To monitor small earthquakes on the ocean bottom or in remote areas on land, a seismic recording system should operate at low power for extended periods of time, should reproduce three components of ground motion with a large dynamic range, and should preferably be small and inexpensive. We describe such a system based on an event detector, which continuously surveys the background noise, sets a threshold, and triggers an inexpensive digital tape recorder when a seismic signal exceeds that threshold. Event recording offers the advantages over conventional continuous recording of more efficient use of storage capacity and easier later interpretation. A key element of the system is a continuously updated semiconductor buffer memory, which assures that first arrivals are included. Average power consumption is about a watt. The system design is easily adaptable to monitoring other types of rare events of unpredictable occurrence.

First Page Preview

First page PDF preview
You do not currently have access to this article.