Morpho-Structure of the 1982 Lava Flow Field at Mount Cameroon Volcano, West-Central Africa

M. N. Wantim, M. Kervyn, G. G. J. Ernst, M.-A. Del Marmol, C. E. Suh, P. Jacobs

Department of Geography and Earth System Science, Vrije Universiteit Brussel, Brussels, Belgium.
Department of Geology and Soil Science, Ghent University, Ghent, Belgium.
Department of Geology, University of Buea, South West Region, Buea, Cameroon.

DOI: 10.4236/ijg.2013.43052                

Abstract

Basaltic eruptions have been observed to produce structurally complex, compound 'a'ā lava flow fields but their morphometry has only rarely been systematically documented. We document the morphology and structures that developed during the emplacement of the 1982 basaltic lava flow field at Mount Cameroon (MC) volcano over a period of one month. Topographic cross-sections (13 in total) were made from the main vent (~2700 m above sea level (a.s.l)) down to a distance of 5.5 km on the cooled lava surface. Details obtained from these cross-sections include: channel width and depth, levee slope, lava surface morphology and structures. These details enabled us to describe the physical characteristics of the 1982 lava flow field. The inclined (12° - 19°) underlying slopes on which this flow field was emplaced resulted in a characteristic channelized basaltic 'a'ā flow field morphology. This includes a proximal zone characterised by reduced flow width and depth with no subsidiary channels. Slab-crusted lava dominates the proximal channel distinctively bent into convex upward shapes. 7 secondary vents were observed for the first time ~2.5 km from the main vent, with heights of 3 - 15 m. This is a very significant observation since it points to the fact that the flow field emplacement may have been a product of 2 eruption sites as observed at other historical MC lava flow fields. This supposition was ruled out by further evidence obtained from other surface features within the flow field. The presence of these secondary vents still has an important bearing in lava flow hazard assessment. Field observations also revealed the presence of tumulus. This is a novel feature for MC lava flow fields. It displayed a close similarity to those observed at other basaltic volcanoes occurring in association with clinker 'a'ā lava, lava tubes, squeeze-ups and pressure ridges. Channels are well-defined, bounded by levees. Accretional and overflow levees dominate in this flow field. This lava flow-field attained a final length of 7.5 km, an area of 2.6 × 10⁶ m² and volume of 1.3 × 10⁷ m³. The presence of tumulus indicates internal inflation together with structures such as pressure ridges and squeeze-ups which are also attributed to compressive forces. Our observations suggest that real-time monitoring of compound lava flow fields evolution at MC may reveal the emplacement mechanisms of complex structures such as the secondary vents (~2180 - 2011 m a.s.l.) observed within the flow field. In addition, documenting the occurrence, morphology and link between lava tubes, tumulus and squeeze-ups may allow us to determine the risk of reactivation of a stalled flow front. This will thereby enhance the ability to track and assess hazards posed by lava flow emplacement from MC-like volcanoes.

Keywords

1982 Eruption; Channels; Levees; Secondary Vents; Slope; Tumulus

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	S. R. Passey and B. R. Bell, “Morphologies and Emplacement Mechanisms of the Lava Flows of the Faroe Islands Basalt Group, Faroe Islands, NE Atlantic Ocean,” Bulletin of Volcanology, Vol. 70, No. 2, 2007, pp. 139-156. doi:10.1007/s00445-007-0125-6
[2]	M. S. Njome, C. E. Suh, R. J. Sparks, S. N. Ayonghe and J. G. Fitton, “The Mount Cameroon 1959 Compound Lava Flow Field: Morphology, Petrology and Geochemistry,” Swiss Journal of Geosciences, Vol. 101, No. 1, 2008, pp. 85-98. doi:10.1007/s00015-007-1245-x
[3]	H. C. Sheth, J. S. Ray, R. Bhutani, A. Kumar and R. S. Smitha, “Volcanology and Eruptive Styles of Barren Island: An Active Mafic Stratovolcano in the Andaman Sea, NE Indian Ocean,” Bulletin of Volcanology, Vol. 71, No. 9, 2009, pp. 1021-1039. doi:10.1007/s00445-009-0280-z
[4]	H. C. Sheth, J. S. Ray, A. Kumar, R. Bhutani and N. Awasthi, “Toothpaste Lava from the Barren Island Volcano (Andaman Sea),” Journal of Volcanology and Geothermal Research, Vol. 202, No. 1-2, 2011, pp. 73-82. doi:10.1016/j.jvolgeores.2011.01.006
[5]	L. J. Applegarth, H. Pinkerton, M. R. James and S. Calvari, “Lava Flow Superposition: The Reactivation of Flow Units in Compound 'a'ā Flows,” Journal of Volcanology and Geothermal Research, Vol. 194, No. 4, 2010, pp. 100-106. doi:10.1016/j.jvolgeores.2010.05.001
[6]	L. J. Applegarth, H. Pinkerton, M. R. James and S. Calvari, “Morphological Complexities and Hazards during the Emplacement of Channel-Fed 'a'ā Lava Flow Fields: A Study of the 2001 Lower Flow Field on Etna,” Bulletin of Volcanology, Vol. 72, No. 6, 2010, pp. 641-656. doi:10.1007/s00445-010-0351-1
[7]	H. El Hachimi, N. Youbi, J. Madeira, L. Martins, A. Marzoli, H. Bertrand, G. Bellieni, S. Callegaro, J. Mata, J. M. Munhá, F. Medina, A. Mahmoudi, K. M. Bensalah, B.M. Abbou, “Morphologies and Emplacement Mechanisms of the Lava Flows of the Central Atlantic Magmatic Province (CAMP) of Morocco,” Proceedings of the II Central & North Atlantic Conjugate Margins Conference, Morocco, 29 September-1 October 2010, pp. 96-100.
[8]	C. E. Suh, S. A. Stansfield, R. S. J Sparks, M. S. Njome, M. N. Wantim and G. G. J. Ernst, “Morphology and Structure of the 1999 Lava Flows at Mount Cameroon Volcano (West Africa) and their Bearing on the Emplacement Dynamics of Volume-Limited Flows,” Geological Magazine, 2010, pp. 1-13.
[9]	D. Takagi and H. E. Huppert, “Initial Advance of Long Lava Flows in Open Channels,” Journal of Volcanology and Geothermal Research, Vol. 195, No. 2-4, 2010, pp. 121-126. doi:10.1016/j.jvolgeores.2010.06.011
[10]	R. J. Brown, S. Blake, N. R. Bondre, V. M. Phadnis and S. Self, “'a'ā Lava Flows in the Deccan Volcanic Province, India, and their Significance for the Nature of Continental Flood Basalt Eruptions,” Bulletin of Volcanology, Vol. 73, No. 6, 2011, pp. 737-752. doi:10.1007/s00445-011-0450-7
[11]	M. N. Wantim, C. E. Suh, G. G. J. Ernst, M. Kervyn and P. Jacobs, “Characteristics of the 2000 Fissure Eruption and Lava Flow Fields at Mount Cameroon Volcano, West Africa: A Combined Field Mapping and Remote Sensing Approach,” Geological Journal, Vol. 46, No. 4, 2011, pp. 344-363. doi:10.1002/gj.1277
[12]	S. W. Anderson, S. E. Smrekar and E. R. Stofan, “Tumulus Development on Lava Flows: Insights from Observations of Active Tumuli and Analysis of Formation Models,” Bulletin of Volcanology, Vol. 74, No. 4, 2012, pp. 931-946. doi:10.1007/s00445-012-0576-2
[13]	J. E. Bailey, A. J. L. Harris, J. Dehn, S. Calvari and S. K. Rowland, “The Changing Morphology of an Open Channel on Mount Etna,” Bulletin of Volcanology, Vol. 68, No. 6, 2006, pp. 497-515. doi:10.1007/s00445-005-0025-6
[14]	A. J. L. Harris, L. P. Flynn, O. Matias, W. I. Rose and J. Cornejo, “The Evolution of An Active Silicic Lava Flow Field: An ETM+ Perspective,” Journal of Volcanology and Geothermal Research, Vol. 135, No. 1-2, 2004, pp. 147-168. doi:10.1016/j.jvolgeores.2003.12.011
[15]	A. J. L. Harris, M. Favalli, M. Francesco and C. W. Hamilton, “Construction Dynamics of A Lava Channel,” Bulletin of Volcanology, Vol. 71, No. 4, 2009, pp. 459-474. doi:10.1007/s00445-008-0238-6
[16]	M. Favalli, A. J. L. Harris, A. Fornaciai, M. T. Pareschi and F. Mazzarini, “The Distal Segment of Etna’s 2001 Basaltic Lava Flow,” Bulletin of Volcanology, Vol. 72, No. 4, 2010, pp. 119-127. doi:10.1007/s00445-009-0300-z
[17]	M. R. James, L. J. Applegarth and H. Pinkerton, “Lava Channel Roofing, Overflows, Breaches and Switching: Insights from the 2008-2009 Eruption of Mt. Etna,” Bulletin of Volcanology, Vol. 74, No. 1, 2012, pp. 107-117. doi:10.1007/s00445-011-0513-9
[18]	A. J. L. Harris and S. K. Rowland, “FLOWGO: A Kinematic Thermo-Rheological Model for Lava Flowing in A Channel,” Bulletin of Volcanology, Vol. 63, No. 1, 2001, pp. 20-44. doi:10.1007/s004450000120
[19]	G. M. Crisci, S. Di Gregorio, R. Rongo, M. Scarpelli, W. Spataro and S. Calvari, “Revisiting the 1669 Etnean Eruptive Crisis Using Cellular Automata Model and Implications for Volcanic Hazard in the Catania Area,” Journal of Volcanology and Geothermal Research, Vol. 123, No. 1-2, 2003, pp. 211-230. doi:10.1016/S0377-0273(03)00037-4
[20]	G. M. Crisci, R. Rongo, S. Di Gregorio and W. Spataro, “The Simulation Model Sciara: The 1991 and 2001 Lava Flows at Mount Etna,” Journal of Volcanology and Geothermal Research, Vol. 132, No. 2-3, 2004, pp. 253-267. doi:10.1016/S0377-0273(03)00349-4
[21]	G. M. Crisci, G. Iovine, S. Di Gregorio and V. Lupiano, “Lava-flow Hazard on the SE Flank of Mt. Etna (Southern Italy),” Journal of Volcanology and Geothermal Research, Vol. 177, No. 4, 2008, pp. 778-796. doi:10.1016/j.jvolgeores.2008.01.041
[22]	A. Ciraudo, C. Del Negro, A. Herault and A. Vicari, “Advances in Modelling Methods for Lava Flows Simulation,” Communications to SIMAI Congress, Vol. 2, No. 4, 2007, pp. 1827-9015.
[23]	A. Vicari, H. Alexis, C. Del Negro, M. Coltelli, M. Marsella and C. Proietti, “Modelling of the 2001 Lava Flow at Etna Volcano by a Cellular Automata Approach,” Environmental Modelling and Software, Vol. 22, No. 4, 2007, pp. 1465-1471. doi:10.1016/j.envsoft.2006.10.005
[24]	Ruxton, “Report on Volcanic Eruptions on the Cameroons Mountain,” 1922.
[25]	C. E. Suh, R. S. J. Sparks, J. G. Fitton, S. N. Ayonghe, C. Annen, R. Nana and A. Luckman, “The 1999 and 2000 Eruptions of Mount Cameroon: Eruption Behaviour and Petrochemistry of Lava,” Bulletin of Volcanology, Vol. 65, No. 4, 2003, pp. 267-281. doi:10.1007/s00445-002-0257-7
[26]	S. Calvari and H. Pinkerton, “Formation of Lava Tubes and Extensive Flow Field during the 1991-93 Eruption of Mount Etna,” Journal of Geophysical Research, Vol. 103, No. B11, 1998, pp. 27291-27302. doi:10.1029/97JB03388
[27]	C. R. J. Kilburn and R. M. C. Lopes, “The Growth of 'a'ā Lava Flow Fields on Mount Etna, Sicily,” Journal of Geophysical Research, Vol. 93, No. B12, 1988, pp. 759-772. doi:10.1029/JB093iB12p14759
[28]	A. Felpeto, V. Arana, R. Ortiz, M. Astiz and A. Garcia, “Assessment and Modelling of Lava Flow Hazard on Lanzarote (Canary Islands),” Natural Hazards, Vol. 23, No. 2-3, 2001, pp. 247-257. doi:10.1023/A:1011112330766
[29]	R. A. Duraiswami, N. R. Bondre, G. Dole, V. M. Phadnis and V. S. Kale, “Tumuli and Associated Features from the Western Deccan Volcanic Province, India,” Bulletin of Volcanology, Vol. 63, No. 7, 2001, pp. 435-442. doi:10.1007/s004450100160
[30]	C. R. J. Kilburn and R. M. C. Lopes, “General Patterns of Flow Field Growth: 'a'ā and Blocky Lavas,” Journal of Geophysical Research, Vol. 96, No. B12, 1991, pp. 721-732. doi:10.1029/91JB01924
[31]	J. E. Guest, A. M. Duncan, E. R. Stofan and S. W. Anderson, “Effect of Slope on Development of Pahoehoe Flow Fields: Evidence from Mount Etna,” Journal of Volcanology and Geothermal Research, Vol. 219, No. 11, 2012, pp. 52-62. doi:10.1016/j.jvolgeores.2012.01.006
[32]	C. R. J. Kilburn, “Lava Flows and Flow Fields,” In: H. Sigurdsson, Ed., Encyclopaedia of Volcanoes, Academic Press, San Diego, 2000, pp. 291-305.
[33]	G. P. L. Walker, “Structure and Origin by Injection of Lava under Surface Crust, of Tumuli, ‘Lava Rises’, ‘Lava-Rise Pits’, and ‘Lava-Inflation Clefts’ in Hawaii,” Bulletin of Volcanology, Vol. 53, No. 7, 1991, pp. 546-558. doi:10.1007/BF00298155
[34]	J. G. Fitton, C. R. J Kilburn, M. F. Thirlwall and D. J. Hughes, “1982 Eruption of Mount Cameroon, West Africa,” Nature, Vol. 306, No. 5941, 1983, pp. 327-332. doi:10.1038/306327a0
[35]	B. Deruelle, J. N’ni and R. Kambou, “Mount Cameroon: An Active Volcano of the Cameroon Line,” Journal of African Earth Sciences, Vol. 6, No. 2, 1987, pp. 197-214.
[36]	B. Ateba and N. Ntepe, “Post-Eruptive Activity of Mount Cameroon (Cameroon) West Africa: A Statistical Analysis,” Journal of Volcanology and Geothermal Research, Vol. 79, No. 1-2, 1997, pp. 25-45. doi:10.1016/S0377-0273(97)00022-X
[37]	R. U. Ubangoh, B. Ateba, S. N. Ayonghe and G. E. Ekodeck, “Earthquake Swarms of Mount Cameroon, West Africa,” Journal of African Earth Sciences, Vol. 24, No. 4, 1997, pp. 413-424. doi:10.1016/S0899-5362(97)00072-9
[38]	C. E. Suh, S. N. Ayonghe and E. S. Njumbe, “Neotectonic Earth Movement Related to the 1999 Eruption of Cameroon Mountain, West Africa,” Episodes, Vol. 24, No. 1, 2001, pp. 9-12.
[39]	C. E. Suh, J. F. Luhr and M. S. Njome, “Olivine-Hosted Glass Inclusions from Scoriae Erupted in 1954-2000 at Mount Cameroon Volcano, West Africa,” Journal of Volcanology and Geothermal Research, Vol. 169, No. 1-2, 2008, pp. 1-33. doi:10.1016/j.jvolgeores.2007.07.004
[40]	B. Ateba, C. Dorbath, L. Dorbath, N. Ntepe, M. Frogneux, F. T. Aka, J. V. Hell, J. C. Delmond and D. Manguelle, “Eruptive and Earthquake Activities Related to the 2000 Eruption of Mount Cameroon Volcano (West Africa),” Journal of Volcanology and Geothermal Research, Vol. 179, No. 3-4, 2009, pp. 206-216. doi:10.1016/j.jvolgeores.2008.11.021
[41]	K. Bonne, M. Kervyn, L. Cascones, S. Njome, E. V. Ranst, E. Suh, S. Ayonghe, P. Jacobs and G. Ernst, “A New Approach to Assess Long-Term Lava Flow Hazard and Risk Using GIS and Low-Cost Remote Sensing: the Case of Mount Cameroon, West Africa,” International Journal of Remote Sensing, Vol. 29, No. 22, 2008, pp. 6537-6562. doi:10.1080/01431160802167873
[42]	P. Thierry, L. Stieltjes, E. Kouokam, P. Nguéya and P. M. Salley, “Multi-Hazard Risk Mapping and Assessment on An Active Volcano: The GRINP Project at Mount Cameroon,” Natural Hazards, Vol. 45, No. 3, 2008, pp. 429-456. doi:10.1007/s11069-007-9177-3
[43]	M. Favalli, S. Tarquini, P. Papale, A. Fornaciai and E. Boschi, “Lava Flow Hazard and Risk at Mt. Cameroon Volcano,” Bulletin of Volcanology, Vol. 74, No. 2, 2012, pp. 423-439. doi:10.1007/s00445-011-0540-6
[44]	P. Lipman and N. G. Banks, “'a'ā Flow Dynamics, Mauna Loa.” In: R. W. Decker, T. L. Wright and P. H. Stauffer, Eds., Volcanism in Hawaii, US Geological Survey Professional Paper, Vol. 1350, No. 2, 1987, pp. 1527-1567.
[45]	L. Lodato, L. Spampinato, A. J. L. Harris, S. Calvari, J. Dehn and M. Patrick, “The Morphology and Evolution of the Stromboli 2002-2003 Lava Flow Field: An Example of A Basaltic Flow Field Emplaced on A Steep Slope,” Bulletin of Volcanology, Vol. 69, No. 6, 2007, pp. 661-697. doi:10.1007/s00445-006-0101-6
[46]	K. Hon, J. Kauahikaua, R. Denlinger and K. Mackay, “Emplacement and Inflation of Pahoehoe Sheet Flows: Observations and Measurements of Active Lava Flows on Kilauea Volcano, Hawaii,” Geological Society of America Bulletin, Vol. 106, No. 3, 1994, pp. 351-370. doi:10.1130/0016-7606(1994)106<0351:EAIOPS>2.3.CO;2
[47]	J. G. Fitton and H. M. Dunlop, “The Cameroon Line, West Africa, and Its Bearing on the Origin of Oceanic and Continental Alkali Basalt,” Earth and Planetary Science Letters, Vol. 72, No. 1, 1985, pp. 23-28. doi:10.1016/0012-821X(85)90114-1
[48]	C. Moreau, J-M. Regnoult, B. Deruelle and B. Robineau, “A New Tectonic Model for the Cameroon Line, Central Africa,” Tectonophysics, Vol. 139, 1987, pp. 317-334.
[49]	A. N. Halliday, A. P. Dickin, A. E. Fallick and J. G. Fitton, “Mantle Dynamics: A Nd, Sr, Pb and O isotopic study of the Cameroon Line Volcanic Chain,” Journal of Petrology, Vol. 29, No. 1, 1988, pp. 181-211. doi:10.1093/petrology/29.1.181
[50]	C. T. Tabod, J. D. Fairhead, G. W. Stuart, B. Ateba and N. Ntepe, “Seismicity of the Cameroon Volcanic Line, 1982-1990,” Tectonophysics, Vol. 212, No. 3-4, 1992, pp. 303-320. doi:10.1016/0040-1951(92)90297-J
[51]	F. T. Aka, K. Nagao, M. Kusakabe, H. Sumino, G. Tanyileke, B. Ateba and J. Hell, “Symmetrical Helium Isotope Distribution on the Cameroon Volcanic Line, West Africa,” Chemical Geology, Vol. 203, No. 3-4, 2004, pp. 205-223. doi:10.1016/j.chemgeo.2003.10.003
[52]	B. Deruelle, I. Ngounouno and D. Demaiffe, “The ‘Cameroon Hot Line’ (CHL): A Unique Example of Active Alkaline Intraplate Structure in both Oceanic and Continental Lithospheres,” Comptes Rendus Geoscience, Vol. 339, No. 9, 2007, pp. 589-600. doi:10.1016/j.crte.2007.07.007
[53]	L. Mathieu, M. Kervyn and G. G. J. Ernst, “Field Evidence for Flank Instability, Basal Spreading and Volcano-Tectonic Interactions at Mt. Cameroon, West Africa,” Bulletin of Volcanology, Vol. 73, No. 7, 2011, pp. 851-867. doi:10.1007/s00445-011-0458-z
[54]	C. Nkoumbou, B. Deruelle and D. Velde, “Petrology of Mt. Etinde Nephelinite Series,” Journal of Petrology, Vol. 36, No. 2, 1995, pp. 373-393. doi:10.1093/petrology/36.2.373
[55]	G. Hulme, “The Interpretation of Lava Flow Morphology,” Geophysical Journal Royal Astronomical Society, Vol. 39, No. 2, 1974, pp. 361-383. doi:10.1111/j.1365-246X.1974.tb05460.x
[56]	H. J. Moore, “Preliminary Estimates of the Rheological Properties of 1984 Mauna Loa Lava.” In: R. W. Decker, T. L. Wright, P. H. Stauffer, Eds., Volcanism in Hawaii, United States Government Printing Office, Washington DC, 1987, pp. 1569-1588.
[57]	A. J. L. Harris, A. L. Butterworth, R. W. Carlton, I. Downey, P. Miller, P. Navarro and D. A. Rothery, “Low-Cost Volcano Surveillance from Space: Case Studies from Etna, Rafla, Cerro Negro, Fogo, Lascar and Erebus,” Bulletin of Volcanology, Vol. 59, No. 1, 1997, pp. 49-64. doi:10.1007/s004450050174
[58]	Y. Bottinga and D. F. Weill, “Densities of Liquid Silicate Systems Calculated from Partial Molar Volumes of Oxide Components,” American Journal of Science, Vol. 269, No. 2, 1970, pp. 169-182. doi:10.2475/ajs.269.2.169
[59]	N. F. Stevens, G. Wadge and J. B. Murray, “Lava Flow Volume and Morphology from Digitised Contour Maps: A Case Study at Mount Etna, Sicily,” Geomorphology, Vol. 28, No. 3-4, 1999, pp. 251-261. doi:10.1016/S0169-555X(98)00115-9
[60]	M. Polacci and P. Papale, “The Evolution of Lava Flows from Ephemeral Vents at Mount Etna: Insights from Vesicle Distribution and Morphological Studies,” Journal of Volcanology and Geothermal Research, Vol. 76, No. 1-2, 1997, pp. 1-17. doi:10.1016/S0377-0273(96)00070-4
[61]	J. A. Naranjo, R. S. J. Sparks, M. V. Stasiuk, H. Moreno and G. J. Ablay, “Morphological, Structural and Textural Variations in the 1988-1990 Andesite Lava of Lonquimay Volcano, Chile,” Geological Magazine, Vol. 129, No. 6, 1992, pp. 657-678. doi:10.1017/S0016756800008426
[62]	M. J. Kennish and R. A. Lutz, “Morphology and Distribution of Lava Flows on Mid-Ocean Ridges: A Review,” Earth Science Reviews, Vol. 43, No. 3-4, 1998, pp. 63-90. doi:10.1016/S0012-8252(98)00006-3
[63]	S. Calvari and H. Pinkerton, “Lava Tube Morphology on Etna and Evidence for Lava Flow Emplacement Mechanisms,” Journal of Volcanology and Geothermal Research, Vol. 90, No. 3-4, 1999, pp. 263-280. doi:10.1016/S0377-0273(99)00024-4
[64]	M. Dragoni and A. Piombo, “Thermoelastic Deformation Associated with A Lava Tube,” Bulletin of Volcanology, Vol. 71, No. 4, 2009, pp. 409-418. doi:10.1007/s00445-008-0248-4
[65]	R. S. J. Sparks, H. Pinkerton and G. Hulme, “Classification and Formation of Lava Levees on Mount Etna, Sicily,” Geology, Vol. 4, No. 5, 1976, pp. 269-271. doi:10.1130/0091-7613(1976)4<269:CAFOLL>2.0.CO;2
[66]	F. Quareni, A. Tallarico and M. Dragoni, “Modelling of the Steady-State Temperature Field in Lava Flow Levees,” Journal of Volcanology and Geothermal Research, Vol. 132, No. 2-3, 2004, pp. 241-251. doi:10.1016/S0377-0273(03)00348-2
[67]	G. A. Macdonald, “Pahoehoe, 'a'ā and Block Lava,” American Journal of Science, Vol. 251, No. 3, 1953, pp. 169-191. doi:10.2475/ajs.251.3.169
[68]	C. R. J. Kilburn, “Fracturing as a Quantitative Indicator of Lava Flow Dynamics,” Journal of Volcanology and Geothermal Research, Vol. 132, No. 2-3, 2004, pp. 209-224. doi:10.1016/S0377-0273(03)00346-9
[69]	J. E. Guest and E. R. Stofan, “The Significance of Slab-Crusted Lava Flows for Understanding Controls on Flow Emplacement at Mount Etna, Sicily,” Journal of Volcanology and Geothermal Research, Vol. 142, No. 3-4, 2006, pp. 193-205. doi:10.1016/j.jvolgeores.2004.09.003
[70]	P. Francis and C. Oppenheimer, “Volcanoes,” 2nd Edition, Oxford University Press, Oxford, 2004.
[71]	M. J. Rossi and A. Gudmundsson, “The Morphology and Formation of Flow-Lobe Tumuli on Icelandic Shield Volcanoes,” Journal of Volcanology and Geothermal Research, Vol. 72, No. 3-4, 1996, pp. 291-308. doi:10.1016/0377-0273(96)00014-5
[72]	A. M. Duncan, J. E. Guest, E. R. Stofan, S. W. Anderson, H. Pinkerton and S. Calvari, “Development of Tumuli in the Medial Portion of the 1983 'a'ā Flow field, Mount Etna, Sicily,” Journal of Volcanology and Geothermal Research, Vol. 132, No. 2-3, 2004, pp. 173-187. doi:10.1016/S0377-0273(03)00344-5
[73]	R. Greeley, “The Role of Lava Tubes in Hawaiian Volcanoes.” In: R. W. Decker, T. L. Wright, P. H Stauffer, Eds., Volcanism in Hawaii, United States Government Printing Office, Washington, 1993, pp. 1589-1602.