It is said that an evil thing never comes alone.

That's true at least for the earthquakes as a new research brought the strongest evidence yet that they can wake up dormant volcanoes.

An early warning signal predicting imminent eruptions would save thousands of lives.

These phenomena originate both from deep within Earth's surface.

Earthquakes are triggered by collisions between tectonic plates moving over the Earth's mantle, which is the producer of the lava expelled through the volcanoes.

That's why finding that the two geological events are interconnected might not be such a great surprise.

Several previous events recorded during the XX century fueled the concept linking these two phenomena.

The 1975 Hawaii's Kilauea Volcano blast sparked less than an hour after an earthquake hit a few kilometers away.

In a similar fashion, Cordon Caulle volcano in Chile threw to the air its top following a 2 day before major earthquake located 240 kilometers away.

With all these observations, till recently, there was no scientific proof binding volcano activity and earthquakes.

This situation changed in May 2006 when by chance, a team of geologists formed by Andrew Harris of the University of Hawaii at Manoa and Maurizio Ripepe of the University of Firenze in Italy were investigating two active Indonesian volcanoes, Merapi (below) and Semeru (above).

The geologists were making a thermal mapping, monitoring the temperature and the speed of lava inside the volcanoes aided by satellite imagery.

On the 16th day of the investigation, a 6.4-magnitude earthquake hit the Java Island.

The quake was located 50 kilometers (30 miles) from Merapi, 280 (170 miles) from Semeru.

After only 3 days, the magma flowing inside both volcanoes increased twice its temperature and speed.

"This enhanced activity lasted for more than a week. The volcanoes are too far apart to influence each other," said Harris.

This lets as the only possible triggering factor for the volcanoes' increased activity the quake, probably due to a "the toothpaste model": underground pressure induced by earthquakes and their aftershocks pushed magma upward, sparking volcanic eruptions.

"It's the first quantitative measure of an increase in activity from thermal mapping," says Emily Brodsky, a seismologist of University of California, Santa Cruz.

"It's a real step forward."