Recent Crustal Movements, 1979

347 Pages·1981·7.157 MB·1-355\347

by  P. VYSKOČIL, R. GREEN and H. MÄLZER (Eds.)

Developments in Geotectonics
FURTHER TITLES IN THIS SERIES
l.J.AUBOUIN
GEOSYNCLINES
2. R.W. VAN BEMMELEN
GEODYNAMIC MODELS
3. A. SUGIMURA AND S. UYEDA
ISLAND ARCS, JAPAN AND ITS ENVIRONS
4. A.R. RITSEMA (Editor)
THE UPPER MANTLE
5. C. LOMNITZ
GLOBAL TECTONICS AND EARTHQUAKE RISK
6. X. LEPICHON, J. FRANCHETEAU AND J. BONNIN
PLATE TECTONICS
7. R.W. GIRDLER (Editor)
EAST AFRICAN RIFTS
8. S. MUELLER (Editor)
THE STRUCTURE OF THE EARTH'S CRUST
9. N. PAVONI AND R. GREEN (Editors)
RECENT CRUSTAL MOVEMENTS
10. S.W. CAREY
THE EXPANDING EARTH
11. A.M. JOHNSON
STYLES OF FOLDING
12. M.H.P. BOTT (Editor)
SEDIMENTARY BASINS OF CONTINENTAL MARGINS AND CRATONS
13. C.A. WHITTEN, R. GREEN AND B.K. ME ADE (Editors)
RECENT CRUSTAL MOVEMENTS, 1977
14. M.N. TOKSÖZ, S. UYEDA AND J. FRANCHETEAU (Editors)
OCEANIC RIDGES AND ARCS
15. CE. KEEN (Editor)
CRUSTAL PROPERTIES ACROSS PASSIVE MARGINS
Developments in Geotectonics 16
RECENT CRUSTAL
MOVEMENTS, 1979
Proceedings of the IUGG Interdisciplinary Symposium No. 9, "Recent
Crustal Movements", Canberra, A.C.T., Australia, December 13—14,1979
Edited by
P. VYSK0ÖIL
International Center on Recent Crustal Movements, 250 66 Zdiby 98,
Prague (Czechoslovakia)
R. GREEN
Department of Geophysics, University of New England, Armidale, N.S.W.
2351 (Australia)
and
H. MÄLZER
Geodetic Institute, University of Karlsruhe, D-7500 Karlsruhe (F.R. Germany)
Reprinted from Tectonophysics Volume 71
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Amsterdam — Oxford — New York 1981
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© Elsevier Scientific Publishing Company, 1981
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Printed in The Netherlands
V
PREFACE
This special issue of Tectonophysics contains the Proceedings of the IUGG
Interdisciplinary Symposium No. 9. "Recent Crustal Movements" held during
the XVII. IUGG General Assembly in Canberra, Australia, December 13—14,
1979. The Symposium was convened by IAG—Commission on Recent Crustal
Movements, and sponsored by the IASPEI, IAVCEI and IAPSO.
The volume contains 25 papers and one abstract of paper presented during
the Symposium. Three papers presented are cumulated in one common
paper (Gubler, Kahle, Klingele, Mueller and Olivier) published in this issue.
Fourteen abstracts of papers registered but not presented on the Symposium
are added. The papers and abstracts of other papers are arranged by the
scientific division of the sessions.
During the Symposium the following topics were discussed:
(1) Instruments and methods for the determination of recent crustal
movements.
(2) Recent crustal movements of tectonic or human origin in different
regions.
(3) Connections between recent crustal movements, seismicity and vol-
canism.
(4) Interpretation of the crustal structure and crustal movements with the
assistence of other geophysical data.
(5) Methods of evaluating recent crustal movements.
The results of papers presented during the Symposium, and conclusions of
the discussion indicate the following trends in recent crustal movement
studies.
New methods using space techniques will be available during the next five
or ten years to determine large-scale movements of tectonic plates. Accuracy
of terrestrial measurements is expected to further increase when instruments
independent from external errors become available. New results of vertical
crustal movements investigations especially in Europe and Canada were
presented. Using these results the map of vertical crustal movements for
Europe and North America is slowly assembled. Analyses of repeated geodetic
measurements show that geodetic methods provide necessary information
about the movements of crustal blocks, showing in particular in fault zones
etc. Repeated geodetic measurements are thus very important for the predic­
tion of seismic or volcanic activities. The increasing amount of accurate
geodetic measurements is accompanied by the development of accurate com­
putational methods for the determination of the movements and separation
of systematic errors. The results presented during the Symposium confirm
that geodetic methods, including precise gravity, strain and tilt measure­
ments, are useful for expanding our knowledge of the laws governing crustal
deformations.
vi
Pavel Vyskocyl of ICRCM, Czecoslovakia, was the convenor of this Sym­
posium and he expresses his deep thanks to the authors and all participants
for their active cooperation and discussion and to the local organizing com­
mittee for their regular help by preparation and organization of the Sym­
posium.
Ronald Green of Annidale, Australia, Hermann Mälzer of Karlsruhe, FRG,
and Pavel Vyskocyl of ICRCM, Czechoslovakia are the co-editors of this
special issue. They express their appreciation to the authors for their coopera­
tion and also thank the editorial staff of Tectonophysics for their continued
help and support by publishing these but also other proceedings of symposia
and meetings on recent crustal movement research.
P. VYSKOCYL
Vil
LIST OF AUTHORS
Adkins, J.S., 267 Kailasam, L.N., 192 Schädlich, M., 353
Arur, M.G., 153, 154, 155, 156 Kasser, M., 73 Schaffrin, B., 354
Baker, T.F., 97 Khosla, K.L., 155 Scheidegger, A.E., 217
Baumann, H., 157 Kistermann, R., 315 Schüler, R., 27
Bender, P.L., 189 Kiviniemi, A., 65 Semakin, V.P., 299
Brunner, F.K., 281 Klingele, E., 125 Singh, A., 156
Coleman, R., 281 Koch, K.R., 301 Slater, L.E., 87
Csâti, E., 41 Lelgemann, D., 1 Soloviev, V.N., 299
Demant, A., 194 Lensen, G.J., 173 Somov, V.l., 41
Edge, R.J., 97 Lepine, J.C., 73 Steinberg, J., 353
Eremin, G.D., 199 Lyapishev, A.M., 299 Sychev, P.M., 299
Fourniguet, J., 195 Mälzer, H., 53 Szameitat, J., 1
Fritsch, D., 301 Mörner, Ν.-Α,, 241 Tarantola, A., 73
Ghalib, M., 253 Mueller, St., 125 Thurm, H., 41
Green, R., 267 Nagar, V.K., 153 Thury, J., 41
Gubler, E., 125 Nagy, D., 75 Torge, W., 227
Harrington, H.J., 267 Niemeier, W., 335 Totomanov, I.N., 41
Hein, G.W., 315 Olivier, R., 125 Ulomov, V.l., 191
Hirsch, B., 281 Ortlieb, L., 194 Untung, M., 267
Hoffers, B., 157 Pavoni, N., 193 Vanicek, P., 75
Huggett, G.R., 29 Popescu, M., 41 Vanko, J., 41
lilies, J.H., 157 Prilepin, M.T., 13 Vogt, J., 195
Isachsen, Y.W., 95 Rajal, B.S., 154, 156 Weber, C, 195
Jeffries, G., 97 Refai, E., 253 Wilson, P., 1
Joó, I., 41 Reilly, W.I., 111 Wyrzykowski, T., 41
Jovanovic, p., 41 Riad, S., 253 Zakharov, V.K., 299
Kahle, H.-G., 125 Ruegg, J.C., 73
Tectonophysics, 71 (1981) 1-12 1
Elsevier Scientific Publishing Company, Amsterdam — Printed in The Netherlands
1. Instruments and methods
ON THE DESIGN AND ERROR CHARACTERISTICS OF A
FUNDAMENTAL GLOBAL GEODETIC NETWORK
D. LELGEMANN, J. SZAMEITAT and P. WILSON
Institut für Angewandte Geodäsie, Weinbergstrasse 9, 6230 Frankfurt am Main-Sindlingen
(F. R. Germany)
(Received July 1, 1980)
ABSTRACT
Lelgemann, D., Szameitat, J. and Wilson, P., 1981. On the design and error characteristics
of a fundamental global network. In: P. Vyskocil, R. Green and H. Mälzer (Editors),
Recent Crustal Movements, 1979. Tectonophysics, 71: 1—12.
The realization of a global terrestrial reference system can be based on a set of 10—15
fundamental stations whose motion is to be monitored using laser ranging to satellites
(Lageos, Starlette) and to the moon, as well as Very Long Baseline Interferometry to
intergalactic radio sources, probably supported by auxiliary observations such as gravity.
The investigation of the underlying model of such a system is separated into the inves­
tigation of a reduction model, a functional model and a stochastic model. Emphasis is
placed on the distinction between the kinematic and dynamic representation of the mu­
tual motion of station and reflector points.
Finally, the possible configuration of a network of about 15 fundamental stations as
well as the instrumental package required for such stations is described.
INTRODUCTION
Possibly the most fundamental problem in earth dynamics today is to
determine what mechanism or combination of mechanisms is causing the mo­
tion of the lithospheric plates that make up the earth's surface, and how the
plates respond to these driving forces. An important contribution to the
investigations of these phenomena may come from the monitoring of the
variation of the positions of well-monumented points at the earth surface.
Using geodetic techniques for the monitoring of these motions, three
major components may be distinguished in an international geodynamics
program:
(1) The use of interlocking networks of fixed and transportable laser rang­
ing and VLBI stations to acquire regional-scale and global-scale data.
(2) The development of improved space techniques for measuring relative
positions at large numbers of points in seismic zones.
(3) The measurements of the earth's gravity field with sufficient accuracy
0040-1951/81/0000—0000/$ 02.50 © 1981 Elsevier Scientific Publishing Company
2
to meet the needs of both basic research in global geodynamics and applica­
tions to the important field of physical oceanography.
The foundation of these methods and therefore a main objective of the
geodetic work is the establishment of a terrestrial reference frame in which
geodynamic phenomena can be monitored in time and space. This reference
frame will be realized by a set of fundamental stations, whose coordinates
have to be monitored permanently. Such a realization of a terrestrial refer­
ence system should meet the following requirements:
(1) Two basic reference systems are required, a rigorously defined inertial
system and a rigorously defined terrestrial system.
(2) The terrestrial system should be associated with the non-rigid earth in
some well-defined way.
(3) The definitions of the reference systems should be compatible with
simple operational descriptions of how the systems can be utilized.
(4) The terrestrial coordinate system should have its origin at the center of
mass of the entire earth.
(5) The realization of the terrestrial system should have low sensitivity to
changes in the distribution of observing stations or the frequency of obser­
vations from individual stations.
(6) The realization of the terrestrial and the inertial system should avoid
as much as possible any dependence on geophysical or astrophysical hypo­
thesis.
The coordinates of the stations of all the other geophysical networks should
be determined within the terrestrial reference frame.
To avoid misinterpretation of geodetic measuring errors as a geophysical
phenomenon a detailed knowledge of the physical model as well as a careful
analysis of the error propagation of the methods used in this context are
essential for a sound discussion between the various disciplines. Fortunately,
two completely different operational methods are known both capable — at
least from our present judgement — of building up a geodetic reference
frame with cm-accuracy: (1) Very Long Baseline Interferometry (VLBI); and
(2) laser ranging to artificial satellites (SLR) and to targets at the moon
(LLR). Especially the difference between the results obtained by both
methods will provide a realistic insight into the influence of both measuring
and model errors.
The goal for the next decade is the evaluation and verification of a simple
operational system, of the model as well as of all practical aspects, which
provide for the realization and the permanent conservation of the terrestrial
reference system based on a set of at least 10—15 fundamental stations
(Coates, 1979; NASA, 1979).
SOME REMARKS ON A NON-STATIONARY GEODETIC MODEL
For the purposes outlined in the first section the present geodetic models
have to be extended from time-invariant (stationary) to time-dependent
3
(non-stationary) ones, both for point positioning as well as for the represen­
tation of the gravity field. Aiming at a careful investigation of all the detailed
aspects of the physical model it is very important to dissolve it into several
component parts. Such a decomposition can often be made in several intui­
tive ways; however, it should illustrate the theoretical and practical relation­
ships of different techniques such as VLBI and laser ranging. The following
comprises three main parts which are further split up into several sub-sec­
tions.
Reduction model
The goal of the reduction model is the transformation of the real mea­
sured quantity (e.g. a time delay in laser ranging) into a geometric quantity
related to two or more points in (a non-Euclidean) space. These reductions
can be broken down into: (a) system-internal reductions; and (b) system-
external reductions.
To the system-internal reductions belong the correction of the clock reading,
calibration correction, analysis of the returned laser pulse etc. . To the sys­
tem-external reductions appertain especially the influence of ionospheric and
tropospheric refraction, which can often be taken into account by multiple-
frequency measurements, radiometer observations etc. .
Functional model
The fundamental stations are considered as points moving in an Euclidean
space and connected to the observed points (the reflectors) by the measure­
ments. The additional reductions due to relativistic effects are very small
and can be taken into account by their theoretical values. Thus, the func­
tional model comprises a set of equations of motion. The principal un­
knowns are the constants of integration of a dynamical model:
(1) Coordinates of the fundamental stations at a fixed epoch given in a
terrestrial system.
(2) Orbital elements of the physical bodies bearing the reflectors at a fixed
epoch defining an inertial system.
(3) Coordinates of the reflector stations at a fixed epoch given in a body-
related coordinate system of the body bearing the reflectors.
Furthermore, a description of the mutual motion of the observing as well
as the observed points has to be given. From the basic principles of mechan­
ics two different kinds of representation of these motions are known: (a)
kinematic representation; and (b) dynamic representation. The two forms
have to be distinguished very carefully, so much more as the final model will
probably be chosen as a combination of a kinematic and dynamic model. A
pure kinematic representation of motion comprehends only geometric quan­
tities (coordinates) and time. Within the dynamic representation of motion
the position of the stations involved are ascertained from a parametric model
4
of the forces acting on the bodies which bear the stations by solving New-
tons equation of motion. Therefore, in addition to the set of coordinates
defining the three coordinate systems mentioned above, another set of (pos­
sibly unknown) parameters are elements of the general model: (1) dynamic
parameters describing the forces acting on the bodies which bear stations and
reflectors; (2) kinematic parameters describing empirically the motion of the
stations and reflectors, respectively. An illustrative example of dynamic
parameters is the set of spherical harmonic coefficients of the earth gravity
potential, of kinematic parameters the set of data describing polar motion as
published e.g. by BIH. It is worthwhile to mention that the dynamic param­
eters are physically well-defined quantities which can be determined by
various methods, as well as including them as unknowns in the present
model.
For obvious reasons it will be the goal of the theoretical development to
achieve a completely dynamic representation of the functional model, since
only in such a case a reasonable prediction of the position of the stations
involved can be expected. However, the first stage of realization must
include empirical-kinematical parameters especially in those parts of the
model where a sufficiently detailed information of the physical structure is
not yet known (IAU, 1974).
Since the realization of a global reference system is certainly an interdisci­
plinary task of at least astronomy, geophysics and geodesy there is a very
practical reason for a further decomposition of the functional model. A
decomposition which seems to be suitable from an interdisciplinary point of
view and which is in full agreement with the present evaluation of the mea­
surements is given in Table I. Nevertheless, such a decomposition may only
be approximately feasible in accordance with theory, e.g. an exact separa­
tion of the rotation and the tectonic motions of the earth may not be prac­
tical.
The area of research concerning the development of the functional model
can almost completely be described by the following three items:
(1) Definition of reference systems likewise suitable for kinematic and
dynamic representation of the motions (IAU, 1974).
(2) Design of observation techniques which depend on different sets of
model parameters.
(3) Design of evaluation techniques which include in an optimal way dy­
namic as well as kinematic parameters.
An illustrative example for the first item is the choice of the center of mass
of the earth as origin of a terrestrial system.
Whereas all the parameters used in VLBI belong to the items 1—3 in Table
I, the parameters used in the evaluation of laser ranging to Lageos and Star­
lette belong to the items 1—4 and the parameters used in the evaluation of
lunar laser ranging to the items 1—6 (Mulholland, 1976).
An illustrative example for the optimal use of dynamic and kinematic
representations of a satellite orbit is the Short-arc technique where the inac-