World Geography Profile

land area about 16 times the size of the US

the land boundaries in The World Factbook total 279,035.5 km (not counting shared boundaries twice); two nations, China and Russia, each border 14 other countries

note 1: the total is actually misleading in terms of accuracy, since one cannot accurately measure every river meander along a boundary; a number rounded slightly higher - to 280,000 km - makes more sense and has been coordinated with and approved by the US State Department

note 2: 46 nations and other areas are landlocked, these include: Afghanistan, Andorra, Armenia, Austria, Azerbaijan, Belarus, Bhutan, Bolivia, Botswana, Burkina Faso, Burundi, Central African Republic, Chad, Czechia, Eswatini, Ethiopia, Holy See (Vatican City), Hungary, Kazakhstan, Kosovo, Kyrgyzstan, Laos, Lesotho, Liechtenstein, Luxembourg, Macedonia, Malawi, Mali, Moldova, Mongolia, Nepal, Niger, Paraguay, Rwanda, San Marino, Serbia, Slovakia, South Sudan, Switzerland, Tajikistan, Turkmenistan, Uganda, Uzbekistan, West Bank, Zambia, Zimbabwe; two of these, Liechtenstein and Uzbekistan, are doubly landlocked

note 3: worldwide, some one-quarter of interior (non-coastal) borders are rivers; South America with 43% leads the continents, followed by North America with 32%, Africa with 30%, Europe with 23%, and Asia with 18%; Australia has no interior national river borders

a variety of situations exist, but in general, most countries make the following claims measured from the mean low-tide baseline as described in the 1982 UN Convention on the Law of the Sea: territorial sea - 12 nm, contiguous zone - 24 nm, and exclusive economic zone - 200 nm; additional zones provide for exploitation of continental shelf resources and an exclusive fishing zone; boundary situations with neighboring states prevent many countries from extending their fishing or economic zones to a full 200 nm

large areas subject to severe weather (tropical cyclones); natural disasters (earthquakes, landslides, tsunamis, volcanic eruptions)

volcanism: volcanism is a fundamental driver and consequence of plate tectonics, the physical process reshaping the Earth's lithosphere; the world is home to more than 1,500 potentially active volcanoes, with over 500 of these having erupted in historical times; an estimated 500 million people live near these volcanoes; associated dangers include lava flows, lahars (mudflows), pyroclastic flows, ash clouds, ash fall, ballistic projectiles, gas emissions, landslides, earthquakes, and tsunamis; in the 1990s, the International Association of Volcanology and Chemistry of the Earth's Interior, created a list of 16 Decade Volcanoes worthy of special study because of their great potential for destruction: Avachinsky-Koryaksky (Russia), Colima (Mexico), Etna (Italy), Galeras (Colombia), Mauna Loa (United States), Merapi (Indonesia), Nyiragongo (Democratic Republic of the Congo), Rainier (United States), Sakurajima (Japan), Santa Maria (Guatemala), Santorini (Greece), Taal (Philippines), Teide (Spain), Ulawun (Papua New Guinea), Unzen (Japan), Vesuvius (Italy); see second note under "Geography - note"

note 1: the world is now thought to be about 4.55 billion years old, just about one-third of the 13.8-billion-year age estimated for the universe; the earliest widely accepted date for life appearing on earth is 3.48 billion years ago, but this date is conservative and may get pushed back further

note 2: although earthquakes can strike anywhere at any time, the vast majority occur in three large zones of the earth; the world's greatest earthquake belt, the Circum-Pacific Belt (popularly referred to as the Ring of Fire), is the zone of active volcanoes and earthquake epicenters bordering the Pacific Ocean; about 90% of the world's earthquakes (81% of the largest earthquakes) and some 75% of the world's volcanoes occur within the Ring of Fire; the belt extends northward from Chile, along the South American coast, through Central America, Mexico, the western US, southern Alaska and the Aleutian Islands, to Japan, the Philippines, Papua New Guinea, island groups in the southwestern Pacific, and New Zealand

the second prominent belt, the Alpide, extends from Java to Sumatra, northward along the mountains of Burma, then eastward through the Himalayas, the Mediterranean, and out into the Atlantic Ocean; it accounts for about 17% of the world's largest earthquakes; the third important belt follows the long Mid-Atlantic Ridge