As Geocosmo, we consider the so-called "Earthquake Early Warning" (EEW) to be a disingenuous effort to solve the serious problem of earthquake early warning. Developed and heavily promoted by a worldwide coalition of seismologists, it is a coordinated, well-funded, and widely hailed effort by the seismology community to instrument every known fault with seismometers linked to supercomputers. The estimated price tag is around 1 billion dollars. 

 

Already the chosen name, "Early Warning System" (EWS), is a shame. It has been borrowed from the Cold War era’s Early Warning System, which had been set up to detect the launch of Soviet intercontinental missiles in Siberia aimed at the United States.  The travel time of such missiles over distances of 5,000 to 10,000 km is on the order of 5-10 min. Early detection of a launch would have therefore provided the US Military some valuable time to initiate countermeasures.  

 

The situation with earthquakes is entirely different.  They occur locally, literally under the feet of the people who are at the highest risk of being affected by the humongous power of seismic waves.  With distance, the risk of damage decreases.

 

The seismological Earthquake Early Warning system is little more than a glorified Earthquake Announcement system.

 

The seismological EEW works as follows: When an earthquake hits, computers will determine whether this is just a local tremor or the beginning of a "big one".  Under the very best of circumstances (earthquake focus at 10-30 km depth along a well-instrumented fault on land) the minimum time to make this determination is quoted to be 5 seconds. Under more realistic circumstances, if an earthquake occurs along an unknown fault (like 1989 Loma Prieta and 1994 Northridge did, just to name two events in California) or far offshore, the minimum time can be expected to be more like 10 sec, even 20-30 seconds.

 

Earthquake primary waves, the P waves, propagate at velocities around 6 km/second, but they don't do much damage.  Secondary waves, S waves, which do the damage, propagate at around 3.5 km/second.

 

In 5 seconds the S waves will have traveled about 17.5 km, 10 seconds, about 35 km, and in 20 sec about 70 km.  Hence, anybody who lives within striking distance of a rupturing fault will get ZERO seconds of "early warning". This is the "blind zone", which the seismologists politely – but systematically – forget to mention in their promotional material. Seismologists like to talk about 10 sec "early warning", even 1 to 1 ½ minutes.  Simple arithmetic tells us that, to get 60 seconds of advanced warning, you have to be 200 km or more from the rupturing fault.  At that distance, the risk is normally low (except in special cases such as Mexico City, built on a shaky water-saturated lakebed, under threat of severe damage from major earthquakes in the Pacific Ocean some 280 km away). Thus the need for early warning decreases.

 

The advocates of the EEW have created an impressive video, which depicts a magnitude 8 earthquake starting in Northern Mexico and causing a rupture that reaches to Los Angeles. In this scenario, which has a probability around 1: 10,000,000 to ever become reality in our lifetimes, the inhabitants of Los Angeles will get 60 seconds, maybe even 90 seconds warning. It is much more realistic to expect the next major earthquake in California or in most other seismically active zones of the world, including Turkey, to occur along a nearby fault and within the striking distance of the S waves inside a “Blind Zone”. Bad luck for all locations less than 20 to 60 km away… they can expect 0 seconds “early warning” or 0 to 10 seconds at best.  

 

In the San Francisco Bay Area and Silicon Valley in California, there is no point more than 15 km from either the San Andreas Fault or the Hayward Fault. The Hayward Fault is expected to be the next one "to go".  90% of the SF Bay Area is inside the blind zone.  Something similar is true for the heavily populated, heavily industrialized region of Northern Turkey, including Istanbul. 

 

Yes:  Japan has a seismological EEW.  Mexico has it too.  But there the tectonic situations are different.  In both countries, magnitude 8's to even 9's occur along their subduction zones some 100-150 km offshore. In Mexico, the special situation is that Mexico City is built on the water-saturated lakebed of the Aztec capital. Though Mexico City is 280 km from the coast, in the 1980s a magnitude 8 event caused havoc there. Thus, in the case of Mexico City, the Earthquake Announcement System can indeed provide 1-2 min early warning that S waves are coming. 

 

For California and most of the rest of the world (including Japan, which is riddled with strike-slip faults on land), the EWS is a total rip-off – unless it is combined with a modern true Earthquake Forecast System, the can alert of increased seismic risk 2-3 days before the disaster strikes.