Residents of the affected areas were caught off guard by the quake because the region is not considered seismically active. Gu Guohua, from the Institute of Earthquake Science under the China Earthquake Administration, said the rarity of earthquakes in the region meant most homes were not built to withstand quakes. 'Local people do not have a good understanding of how to survive earthquakes, unlike in north China. Houses were mostly only built with one layer of bricks, so it is no surprise that many collapsed,' Professor Gu said. Though it was a medium-sized quake, Professor Gu and other experts noted that it occurred relatively close to the surface, which heightened its effects. His colleague at the institute, Wang Xiaoqing , said the impact of an earthquake depended on its strength, geological features and conditions on the Earth's surface. 'An earthquake measuring 5.7 on the Richter scale can only be regarded as a medium earthquake, but its impact was big for a quake that size,' he said. 'It happened on Saturday morning, when most people were indoors.' Professor Gu said predicting earthquakes remained a difficult task worldwide. 'Researchers may observe some phenomena before an earthquake, but it is very difficult to judge how big it will be and when it will happen,' he said He said China's earthquake knowledge did not lag behind other countries, but investment in the field was limited. 'However, a big investment in earthquake research does not necessarily lead to results,' Professor Gu said. Jiangxi was last hit in 1987, when a 5.5-magnitude quake struck. Although China has frequent earthquakes, they are mainly seen in the west, southwest and north.