The island of Guam is 30 miles (48 km) long and 4 mi (6 km) to 12 mi (19 km) wide. The island experiences occasional earthquakes due to its location on the western edge of the Pacific Plate and near the Philippine Sea Plate. In recent years, earthquakes with epicenters near Guam have had magnitudes ranging from 5.0 to 8.7. Unlike the Anatahanvolcano in the Northern Mariana Islands, Guam is not volcanically active.17 - However, due to its proximity to Anatahan, vog does occasionally affect Guam.18 - A coral table reef with deepwater channels surrounds most of Guam. Sandy beaches, rock cliff lines and mangroves characterize the coastline area. Sheer limestone coastal cliffs dominate the north, while the southern end of the island is mountainous, with lower hills in between. 19 -