A bit of notice of an impending tremor need not be restricted to rich countries

IN THE early second century AD, the ingenious "earthquake weathervane" of Zhang Cheng (PIC AT LINK), a Chinese engineer and polymath, released a metal sphere indicating the direction of an earthquake. That could happen days before a hand-carried confirmation of a far-flung tremor would arrive. But what neither that first seismometer nor any produced since can do is predict quakes. All seismologists have now is a tiny bit of early warning, and a study out this week suggests how to make the most of that precious window of time.

[link to www.economist.com]