European Seismological Commission

446 Pages·1983·18.539 MB·English

by  E. BISZTRICSÁNY and GY. SZEIDOVITZ (Eds.)

FURTHER TITLES IN THIS SERIES
/ F. A. VENING MEINESZ
THE EARTH'S CRUST AND MANTLE
2 T. RIKITAKE
ELECTROMAGNETISM AND THE EARTH'S INTERIOR
3 D. W. COLLINSON, K. M. CREER and S. K. RUNCORN
METHODS IN PALEOMAGNETISM
4 M. BÀTH
MATHEMATICAL ASPECTS OF SEISMOLOGY
5 F. D. STACEY and S. K. BANERJEE
THE PHYSICAL PRINCIPLES OF ROCK MAGNETISM
6 L. CIVETTA, P. GASPARINI, G. LUONGO and A. RAPOLLA
PHYSICAL VOLCANOLOGY
7 M. BÂTH
SPECTRAL ANALYSIS IN GEOPHYSICS
8 O. KULHANEK
INTRODUCTION TO DIGITAL FILTERING IN GEOPHYSICS
9 T. RIKITAKE
EATRHQUAKE PREDICTION
10 N. H. RICKER
TRANSIENT WAVES IN VISCO-ELASTIC MEDIA
11 W. L. PILANT
ELASTIC WAVES IN THE EARTH
12 A. J. BERKHOUT
SEISMIC MIGRATION
13 V. C. DRAGOMIR, D. N. GHITAU, M. S. MIHAILESCU
and M. G. ROTARU THEORY OF THE EARTH'S SHAPE
14A A. J. BERKHOUT
SEISMIC MIGRATION. Imaging of acoustic energy by wave field
extrapolation. A. Theoretical Aspects (second, revised and enlarged edition)
Developments in Solid Earth Geophysics
15
PROCEEDINGS
OF THE SEVENTEENTH
ASSEMBLY OF THE
EUROPEAN
SEISMOLOGICAL
COMMISSION
Budapest, 24—29 August 1980
EDITED BY
E. BISZTRICSANY and GY. SZEIDOVITZ
Seismological Observatory of GGRI,
Hungarian Academy of Sciences
Budapest, Hungary
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Amsterdam — Oxford — New York 1983
Joint edition published by
Elsevier Scientific Publishing Company, Amsterdam, The Netherlands and
Akadémiai Kiado, The Publishing House of the Hungarian Academy of Sciences, Budapest, Hungary
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© Akadémiai Kiado, Budapest 1983
Printed in Hungary
PREFACE
The European Seismological Commission /ESC/ held its 17th
General Assembly in Budapest between 21 and 2 3 August, 1980,at
the invitation of the Hungarian Academy of Sciences and the
Hungarian Geophysical Society. At the same venue, the European
Geophysical Society /EGS/ held its Seventh Annual Meeting from
24 to 29 August, at the invitation of the Lorand Eötvös Uni-
versity and the Hungarian Geophysical Society.
The present Volume contains papers presented on the ESC
Assembly, respectively on the ESC-EGS Joint Meetings. General-
ly, the manuscripts are reproduced in their original form.
Editorial interventions were restricted to improving some
figures and removing misprints and errors of spelling but
those of division were not corrected. Consequently the authors
are fully responsible for their contributions in all respects.
The editors would like to thank all authors for contribut-
ing to the success of this Volume. Thanks are also due to the
Publishing House of the Hungarian Academy of Sciences for
pleasant collaboration, consideration in several matters and a
job well done.
XIII
PRESIDENTIAL ADDRESS
A. REINIER RITSEMA
1. The European Seismological Commission was created during the
IUGG General Assembly in Brussels on the 28th of August 1951.
Personally, it was also my first international geophysical
conference. Sixteen General Assemblies of ESC have followed,
most of them highly successful and attended by many European
seismologists. The increasing interest in these meetings is
shown in the larger numbers of participants /more than 150
from 25 countries in the present case/, and of contributing
papers /a total number of 152 scientific papers was present-
ed in the Budapest meetings/. Specially gratifying is the
steadily rising attendance from countries outside the
European region, indicating the improtance that is attribut-
ed to the ESC meetings.
The internal rules and statutes of ESC say that it is the
task of its members to promote work in seismology in the
European area, defined as the region between 30-90°N and
30°W - 40/60°E. As positive developments during the 29
years of ESC we may point to the impressive increase of
active seismologists in the region, to the even more spec-
tacular extension of the seismic network of the region, and
to the multitude of scientific publications of which many
were produced for and presented in meetings of the ESC. Im-
portant progress was made in the study of seismicity of the
European area, of instrumentation and data acquisition, of
the physics of the earthquake source, of the structure of
the crust and upper mantle of the region, of microseisms and
seismic noise, and of more theoretical problems, such as
wave propagation and earthquake generating stress fields.
2. For the record, some salient points of the past two years
since the 16th General Assembly in Strasbourg have to be
layed down and remembered:
2.1 With regret we have to mention the decease of a number
of colleagues and friends, among them three former
presidents and one titular member. They are:
XV
Prof.P.Caloi /-1978/: after his presidency ended in
Utrecht, 1958, he did not attend another ESC meeting;
as a European seismologist, however, he was extremely
productive till the last;
Prof.E.F.Savarensky /18 July 1911 - 27 January 1980/:
for many years the nestor of USSR seismologists and for
more than 20 years active in ESC; many of us did meet
him apparently in good health a month earlier in the
IUGG meetings of Canberra;
Prof.W. Hiller /2 February 1899 - 31 July 1980/: first
president of ESC and initiator of the European coopera-
tion in the Commission; he reached the age of 81;
Mme. Dr. M.Grigorova /1980/: for many years the ESC ti-
tular member for Bulgaria and the driving force behind
the expansion of seismology in her country;
Dr.M.A.Choudhury / - 17 December 1979/: born and educat-
ed in Pakistan, he worked in the IPG's of Paris and
Strasbourg on earthquake mechanisms, wave propagation
a.o.; he reached the age of only 53;
Dr.I.Miyashkin /1980/: not a regular participant at ESC
meetings; active in the USSR programs on earthquake
prediction.
These European seismologists, our colleagues and friends,
will be missed by many of us. Their names will stay on
file with ESC.
2.2 In the past two years period at least 12 earthquakes
occurred in the European area causing important damage
to human structures. It all started with the Tailfingen
earthquake of September 3, 1978 causing damage in
Southern Germany and felt by many participants of the
Strasbourg General Assembly.
In total, there were nearly 200 casualties in the past
two years and several thousands of injured in our re-
gion, most of them in the M7 Montenegro-Albanian earth-
quake of April 15, 1979 and in the M6.9 Azores earth-
quake of January 1, 1980. On the invitation of our
Albanian colleagues some ESC officers visited the
country a year after the main shock to witness the re-
markable recovery of destroyed villages in the North.
Other presidential terms may have been more disastrous
with respect to earthquakes, but also now after 29
years of ESC, none of the many European earthquakes in
this period were forecasted.
2.3 European seismologists have been very active during
this period. The reports of the subcommissions will
be presented elsewhere and therefore will not be re-
peated here. The list of symposia, workshops, study
groups and seminars taking place during the period and
having some relationship with the case of general and
XVI
European seismology, comprises the formidable number of
25, with an accumulated duration of 140 days! This
extreme expansion of opportunities to meet colleagues
working in the same field asks for some co-ordination
in future years.
2.4 Another matter of some concern is the fact that most of
these meetings were not /co-/sponsored by ESC. Agencies
apparently interested in problems related to seismology
in general and in the European area in particular are
IASPEI, ICG, IAEE, EAEE, EGS local and regional seismo-
logist groups, UNESCO, UNDP, UNDRO, CSCE, KAPG, Council
of Europe, CCMS, UNCD, ESA, ICTP, a.o. In principle,
ESC stimulates initiatives of individuals as well as of
interested organizations. It is hoped, however, that
in future, also through actions of the ESC subcommis-
sions the needed co-ordination between outside activ-
ities and ESC will be strengthened and expanded.
3. For the next two years period ESC should pay special atten-
tion to the problems in the applied side of seismology, and
notably in terms of research in the field of earthquake pre-
diction.
3.1 In the past five years the demands for expert state-
ments on earthquake hazard, risk and prediction have
grown abundantly. ESC reacted in some modest way by
the organization of special symposia specially devoted
to the problems, such as that on earthquake risk for
nuclear power plants in Luxemburg /fall 1975/, and that
on the analysis of seismicity and seismic risk in
Liblice /fall 1977/. In the meantime many ESC members
are working hard on the problem of the assessment of
seismic risk and the preservation of life and human
structures in the case of an earthquake. But the stage
of the actual fieldwork in Europe in this branch of
seismology is still very preliminary.
3.2 In the fall of 1979 ESC started a rapid survey of earth-
quake prediction programs known to our titular members.
It revealed that nearly all European countries are en-
gaged in work that somehow is related to earthquake
prediction. Specific topics range from the compilation
of catalogues, the study of earthquake statistics, seis-
mic sequences, geological and geodetic aspects, earth-
quake mechanisms, instrumentation and laboratory experi-
ments to historical case studies. At some specific time
each of these subjects can contribute significantly to
the prediction of earthquakes, but on its own they are
insufficient to be classified as such. Integrated
programs of multidisciplinary kind are known of:
Portugal, Spain, Italy, Yugoslavia, Albania, Greece,
Turkey, Bulgaria, Rumania, the USSR and Iceland /see
also Proceedings 2nd Workshop on European Earthquake
Prediction Programme. ESA publication SP-156, 1980/.
2
XVII
Some of these programs are actively supported by other
nations, such as the UK, France, the FRG, Switzerland,
the USSR and the USA. Some of the programs have al-
ready started, but the majority still is in the pre-
paratory stage. This means that, in comparison with
some other countries outside Europe, we are not yet in
the frontline.
3.3 Yet, what the variety of earthquake types concerns,
Europe is in a favourable position for significant con-
tributions in the field. The European area comprises
not only seismic zones of the transcurrent fault type
/North Anatolian zone/, but also the subduction type
/Hellenic- and Calabrian Arcs/, of the tensional type
/Iceland and Mid-Atlantic ridge/, and of the very low
seismicity type /non-Alpide part of Europe/.
It seems clear that co-ordination of the different act-
ivities and programs is a necessity. And it is here
that a real task lies for the ESC.
3.4 It is with satisfaction/therefore, that as a first step
two new subcommissions have been installed during the
17th General Assembly of ESC in Budapest, one on earth-
quake prediction research, and the other on engineering
seismology. We do not expect immediate positive results
in the form of predictions in time, place and magnitude,
but we have confidence that ESC, through this inter-
mediancy, will contribute more directly to the factual
problems of a great part of the European population
living in earthquake-prone regions. Moreover, the
steering and co-ordination function of ESC with outside
parties could find a solid base here.
4. In 1964 the 10th General Assembly of ESC was held in Buda-
pest. In the 29 years of ESC existence it is the only case
that a town for the second time takes the responsibility to
act as host for ESC. This is a compliment to the country of
Hungary. We thank the Hungarian Academy of Sciences for
their generous hospitality, the members of the local organiz-
ing committee under the chairmanship of Prof.L.Stegena for
their arrangements and efficient help to participants, and
the editorial committee under the chairmanship of Prof. E.
Bisztricsâny for their care for the scientific proceedings.
We are grateful for all work done by these and the numerous
uncalled officials and non-officials that made the 17th
General Assembly of ESC a great success. The present Volume
is a token for their efforts.
XVIII
PMC. oi tkdUtk A&AZjnbly ofi tiin ESC
Budapest, 19 SO
THE BULGARIAN NATIONAL TELEMETRIC SYSTEM FOR SEISMIC DATA
INTERPRETATION.
L.CHRISTOSCOV, D.SAMARDJIEV, P.DANEV, TZ.GEORGIEV AND L.PETROV
Geophysical Institute, Bulgarian Academy of Sciences,
Sofia, Bulgaria
The recent years were characterized by the activation of the
seismic processes in the Balkan region* The strong earthquakes
which occurred in Vrancea, Velingrad, Thessaloniki and
Montenegro have shown that the available seismic station network
was not sufficiently effective. The quick operation in the
damaged regions required rapid and correct information on major
earthquake parameters.
Since 1978 the Bulgarian authorities started to establish a
principally new national telemetric system for seismic data
interpretation to solve the following main problems:
a/ Exact registration of all the shocks on the territory of
Bulgaria and surrounding areas within the magnitude range
3-6,5 and rapid interpretation of the data.
b/ Using these data for deeper investigations of the seismic
situation in the country.
The Bulgarian telemetric system at present includes 7
peripheral stations /see Fig. 1/:
Dimitrovgrad DIM
Kurdzhali KDZ
Musomishta MSM
Preselentzi PSN
Pavlikeni PVL
Sofia SOF
Vitosha VTS
These stations are located in the. most active seismic zones of
the country. The system will be extended to 16 stations for
which technical opportunities exist.
Each station runs like an.autonomous one /on-site record/ and
in the same time like a peripheral station of the seismic
system. All the seismological and telemetric equipment were
produced by Teledyne Geotech.
Each peripheral station includes the following main units:
- seismometer type S-13, short period /natural period 1 s/,
vertical mode operation;
- twc stages preamplifier with low gain output LG
/magnification up to 1000 times - 60 dB/ and high gain output
HG /magnification up to 1000000 times - 120 dB/. Both gains are
selectable in 6 dB steps depending on the seismic noise. The
magnifications used are shown in Fig. 2.
3
BULGARIAN TELEMETRIC SEISMIC NETWORK
August 1980
N ^ ^ " ^ " ^ ^ ^ ^^
y %!>^^^^ 1
) Jk?^^^ J
1 :
/ ^ \ \\ S
Μ
Ί 1 \Γ^' ^ 0>
1 ? ^MSM KDN Ç
\
Fig. 1
STANDARD FREQUENCY RESPONSE DIAGRAM
MAGNIFICATION V
if
tao Hi
FREQUENCY
MAGNIFICATION FOR EACH STATON
SOF V x 008
VTS V x 16
MSM V x 16
PVL V x 1
PSN V x 4
DIM v x ;
KDZ V x 1
Fig. 2
4.