The geologically active Ballenas Fault runs along the seabed of the linear Canal de Ballenas. A 6.9 magnitude earthquake occurred on this fault in 2009.
Geography
The island is extremely dry, with no sources of freshwater other than washes following rainfall. It has an area of 931 square kilometers (359 sq mi) and a chain of mountains runs along its 69 km length, reaching a maximum of 1,305 m (4,281 ft) above sea level. It runs northwest to southeast. The west coast is roughly straight in that direction, but the east coast runs inward near the middle before heading outward until it reaches the island's widest point. The coast then runs south for a while before finally returning to its southeasterly direction.
Topographic map of the area around Isla Ángel de la Guarda
Much of the island is inaccessible due to mountains at or near the shore, especially on the west coast. There are a few flat areas on the coast at the outlets of washes that were created by sediment. These alluvial fans are mostly on the east coast, but a large one is found on the west coast where the island narrows in the middle. Much of the island's geology is made up of volcanic and alluvial sand deposits.[1]