Complex sentence: Of these eruptive vents escaped from lava basalt which sometimes reaches the sea on the east, north and west sides of the volcano and some of which are still visible as few recolonized by tropical vegetation on the island.
Split into simpler sentences: Of these eruptive vents, lava basalt escapes sometimes reaching the sea on the east, north and west sides of the volcano. Many lava flows are still visible as few are rapidly recolonized by tropical vegetation on the island.