I have added the pictures found from another source
Answer and explanation:
If we compare the images, we will realize that there was a little or no vegetation in 1983. However, in 1989, there were shrubs or some plants growing. As mentioned in the statement, there was an eruption in 1980 and so the conditions were not favorable for plants to grow even after 3 years. However, in 6 more years, there was a slow plant growth because the harsh environmental conditions were diminshing and favorable conditions started developing. This process of slow growth has been recognized as a Ecological Succession in biology.