Updated

Two strong aftershocks have rocked the western Greek island of Lefkada, where a 6.1-magnitude quake killed two people this week and caused extensive damage.

The Athens Geodynamic Institute said Friday's aftershocks were of magnitude 4.8 and 4.6 and struck under the sea off Greece's western mainland, 300 kilometers (186 miles) west of Athens. No injuries or damage were immediately reported.

Tuesday's initial earthquake severely damaged scores of buildings on Lefkada and nearby islands, and caused landslides that damaged Lefkada's road network.

Earthquakes are common in Greece, which is one of the world's most seismically active areas, though serious injuries and deaths are rare. A severe quake near Athens in 1999 killed 143 people and caused extensive damage throughout the Greek capital.