Debris in a general sense means man-made garbage. Debris is the scattered remains of something that is discarded or destroyed. There are many types of debris, depending on the context. When natural disasters happen, debris is the remains of destroyed buildings and land. In the context of geology, debris is the remains of geological activity such as landslides, volcanic eruptions, avalanches, and so on.
The average American produces garbage, also called trash, at the rate of four pounds per day per person, which translates to 600,000 tons per day, or about 220 million tons per year. This is almost twice the rate of trash generation per person as most other major countries. Trash levels can be reduced primarily by recycling, re-use, and reduced consumption.
Miller, 1989, Potential Hazards from Future Volcanic Eruptions in California: USGS Bulletin 1847