principles and applications of microearthquake networks

3. Data Processing Procedures
Microearthquake networks are designed to record as many earthquakes
as nature and instruments permit, and they can produce an immense
volume of data. For small microearthquake networks in areas of relatively
low seismicity, data processing should not be a problem. But for small
networks in areas of high seismicity, or for large microearthquake networks,
processing voluminous data can be a serious problem. For example,
the USGS Central California Microearthquake Network generates
about I@" bits of raw observational data per year. This annual amount is
equivalent to a few million books, or the holdings of a very large library.
Compared with a traditional seismological observatory, a microearthquake
network can generate orders of magnitude more data. The general
aspects of the data processing procedures do not differ greatly
between these two types of operations. However, the larger volume of
microearthquake data requires careful planning and application of modern
data processing techniques.
For traditional seismological observatories, a manual of practice containing
much useful information is available (Willmore, 1979). Some of
this information can be applied to the operation of microearthquake networks.
A comparable manual of practice for microearthquake networks is
not known to us at present. In this chapter, we are not writing a manual of
practice for microearthquake networks, but rather discussing some of the
problems and possible solutions in processing microearthquake data. In
the following sections, we discuss first the nature of data processing and
then some of the procedures for record keeping, event detection, event
processing, and basic calculations.
3.1. Nature of Data Processing
Many scientific advances are based on accurate and long-term observations.
For example, planetary motion was not understood until the seven-