Earthquake experts confirmed Thursday that the vibrations felt in Tibet were caused by the strong quakes shaking northern Sumatra, and has little connection with any geological movement within China.

"It's normal to feel tremors in China's Tibetan areas because this is a result of the high-magnitude of the earthquakes which hit in Indonesia on Wednesday," said Jiang Haikun, vice director of the China Earthquake Networks Center (CENC) forecast department.

But he said further research is needed to explain why people in Yunnan and Guangxi, both comparatively closer to the epicenter, felt no tremor.

As to whether tremors were felt or not, the key factor lies in the radiative direction of the seismic energy, he added. "Although the local geological environment and the individuals' sensory ability are also factors."

For some deep-seated quakes, no tremor is be felt at the epicenter areas but can be felt further away, Jiang explained.

As to why the massive quake didn't trigger a deadly tsunami, Jiang said it was to do with the way the tectonic plates moved. The plate movement was horizontal, rather than vertical, which is why the damage was more limited.