A strong quake in the sea off Crete yesterday morning was felt throughout southern Greece but caused no injuries or damage to property. The earthquake registered 6.3 on the open-ended Richter scale, and occurred at 7.21 a.m. some 40 km (25 miles) south of Crete, 330 km (205 miles) southeast of Athens, at an estimated depth of 20-25 km, seismologists said. According to Gerasimos Papadopoulos, head of research at the Athens Geodynamic Institute, the quake, which was felt as far north as Attica and the Ionian islands, occurred where the European and African tectonic plates meet. «The area is highly seismic, but this activity is generally not unusual and does not appear to pose any particular problems,» he said. Although the quake lasted a full 30 seconds, according to officials on Crete, no damage was reported. Meanwhile, at 2.32 p.m., a tremor that registered 3.5 on the Richter scale occurred some 20 kilometers (12.4 miles) northwest of Athens, along the same fault that produced a 5.9-Richter quake in September 1999, which killed 143 people in the city.