Marine Geodesy

The contribution of bathymetry to the estimation of gravity field related quantities is investigated in an extended test area in the Mediterranean Sea. The region is located southwest of the island of Crete, Greece, bounded between 33 ≤ ϕ ≤ 35 and 15 ≤ λ ≤ 25. Gravity anomalies from the KMS99 gravity field and shipborne depth soundings are used

The 2004 Sumatra tsunami left a deep and dark footprint on coastal Cuddalore in southeast India, which was one of the worst affected districts in the mainland. Assessment of natural hazards typically relies on analysis of past occurrences of similar disaster events. Assessment of tsunami hazard to the Indian coast poses a scientific challenge because of the paucity of both historical events and data. However, construction of tsunami hazard maps is the key step in tsunami risk assessment and forms the basis for evacuation and future land use planning along coastal areas. To this end, a set of inundation scenarios was built based on realistic tectonic sources that can generate tsunamis in the Indian Ocean. From historical records, three earthquake sources have been identified and a hypothetical worst case scenario was generated. Numerical models were constructed to predict the extent of inundation and run-up in each case, using a finite difference code on nested grids derived from the high resolution elevation and bathymetry datasets collected for the study area. The model was validated using field data collected immediately after the 2004 tsunami and was then used to generate the other inundation scenarios. Tsunami hazard maps for coastal Cuddalore were prepared by overlaying the numerical model outputs along with details on land use, elevation, cadastral land parcels, infrastructure, high tide line, and coastal regulation zones.

In the 1980s computing power increased sufficiently to allow more rigorous techniques for processing and quality control/assessment to be introduced in position determination in the offshore industry. This paper is one of the pioneering efforts to introduce such techniques. The paper was presented at Hydro 88 Conference in Amsterdam, organised by the Hydrographic Society and was published in its proceedings.
The paper introduces concepts and methods from what is known as the “Delft School of Geodesy” to the offshore industry. Although nearly 33 years ago now, these principles are still valid and are actively used.

The rapid uptake of GPS in the offshore positioning industry of the early 1990s led to quality control becoming a topical, but controversial issue. The providers of GPS positioning services used their own, usually arbitrary, ways of defining positioning quality and monitoring the performance of their services, which created significant problems in the management of positioning contracts. Driven and written by Shell (Nicolai), the UK Offshore Operators Association (UKOOA) published a set of standardised quality measures in 1992, which this paper describes and elaborates. It was later in 1994 superseded by the publication of full UKOOA guidelines, which, in turn are now superseded by the “Guidelines for GNSS positioning in the oil and gas industry”, published in 2011 as report OGP 373-19. The principles described in the paper are still valid.

Satellite and acoustic remote sensing enable the collection of high-resolution seafloor bathymetry data for integration with terrestrial elevations into coastal terrain models. A model of Tutuila Island, American Samoa, is created using depths derived from IKONOS satellite imagery to provide data in the near-shore gap between sea level and the beginning of sonar data at 10–15 m depth. A derivation method gauging the relative attenuation of blue and green spectral radiation is proven the most effective of several proposed in recent literature. The resulting coastal terrain model is shown to be accurate through statistical analyses and topographic profiles.

The 2004 Sumatra tsunami left a deep and dark footprint on coastal Cuddalore in southeast India, which was one of the worst affected districts in the mainland. Assessment of natural hazards typically relies on analysis of past occurrences of similar disaster events. Assessment of tsunami hazard to the Indian coast poses a scientific challenge because of the paucity of both historical events and data. However, construction of tsunami hazard maps is the key step in tsunami risk assessment and forms the basis for evacuation and future land use planning along coastal areas. To this end, a set of inundation scenarios was built based on realistic tectonic sources that can generate tsunamis in the Indian Ocean. From historical records, three earthquake sources have been identified and a hypothetical worst case scenario was generated. Numerical models were constructed to predict the extent of inundation and run-up in each case, using a finite difference code on nested grids derived from the high resolution elevation and bathymetry datasets collected for the study area. The model was validated using field data collected immediately after the 2004 tsunami and was then used to generate the other inundation scenarios. Tsunami hazard maps for coastal Cuddalore were prepared by overlaying the numerical model outputs along with details on land use, elevation, cadastral land parcels, infrastructure, high tide line, and coastal regulation zones.

In this article, sensitivity of the SWAN coastal wave model towards wind inputs and physics options has been performed over the Indian Ocean by forcing the model with analyzed GDAS winds. Wind forcing simulations show that the model is sensitive to the wind errors. The simulations obtained using different physics options have been compared with altimeter and in situ data. The study indicates that the model with Janssen physics options simulates the significant wave height with a fairly high degree of accuracy. It has also been observed that the simulations are not too sensitive to the choice of propagation schemes.

Marine Geodesy, 27: 683–701, 2004 Copyright C Taylor & Francis Inc. ISSN: 0149-0419 print / 1521-060X online DOI: 10.1080/01490410490883441 ... Vertical Land Motion in the Mediterranean Sea ... LUCIANA FENOGLIO-MARC CAROLA DIETZ ERWIN GROTEN

In geophysical studies investigating the lithosphere structure, topographic, bathymetric, and density contrasts stripping corrections are applied to gravity data. The ocean density contrast is typically calculated as the difference between the mean densities of crust and seawater. The approximation of the actual seawater density by its mean value yields relative errors up to 2%. To reduce these errors, we adopt a depth-dependent seawater density model to account for increasing density with pressure/depth. This approximation reduces errors to less than 0.1%. This density model is utilized in newly derived expressions for the bathymetric stripping corrections.

The 2004 Sumatra tsunami left a deep and dark footprint on coastal Cuddalore in southeast India, which was one of the worst affected districts in the mainland. Assessment of natural hazards typically relies on analysis of past occurrences of similar disaster events. Assessment of tsunami hazard to the Indian coast poses a scientific challenge because of the paucity of both historical events and data. However, construction of tsunami hazard maps is the key step in tsunami risk assessment and forms the basis for evacuation and future land use planning along coastal areas. To this end, a set of inundation scenarios was built based on realistic tectonic sources that can generate tsunamis in the Indian Ocean. From historical records, three earthquake sources have been identified and a hypothetical worst case scenario was generated. Numerical models were constructed to predict the extent of inundation and run-up in each case, using a finite difference code on nested grids derived from the high resolution elevation and bathymetry datasets collected for the study area. The model was validated using field data collected immediately after the 2004 tsunami and was then used to generate the other inundation scenarios. Tsunami hazard maps for coastal Cuddalore were prepared by overlaying the numerical model outputs along with details on land use, elevation, cadastral land parcels, infrastructure, high tide line, and coastal regulation zones.