Geography of Indonesia is responsible for the creation of the Sunda Trench, and mountain ranges across Sumatra, Java, and the Lesser Sunda Islands. Many great earthquakes occurred in the vicinity of the fault, such as the 2004 Indian Ocean earthquake. Mount Merapi, located in the Java portion of the megathrust, is the most active volcano in Indonesia and is designated as one of world's Decade Volcanoes due to the hazard it poses to the surrounding populated areas. The northern part of Sulawesi and Maluku Islands lie on the convergence of Sunda Plate and Molucca Sea Plate, making it an active tectonic region with
Mariana Trench during the "Challenger" expedition in 1875, using a weighted rope, which recorded a depth of . In 1877, a map was published called "Tiefenkarte des Grossen Ozeans" ("Deep map of the Great Ocean") by Petermann, which showed a "Challenger Tief" ("Challenger deep") at the location of that sounding. In 1899, USS Nero, a converted collier, recorded a depth of . In 1951, "Challenger II" surveyed the trench using echo sounding, a much more precise and vastly easier way to measure depth than the sounding equipment and drag lines used in the original expedition. During this survey, the deepest part of