Karthala is an active 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...

 and the highest point of the Comoros

Comoros

The Comoros , officially the Union of the Comoros is an archipelago island nation in the Indian Ocean, located off the eastern coast of Africa, on the northern end of the Mozambique Channel, between northeastern Mozambique and northwestern Madagascar...

 at 2361 m (7,746 ft) above sea level. It is the southernmost and larger of the two shield volcano

Shield volcano

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...

es forming Grande Comore

Grande Comore

Grande Comore is an island in the Indian Ocean off the coast of Africa. It is the largest island in the Comoros nation. Most of its population is of the Comorian ethnic group. Its population as of 2006 is about 316,600. The island's capital is Moroni, which is also the national capital...

 island, the largest island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 in the nation of Comoros. The Karthala volcano is notoriously active, having erupted more than 20 times since the 19th century. Frequent eruptions have shaped the volcano’s 3 by 4 km summit caldera

Caldera

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

, but the island has largely escaped broad destruction. Eruptions on April 17, 2005, and May 29, 2006 have ended a period of quiet.

April 2005 eruption

The eruption, which carried a risk of lava flows and deadly volcanic gas

Volcanic gas

|250px|thumb|right|Image of the [[rhyolitic]] [[lava dome]] of [[Chaitén Volcano]] during its 2008-2010 eruption.Volcanic gases include a variety of substances given off by active volcanoes...

, caused the evacuation of 40,000 residents.

The crater was clearly changed by the April 2005 eruption. A grey field of ash surrounds the crater and the caldera

Caldera

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...

 itself seems larger and deeper. The crater lake

Crater lake

A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...

, which formed after Karthala's last eruption in 1991 and once dominated the caldera, is now gone completely. In its place were rough, dark grey rocks, possibly cooling lava or rubble from the collapsed crater.

May 2006 activity

On May 29, Reuters

Reuters

Reuters is a news agency headquartered in New York City. Until 2008 the Reuters news agency formed part of a British independent company, Reuters Group plc, which was also a provider of financial market data...

 reported that residents of Moroni

Moroni, Comoros

-References:...

 could see lava at the top of the volcano http://today.reuters.com/news/newsArticle.aspx?type=scienceNews&storyID=2006-05-29T082108Z_01_L29707275_RTRUKOC_0_US-COMOROS-VOLCANO.xml Within a few days the volcanic activity subsided. http://www.alertnet.org/thenews/newsdesk/B590859.htm

Flora and fauna

The mountain is covered by moist evergreen forest up to about 1800 metres above sea-level. Higher up the vegetation consists of stunted trees and heathland where the giant heath Erica comorensis grows.

Many of the species found on the mountain are unique to the Comoros and four bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

 species are found only on the slopes of Mount Karthala: Humblot's Flycatcher

Humblot's Flycatcher

Humblot's Flycatcher or the Grand Comoro Flycatcher is a small passerine bird belonging to the Old World flycatcher family. It is the only member of the its genus...

, Comoro White-eye, Comoro Drongo and Comoro Scops Owl

Comoro Scops Owl

The Comoro Scops Owl, Otus pauliani, is an owl endemic to the Comoro Islands.This species is a part of the larger grouping of owls known as typical owls, Strigidae, which contains most species of owl. The other grouping is the barn owls, Tytonidae....

.

The mountain's forest is threatened by logging

Logging

Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

 and the spread of agriculture. A nature reserve

Nature reserve

A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...

has been proposed to cover the mountain but it has not yet been created.