(added on 2011/04/07)
Moving plates, shaking ground 板塊移。地殼動
Earthquake is a phenomenon in nature which tends to cluster in some parts of the world. Globally, several million earthquakes are estimated to have occurred every year. Many of these hit remote areas or may be too small in magnitude to be appreciated.
The map shows the distribution of earthquakes of magnitude 4.0 or higher on the Richter scale detected between 2008 and March 2011. As indicated by coloured dots, most earthquakes occurred along the boundaries of plates. Referred as "Pacific Ring of Fire", the lands encircling Pacific Ocean are zones of frequent earthquakes and volcanic eruptions. The exact time and epicentre of earthquakes cannot be easily predicted. To protect lives and reduce damages, it is crucial to enhance understanding of earthquake risks, improve engineering design and uphold preparedness.
Data for the map were obtained from U.S. Geological Survey (USGS) and Environmental System Research Institute (ESRI).