Crustal motion and deformation in Greece from a decade of GPS measurements, 1993–2003

Tectonic stress is one of the fundamental data sets in Earth sciences comparable with topography, gravity, heat flow and others. The importance of stress observations for both academic research (e.g. geodynamics, plate tectonics) and applied sciences (e.g. hydrocarbon production, civil engineering) proves the necessity of a project like the World Stress Map for compiling and making available stress data on a global scale. The World Stress Map project offers not only free access to this global database via the Internet, but also continues in its effort to expand and improve the database, to develop new quality criteria, and to initiate topical research projects. In this paper we present (a) the new release of the World Stress Map, (b) expanded quality ranking schemes for borehole breakouts and geological indicators, (c) new stress indicators (drilling-induced fractures, borehole slotter data) and their quality ranking schemes, and (d) examples for the application of tectonic stress data. Tectonic stress is felt most extremely during its release in catastrophic earthquakes, although less spectacular tectonic stress is a key safety factor for underground constructions such as tunnels, caverns for gas storage or deposits of nuclear waste (Fuchs & Muller 2001). Furthermore, the economic aspect is of increasing importance in hydrocarbon recovery. Knowledge of the stress field is used in the hydrocarbon industry to foresee stability problems of boreholes and to optimize reservoir management through tectonic modelling in combination with correlation with other data sets such as 3D-structural information, e.g. location and orientation of faults. Geodetic measurements (e.g. Global Positioning System, GPS; Very Long Baseline Interferometry, VLBI; Satellite Laser Ranging, SLR) have become available in increasing numbers and enhanced quality. They provide surface displacement vectors from which the strain rate field can be deduced. The combined interpretation of stress and strain rate data provides unique challenges for Earth scientists in a number of fields. In tectonics, plate boundary forces confine the kinematics of plate motion and the dynamics of plate deformation resulting, for example, in major differences between intraplate and plate boundary deformation zones. The width of the latter even varies for the different types of plate boundaries (Gordon & Stein 1992). These differences express the laterally and vertically heterogeneous deformation pattern of the crust due to its composition, mechanical properties and tectonic setting. The comparison of the strain rate field at the surface with earthquake data from the seismogenic part of the crust will give information on the depth variation of strain. The relationship of strain and stress is of special importance at active fault zones, where accumulated stress is abruptly released in earthquakes. The scale of stress impact ranges from a continent-wide scale in order to explain tectonic processes, to a metre scale at reservoir and construction sites. The global database World Stress Map (WSM) provides information on the contemporary tectonic stress in the Earth's crust in a compact and comprehensive way. The WSM project was initiated as a task force of the International Lithosphere Program under the leadership of M. L. Zoback. The database is now maintained and expanded at the Geophysical Institute of Karlsruhe University as a research project of the Heidelberg Academy of Sciences and Humanities. The WSM team regards itself as 'brokers' for these fundamental data: data of different types from all over the world are integrated into a compact database following standardized procedures for quality assignFrom: NIEUWLAND, D.A. (ed.) New Insights into Structural Interpretation and Modelling. Geological Society, London, Special Publications, 212, 101-116. 0305-8719/03/$15 © The Geological Society of London 2003. 102 B. SPERNER ET AL. ment and for data format conversion. The resulting database is available to all via the Internet (http://www.world-stress-map.org) for further investigations. We are indebted to numerous individual researchers and working groups all over the world for providing data for the database and we are looking forward to receiving new data for upgrading the database in the near future. For its successful continuation the WSM project is dependent on further data release from industry and academia. Since the presentation of the WSM project in a special volume of the Journal of Geophysical Research in 1992 (Vol. 97, no. B8), relevant changes took place, not only concerning the amount of data available in the WSM database, but also regarding new methods for stress investigations (e.g. drilling-induced fractures, borehole slotter) as well as improved quality criteria for geological indicators and for borehole breakouts. Here, we give an overview about the state-of-the-art of the database complemented by an outlook on the capability of stress data for practical applications in industry and academia. Thereby, we concentrate on the new features of the WSM; for basic information about the project we refer readers to the Journal of Geophysical Research special volume (as mentioned above). Database and Internet access Information about the tectonic stress field in the Earth's crust can be obtained from different types of stress indicators, namely earthquake focal mechanisms, well bore breakouts, hydraulic fracturing and overcoring measurements, and young (Quaternary) geological indicators like fault-slip data and volcanic alignments. The reliability and comparability of the data are indicated by a quality ranking from A to E, with A being the highest quality and E the lowest (for further investigations only the most reliable data with a quality of A, B or C should be used). An overview about the quality ranking scheme is given in Zoback (1992) as well as on the WSM website (http://www.world-stressmap.org). The WSM website gives a detailed description of the database comprising not only data on the orientation of the maximum horizontal compression (SH), which are usually plotted on the stress maps, but also information such as the depth of the measurement, the magnitude, the lithology and so on. The complete database can be downloaded from the website either as dBase IV or as an ASCII file. In addition, the website provides instructions for stress regime characterization, abstracts from the two WSM Euroconferences, interpretations of the stress field in selected regions, guidelines for data analysis (which until now are available for borehole breakouts), and much more. Numerous stress maps for different regions of the world are available on the Internet as postscript files. As an additional service the program CASMO (Create A Stress Map Online) offers the possibility to create user-defined stress maps, for example by adding topography, plotting only data of a specific type (e.g. only earthquakes), or plotting data from a certain depth range. CASMO is available on request and takes less than two hours for a return of the stress map via e-mail. All stress maps are plotted with GMT provided by Wessel & Smith (1991, 1998; http://www.soest.hawaii.edu/gmt/); plate boundaries come from the PLATES project (http://www.ig.utexas.edu/researchlprojects/plates/ plates.html). The new release of the WSM The new release of the WSM (Muller et at. 2000; Fig. 1) encompasses 10 920 data records, each with up to 56 detail entries. As in the earlier releases (e.g. Zoback 1992; Muller et at. 1997) most data come from earthquakes (63%; with Harvard University being the major 'data contributor'; CMT solutions; http://www.seismology.harvard.edu/projects/CMT/) and borehole breakouts (22%; Table 1, Fig. 2). About two-third of the data (68%) have a quality of A, B or C and thus can be used for further investigations (D and E quality data are too unreliable, but are kept for book-keeping purposes in order to inform future researchers that these data have already been analysed). New data mainly came from Europe, Australia and America. The WSM database is designed as a tool to work with stress data. Due to the structure of the database the data can be selected according to a number of criteria such as type, location, regime, depth, and so on. Additionally, data from mid-ocean ridges which may be directly related to plate boundary processes and which had so far been excluded from the WSM database are now included. These data with less than 2° distance to the next plate boundary are marked by 'PBE' (Possible Plate Boundary Event) in the last field of the database (field PBE), so that they can easily be filtered if necessary. New database structure A three-letter country code is used for the numbering of the data; it is based on ISO 3166 provided by the United Nations (http://www.un.orglDepts/un sdlmethods/m49alpha.htm). We opted for a new WORLD STRESS MAP PROJECT 103 Method: 1 ~%~~~hanism ~ ~~~e~~~~"~~C. ~ ~~;~;:~~~ _60· ONF :e:s1m;:Tf 0U

/pdf/tectonic-stress-in-the-earth-s-crust-advances-in-the-world-3hf00rnvv7.pdf

Tectonic stress in the Earth’s crust: advances in the World Stress Map project

/pdf/quaternary-fault-kinematics-and-stress-tensors-along-the-3gwlrx4dcw.pdf

Quaternary fault kinematics and stress tensors along the southern Caribbean from fault-slip data and focal mechanism solutions

Seismic strain rates and distributed continental deformation in the northern Andes and three-dimensional seismotectonics of northwestern South America

. We provide a present-day surface-kinematics model for the Alpine
region and surroundings based on a high-level data analysis of about 300
geodetic stations continuously operating over more than 12 years. This model
includes a deformation model, a continuous surface-kinematic (velocity)
field, and a strain field consistently assessed for the entire Alpine
mountain belt. Special care is given to the use of the newest Global Navigation Satellite Systems
(GNSS) processing standards to determine high-precision 3-D station coordinates. The
coordinate solution refers to the reference frame IGb08, epoch 2010.0. The
mean precision of the station positions at the reference epoch is ±1.1  mm in N and E and ±2.3  mm in height. The mean precision of the
station velocities is ±0.2  mm a −1 in N and E and ±0.4  mm a −1 in height. The deformation model is derived from the point-wise station
velocities using a geodetic least-squares collocation (LSC) approach with
empirically determined covariance functions. According to our results, no
significant horizontal deformation is detected in the Western Alps, while
across the Southern and Eastern Alps the deformation vectors describe a
progressive eastward rotation towards Pannonia. This kinematic pattern also
makes evident an increasing magnitude of the deformation from 0.1 mm a −1 in
the western part of Switzerland up to about 1.3 mm a −1 in the Austrian Alps.
The largest shortening is observed along the southern front of the Eastern
Alps (in the northern area of the Venetian-Friuli Basin) and in the northern
part of the Apennine Peninsula, where rates reach 2 and 3 mm a −1 ,
respectively. The average accuracy of the horizontal deformation model is
 ±0.2  mm a −1 . Regarding the vertical kinematics, our results clearly
show an ongoing average uplift rate of 1.8 mm a −1 of the entire mountain
chain, with the exception of the southern part of the Western Alps, where no
significant uplift (less than 0.5 mm a −1 ) is detected. The fastest uplift
rates (more than 2 mm a −1 ) occur in the central area of the Western Alps, in
the Swiss Alps, and in the Southern Alps in the boundary region between
Switzerland, Austria, and Italy. The general uplift observed across the
Alpine mountain chain decreases towards the outer regions to stable values
between 0.0 and 0.5 mm a −1 and, in some cases, to subsidence like in the
Liguro-Provencal and Vienna basins, where vertical rates of −0.8 
and −0.3  mm a −1 are observed, respectively. In the surrounding region, three
regional subsidence regimes are identified: the Rhone-Bresse Graben with
 −0.8  mm a −1 , the Rhine Graben with −1.3  mm a −1 , and the Venetian-Friuli Basin
with −1.5  mm a −1 . The estimated uncertainty of our vertical motion model
across the Alpine mountain belt is about ±0.3  mm a −1 . The strain field
inferred from the deformation model shows two main contrasting strain
regimes: (i) shortening across the south-eastern front of the Alps and the
northern part of the Dinarides and (ii) extension in the Apennines. The pattern
of the principal strain axes indicates that the compression directions are
more or less perpendicular to the thrust belt fronts, reaching maximum
values of 20 × 10 - 9  a −1 in the Venetian-Friuli and Po basins.
Across the Alpine mountain belt, we observe a slight dilatation regime in
the Western Alps, which smoothly changes to a contraction regime in western
Austria and southern Germany, reaching maximum shortening values of 6 × 10 - 9  a −1 in north-eastern Austria. The numerical results of
this study are available at https://doi.pangaea.de/10.1594/PANGAEA.886889 .

/pdf/present-day-surface-deformation-of-the-alpine-region-31b7uxrimv.pdf

Present-day surface deformation of the Alpine region inferred from geodetic techniques

Monitoring West Hellenic Arc Tectonics and Calabrian Arc Tectonics (“What a Cat”) Using the Global Positioning System

Position changes due to recent crustal deformations along the Caribbean- South American plate boundary derived from the CASA GPS project

The CASA'93 GPS campaign for crustal deformation research along the South Caribbean plate boundary

The Central and South America (CASA) GPS project aims at monitoring crustal deformations in the complex tectonic zone of the Caribbean, Cocos, Nazca and South American plate boundaries. Since 1988 several GPS campaigns have been carried out, unfortunately not always covering the whole area simultaneously.

Crustal Deformation along the Caribbean — South American Plate Boundary Derived From The Casa GPS Project

130. Jg. 1/2005 zfv 41 Summary Simultaneous observations from two co-located permanent GPS stations at Bogotá, Colombia, are analyzed with regard to local movements. The two years time series of daily estimates of the 192 m long baseline yields a linear change of the vector components of 7.4, –4.6 and –7.0 mm/yr in north, east and vertical direction respectively. In addition, the baseline height component shows systematic effects during periods of between some days and several weeks. For assessing the effects absolutely and for identifying the responsible station, observations from two distant permanent GPS stations are included in the analysis. The results prove that the relative movement is real and is caused by the building housing one of the stations. The offsets in the height estimates can be allocated to the other station. Its antenna is mounted on a concrete pad with bordering which seems to be flooded during periods of heavy rainfall. This leads most likely to multipath effects and to changes of the electrical properties of the antenna, and consequently to apparent positive height changes. Comparisons with precipitation data support this finding. Zusammenfassung Die simultanen Beobachtungen zweier benachbarter GPSPermanentstationen in Bogotá, Kolumbien, werden hinsichtlich lokaler Bewegungen analysiert. Die zweijährige Zeitreihe täglicher Ausgleichungen der 192 m langen Basislinie zeigt lineare Änderungen des Vektors zwischen beiden Antennen von 7.4, –4.6 und –7.0 mm/Jahr in Nord-, Ostund Höhenkomponente. Außerdem treten in der Höhe systematische Abweichungen während Perioden von einigen Tagen bis zu mehreren Wochen auf. Um die Bewegungen absolut zu erfassen und die verursachende Station zu identifizieren, werden Messungen zweier entfernter Permanentstationen einbezogen. Die Ergebnisse belegen, dass die Relativbewegung zwischen den beiden Stationen in Bogotá real ist und durch das Gebäude verursacht wird, auf dessen Dach eine der beiden Antennen montiert ist. Die systematischen Abweichungen in den Höhenergebnissen können der anderen Station zugeordnet werden, deren Antenne auf einem ebenerdigen Betonfundament mit Randeinfassung montiert ist. Dieses Fundament scheint bei starken Regenfällen überflutet zu werden. Dadurch werden MehrApparent and Real Local Movements of two Co-Located Permanent GPS Stations at Bogotá, Colombia

Apparent and Real Local Movements of two Co-Located Permanent GPS Stations at Bogotá, Colombia

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