Analysis of tidal strain observations in Lanzarote Island

Comunicación presntada a la 3ª Asamblea Hispano-Portuguesa de Geodesia y Geofísica = 3ª Assembleia Luso-Espanhola de Geodesia e Geofisica, celebrada en Valencia entre el 4 y el 8 de febrero de 2002.The strain response of the Earth to tidal forces is observed in the Geodynamics Laboratory of Lanzarote Island. The instruments, installed in a gallery inside the lava tunnel of Cueva de los Verdes, are kind of horizontal ceramic-tube extensometers. Their base fines comprise from 8 to 38 m length and are orientated in two orthogonal directions (45º.2 N Y 135°.2 N), which depend on the situation in the gallery. The reliability of this instruments, which measure the variation of distance between two fixed points with a resolution of 10 -10, allow us to dispose long term series of tidal strains since 1992. The data series are analysed in order to study the stability of the instruments. Also, with these data we can determine the tidal strain models, as well as the tidal deformation and the long-term variations of strains in this island. Due to the dependence of the local conditions of the station, which is located in an island, the oceanic influence will be investigated together with local atmospheric disturbing effects. These effects are carefully studied for this station, in order to allow the identification and, if possible, its separation from other signals of interest, given the volcanic feature of the island.Peer reviewe

Venedikov, A. P., Vieira, R., & Toro y Llaca, C. D. (1993). Nuevas aportaciones al análisis de observaciones de mareas terrestres.

A new method recently developed in Spain is briefly discussed. The method suggests to use a sophisticated scheme for the appproximation of the drift of the tidal records. The drift is represented separately in subintervals of the record through polynomials of a variable power. An optimum power is estimated for every subinterval by testing statistical hypotheses through the criteria of Fisher and Akaike (AJC) and multiple analysis of all data for every value of the polynomial's power

Program VAV/2000 for tidal analysis of unevenly spaced data with irregular drift and colored noise

Comunicación presentada en el XIV International Symposium on Earth Tides (ETS2000), celebrado en Mizusawa, Japón, entre el 28 de agosto y el 1 de septiembre de 2000. Las actas del congreso han sido publicadas como special issue del Journal of the Geodetic Society of Japan.A general description of the algorithm used by a new computer program for tidal data processing is presented. The main stages of the algorithm are: (i) filtration of intervals without overlapping and (ii) application of the Method of the Least Squares on the filtered numbers. A new element is that all series of filtered numbers, related with different tidal species are processed all together. It is shown that this way of analysis may be equivalent to a direct processing of the data, without any filtration. However, the processing of the filtered numbers has the advantage to provide frequency dependent estimates of the precision. Another new element is that the program can be applied on totally unevenly spaced data.Peer reviewe

Study and evaluation, with geodetic purposes, of the tide gauge data in the Laboratory of Geodynamics of Lanzarote

VÉLEZ, E. "Estudio y evaluación, con fines geodésicos, de la serie temporal de datos mareográficos del Laboratorio de Geodinámica de Lanzarote". En: 6ª Asamblea Hispano Portuguesa de Geodesia e Geofísica, (Tomar, 11-14 de febrero de 2008)One of the main purposes in Geodesy is the determination of the sea level, because the Geoid is the reference surface, not only for the geodetic works, but also for practically all the related disciplines, and it 's defined from the oceans mean leve/. Moreover, the continuous determination ofthe mean sea level, and its possible variations, is one of the best tools that al/ow to us /0 understand and evaluate the Global Change. The Observation Module of the Jameos del Agua, in the Laboratory of Geodynamic of Lanzarote (LGL) is special/y dedicated to the precise observation of the sea level variations and deformations, combining space techniques, as geodetic GPS, with tide gauges, deforma/ion measurements, physical and chemical parameters of the sea water, and meleorological parameters. lts geodetic use now is, mainly, as reference and scale station in the determina/ion of the local Geoid CANGEo. To obtain the absolute variations of the sea level in a global reference frame, /0 study the geodesical, geodynamical, me/eorological and oceanographical perturbations presents in the sea level observations, /0 study the correlation between its relative variations and the vertical movements of the crust, and /0 compare the results with the measurements made with satellite, are, between others, some of the scientific goals planned. In this communication we present the study and evaluation ofone serie of tidal gauge da/a using the VAVprogramfor the lime series analysis.Peer reviewe

A new method for Earth tide data analysis

Publicado además en Bulletin d'Informations Marées Terrestres, nº 116, pp. 8557-8586Peer reviewe

Study of the sensitivity variations of the Earth tide records

Unidad Deptal. de Astronomía y GeodesiaFac. de Ciencias MatemáticasTRUEpu