Local Taliban officials said 100 had died in the 6.3 magnitude quakes, however the UN gave a preliminary figure of 320 deaths.
Local official Mohammad Abdullah Jan said four villages in the Zenda Jan district in Herat province bore the brunt of the quakes and aftershocks.
Video posted online showed rubble where houses once stood.
The Taliban have urged local organisations to reach earthquake-hit areas as soon as possible to help take the injured to hospital, provide shelter for the homeless, and deliver food to survivors.
They said security agencies should use all their resources and facilities to rescue people trapped under debris.
The United States Geological Survey reported the 6.3 magnitude tremblors. It said the epicentre was 40 kilometres northwest of Herat city. There was an aftershock with a 5.5 magnitude.
A map on the USGS website indicates seven earthquakes in the area. At least five powerful earthquakes struck the city around noon, Herat city resident Abdul Shakor Samadi said.
“All people are out of their homes,” Samadi said. “Houses, offices and shops are all empty and there are fears of more earthquakes. My family and I were inside our home, I felt the quake.” His family began shouting and ran outside, afraid to return indoors.
The World Health Organisation in Afghanistan said it dispatched 12 ambulance cars to Zenda Jan to evacuate casualties to hospitals.
Telephone connections went down in Herat, making it hard to get details from affected areas. Videos on social media showed hundreds of people in the streets outside their homes and offices in Herat city.
Herat province borders Iran. The quake also was felt in the nearby Afghan provinces of Farah and Badghis, according to local media reports.
Abdul Ghani Baradar, the Taliban-appointed deputy prime minister for economic affairs, expressed his condolences to the dead and injured in Herat and Badghis.