The island of Guam is 30 miles (50 km) long and 4 to 12 miles (6 to 19 km) wide, 3⁄4 the size of Singapore. 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 Anatahan volcano in the Northern Mariana Islands, Guam is not volcanically active. However, due to its proximity to Anatahan, vog (i.e. volcanic smog) does occasionally affect Guam.