As they continued along the driveway that would take them to the road leading through the forest, they heard a loud grumbling noise, as if tectonic plates were grinding against each other.
This belt straddles the area in which the Arabian tectonic plate of the earth's crust is grinding gradually northeastward, from half an inch to five inches a year, and colliding with the larger Eurasian plate.
The quake near Kobe was ordinary in that it was part of the age-old process in which oceanic plates grind past one another near Japan to produce earthquakes, volcanoes and the huge waves known as tsunamis.
As it was still on its knees, the plates covering most of the beast's stomach slid out to its sides-gurgling and grinding like a breaking nose, but repeated a hundred times.
Some plates grind past one another while others crash head-on in such a way that one plate dives beneath the other, generating especially devastating earthquakes.
Driven by hot, upwelling fluids, the plates grind past one another at a rate of two to four inches a year, creating vast fault zones that produce earthquakes.
Colliding plates grind past one another about as fast as fingernails grow.
The colliding plates grind past one another about as fast as fingernails grow and over time produce mountains and swarms of earthquakes as frictional stresses build and release.
The frequency and intensities of sand pile avalanches closely match the patterns seen in earthquake activity as tectonic plates continuously grind against each other, said Per Bak, a Brookhaven theorist.
In a state with great college basketball and little else in the way of nationally ranked sports, the tectonic plates of the Husky men and Husky women grind perpetually against one another.