A low-cost, ANSS class B, networked Accelerometer
for Earthquake Early Warning
A 2013 study commissioned by the Insurance Bureau of Canada  suggests that an earthquake causing significant damage may occur with a chance of roughly 30 % within the next 50 years. Current efforts in the Province of British Columbia focus on the early detection of Cascadia subduction events with a small number of high sensitivity strong motion seismometers and GNSS instruments at relative large inter-station distances. This network could be supplemented with less sensitive accelerometers to increase station density in particular in urban areas and to address crustal earthquakes which can occur anywhere in south-western BC and Haida Gwaii.
Any low-cost instrument in this network should not transmit full
waveform data to a central facility for processing and analysis but
should compute relevant parameters on-line, on-site and in real
time by means of an integrated (embedded) computer system. Only EEW
relevant parameters are transmitted to a warning centre. This will
reduce system latencies substantially.
We have built a prototype of a low-cost strong motion seismometer
and have implemented capabilities from established methods and
technologies, focused on what has been achieved in California and the
European Union Framework Program projects "SAFER"
and "REAKT". We use a
software architecture where future extensions are possible.
- Versatile: 3-axis accelerometer, digitizer, recorder in
- Small: Form-factor suitable for a pressure-case or
- Low power: Long operation on UPS in case of line-power loss
- Sensitive: Self noise ≈ 50μg RMS in 50 Hz
- Smart: On board real-time EEW signal processing
- Networked: Internet telemetry, NTP/PTP time synchronization
- Fast: Direct, real-time reporting of EEW relevant events
- Options: Relay output for On-Site warning [Zollo et al., 2010]
- Full backward compatibility: Will fit seamlessly into
existing MoT-I/GSC BCSIMS S/M network.
Specifications of a Prototype/Proof-of-Concept and First Test
Figure 1: Computer and Accelerograph in one small package
- 3 othogonal MEMS sensors, Silicon Designs, range ±2.0 g, sensitivity ≈
- Physical dimensions: 10 cm x 6 cm x 6 cm
- Power consumption: ∼ 1.8 W
- Self noise 60 μg (0.06 cm/s2) RMS in 50 Hz (analog 90
- Embedded system ARM6/ARM7 CPU, OS: Linux
- Digitizer 18 ENOB (108 dB), time multiplex, slew < 40 μs
- Relay output for control of external electrical device
- On-board continuous data storage, ∼ 30 days, miniSEED format
- Real-Time P-wave detection via Polarization Analysis (,,,),
real-time UC-Berkeley τp, Pd computation (,,,,,)
- P-wave detection time (mili-second precision), event parameters τp,
reporting via UDP Syslog protocol
- Compatible with BC MoT-I/GSC BCSIMS S/M network, adaptable to ONC's WARN/EEW network.
- Estimated costs, not including enclosure and external
power-supply/UPS: < 2,500 Can$
Figure 2: Schematic embedded system, real-time signal processing.
Yellow labels mark backward compatibility units, red labels mark EEW
specific signal processing ,,,,. A general purpose input/output (GPIO)
can steer a relay. On-site alert levels for Pd and τp
are from 
Study of impact and the insurance and economic cost of a major
earthquake in British Columbia and Ontario/Québec, October 2013.
Commissioned by the Insurance Bureau of Canada.
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