During a seismic survey, shots located close to one another are fired at a time interval shorter than an echo time interval and longer than a closest receiver time interval. During the echo time interval which follows a first shot, receivers located within a predetermined distance from the first shot location detect seismic reflections related to the first shot. During the closest-receiver time interval which follows the first shot, at least one seismic receiver located closest to the first shot location detects all the reflections from the first shot reaching this seismic receiver.