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Requirements, needs, wants: • There is an impending CRISIS in the low frequency seismological research community now that the STS1 seismometer is no longer manufactured: there is a danger of losing the capability to capture unique information about the Earth. (What makes the STS-1 unique? Instrument noise at frequencies below ~ 10-2 Hz • We also want to take advantage of opportunities to go beyond what we can now record to resolve even lower amplitude signals.
Requirements, needs, wants: • We can resolve most signals of seismological interest for frequencies above about 1 Hz at most sites with existing, readily available seismometers. (With the possible exception of NE detection.) • For frequencies below about 0.05 Hz, we need to seismometers capable of resolving signals perhaps at or below the currently observed noise background.
Requirements, needs, wants: • wish to resolve true ground noise throughout band (note LNM (??) not well known at frequencies above a few Hz). • want to record 6 components of motion (rotation as well as translation)(see Langston eg) (near field)
Requirements, needs, wants: @ observatories (<10-4 to ~10-2 Hz) • There are ~ 200?? observatory class stations now extant • less sensitive to cost • very sensitive to noise floor • better recording of horizontal motion esp compensating for tilt -( better installation techniques & new types of instrumentation) • need both vault and borehole instruments for existing observatories.
Requirements, needs, wants: @ observatories (<10-4 to ~10-2 Hz) (cont) • need borehole instruments for ocean floor and islands • need to better understand noise in this band
Requirements, needs, wants: Intermediate band (~10-2 -20Hz) • includes both observatory and portable sensors (separate) • need lower noise performance above ~ 1 Hz • prefer compact packaging for ease of deployment for portable versions • need to track metadata (location, orientation) • more price sensitive • Total of XX units over yy years
Requirements, needs, wants: High Frequency (EQ Engineering) • place in high cultural noise background • Data acquisition system included • need greater sensitivity than now exists • very price sensitive (need <$1K/channel) • low gain velocity sensor desirable • continuous recording
Requirements, needs, wants: Above ~20 Hz • cheap, stable, rugged, watertight, quiet(er) • more sensitive than MEMs now offers (at least 10 dB lower - what resolution ?) • want to use in arrays and still be cost effective xxx units over yy years