Holocene Volcanic Activity
in the Western Caribbean Plate Margins:
Forecast and Risk Assessment

13 November 2002
The western Caribbean area primarily consists of the countries of Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Columbia and Venezuela. Mexico, and most of the volcanoes therein are located predominately within the Guerrero Block and includes the Paleogene and Neogene/Quarternary arcs. Guatemala, Honduras and Nicaragua are both located within the Chortis Block whereas the Nicoya Complex flanks Costa Rica on the east by the Limon Basin and on the west. Panama is also part of the Nicoya Basin, flanked on the west and on the east, flanked by the North Panama Fold Belt. Columbia, part of the Guyana Shield and lies basically in the Lianos Basin, Barinas-Apure Basin and the El Baul Swell Basin. Venezuela, also part of the Guyana Shield predominately lies within the Eastern Venezuelan Basin. Both Columbia and Venezuela form the Southern Caribbean Plate Boundary Zone.

Colima
The Colima volcanic complex is the most prominent volcanic centre of the western Mexican Volcanic Belt. It consists of two southward-younger volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of probable late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the south that has been the source of large debris avalanches. Major slope failures have occurred repetitively from both the Nevado and Fuego cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth. Colima is considered near-continuously erupting volcano and was correctly forecasted to erupt in 2002 and is forecasted to erupt in 2003 with =>50% probability by ERUPTION Pro 10.4.

Popocatépetl
Volcano Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5426 m 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 250-450 m deep crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas south of the volcano. The modern volcano was constructed to the south of the late Pleistocene to Holocene El Fraile cone. Three major plinian eruptions, the most recent of which took place about 800 AD, have occurred from Popocatépetl since the mid Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since pre-columbian time. Popocatepetl is currently an erupting volcano and was correctly forecasted to erupt in 2002 and is forecasted to erupt in 2003 with =>50% probability by ERUPTION Pro 10.4.

Fuego
Volcano Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Collapse of the ancestral Meseta volcano about 8500 years ago produced the massive Escuintla debris avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango volcano, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. Fuego has erupted in 2002 and was correctly forecasted by ERUPTION Pro 10.4. It is currently forecasted to erupt in 2003 with =>73.54% probability.

Santa Maria
Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1.5-km-wide crater. The oval-shaped crater extends from just below the summit of Volcano Santa María to the lower flank and was formed during a catastrophic eruption in 1902. The renowned plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-young vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. Santa Maria has erupted in 2002 and was correctly forecasted by ERUPTION Pro 10.4. With current data, this volcano is currently forecasted to erupt in 2007 with =>25.59% probability.

San Cristobal
The San Cristobal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1745-m-high youngest cone, named San Cristobal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km to the west of San Cristobal; it and the eroded Moyotepe volcano, 4 km to the NE of San Cristobal, are of Pleistocene age. Volcán Casita, containing an elongated summit crater, lies immediately east of San Cristobal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the San Cristobal complex. Historical eruptions from San Cristobal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes. San Cristobal has erupted in 2002 and was correctly forecasted by ERUPTION Pro 10.4. With current data, this volcano is currently forecasted to erupt in 2003 with =>50% probability.

Arenal

Arenal photo provided by the Smithsonian Institution.

Conical Volcano Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1657-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. Arenal lies along a volcanic chain that has migrated to the NW from the late-Pleistocene Los Perdidos lava domes through the Pleistocene-to-Holocene Chato volcano, which contains a 500-m-wide, lake-filled summit crater. The earliest known eruptions of Arenal took place about 7000 years ago, and it was active concurrently with Cerro Chato until the activity of Chato ended about 3500 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank. Arenal has erupted in 2002 and was correctly forecasted by ERUPTION Pro 10.4. It is currently forecasted to erupt in 2003 with =>100% probability.

Barú
The westernmost volcano in Panama, Barú, is a complex dominantly andesitic stratovolcano in the Talamanca Range near the Costa Rica border. The forested 3474-m-high Volcano Barú (also referred to as Volcán de Chiriqui) is the highest peak in Panama, and the summit now bristles with communication towers. A large 6-km-wide summit caldera breached widely to the west was formed by a large volcanic landslide, which created a massive debris-avalanche deposit that extends onto the Pacific coastal plain. Post-collapse eruptions have constructed lava domes inside the caldera that have grown to a height exceeding that of the caldera rim. A strong explosive eruption at about 600 AD ended human occupation at the Cerro Punta archaeological site NW of the volcano. Montessus de Ballore (1884) reported a strong eruption at Barú in the mid-16th century. Sapper (1917) considered this report to be uncertain, but radiocarbon dates have since been obtained for tephra deposits younger than about 500 years. Volcano Barú is the youngest major volcano in Panama, and geothermal exploration projects have been undertaken to determine its energy potential. Barú last erupted in 1550 and is not expected to erupt in the near future. It is currently forecasted to erupt in the year 2035 by ERUPTION Pro 10.4 with =>50% probability.