The simulation problem for broad-band seismograms

Abstract

A fundamental problem in the numerical data preprocessing of digital broad-band seismograms is the simulation of arbitrary analog seismograph systems, especially seismometer-galvanometer combinations.A special case of this simulation problem is the deconvolution or restitution problem as the realization of a wide-band seismograph system with a transfer function proportional to ground displacement, velocity or acceleration.The simulation problem can be solved by a digital cascade recursive filter using the bilinear z-transformation.Applications of the simulation filter are: a combined interpretation of digital broad-band and analog narrow-band recordings, a routine analysis of broad-band seismograms consistent with ordinary analog stations, the determination of the local magnitude from simulated Wood-Anderson seismograms and the restitution of broad-band recordings.The relationship between bandwidth, fine structure and information content of seismograms can be demonstrated in an obvious way by comparing broad-band recordings of the Graefenberg-array with simulated seismograms for different standardized seismometer-galvanometer systems.