JAKARTA: A strong earthquake rocked eastern Indonesia on Friday, apparently knocking out communications on islands near the epicentre. Information on damage and injuries was not available due to the communication problems. Rescuers were being sent by sea to the area, Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho said. Indonesia's Meteorology and Geophysics Agency said the magnitude-6.6 quake had no potential to trigger a tsunami. The US Geological Survey measured the quake at 6.5 magnitude and said it was centered about 94 kilometres (58 miles) west of Waingapu, a coastal town on Sumba island in East Nusatenggara province, with a depth of 30 kilometres (19 miles). The quake was also felt on the tourist destination of Lombok island in neighbor West Nusatenggara province, causing people run out of houses and buildings in panic, he said. Sumba island is often hit by earthquakes that cause no significant damage since there are not many tall buildings and most homes are made of wood. The population in the closest areas to the epicentre is about 110,000. The world's largest archipelago, Indonesia is prone to seismic upheaval due to its location on the so-called Pacific 'Ring of Fire,' an arc of volcanoes and fault lines encircling the Pacific Basin. A monster temblor off Indonesia in 2004 triggered a tsunami that killed 230,000 people in a dozen countries. Most of the deaths were in Aceh province.