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Earthquake strong motions recorded by a large near‐source array of digital seismographs
Author(s) -
Bolt B. A.,
Tsai Y. B.,
Yeh K.,
Hsu M. K.
Publication year - 1982
Publication title -
earthquake engineering and structural dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.218
H-Index - 127
eISSN - 1096-9845
pISSN - 0098-8847
DOI - 10.1002/eqe.4290100406
Subject(s) - seismometer , seismology , geology , peak ground acceleration , azimuth , acceleration , seismic array , waveform , magnitude (astronomy) , geodesy , seismic wave , ground motion , physics , optics , classical mechanics , quantum mechanics , voltage , astronomy
Specially designed arrays of strong‐motion seismographs near to the earthquake source are required for seismological and engineering studies of the generation and near‐field properties of seismic waves. The first such large digital array, called SMART 1 (with radius 2 km and 37 accelerometers), to record substantial ground motion (up to 0·24g horizontal acceleration) became operational in late 1980 in a highly seismic region of Taiwan. During the first 6 months of operation, SMART 1 recorded nine earthquakes with magnitudes ranging from M L 3·8 to 6·9. Three were located directly below the array at focal depths of 59 to 76 km. The remaining six had shallow depths and epicentral distances from 7 to 193 km. Digital records from 27 three‐component accelerographs were obtained from a magnitude 6·9 (M L ) local earthquake on 29 January 1981. Representative measurements are described of seismic wave coherency and power spectrum as a function of wave number, frequency, azimuth of propagation and wave type. Acceleration waveforms varied significantly across the array for each event. On average, peak acceleration of horizontal components was about three times that of the vertical component. Relative spectral changes from earthquake to earthquake were large.

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