29 research outputs found
Strain patterns along the Kaparelli–Asopos rift (central Greece) from campaign GPS data
No full textWe present results from four GPS campaigns in the broader Kaparelli–Asopos area in central Greece. This area is undergoing extension as demonstrated by seismological, geodetic and geological data. The east-west striking Kaparelli normal fault ruptured during the March 4, 1981, M = 6.3 earthquake and created km-long surface breaks with the downthrown side to the south. The geodetic results include: determination of station coordinates in the ITRF 2005 frame, computation of station velocities with respect to stable Europe and strain rate tensor estimates. The pattern of velocities along the east-west direction (parallel to the rift axis; 40 km E-W × 12 km N-S) and azimuth of strain axes are compared to geological data and to other GPS results in central Greece. We find that strain in this region consists of an amount of shortening (66 ns/yr) in the direction approximately N 58°E, and about three times more extension (187 ns/yr) at N 32°W. A large change in strain orientation (from NW to NNE) is observed from west to east, along the active faults of Asopos rift in agreement with fault slip data. This change signifies the need for using local GPS networks to map local strain rate patterns in actively extending regions of Greece.</p
New Meridian Arc formulas for Sailing Calculations in Navigational GIS
No full textThis paper presents simple compact formulas for the computation of the length of the meridian arc. The proposed alternative formulas are to be primarily used for accurate sailing calculations on the ellipsoid in a GIS environment as in ECDIS and other ECS. Their validity and effectiveness in terms of the accuracy achieved and the CPU time required are assessed and compared to standard geodetic methods. The results of this study show that the proposed formulas are simpler, shorter and more than twice as fast as other geodetic methods of the same accuracy, used for sailing calculations on the ellipsoid, such as “rhumb-line sailing” and “great elliptic sailing”
Spatiotemporal gravity changes at the Santorini Volcanic complex and their interpretation
No full textUnderstanding the complex dynamics of volcanic systems demands a multidimensional approach that combines geophysics, geology, and geodetics. In this study, we examine observed spatiotemporal gravity changes within the Santorini volcanic complex from 1975 to 2014. The historical data indicates that gravity has been increasing continuously since at least 1966 until our latest measurements in 2014, albeit with a decreasing rate of increase over time. Utilizing gravity inversion of various gravity datasets and evidence from other studies, we explore different scenarios to shed light on the underlying processes. Our preferred interpretation involves both a magmatic episode and continuous evolution of the shallow structure. We find that the 2011-12 unrest period resulted from the intrusion of ∼3.3x1011 kg of basaltic magma at 3 km depth near the previously identified Mogi source. We attribute the continuous gravity increase beneath Nea Kameni to a density increases at about 1350 m depth. We infer these are a result of hydrothermal fluctuations, degassing, and/or vesicle collapse within the stored magma. Units: 1mGal = 10-5 m/s2 (SI) © 2023 The Author
Adaptive Non-Linear Modeling for Ionospheric Disturbances Behavior Estimation on Spaceborne Synthetic Aperture Radar Interferometry
No full textTemporal Feature Variation as an Efficient Method for Real-Time Video Summarization Captured from Unmanned Aerial Systems
No full textEnsemble Classifiers in Optimal Estimation for Ionospheric Disturbances Behavior on Spaceborne Interferometric SAR Systems
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Spatiotemporal gravity changes at the Santorini Volcanic complex and their interpretation
No full textUnderstanding the complex dynamics of volcanic systems demands a multidimensional approach that combines geophysics, geology, and geodetics. In this study, we examine observed spatiotemporal gravity changes within the Santorini volcanic complex from 1975 to 2014. The historical data indicates that gravity has been increasing continuously since at least 1966 until our latest measurements in 2014, albeit with a decreasing rate of increase over time. Utilizing gravity inversion of various gravity datasets and evidence from other studies, we explore different scenarios to shed light on the underlying processes. Our preferred interpretation involves both a magmatic episode and continuous evolution of the shallow structure. We find that the 2011-12 unrest period resulted from the intrusion of ∼3.3x1011 kg of basaltic magma at 3 km depth near the previously identified Mogi source. We attribute the continuous gravity increase beneath Nea Kameni to a density increases at about 1350 m depth. We infer these are a result of hydrothermal fluctuations, degassing, and/or vesicle collapse within the stored magma. Units: 1mGal = 10-5 m/s2 (SI
Applied Optimal Estimation for Ionospheric Disturbances Behavior on Spaceborne Interferometric Synthetic Aperture Radar Systems
No full textAn Echo State Network for Ionospheric Disturbances Behavior Modeling on Spaceborne Interferometric Synthetic Aperture Radar
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