Broad-Band Seismometry—A Unified Approach Towards a Kinematic and Dynamic Interpretation of Seismograms

Abstract

An important aspect of a global seismic system for identification of seismic sources concerns the standardisation of seismographs on a modern level. The development of digital broad-band seismographs is a successful technical approach. A broad-band seismogram is an overall picture of the seismic wave field at the recording station. The high dynamic range of digital data acquisition allows to focus upon special features by digital filters. These filters can simulate arbitrary seismographs. Thereby an old dispute among seismologists on the best instrument may after all be solved. There is no longer a need for restriction to special instruments which would make standardization more difficult because different instruments have been found optimal by different seismological groups in the world. The lecture describes the seismological contraints and the technical realization of digital broad-band seismographs at the Central Seismological Observatory Graefenberg (GRF). Using data from this instrumentation the filter effect of conventional narrow-band seismographs will be demonstrated. These seismographs filter the original broad-band seismic signal and reduce its information content. The loss of information is irreversible and depends on bandwidth, resolution and instrumental noise.