COTALO, Ecuador (Reuters) -- Tungurahua, or "Throat of Fire" in the
                  Quechua Indian language, rumbled and rained ash on Monday, raising
                  fears of an eruption in the near future that could pour lava into one of
                  Ecuador's top tourist attractions.

                  Many of the 20,000 residents of nearby Banos, about 105 miles (170
                  km) south of the capital, Quito, evacuated their homes on Sunday, while
                  authorities monitored the volcano and began preparing on Monday to
                  evacuate 162 animals from a zoo.

                  With its hot springs and waterfalls tumbling down green slopes, Banos is one
                  of Ecuador's biggest tourist attractions. Just below the equator but at 5,900
                  feet (1,800 meters) above sea level, it enjoys a crisp climate of eternal spring
                  and a spectacular view of snowcapped Tungurahua.

                  Tungurahua began to rumble in September and last erupted in 1918, when locals
                  fled wearing wooden bowls on their heads to protect against falling rocks.

                  It towers 15,060 feet (5,020 meters) above sea level and is one of
                  Ecuador's 31 active volcanoes. Tungurahua has erupted 81 times in the past
                  3,000 years. Scientists say the volcano erupts about every 100 years and
                  lava could flow over a ridge into parts of Banos.

                  Scientists declared an "orange alert" on Saturday for Tungurahua, meaning
                  Banos and residents of other villages on the volcano's slopes must move.

                  At dawn on Monday, Tungurahua belched a dense column of ash and vapor
                  that could be seen 25 miles (40 km) away.

                  "All the conditions are ripe for an imminent eruption," said volcanologist
                  Patricia Mothes of Ecuador's Geophysical Institute.

                  Fellow volcanologist Minard Hall said, "There's no doubt there will be an
                  eruption."

                  Volcanologists said there was an 80 percent chance Tungurahua would
                  erupt, but they could not pinpoint when.

                  Armed troops controlled the movement of people and cars around Cotalo
                  to turn away the curious and discourage pillaging in the abandoned towns.

                  The volcano "hasn't stopped throwing up ash, it seems it's increasingly
                  active," a soldier told Reuters at Cotalo in increasingly cold weather.

                  Banos seemed like a ghost town on Monday after most residents went to
                  Ambato about 25 miles (39 km) from Tungurahua. But experts said that city
                  of 173,000 could be showered with ash depending on the wind's direction.

                  Only a few weeks ago, about 2,000 people living near Quito were forced to
                  evacuate their homes due to the possibility that the nearby Guagua Pichincha
                  volcano could erupt. Quito, a city of 1.2 million people, is surrounded by
                  nine volcanoes, and Guagua Pichincha has begun to shower it with ash.