Fogo Volcano

Fogo volcano is a massive stratovolcano rising about 6000 meters above the sea floor which mostly erupts highly alkaline basaltic lavas (Basanites / Tephrites). It is the only historically active volcano of the Cabo Verde Island state, formed by rising magma from the Cape Verde mantle hotspot, located off the west coast of Africa. The edifice comprises the large up to 9 km wide NS-elongated "Cha" caldera, which is open to the east but otherwise has up to several hundred meter high near-vertical walls. Numerous cones are found within the caldera, including the prominent Pico de Fogo cone (summit elevation 2829m) which is currently the highest point on the island and around which most recent activity has been focused. The summit of Pico was last active in 1785, yet subsequent eruptions have generally been from fissures on or near its flanks.

Evening view of Fogo Island from Ferry

Eruptions of Fogo have been observed in 1500, 1680, 1769, 1785, 1799, 1816, 1847, 1852, 1857, 1909, 1951, 1995 and 2014. It is further possible that Fogo was close to erupting in the period from Sept. 1999 - June 2000, since increased seismicity and inflation were measured by the permanent monitoring network, and eyewitnesses (actually nosewitnesses) reported sulfurous smells, suggesting degassing. Fogo settled down again after this period with no magma reaching the surface. The 1680 eruption is notable in that it produced intense ashfall over much of the island, destroying crops on the flanks of the volcano, and forcing much of the population to flee. The eruption was apparently visible over a great distance and resulted in the Island being named Fogo (its previous name was Sao Felipe).

Images and footage below are from the 2014 eruption which started on 23 Nov. 2014. Whilst similar in style to the previous 2 eruptions, the 2014 event has been particularly destructive with lava flows destroying about 200 buildings within the caldera, in particular completely destroying the agricultural settlement of Portela, together with its wine processing facility, and a significant amount of nearby agricultural land. The town was destroyed over a period of 2 weeks, with first buildings, including the park headquarters being affected on the 24th of November as flows reached a distance of 4 km from the vent in just one day. The initial flows then more or less stopped, yet later remobilized or were joined by further flows. The town center was lost on 2. Dec, and the remainder of the town, including the wine processing facility, on 6. Dec.

By 7 Dec, flows were cutting through the town of Bangaeira which lies downslope of Portela. A third lava flow branch heading southwards developed in late december and destroyed the small settlement of Ilheu de Losna on 23. Dec.

Intense Strombolian activity	Ash eruptions from two vents along fissure

Whether the "Cha" Caldera is a true caldera or merely a partially filled landslide scar has been the subject of some debate in the past. Amelung and Day (Geophys. Res. Lett. 29(12), 2002) suggested that since there was little deformation of the Fogo edifice during the 1995 eruption, this demonstrated that no shallow magma chamber exists in the edifice. Magma must have risen to the surface via an array of feeder dykes from a deep chamber. They further suggested that the absence of a shallow magma chamber suggests that the "Cha" caldera could not have been formed by collapse of a shallow magma chamber, and thus most likely represents a collapse scar which has ben partially filled by subsequent eruptinve activity. However, Amelung and Day did note that a shallow magma chamber could have existed prior to formation of the "caldera". In this case the eruption would have removed it and been caldera-forming in the classical sense. It was hypothesized that if Fogo's geology is generally amenable to the formation of shallow magma chambers, it may take many tens of thousands of years for a new shallow chamber to establish itself.

Later publications (see Madeira et al., 2008 Comunicacacoes Geologicas 95, p.93-106; references therein) conclude that the formation of "Cha" caldera was initiated by the formation of two coalescing collapse calderas. Block and ash flow deposits attributed to powerful potentially caldera-forming eruptions can be found separating pre- and post-caldera deposits. The formation of the twin-caldera was then followed by a massive and subsequent smaller landslide, which together mobilized about 60-70 cubic kilometers of volcanic material. The calderas, subsequent collapse and post-collapse volcanism (starting about 62000 years ago) have shaped the edifice one sees today.

The geology of Fogo is further interesting in that there may be a connection between the edifice of Fogo and nearby Brava Island. It is remarkable that while Brava has not erupted in historical times, it is generally seismically more active than Fogo (Fonseca et al, 2013. J. Volc. Geotherm. Res. 125, p.30-36). It is possible that magma rising through the Fogo edifice may come from a source lying near to Brava. Certainly, both volcanoes share the same submarine platform.

Explosive Eruptions during Daylight

	Ash-rich Eruptions

Eruptive fissure with Pico de Fogo on right	Eruptive fissure with Pico de Fogo on right

	Strombolian Eruptions

Fogo Eruption at Night - Strombolian Activity

Approaching The Effusive Vent

	Extremely Fluid Lava in Channel near Effusive Vent

Lava Channel Coming from Base of Eruptive Fissure	Lava Channel Coming from Base of Eruptive Fissure

	Channelled Lava Flow at Base of 2014 Eruptive Complex

	Close-up of Flow (intense radiant heat virtually unbearable at this distance)

Slightly further downstream	Flow Turns in Direction of Portela Village

	Large Fragments of Channel Wall Break off and are Embedded in Flow

Viscous Clump of Lava is Carried by Flow	Lava Flow in Channel

Fresh Lava Erupts from Skylight	Glowing Flow Field Below Skylight at Dusk	Heat from Recent Flows Melts Tripod Feet

Overflow from Channel	Parts of Shelly Flow Enter Channel and are Carried Away

Shelly Lava Flow from Skylight Overflow	Shelly Lava Flow from Skylight Overflow

Extent of Lava Flow field

Farm overlooking Fissure. Flows Extend to Left and Right.	Large areas of Caldera Floor Covered	Active Flow Glowing, Inactive Flow in Foreground

Main Road into Caldera Cut by Lava Flows	Lava Detail	Shelly A-a Deposits

Emergency Road Circumventing Fresh Deposits	Main Flow Field Approaching Portela Settlement

Portela Village - Destruction by Massive Lava Flows

	Lava Flow Crossing Road

	Flows Destroying Remains of Park Headquarters

	Electricity Cables cut By Flows

	Flow Deposits Surrounding Buildings

Flows in Portela, Belongings Carried to Higer Ground Behind	Overladen Pick-up Struggling up Emergency Road

Family Preparing to Evacuate House	Belongings are Evacuated by Pick-Up

Police Patrolling Near Town Hall (Behind blue car)	Town Hall 3 Days After Picture to the Left	Town Hall Engulfed by Lava

Belongings of Inhabitants on Hillside	Simple Shelter on Hillside above Portela

Half of Portela is Already Lost	Abandoned Teddy Bear

Inhabitants Overlooking Remains of Portela	Inhabitants Overlooking Remains of Portela

Doors, Benches, Sinks on Hillside	Sinks, toilets - Everything Reuseable is Salvaged

	Organ on Hillside above Portela

Loading Possessions onto Trucks at Entrance to Town	Loading Possessions onto Trucks at Entrance to Town

Mangled Remains of Park HQ Building	Mangled Remains of Park HQ Building	Large Building Engulfed by Lava

House Engulfed by Lava	Lava Deposits on Outskirts of Portela

	Lava Flow Deposits and Damaged Buildings

Building at Edge of Flow	Glowing Rock Breaks off Flow

Traditional Farm Houses with Flow Behind	x

Flow Cutting one of Main Roads in Portela	Road Covered by Lava Flow Deposits

Dog Abandoned in Town	Flow Temporarily Stopped at Road Leading to Wine Cooperative

Fertile Land - Reason for Settling in High Risk Environment

Fertile Landscape at Foot of Cliffs	Layers of Ash / Lapilli on Caldera Floor	Crater with pits for agriculture

Grapevines Close to Eruptive Fissure	Vegetables Grow well on Caldera Floor

Lava adjacent to Grapevine	Red Flowers in Fertile Area at Foot of Cliffs	Further Vegetables (A Wide Variety are Grown in Caldera)

Salvage Operation at Wine Cooperative:

Main Buildings of Wine Cooperative, Housing Fermenters and Bottling Plant	Main Buildings of Wine Cooperative with Salvaged Wine, Equipment on Hillside

	Soldiers Carrying Barrels up Hill

Barrels are Placed on Artificial Terraces on Hillside	Barrel Slides into Place

	Soldiers Carrying Fermentation Tank up Hill

Barrels on Hillside Waiting for Collection	Barrels and Fermenters of Hillside

Visitor Information:

Fogo volcano forms the island of the same name within the independent island state of Cabo Verde (often referred to as Cape Verde). Fogo island may be reached by local flights or ferry connections to the town of Sao Felipe on its west coast, yet air connections have been suspended during the 2014 eruption and the ferry service may be irregular and uncomfortable (large numbers of people suffering from seasickness). Several accommodations are available on the island including the recommendable Tortuga Guest House just outside Sao Felipe. Taxis can be used for transport (up to the caldera rim), with day rates of about 80 Euros (8000 CV Escudos) per day being customary.

Access restrictions to the caldera have been in place to avoid danger to visitors and reduce looting of abandoned houses. Police, Civil Protection staff and Military staff are on site. It may thus not be possible to enter the caldera at times. The road within the caldera to Portela was cut by lava within the first days of the eruption and a simple emergency road has been built at the base of the steep caldera walls circumventing the lava flows. This road has however subsequently repeatedly been cut by lava, forcing excavation of further tracks higher up the flank of the caldera. The roads primary use was to assist in evacuation of people and materials from Portela. To what extent the road will be maintained following the loss of the town is unclear.

Speed Ferry Connecting Praia and Fogo	Inside Ferry

Eruption Viewed from Approaching Ferry	Policing Portela - Access requires Permits (if possible at all)

Main Road into Caldera is Cut	Large Rock has Torn Up Cobbled Road Surface	Replacement Roads into Portela

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