AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. The Future of the Very Broadband Sensor S. Ingate (IRIS) J. Berger (UCSD) J. Collins (WHOI) W. Farrell (SAIC) J. Fowler (IRIS) P. Herrington (DoE) R. Hutt (USGS) B. Romanowicz (UCB) S. Sacks (Carnegie) F. Vernon (UCSD) E. Wielandt (Stuttgart)

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. The future of the VBB sensor Should we worry? Yes!

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. The VBB sensor is the cornerstone of the GSN Current research includes: “Hum” (fundamental mode peaks 2-7 mHz) Low & odd degree elastic structure (e.g., density, Q, etc) from free oscillations Tomographic models at level 2 & 4 heterogeneity from normal modes Lower mantle lateral density variations Rate of relative motion of inner core

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. The Challenge

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Workshop! Broadband Seismometer Workshop Granlibakken Conference Center Tahoe City, California March 24-26, attendees Govt, industry, academe, NGOs US, Germany, Japan, Canada, France, UK, Russia Seismologists, physicists, engineers, inventors, managers, owners

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Breakout Group I Requirements, Needs, and Wants Geophysical (bandwidth, dynamic range, self-noise) Borehole or vault design? Life-cycle of system? Packaging (power, size, shape, operating temps) for different environments and survivability How many will be needed? By whom (e.g., GSN/FDSN, regional networks, Universities, etc)? What is threshold of pain for manufacturing cost? Use new technology, or is the triaxial still OK?

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. observatories (< to ~0.01 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.  need borehole instruments for ocean floor and islands  need to better understand noise in this band Intermediate band (~ Hz) 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 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 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 XX units over YY years

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Breakout Group II New Ideas, Concepts, and Designs Gather a summary of new ideas What is their potential? How much will it cost to develop? How long? Can they be manufactured reliably? At what cost? Other factors such as reliability, OBS use, O&M costs? Do they need to be complimented with other sensors? Life-cycle of components? Will they be unrepairable in 10 years?

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Breakout Group III Testing and Testing Facilities Who/where are current testing facilities? How to test new designs (e.g. SCG, laser designs, etc)? What is required to upgrade test facilities to support new designs? Should test data be made public? What are we missing (durability?

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Breakout Group IV Academic/Industrial Partnerships Who are the key players? What is an appropriate relationship? Who would be interested? If a graduate program in sensor design was develop, would industry be interested? How could they contribute? Cross-market utilization? Other programs such as NEES, LIGO, SLA?

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Breakout Group V Educational Perspectives and Funding Strategies Develop road-map for long-term research Which funding agencies to target? If NSF, how to engage ENG/GEO/OCE? Use of matched funding? Develop graduate program in sensor design. How to encourage industry to participate? Scale of graduate program? Duration, number of students, cost? Can new designs be used in other educational programs? Schools?

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Optical Displacement Transducers (Zumberge et al) Optical Tiltmeter (Araya) Laser Strainmeter (Araya) Laser Interferometer Seismometer (Araya) LIGO (DeSalvo) Michelson interferometer & pendulum designs have self- noise below NLNM 50mHz Hz. Also horizontal long-baseline strainmeter. Gravity wave detectors measure 10e-18 m.

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Other Technologies Magnetic Levitation By isolating barometric effects, should approach STS2 Folded Pendulums Used in accelerometers and gravity- wave detectors; need to minimise elastic contributions of flexures Ring Laser Gyro Installed at Black Forest, New Zealand and soon Pinon Flat, used to detect variations in G. UCSD will evaluate. Martian Seismometers Triaxials on a weight diet 20 cm Normal Pendulum Inverted Pendulum Payload Frame Flexures / Hinges

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Other Technologies II MEMS Full-scale 2 m/s/s, noise floor of 30x10e-9 g/√Hz, $ axis Electrochemical (MET) No springs, could be extended to 1000 sec with new “soft” membrane. Convective diffusion of electrolyte between electrodes is converted to electric current. Hydraulic impedance analogous to Nyquist noise of resistor. Superconducting Gravimeter Less noise than STS-1 (5e-3 nm/s), vertical, $100,000

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. Emerging Technologies SQUID Displacement Detector Superconducting Quantum Interference Devices offer 100 x sensitivity than capacitive devices. SLAC Strainmeter Uses 200 remote-controlled fresnel lenses along a 3 km light tube to detect deformations over its length. Available for experiments. Quartz Seismometer Suspension Operate in magnetic environments (SLAC), close to STS-2 performance Atomic Fountains Cold atom fountains have accuracy of 10e-9 G, need to scale for geophysical measurements Ferro-Fluid Suspension Suspends magnetic mass to measure ground velocity. Needs to incorporate force- feedback

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. What next? Report to NSF Arrange for a presentation to NSF Officers Within IRIS, continue to monitor emerging technologies Continue dialog between IRIS, NSF, industry and international partners

AFRL Review, Sep 2004 The Future of the Very Broadband Sensor S. Ingate, et al. More Information?