Study rules out speculation that Christchurch and Japan quakes were related

Ruling out laymen speculation on a connection between the earthquakes that have stuck nations across the world including the powerful ones that hit New Zealand and Japan in the recent past, a new study has found that large quakes do not cause powerful temblors in far away lands.

A new study from the Geographic Survey and the University of Texas has established that large quakes do set off aftershocks in the vicinity of up to 600 miles but have have no effect beyond that distance.

Published by the US Geological Survey (USGS), the study by Tom Parsons and Aaron Velasco of the US Geological Survey and the University of Texas at El Paso counters the existing contention that a large quake in one continent can unleash a quake in another.

With an aim to determine if large quakes triggered after-effects across the planet, the study was carried out on using data on earthquakes over the last 30 years. This included 205 earthquakes with a magnitude of over seven, and 25,222 moderate quakes with magnitudes of between five and seven.

On the checking if the moderate quakes could have been triggered by larger ones, the team found that while there was an increase in moderate quakes in the 24 hours following a large one, these all took place within 600 miles of the original quake. Majority of them were within 375 miles.

Based on this, the team concluded that regional hazard of larger earthquakes is increased after a mainshock, but the global hazard is not.

Although this is not a ground-breaking finding for seismologists, the report has been released at a time when there have been questions if the earthquakes across the globe were connected, especially the Christchurch earthquake and the subsequent 9.0-magnitude March 11 Japan quake.

Besides these two powerful quakes, countries such as China have been reporting moderate quakes in the recent past. As recent as Thursday, three earthquakes measuring between 7 and 5 in magnitude jolted Myanmar, flattening buildings and killing as many as 100.