Rates Of Vertical Movement Research Articles

Improvement of the Estimation of the Vertical Crustal Motion Rate at GNSS Campaign Stations Based on the Information of GNSS Reference Stations

With the enrichment of GNSS data and the improvement in data processing accuracy, GNSS technology has been widely applied in fields such as crustal deformation. The Crustal Movement Observation Network of China (CMONOC) has provided decades of Global Navigation Satellite System (GNSS) data and related data products for crustal deformation research on the Chinese mainland. The coordinate time series of continuously observed reference stations contain abundant information on crustal movements. In contrast, the coordinate time series of periodically observed campaign stations have limited data, making it difficult to separate or remove instantaneous non-tectonic movements from the time series, as performed with reference stations, to obtain a stable and reliable crustal movement velocity field. To address this issue, this paper proposes a method to improve the estimation of crustal movement velocity at campaign stations using the information of neighboring reference stations. This method constructs a Delaunay triangulation of reference stations and fits the periodic movement of each campaign station using an inverse distance weighted interpolation algorithm based on the reference station information. The crustal movement velocity of the campaign stations is then estimated after removing the periodic movement. This method was verified by its application to the estimation of the vertical motion rate at some reference and campaign stations in Yunnan Province. The results show that the accuracy of vertical motion rate estimation for virtual and real campaign stations improved by an average of 24.4% and 9.6%, respectively, demonstrating the effectiveness of the improved method, which can be applied to estimate crustal movement velocity at campaign stations in other areas.

Impact of hydrological changes and vertical motions on Pleistocene marine environments of the eastern coast of the island of Rhodes (Greece)

The island of Rhodes in the eastern Mediterranean Sea is situated in an area affected by an ongoing plate convergence, and its Pleistocene marine environments were influenced by recurring hypoxia and changes in organic matter fluxes. This makes the island an important site to study the influence of orbital-driven climate changes and tectonic-induced vertical motions on the marine benthic ecosystems in near-coastal areas at local and regional scales. We investigated the Early and Late Pleistocene sediment sections at Agathi Beach and Lardos, located on the middle-eastern coast of the island. Our results show variations in oxygen and food levels at the sea floor, including transient phases of enhanced fresh-water and nutrient input to near-coastal environments. These phases occurred at times of Northern Hemisphere summer insolation maxima, simultaneously to the formation of sapropels in the deep-sea basins of the eastern Mediterranean Sea. The application of a benthic foraminiferal transfer function revealed that both sections were influenced by tectonic-driven long-term and short-term vertical motions with higher rates than expected on the island of Rhodes. While Agathi Beach underwent two short-term cycles of uplift and subsidence, Lardos indicates at least three cycles with average rates of vertical motion as high as 8.6 mm/a.

Landscape evolution modeling of the normal-fault scarps (Baikal rift system): new experience

The paper considers a new method for determining the quantitative parameters of the relief-forming processes characteristic of the mountainous framing of the basins of the Baikal Rift System (BRS), based on the use of a computer program for numerical simulation of the evolution of the relief CHILD. Particular emphasis was placed on the calculation of approximate values of the rate of tectonic uplift of the near-fault block structures of the Baikal rift. The novelty of the study lies in the adaptation of the CHILD program for solving fault tectonics problems, as well as in the development of a morphotectonic analysis algorithm aimed at searching for specific geomorphological objects that can be considered as uplift indicators. As a result of a series of experiments performed using radioisotope data, three-dimensional models were obtained that simulate the development of near-fault slopes at the Late Cenozoic stage of the development of the BRS, and the probable rates of vertical movements along the faults of the region were determined. It was found that the average Late Cenozoic uplift rates vary within a narrow range of 0,3–0,5 mm/yr, with higher values associated with the northern and northwestern flanks.

Freshwater salinization reduces vertical movement rate and abundance of Daphnia: Interactions with predatory stress

Contaminants in human-dominated landscapes are changing ecological interactions. The global increase in freshwater salinity is likely to change predator-prey interactions due to the potential interactive effects between predatory stress and salt stress. We conducted two experiments to assess the interactions between the non-consumptive effects of predation and elevated salinity on the abundance and vertical movement rate of a common lake zooplankton species (Daphnia mendotae). Our results revealed an antagonism rather than a synergism between predatory stress and salinity on zooplankton abundance. Elevated salinity and predator cues triggered a >50% reduction in abundance at salt concentrations of 230 and 860 mg Cl−/L, two thresholds designed to protect freshwater organisms from chronic and acute effects due to salt pollution. We found a masking effect between salinity and predation on vertical movement rate of zooplankton. Elevated salinity reduced zooplankton vertical movement rate by 22–47%. A longer exposure history only magnified the reduction in vertical movement rate when compared to naïve individuals (no prior salinity exposure). Downward movement rate under the influence of predatory stress in elevated salinity was similar to the control, which may enhance the energetic costs of predator avoidance in salinized ecosystems. Our results suggest antagonistic and masking effects between elevated salinity and predatory stress will have consequences for fish-zooplankton interactions in salinized lakes. Elevated salinity could impose additional energetic constraints on zooplankton predator avoidance behaviors and vertical migration, which may reduce zooplankton population size and community interactions supporting the functioning of lake ecosystems.

Brief immersion of southern Australia by change in relative plate speed

AbstractDynamic subsidence and uplift of plates are often explained by the vertical motion of density anomalies in the mantle. Such models predict surface vertical motion rates of less than 100 m Myr−1 at long‐wavelengths with a timespan of tens of Myr. However, during periods of relative sea‐level stability, some of the phases of vertical motion on stable portions of plates have occurred at rates greater than 100 m Myr−1 during episodes that may last only a few Myr. Here, we show that vertical surface motions, with rates greater than 100 m Myr−1 and durations less than a few Myr, can be explained by changes in basal shear stress caused by variation in horizontal motion of a viscous plate relative to the asthenosphere. We apply our physical model to the short‐lived mid‐Eocene immersion of the southern margin of Australia.

Determination of tectonic and nontectonic vertical motion rates of the North China Craton using dense GPS and GRACE data

• The elastic (un-)loading response to mass changes is calculated using GRACE data. • The average estimated tectonic uplift rate in the mountain areas is 1.37 ± 0.6 mm/yr. • The maximum land subsidence rate in the North China Plain is 72.0 ± 1.2 mm/yr. • A high-resolution water mass variation model is needed. Previous geodetic vertical observations show that both uplift and subsidence occur in the North China Craton. While significant land subsidence occurs in the North China Plain, uplift is observed in the surrounding mountain areas. However, previous studies neither separate the tectonic and nontectonic vertical motions nor correct for elastic response to near surface mass changes. Here, we reply on the more GPS data from 1999 to 2020 and GRACE data from 2002 to 2020 to estimate the vertical motion rates. After removing the elastic (un-)loading deformation due to near surface mass variations, we obtain the tectonic uplift rates at GPS stations built on bedrock in the mountain areas like the Shanxi Plateau and land subsidence rates mainly in the North China Plain. The tectonic rock uplift mainly occurs in the Shanxi Plateau, Yanshan Montains, Shandong Peninsula and Dabie orogen, with an average uplift rate of 1.37 ± 0.6 mm/yr, which is larger than the long-term geological uplift rate. The land subsidence mainly concentrates in the North China Plain, Shanxi Graben, and Jiangsu province with the maximum subsidence rate of 72 ± 1.2 mm/yr. The mismatch between the geodetic and geological uplift rates suggests that a high-resolution water mass loss in the North China Plain is needed.

Isostatic Adjustment, Vertical Motion Rate Variation and Potential Detection of Past Abrupt Mass Unloading

Intraplate volcanic islands are often considered as stable relief with constant vertical motion and used for relative sea-level reconstruction. This study shows that large abrupt mass unloading causes non-negligible isostatic adjustment. The vertical motion that occurs after abrupt mass unloading is quantified using a modeling approach. We show that a giant landslide causes a coastline uplift of 80–110 m for an elastic thickness of 15 km < Te < 20 km in Tahiti. Theoretical cases also reveal that a coastal motion of 1 m occurs for an abrupt mass unloading involving a displaced volume of 0.2 km3 and influences relative sea-level reconstruction. In Tahiti, a change in the subsidence rate of 0.1 mm/yr (from 0.25 to 0.15 mm/year) occurred during the last 6 kyr and could be explained by an abrupt mass unloading involving a minimum volume of 0.2 km3, 6 ± 1 kyr ago.

Studying the Sensitivity of Satellite Altimetry, Tide Gauge and GNSS Observations to Changes in Vertical Displacements

Tide gauge observations provide sea level relative to the Earth’s crust, while satellite altimetry measures sea level variations relative to the centre of the Earth’s mass. Local vertical land motion can be a significant contribution to the measured sea level change.Satellite altimetry was traditionally used to study the open ocean, but this technology is now being used over inland seas too.The difference of both observations can be used to estimate vertical crustal movement velocities along the sea coast. In this paper, vertical crustal movement velocities were investigated at tide gauge sites along the Adriatic Sea coast by analyzing differences between Tide Gauge (TG) and Satellite Altimetry (SA) observations. Furthermore, the estimated vertical motion rates were compared with those from nearby GNSS measurements.The study determines the practical relationships between these vertical crustal movements and those determined from unrelated data acquired from the neighbouring GNSS stations. The results show general consistence with the present geodynamics in the Adriatic Sea coastal zone.

Implications of glacial isostatic adjustment on petroleum reservoirs in the Grand banks of Newfoundland

Glacial Isostatic Adjustment (GIA), or postglacial rebound refers to the crustal response to glacial loading and unloading processes. In this investigation, we run numerical simulations using different rheological parameters and ice loading histories to obtain models of the glacial isostatic response for the Grand Banks of Newfoundland. The objective is to assess in general the potential impact of GIA on hydrocarbon reservoirs and trapping structures in terms of tilting, deformation, fault activity or geochemical implications on the trapped fluids. Comparisons may be drawn to related studies, including analogous impacts on reservoirs in the Barents Sea, as well as validation of GIA model predictions of vertical crustal motion using GNSS stations, levelling networks and relative sea level (RSL) observations at numerous sites across eastern Canada. By running a series of GIA models, a range of vertical motion rates are output through time to determine displacement amounts, and calculations are performed on these outputs to disseminate other valuable data attributes such as the displacement gradient and differences in time and space. In general, the vertical motion rate is seen to change drastically over time for certain points, as the lag in response of regions near the ice periphery leads to a distinct pattern of uplift and subsidence. The Grand Banks generally experienced between 57 m of subsidence to 34 m of uplift since the last glacial maximum, depending on the specific location and the GIA model parameters. At the reservoir scale, model results along a 10 km baseline show up to −1.0–1.5 m of differential vertical displacement, which could have led to reservoir tilting or even hydrocarbon migration. As a result of this study, it is clear that there are implications of GIA on hydrocarbon reservoirs since the Last Glacial Maximum, and these effects are ongoing.

Slow movement of alkali from surface-applied lime warrants the introduction of strategic tillage for rapid amelioration of subsurface acidity in south-western Australia

Conventional surface-application of agricultural lime takes many years to increase pH deeper in the soil profile, which is a barrier to increased adoption of liming. We conducted a series of experiments to measure the rate of vertical movement of alkali and identify the factors that determine this movement into the subsurface, to evaluate the feasibility of ameliorating acidic subsurface soil using residual (undissolved) lime (CaCO3) at Wongan Hills (30.85°S, 116.74°E) and Merredin (31.48°S, 118.21°E) and to test whether deep tillage and lime incorporation can significantly speed up the amelioration of subsurface soil acidity at Kalannie (30.42°S, 117.29°E). Multiple applications of lime to the surface of the soil at higher rates (total 6–8.5 Mg ha–1) significantly increased subsurface soil pH but only in the 0.10–0.20 m depth by 0.049 pH units per year over 10–24 years. A large proportion of the surface-applied lime was stratified in the top few centimetres of the soil and incorporation of this undissolved lime with a rotary hoe to a depth of 0.25 m significantly increased soil pH (by 0.63 units) within a year in the Wongan Hills field experiment. Deep incorporation of 6 Mg ha–1 lime to a depth of 0.45 m through excavation and spading with a small rotary hoe also increased soil pH by more than a unit and decreased Al concentration to below the toxic level within two months in the Kalannie experiment, allowing wheat (Triticum aestivum L.) plants to produce root systems up to 0.59 m deep compared with 0.26 m for the control. Our soil column leaching experiment indicated that surface incorporation of lime in higher rainfall regions can be useful to treat subsurface soil acidity but that the rate of improvement in subsurface pH was slow. Therefore, deeper incorporation of lime using cost-effective strategic deep tillage is likely to be necessary.

The Complex Vertical Motion of Intraplate Oceanic Islands Assessed in Santiago Island, Cape Verde

AbstractDated paleosea level markers and eustatic sea level changes are necessary but not sufficient information to calculate vertical motion rates on oceanic islands. Therefore, we use a procedure in which we work progressively back in time to incorporate the more recent vertical motion rates implied by the youngest paleoshorelines into the vertical motion history of all older shorelines. Specifically, we calculate the time‐averaged vertical motion rates required to explain the present‐day elevations of the dated sequence of paleoshorelines on Santiago volcanic island (Cape Verde). We thus obtain a vertical motion history consisting of time‐averaged vertical motion rates spanning the five intervening periods between paleoshoreline formation and the present day: (1) 5.06 to 3.29 Ma—seamount growth or island subsidence because all the rocks in this period are submarine; (2) fast uplift (approximately 0.96 mm/a) from 3.29 to 2.87 Ma, mostly responsible for putting submarine lavas currently close to 410 m altitude; (3) relatively fast subsidence (approximately −0.11 mm/a) between 2.87 and 2.18 Ma; (4) stagnation from 2.18 to 0.811 Ma; and (5) relatively fast uplift (approximately 0.14 mm/a) between 0.811 and 0 Ma. We numerically tested top‐down (volcanic loading) and bottom‐up (lithosphere thinning, underplating, and mantle plume) mechanisms to explain the inferred vertical movements, and we conclude that volcanic loading and crustal underplating are capable of producing the observed subsidence and uplift, respectively.

Late Quaternary paleo sea level geomorphological markers of opposite vertical movements at Salina volcanic island (Aeolian Arc)

AbstractRaised marine terraces and submerged insular shelves are used through an integrated approach as markers of relative sea level changes along the flanks of the Salina volcanic island (Aeolian Arc, southern Italy) for the purpose of evaluating its crustal vertical deformation pattern through time. Paleo sea level positions are estimated for the terrace inner margins exposed subaerially at different elevations and the erosive shelf edges recognized offshore at different depths. Compared with the eustatic sea levels at the main highstands (for the terraces) and lowstands (for the shelf edges) derived from the literature, these paleo sea level markers allowed us to reconstruct the interplay among different processes shaping the flanks of the island and, in particular, to quantify the pattern, magnitudes and rates of vertical movements affecting the different sectors of Salina since the time of their formation. A uniform uplift process at rates of 0.35 m ka−1 during the Last Interglacial is estimated for Salina (extended to most of the Aeolian Arc) as evidence of a regional (tectonic) vertical deformation affecting the sub‐volcanic basement in a subduction‐related geodynamic context. Before that, a dominant subsidence at rates of 0.39–0.56 m ka−1 is instead suggested for the time interval between 465 ka (MIS 12) and the onset of the Last Interglacial (MIS 5.5, 124 ka). By matching the insular shelf edges with the main lowstands of the sea level curve, a relative age attribution is provided for the (mostly) submerged volcanic centres on which the deepest (and oldest) insular shelves were carved, with insights on the chronological development of the older stages of Salina and the early emergence of the island. The shift from subsidence to uplift at the Last Interglacial suggests a major geodynamic change and variation of the stress regime acting on the Aeolian sub‐volcanic basement. © 2019 John Wiley & Sons, Ltd.

A Lower Pleistocene to Holocene terrestrial record from the Eskişehir Graben (Central Anatolia): Paleoclimatic and morphotectonic implications

As one of the rare terrestrial archive with continuous sedimentation back to almost 1 Ma in Anatolia, the Eskişehir Graben was investigated in outcrops and cores by multi-proxy analysis regarding chronology and paleoclimatology. The present study comprises significant implications for both the impact of climate changes on fluvial systems in the timescales of the Milankovitch band and the controversial age and rate of the crustal extension in western Anatolia. Our findings indicate that LOI950 and δ18Ocarb, which are indicators for the amount of soil carbonate and paleo-temperature respectively are collectively capable of distinguishing between glacial and interglacial periods in the predominantly floodplain deposits of the graben infill. Secondarily, LOI550 and δ13Ccarb values further help this discrimination via primary production and composition of vegetation cover respectively. Pollen data, albeit highly discontinuous due to poor preservation under subaerial conditions, point out a steppe-like vegetation cover where the forest components expand particularly in the wet interglacial periods. In the other hand, the chronological frame provided by astronomical calibration of certain proxy-records strongly suggest that the Eskişehir Fault Zone initiated as a boundary fault of a half-graben some 900 ka. The rate of vertical movement on its southern branch since the last 70 ka is unexpectedly high (2.3 mm/a), a phenomenon that requires urgent risk assessment analysis in the vicinity of the Eskişehir city.

Coupling cosmogenic nuclides and luminescence dating into a unified accumulation model of aeolian landforms age and dynamics: The case study of the Kalahari Erg

Abstract Sand deposits cover extensive areas both in the northern and southern hemispheres and the timing and chronology and processes that govern their dynamics are of major interest. Luminescence-based dating methods, are used to date episodic aeolian events but are restricted to late Quaternary deposits, and only reveal the last cycle of sediment burial and not the time of sand existence in the landscape. Burial ages modelled from cosmogenic nuclides reach further back in time, but are usually inferred as minimal deposition ages. It is apparent that standard dating methods, when applied individually, have limited applicability for determining both the age and the processes that form aeolian deposits. This study presents an approach that integrates luminescence dating and cosmogenic burial dating into a stochastic model developed to reproduce sand formation and migration. The model is based on a process in which quartz grains are vertically displaced through a sand column simulating dune migration across the landscape. A range of vertical displacement rates is compiled from published luminescence ages of dated dune fields of varied settings throughout the world. Using these vertical movement rates, sand is recycled up and down a depth profile coupled with a step-wise calculations of cosmogenic nuclides accumulation and decay, alongside OSL signal accumulation. When the modelled sand grains are buried, their luminescence signal grows while 26Al and 10Be decay or accumulate as a function of their respective radioactive decay and production rate, which is governed by cosmic rays attenuation. When sand is exposed at the surface, the luminescence signal is reset and cosmogenic nuclide production is maximized. Each simulation is terminated when the modelled concentrations of 26Al and 10Be reach measured concentrations in actual sand samples. Luminescence data therefore provide the time since last exposure at the surface (i.e. the last depositional cycle), whereas the cosmogenic nuclides provide a long-term estimate of sand residence in the landscape reflecting also weathering and erosion of the source bedrock. The southern Kalahari dune field at Mamatwan, South Africa, is used as a case study to test the presented approach. Model results show that optically stimulated luminescence ages which range between 1 and 10 Ka, only reflect the last cycle of sand migration, while cosmogenic nuclides minimal burial ages are greater than 1 Ma. Furthermore, the simulation results indicate two peaks at 1.5–2.2 Ma and at 4.2–5.2 Ma, suggesting two main phases of sand introduction to the Kalahari during the Pliocene and Pleistocene. Finally, the modelled ages are concurrent with regional environmental and climatic events. The model presented in this study provides a powerful tool for estimating the emergence of sand in a given landscape, and also for understanding the dynamic evolution of any dune field and the mechanisms behind dune migration.

Morphotectonics in a low tectonic rate area: Analysis of the southern Portuguese Atlantic coastal region

South Portugal is characterized by low tectonic rates (<0.3 mm/a), with infrequent large seismicity. Recent studies indicate a coastal region in southwest Portugal uplifting at higher rates (0.11 ± 0.01 mm/a) than the remaining southern portion of Portugal (~0.04 mm/a); however, the mechanisms that drive this uplift are poorly understood. With the purpose of investigating the regional Quaternary deformation and its patterns, as well as the difference in the uplift rate, 77 exorheic drainage basins along 460 km of the southern Portuguese coastline were analysed through the application of geomorphic indices. In this study we applied stream channel sinuosity S, basin relief ratio Rh, elongation Re, basin shape ratio Bs, valley height-width ratio Vf, basin asymmetry factor AF, hypsometry HI and, the stream-length gradient index SL, and we propose the terminal basin shape index TBS. This study aims to (1) identify Quaternary deformation along presumed tectonic structures; (2) recognize uplift or subsidence along the coastline; and (3) test the application of geomorphic indices in low deformation rate environments. The cross-correlation of results led to the recognition of the São Teotónio-Aljezur-Sinceira fault system and the São Marcos-Quarteira Fault as major regional Quaternary faults, as well as to the interpretation of Quaternary activity for other structures. Spatial differences in uplift rates are identified through basin shape indices and valley height-width ratios, even for low vertical motion rates, whereas other indices were found to be not as sensitive to variations in uplift rate.

Transport Time Scales in Soil Erosion Modeling

Core Ideas Erosion timescales inherent in the Hairsine–Rose soil erosion are exposed. Both fast and slow timescales are isolated and can be estimated a priori. The maximum sediment settling rate controls the possible range of timescales. In practice, the full range of erosion timescales are not seen in flume experiments. Unlike sediment transport in rivers, erosion of agricultural soil must overcome its cohesive strength to move soil particles into suspension. Soil particle size variability also leads to fall velocities covering many orders of magnitude, and hence to different suspended travel distances in overland flow. Consequently, there is a large range of inherent timescales involved in transport of eroded soil. For conditions where there is a constant rainfall rate and detachment is the dominant erosion mechanism, we use the Hairsine–Rose (HR) model to analyze these timescales, to determine their magnitude (bounds) and to provide simple approximations for them. We show that each particle size produces both fast and slow timescales. The fast timescale controls the rapid adjustment away from experimental initial conditions—this happens so quickly that it cannot be measured in practice. The slow timescales control the subsequent transition to steady state and are so large that true steady state is rarely achieved in laboratory experiments. Both the fastest and slowest timescales are governed by the largest particle size class. Physically, these correspond to the rate of vertical movement between suspension and the soil bed and the time to achieve steady state, respectively. For typical distributions of size classes, we also find that there is often a single dominant timescale that governs the growth in the total mass of sediment in the non‐cohesive deposited layer. This finding allows a considerable simplification of the HR model, leading to analytical expressions for the evolution of suspended and deposited layer concentrations.

Pop-up satellite archival tag (PSAT) temporal data resolution affects interpretations of spawning behaviour of a commercially important teleost

BackgroundThe effects of temporal data resolution on the interpretation of fish behaviours are questions fundamental to research programs using electronic tags with finite data storage and data transmission capacities. However, understanding these effects requires sub-sampling high-resolution data at multiple temporal resolutions. In pop-up satellite archival tags (PSATs), data transmissions via satellite are limited, so temporal resolution is a decreasing function of the deployment duration. Physical recovery of PSATs overcomes this limitation, providing data on temperature, depth, etc., at rates at least 15–30 times greater than transmitted data.ResultsUsing PSATs physically recovered from Atlantic halibut (Hippoglossus hippoglossus), we evaluated the effects of data resolution (2, 30, 60 min) on interpreting vertical movements including rapid ascents during the expected spawning season. Putative ‘spawning rises’ of 6–20 min were only present within highest temporal resolution data. Vertical movement rates during spawning rises identified with high-resolution data exceeded rates in all other periods; such movement rates were virtually absent in all other tagged fish within the spawning period. Mean maximum ascent rates were 13 and 23 times higher when the sampling interval was 2 versus 30 or 60 min, respectively.ConclusionsWe illustrate the limitations of using satellite-transmitted data to quantify vertical movement rates and detect potential spawning events in marine teleosts. Such low temporal resolution data suggest spurious results by masking important behaviours that archived data reveal as occurring at high frequencies. We highlight new technologies that facilitate PSAT recoveries at sea to overcome these limitations and facilitate analyses of high-frequency archived data.

Vertical land motion along the Black Sea coast from satellite altimetry, tide gauges and GPS

Tide gauge records comprise of relative sea level change and vertical land motion, while satellite altimetry provides absolute sea level change in the Earth’s center fixed frame. Accordingly, the difference of both observations can be used to estimate geocentric vertical land motion along the coasts. In this paper, the vertical land motion rates are investigated at 13 tide gauge sites along the Black Sea coast by analyzing differences between Tide Gauge (TG) and Satellite Altimetry (SA) observations. Furthermore, the estimated vertical motion rates are compared with those from nearby the Global Positioning System (GPS) measurements. The results show general consistence with the present geodynamics in the Black Sea coastal region. For example, our estimates support the general subsidence at Bourgas and Varna.

Historical Sea Level in the South Pacific from Rescued Archives, Geodetic Measurements, and Satellite Altimetry

Automatic sea-level measurements in Noumea, South Pacific, started in 1957 for the International Geophysical year. Data from this location exist in paper record for the 1957–1967 period, and in two distinct electronic records for the 1967–2005 and 2005–2015 period. In this study, we digitize the early record, and established a link between the two electronic records to create a unique, nearly 60 year-long instrumental sea-level record. This work creates one of the longest instrumental sea-level records in the Pacific Islands. These data are critical for the study of regional and interannual variations of sea level. This new data set is then used to infer rates of vertical movements by comparing it to (1) the entire satellite altimetric record (1993–2013) and (2) a global sea-level reconstruction (1957–2010). These inferred rates show an uplift of 1.3–1.4 mm/year, opposite to the currently accepted values of subsidence found in the geological and geodetic literature, and underlie the importance of systematic geodetic measurements at, over very near tide gauges.

Determination of mantle upwelling rate beneath Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data

The Taiyuan basin is in the Shanxi rift system of China. Results of tectonic studies indicate that the Moho is uplifted by 2–3km under the Taiyuan basin. However, there is no quantitative evidence showing whether the rift is still in the status of mantle upwelling. Herein, we estimated mantle upwelling rate of Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data in this paper. In order to utilize the absolute gravity measurements in terms of tectonic study it is necessary to reduce all disturbing environmental effects. Many of those can be modeled, such as tide, polar motion, ocean tidal loading and atmospheric mass components. The Taiyuan station located in the Taiyuan basin, and absolute gravity measurements with a FG5 instrument were performed from 2009 to 2014, a secular trend was obtained. In-situ GPS data was used to estimate the vertical motion rate since 2011, and the result indicated a land subsidence. In-situ groundwater level was collected with daily surveys from 2009 to 2015, and local hydrology impact on effect was made. The global terrestrial water storage loading effect on gravity at Taiyuan station was computed by using GLDAS global hydrology model. Furthermore there is a good agreement between GRACE results and GLDAS hydrological model results. Subtracting the gravity change rate attributable to the land subsidence, groundwater level and global hydrology from the absolute gravity change rate, the residual gravity change rate was obtained. It reflects mantle upwelling about 2.1±2.6cm/yr beneath Taiyuan basin.