Earthquake prediction, the Japanese way !

People continue to ask whether the time of upcoming earthquakes can be predicted accurately or not.
If you would surf the web, thousands of pages will be found with the weirdest theories on prediction signs for a major upcoming earthquake.
The reality of "when" is an easy answer : NO
The reality of "where" has a certainty of 95%. Most fault lines worldwide are mapped and scientist know very well most cities, areas and countries at risk. However as the  "when" cannot be answered, most of their predictions are waved away or are not taken seriously enough by most politicians and lawmakers.

Can't we do anything else to predict the shockwaves ?
Yes,  a little which is still better than nothing. Today's technology has to help us out.
How ? : An earthquake's P wave travels much faster through the earth. Depending on the strength of the earthquake and the distance of a certain point to the epicenter it will give us from tens of a second to almost 30 seconds preparation for areas at risk.

An example of a P-wave in a recent Iran earthquake measured at Ankara, Turkey

For the epicenter area, this P-wave delay is of NO value as the destructive shocks will arrive almost instantly.
For other cities and villages in the area, the saved time can be used to do some automatic things like stopping elevators the next floor, slowing down trains etc.
A viable system must be behind such automation.

Japan's JMA takes the lead in 2007 with their "Earthquake Early Warning" system

The Earthquake Early Warning system provides advance announcement of the estimated seismic intensities and expected arrival time of principal motion. These estimations are based on prompt analysis of the focus and magnitude of the earthquake using wave form data observed by seismographs near the epicenter.

The Earthquake Early Warning is aimed at mitigating earthquake-related damage by allowing countermeasures such as promptly slowing down trains, controlling elevators to avoid danger and enabling people to quickly protect themselves in various environments such as factories, offices, houses and near cliffs.

JMA's Earthquake Early Warning system - Courtesy JMA - Click on the picture to go to the JMA website

Graphics and some some text : courtesy Japan Meteorological Agency