Characteristics of the 2000 fissure eruption and lava flow fields at Mount Cameroon volcano, West Africa: a combined field mapping and remote sensing approach

Abstract

This study focuses on the compound pahoehoe lava flow fields of the 2000 eruption on Mount Cameroon volcano, West Africa and it comprehensively documents their morphology. The 2000 eruption of Mount Cameroon took place at three different sites (sites 1, 2 and 3), on the southwest flank and near the summit that built three different lava flow fields. These lava flow fields were formed during a long-duration (28th May-mid September) summit and flank eruption involving predominantly pahoehoe flows (sites 2 and 3) and aa flows (site 1). Field observations of flows from a total of four cross-sections made at the proximal end, midway and at the flow front, have been supplemented with data from satellite imagery (SRTM DEM, Landsat TM and ETMþ) and are used to offer some clues into their emplacement. Detailed mapping of these lava flows revealed that site 1 flows were typically channel-fed simple aa flows that evolved as a single flow unit, while sites 2 and 3 lava flow fields were fed by master tubes within fissures producing principally tube-fed compound pahoehoe flows. Sites 2 and 3 flows issued from $ 33 ephemeral vents along four NE-SW-trending faults/fissures. Pahoehoe morphologies at sites 2 and 3 include smooth, folded and channelled lobes emplaced via a continuum of different mechanisms with the principal mechanism being inflation. The dominant structural features observed on these flow fields included: fissures/faults, vents, levees, channels, tubes and pressure ridges. Other structural features present were pahoehoe toes/lobes, breakouts and squeeze-ups. Slabby pahoehoe resulting from slab-crusted lava was the transitionary lava type from pahoehoe to aa observed at all the sites. Transition zones correspond to slopes of > 108. Variations in flow morphology and textures across profiles and downstream were repetitive, suggesting a cyclical nature for the responsible processes.

Numerical experiments on the dynamics of channelised lava flows at Mount Cameroon volcano with the FLOWGO thermo-rheological model

“…MC lavas are primarily open-channel ′a′a-dominated flows similar to those observed at Etna although pahoehoe flow fields were documented in proximal areas and for the 1922 and 2000 eruptions (Wantim et al, 2011). Compositionally, MC lavas are generally picrites, alkali-basalts and hawaiites (Suh et al, 2003 erupted during Strombolian and Hawaiian-style eruptions.…”

“…Historical lava flows caused damage to plantations, forests, road infrastructure and aquatic life in 1922in , 1959in , 1982in (Wantim et al, 2011. MC lavas are primarily open-channel ′a′a-dominated flows similar to those observed at Etna although pahoehoe flow fields were documented in proximal areas and for the 1922 and 2000 eruptions (Wantim et al, 2011).…”

“…Similarities in open channel morphology (e.g. dominant clinker ′a′a lava within channels bounded by accretionary levees) and eruption temperature at Etna (Bailey et al, 2006), some Hawaiian lava flow fields (Harris et al, 2009) and MC (Suh et al, , 2010Wantim et al, 2011) led to the choice of the model. FLOWGO is the only model that enables full inversion of the thermo-rheological properties of lava flows.…”

“…MC is an elongated volcano, 4095 m above sea level (a.s.l.) high, 35× 55 km across at its base, with a volume of~1,400 km 3 (Wantim et al, 2011). MC erupted at least seven times in the last 100 yr: 1909, 1922, 1954, 1959, 1982, 1999, 2000.…”

“…Suh et al (2003Suh et al ( , 2008 described the physical characteristics and provided some petrographic and geochemical data for the 2000 eruption and lava flow field. Recently, Wantim et al (2011) provided details on the 2000 eruption chronology from satellite imagery and documented its lava flow field morphology at all its eruption sites.…”