggregation zone, facilitating the material transport from the deep mantle to the surface and ultimately leading to the formation of Sn-enriched granite. The collection area of tungsten ore is more weakly associated with the Chenzhou–Linwu fault, and through deep heat transfer, tungsten components are primarily concentrated in the Earth’s crust to produce W-enriched granite. The primary source of REE enrichment in the parent rocks associated with REE mineralization is predominantly derived from the felsic crust, and the rapid intrusion of deep magma resulting from the subduction and retraction of the Palaeo-Pacific Plate is a contributing factor to the contrasting enrichment of light and heavy rare-earth elements. Mineral crystalline differentiation is relatively high, leading to the formation of ore-forming parent rocks with high heavy rare-earth element contents.

A Seismic Tomography, Gravity, and Flexure Study of the Crust and Upper Mantle Structure Across the Hawaiian Ridge: 2. Ka'ena

AbstractThe Hawaiian Ridge, a classic intraplate volcanic chain in the Central Pacific Ocean, has long attracted researchers due to its origin, eruption patterns, and impact on lithospheric deformation. Thought to arise from pressure‐release melting within a mantle plume, its mass‐induced deformation of Earth's surface depends on load distribution and lithospheric properties, including elastic thickness (Te). To investigate these features, a marine geophysical campaign was carried out across the Hawaiian Ridge in 2018. Westward of the island of O'ahu, a seismic tomographic image, validated by gravity data, reveals a large mass of volcanic material emplaced on the oceanic crust, flanked by an apron of volcaniclastic material filling the moat created by plate flexure. The ridge adds ∼7 km of material to pre‐existing ∼6‐km‐thick oceanic crust. A high‐velocity and high‐density core resides within the volcanic edifice, draped by alternating lava flows and mass wasting material. Beneath the edifice, upper mantle velocities are slightly higher than that of the surrounding mantle, and there is no evidence of extensive magmatic underplating of the crust. There is ∼3.5 km of downward deflection of the sediment‐crust and crust‐mantle boundaries due to flexure in response to the volcanic load. At Ka'ena Ridge, the volcanic edifice's height and cross‐sectional area are no more than half as large as those determined at Hawai'i Island. Together, these studies confirm that volcanic loads to the west of Hawai'i are largely compensated by flexure. Comparisons to the Emperor Seamount Chain confirm the Hawaiian Ridge's relatively stronger lithospheric rigidity.

Leveraging the Gravity Field Spectrum for Icy Satellite Interior Structure Determination: The Case of Europa with the Europa Clipper Mission

Understanding the interior structures of icy moons is pivotal for addressing their origins and habitability. We introduce an approach employing the gravity field spectrum as an additional constraint for the inversion of differentiated icy bodies’ interior structures. After developing the general methodology, we apply it to Europa, utilizing the predicted measurement capability of NASA’s Europa Clipper mission, and we prove its effectiveness in resolving key geophysical parameters. Notably, we show that using the gravity field spectrum in combination with the mass and moment of inertia of the body allows us to estimate, depending on the considered end-member interior structure, the hydrosphere thickness with 4–20 km uncertainty and reliably determine the seafloor maximum topographic range and elastic thickness to within 100–600 m and 5–15 km, respectively, together with the power–degree relationship of the seafloor topography. We also show that the proposed method allows us to determine the density of the silicate mantle and the radius of the core to within 0.25 g cc−1 and 50 km, respectively.

Variations of the effective elastic thickness evidence for a wide diffusive boundary between the North American and Eurasian plates in Siberia

Northeastern Eurasia is one of the least explored regions in the world. Very little geophysical data is available for this inaccessible area. Even the exact location of the plate boundary between Eurasia and North America remains a subject of ongoing debate. The effective elastic thickness (EET) of the lithosphere is a proxy for lithospheric strength and can provide insight into the thermal regime and tectonic processes. We have computed a high-resolution map of the EET for northeastern Eurasia using the fan wavelet coherence technique applied to the Bouguer gravity anomalies and topography/bathymetry data, appropriately adjusted to account for the influence of density variations within sediments. The results obtained provide insights into different tectonic regimes within this predominantly understudied region. In particular, we identify the boundary between the Eurasian and North American plates in Siberia as a rheologically weak diffusive zone extending from the Verkhoyansk and Sette-Daban Ranges to the eastern boundary of the Chersky Range. Unlike the Sette-Daban and Verkhoyansk Ranges, which were formed by plate collision and have an EET of 30–50 km, other mountainous regions have much lower EET values, usually less than 15 km. These areas have recently experienced tectonic activity that has weakened the lithosphere.

Determining the effective elastic thickness through cross-correlation between isostatic disturbances

The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data (representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region.

Estimating geodynamic model parameters from geodetic observations using a particle method

SUMMARY Bayesian-based data assimilation methods integrate observational data into geophysical forward models to obtain the temporal evolution of an improved state vector, including its uncertainties. We explore the potential of a variant, a particle method, to estimate mechanical parameters of the overriding plate during the interseismic period. Here we assimilate vertical surface displacements into an elementary flexural model to estimate the elastic thickness of the overriding plate, and the locations and magnitudes of line loads acting on the overriding plate to produce flexure. Assimilation of synthetic observations sampled from a different forward model than is used in the particle method, reveal that synthetic seafloor data within 150 km from the trench are required to properly constrain parameters for long wavelength solutions of the upper plate (i.e. wavelength ∼500 km). Assimilation of synthetic observations sampled from the same flexural model used in the particle method shows remarkable convergence towards the true parameters with synthetic on-land data only for short to intermediate wavelength solutions (i.e. wavelengths between ∼100 and 300 km). In real-data assimilation experiments we assign representation errors due to discrepancies between our incorrect or incomplete physical model and the data. When assimilating continental data prior to the 2011 Mw Tohoku-Oki earthquake (1997–2000), an unrealistically low effective elastic plate thickness for Tohoku of ∼5–7 km is estimated. Our synthetic experiments suggest that improvements to the physical forward model, such as the inclusion of a slab, a megathrust interface and viscoelasticity of the mantle, including accurate seafloor data, and additional geodetic observations, may refine our estimates of the effective elastic plate thickness. Overall, we demonstrate the potential of using the particle method to constrain geodynamic parameters by providing constraints on parameters and corresponding uncertainty values. Using the particle method, we provide insights into the data network sensitivity and identify parameter trade-offs.