Two powerful aftershocks struck eastern Afghanistan 12 hours apart, triggering fears of more deaths and destruction on Friday in a region where earthquakes have killed about 2,200 people as rescuers battled mountainous terrain and harsh weather.

Survivors in the earthquake-prone region are scrambling for basic amenities as the United Nations and other agencies warn of a critical need for funds, food, medical supplies and shelter, with the World Health Organization seeking funds of $4 million.