Earthquake Early Warning from Cheap Accelerometers: An Honest Latency-and-Geometry Budget, a Blind Zone, and a Priced Verdict

SIMULATED, NOT MEASURED design/bound study. From P- and S-wave speeds, stated latency budgets, and MEMS noise floors (phone-grade and ~US$100 dedicated nodes), this paper computes the warning time a low-cost earthquake early warning network delivers versus epicentral distance, magnitude, and node density; derives blind-zone radii of about 15 km (dedicated) and 25 km (phone) inside which no warning is possible at any density; shows node density past ~1 per 100 km2 buys almost no time; and costs the false-alarm rate of fast triggering in the same arithmetic. All numbers reproduce from the archived compute script.