Ten Years of the Gräfenberg Array

Defining the frontiers of broadband seismology

Ed.: Burkhard Buttkus

1986. 135 pages, 73 figures, 2 tables, 17x24cm, 390 g
Language: English

(Geologisches Jahrbuch Reihe E, Band E 35)

ISBN 978-3-510-96051-4, paperback, price: 21.00 €

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Synopsis top ↑

The tenth anniversary of the Gräfenberg array is taken as an opportunity to review the development of broadband seismology in the Federal Republic of Germany over the last decade.
At the end of the sixties, the geophysical institutes of the universities in the Federal Republic, the Deutsche Forschungsgemeinschaft (DFG) and the Bundesanstalt für Geowissenschaften und Rohstoffe (BOR) initiated the construction of a broadband array. This project combines advanced array technology with broadband instrumentation and provides a technical basis for research for keeping abreast of the leading countries in seismology. These efforts have given new impetus to national and international seismological activities: With the installation of the Gräfenberg array, broadband seismology is now a current field of seismological research.

The various aspects of broadband seismology given in this book include technical developments related to the Gräfenberg array, as well as scientific studies of earthquake mechanisms, structural evaluation-of the earth and monitoring of underground nuclear tests.
Moreover, the book discusses the future development of the Gräfenberg array within the international framework of seismology for the next decade. Ten years of practical experience with the Gräfenberg array and the present worldwide trends in seismology clearly demonstrate the importance of the Gräfenberg array in this field.

Contents top ↑

1 Foreword (H.-J. DÜRBAUM & H.-P. HARJES) 8
2 The Grafenberg Observatory as the Central Seismological Installation
of the Ferderal Republic of Germany (B. BUTTKUS & H. AICHELE) 10
2.1 Functions of the Central Seismological Observatory Grafenberg 10
2.2 Instrumentation at the Central Seismological Observatory
Grafenberg 11
2.3 Seismological Data Evaluation at the SZGRF 11
2.4 Seismological Data Basis and Data Exchange 13
3 Design and Technology of the Grafenberg Array 15
3.1 The Array Concept (M. HENGER) 15
3.2 Seismometers and Analog Electronics (E. WIELANDT) 17
3.2.1 Historical Observations 17
3.2.2 Technical Requirements 17
3.2.3 The Seismometer 18
3.2.4 Analog Signal Processing 19
3.2.5 Recent Developments 20
3.3 Digital Acquisition, Transmission and Recording of Array Data
4 Analysis and Interpretation of Array Broadband Data 28
4.1 Analysis of Grafenberg Broadband Seismograms (D. SEIDEL) 28
4.1.1 Determination of Standard Parameters from Grafenberg Broadband
Seismograms 28 Interactive Analysis Program 30 Signal Detection in Broadband Seismograms 32 Magnitude Determination with Broadband Seismograms 35
4.1.2 Standard Analysis 36 Restitution and Simulation 36 Polarization Analysis 40
4.2 Signal Processing of Grafenberg Array Data (W. HANKA & D. SEIDL) 44
4.2.1 Characteristics of a Seismic Wave Field and Signal Processing of
Array Data 44
4.2.2 Analysis of Grafenberg Array Data 46 Spatial Coherence and Signal Spectrum 46 Beam Forming in the Time Domain and Signal Detection 46 Analysis in the w-k- and s-t Domain 48
4.3 Array Calibration (S. FABER) 56
5 Seismological Research Work with the Grafenberg Array 60
5.1 Source Mechanics 60
5.1.1 Investigation of Source Processes with the Grafenberg Array
5.1.2 Source-depth Determination of Regional and Teleseismic Earthquakes
from Broadband Data (R. KIND & S. FABER) 64
5.1.3 The Spectra and Magnitudes of Earthquakes (S. J. DUDA) 71 Introduction 71 Definition of the Spectral Magnitude 72 Spectral Magnitudes from Broadband Observations 72 Source Parameters 76 Conclusion 78
5.1.4 Determination of Source Energy from Broadband Seismograms
5.2 Structural Investigations 83
5.2.1 The Structure of the Lithosphere beneath the Grafenberg Array
5.2.2 Investigation of Converted Phases and the Reflection PcP at the
Core-Mantle Boundary (G. MÜLLER, S. FABER & J. SCHLITTENHARDT) 88
5.2.3 Lateral Inhomogeneities: Observation of Anisotropy and Converted
Shear Waves (R. KIND) 95
5.2.4 Anelastic Absorption of Seismic Waves (H. BERCKHEMER) 99
6 The Contribution of Broadway Array Seismology to Seismic Monitoring of
Underground Nuclear Explosions (H.-P. HARJES & W. HANKA) 105
6.1 Introduction 105
6.2 The Relations between Seismic Magnitude and Explosion Yield 106
6.3 Discrimination between Earthquakes and Nuclear Explosions 108
6.4 Special Array Contribution to the Discrimination Problem 117
6.5 Summary 120
7 The Gralfenberg Array as a Seismological Research Instrument within the
Framework of a Future Regional and Global Digital Station Network
8 The Work of Foreign Guest Scientists at the Central Seismological Observatory
Grafenberg 128
9 Publicationes with Data from the Grafenberg Array 132