Spain's National Geographical Institute says the Canary Island of El Hierro has been rocked by more than 50 tremors in 24 hours, two years after a new volcano began to appear off its southern coast. So far the resurgent seismic activity has caused no damage, a regional government spokeswoman said Monday. She spoke on condition of anonymity because she was not authorized to be identified in the media. The last time the nascent volcano rattled the island the government evacuated the port of La Restinga, banned aircraft from flying over the southern tip and ordered ships to avoid the area. At one point residents could see smouldering volcanic rocks spewing from the sea. El Hierro has some 11,000 residents and was originally formed by volcanic activity.