The Nevado del Ruiz, also known as La Mesa de Herveo (Table of Herveo

Herveo

Herveo is a town and municipality in the Tolima department of Colombia. The population of the municipality was 10,292 as of the 1993 census....

) or Kumanday in the language of the local pre-Columbian

Pre-Columbian era

The pre-Columbian era incorporates all period subdivisions in the history and prehistory of the Americas before the appearance of significant European influences on the American continents, spanning the time of the original settlement in the Upper Paleolithic period to European colonization during...

 indigenous people

Indigenous peoples in Colombia

The indigenous peoples in Colombia comprise a large number of distinct ethnic groups who inhabited the country's present territory prior to its discovery by Europeans around 1500.-Origins:...

, is a volcano

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 located on the border of the departments

Departments of Colombia

Colombia is an unitary republic formed by thirty-two departments and a Capital District . Each department has a Governor and a Department Assembly , elected by popular vote for a four-year period. The governor cannot be re-elected in consecutive periods...

 of Caldas

Caldas Department

Caldas is a department of Colombia named after Colombian patriotic figure Francisco José de Caldas. It's part of the Paisa Region and its capital is Manizales. The population of Caldas is 1,030,062, and its area is 7,291 km²...

 and Tolima in Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, about 129 kilometres (80 mi) west of the capital city Bogotá

Bogotá

Bogotá, Distrito Capital , from 1991 to 2000 called Santa Fé de Bogotá, is the capital, and largest city, of Colombia. It is also designated by the national constitution as the capital of the department of Cundinamarca, even though the city of Bogotá now comprises an independent Capital district...

. It is a stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

, composed of many layers of lava

Lava

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 alternating with hardened volcanic ash

Volcanic ash

Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...

 and other pyroclastic rock

Pyroclastic rock

Pyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic...

s. Nevado del Ruiz has been active for about two million years, since the early Pleistocene or late Pliocene epoch, with three major eruptive periods.