NEW FAMILY OF INEXPENSIVE BROAD BAND SEISMOMETERS

IN THE PAST DECADE SEISMOLOGISTS HAVE WITNESSED A SPECTACULAR DEVELOPMENT IN SEISMIC INSTRUMENTATION. BROAD BAND SEISMOMETERS NOW ROUTINELY RECORD SIGNALS DOWN TO MILLIHERTZS WITH A DYNAMIC RANGE APPROACHING 140 DB. DATA COLLECTED BY THESE INSTRUMENTS TEACH MUCH ABOUT THE EARTH'S STRUCTURE AND SEISMIC WAVE PROPAGATION. HOWEVER, INCREASING DEMAND TO SAMPLE THE WAVEFIELD WITH A MUCH HIGHER DENSITY CANNOT BE SATISFIED BY THE USE OF THESE VERY EXPENSIVE INSTRUMENTS. THERE IS A STRONG NEED FOR INEXPENSIVE, PORTABLE SEISMOMETERS WITH A BROAD BAND FREQUENCY RESPONSE AND DYNAMIC RANGE AROUND 120 DB. RESEARCHERS ARE DEVELOPING A NEW SEISMOMETER BASED ON MOLECULAR ELECTRONIC TECHNOLOGY. PREVIOUS ATTEMPTS TO USE THIS TECHNOLOGY HAVE FAILED, ESPECIALLY IN ACHIEVING ACCEPTABLE TRANSFER CHARACTERISTICS AND LONG-TERM PARAMETER STABILITY. PRELIMINARY THEORETICAL AND EXPERIMENTAL STUDIES HAVE YIELDED NEW METHODS OF OVERCOMING THESE PROBLEMS AND THE FIRST CONCEPTUAL PROTOTYPES HAVE BEEN BUILT AND SUCCESSFULLY TESTED. RESEARCH WOULD FOCUS ON PROVING THE FEASIBILITY OF A PRACTICAL IMPLEMENTATION OF A MOLECULAR ELECTRONIC SEISMOMETER WITH A CONSISTENT, BROAD FREQUENCY RESPONSE AND WIDE DYNAMIC RANGE. THESE INSTRUMENTS WOULD BE COMPACT, RUGGED (NO MOVING PARTS), VERY INEXPENSIVE, AND WELL FITTED FOR FIELD INSTALLATION (NO PRECISE EQUILIBRATION REQUIRED).