150°C 0°C Hot Central Core Cool Inner Annulus Hot Outer Annulusdiscontinuity N S E W 100 m Conduit thermal patterns as revealed by infrared imagery at Santiaguito, Guatemala W I Rose, Lara Kapelanczyk, Adam Blankenbicker, Luke Bowman, Otoniel Matías, Rüdiger Escobar Wolf, John Lyons, Kyle Brill, José Luis Palma Santiaguito is a lava dome that has been continuously active since A new orthophoto geological map of Santiaguito (Escobar et al., this meeting) reveals the pattern of continued exogenous growth of the Caliente Vent region in the last decade, consisting mainly of thick flows to the S. Extrusion has been focused on the cylindrical 80 m diameter vent region which displays a thermal circular ring pattern of high temperatures on most observed occasions. This ring marks the alignment of ash vents which drive periodic (about every 0.2 to 2 hour) vertical thermal explosions. Extruded lava moves upward and down the side of the dome, usually to the south. In recent years systematic thermal observations from helicopter and ground sites have supplemented satellite data and DEMs to provide data to estimate extrusion rates. Santiaguito is a site of significant pyroclastic flows, dome collapses and lahars. It is hoped that frequent observations and eruption rate estimates will lead to improved hazard forecasts. 100°C -10°C S N W E Profile Distance (m) Temperature (°C) Inner Annulus Outer Annulus Central Core Summit Crater 150 °C 0 °C Hot Central Core Cool Inner Annulus Hot Outer Annulus discontinuity 150 °C 0 °C Hot Central Core Cool Inner Annulus Hot Outer Annulusdiscontinuity Caliente vent Santa Maria Santiaguito Lava Dome Complex Caliente vent July 2, 2008 Jan 12, 2008 Jan 16, 2005 Core (young lava) Cold inner annulus (old lava) Outer annulus fill Total MinMaxMinMaxMinMaxMinMax Area (m 2 ) 3,780 1,626 10,459 15,866 T surf (°C) q rad (x 10 3 J s -1 m -2 ) q free (x 10 3 J s -1 m -2 ) q surf (x 10 3 J s -1 m -2 ) Q rad (MJ s -1 ) Q free (MJ s -1 ) Q surf (MJ s -1 ) Temperature profiles across the summit conduit at Caliente in 2005 (left) and 2008 (right). Note that 2005 conduit areas are 25% higher, maximum temperatures are 140 degrees higher and total heat flow is more than double. There is also a slight temperature decrease from January to June 2008, but this may be explained by wet and dry season effects. Above the conduit, lava flows downslope and may move in a variety of directions. This oblique view of the Caliente vent region centers on the conduit and green shading outlines the two most recent flow lobes of (eastward) and (westward). Flow front rockfalls conduit Sahetapy-Engel & Harris 2008, Bull Volc Jan 12, 2008 EW S N EW S N Thermal IR views of the active lava flow of Jan Heat loss from the flow surface is ~4 times more than the conduit alone. Seen from the east, a lava flow extruded about a year ago still shows residual heat. Thermal IR images obtained with a FLIR device show a hot ring pattern which has been observed repeatedly at Santiaguito. The hot ring is sustained by weak vertical eruptions that occur every minutes and preferentially heat the ring while slight slippage occurs along the conduit margin, extruding lava which feeds a lava flow descending one flank of the dome. During the brief eruptions, points in the outer annulus of the conduit are heated by about 100 degrees by the rising gases and fine ash moving through the conduit edges. Overall the heat flow from the conduit increases by about 10% after each event. Acknowledgments: This research is supported by the US National Science Foundation through OISE and PIRE Thermal imaging equipment purchased with NSF EAR The US Peace Corps supports collaborative field work at Guatemalan volcanoes. Our Guatemalan partner organizations INSIVUMEH and CONRED work with us and provide logistical support. Steve Sahetapy-Engel provided data and advice. Telephoto of conduit from Santa María in 2007 (Jeff Johnson), during period when lava was flowing eastward from the conduit. This flow disrupted the symmetry of the ring, causing it to deform by flow. Compare with photos at top when flow was moving W. Lava flow Jan 11, 2008 Jan 10, 2008 Jan 9, 2008 References: Ball M and H Pinkerton, 2006, Factors affecting the accuracy of thermal imaging cameras in volcanology, J Geophys Res 111, B 11203, doi: /2005JB Barmin, A, O Melnik and RSJ Sparks, 2002, Periodic behavior in lava dome eruptions, EPSL 199: Bluth G J S and W I Rose, 2004, Observations of eruptive activity at Santiaguito volcano, Guatemala, J Volcanol Geoth Res 136: J Volcanol Geoth Res 136: Durst, KS, W I Rose, R Escobar-Wolf, A Maclean and MR Sanchez, 2008, Erupted magma volume estimates at Santiaguito and Pacaya Volcanoes, Guatemala, using digital elevation models, Bulletin of Volcanology, in review. Escobar Wolf, R P, O Matías Gomez and W I Rose, 2008, Geologic map of Santiaguito, Guatemala, unpublished map presented at IAVCEI, Reyjavik, August Gonnermann HM and M Manga, 2003, Explosive volcanism may not be an inevitable consequence of magma fragmentation, Nature 426: Harris, A.J.L., Flynn, L.P., Matías, O. and Rose, W. I., 2002, The thermal stealth flows of Santiaguito: implications for the cooling and emplacement of dacitic block lava flows, Geol. Soc. Am. Bull., 114: Harris, A.J.L., W I Rose and Flynn, L.P., 2003, Temporal trends in Lava Dome extrusion at Santiaguito, , Bulletin of Volcanology 65: Harris, Andrew J. L., Luke P. Flynn, Otoniel Matías, William I. Rose and Julio Cornejo, 2004, The evolution of an active silicic lava flow field: an ETM+ perspective, J Volcanol Geoth Res 135: Johnson, J B, A J L Harris, S T M Sahetepy-Engel, R Wolf and W I Rose, 2004, Explosion dynamics of pyroclastic eruptions at Santiaguito Volcano, Geophys Res Lett 31: L Geophys Res Lett 31: L Rodríguez, L.A., Watson, I.M., Rose, W.I., Branan, Y.K., Bluth, G.J.S., Chigna, G., Matías, O., Escobar, D., Carn, S.A. and Fischer, T., 2004, SO 2 emissions to the atmosphere from active volcanoes in Guatemala and El Salvador, , Journal of Volcanology and Geothermal Research, 138 (3-4), pp Journal of Volcanology and Geothermal Research, 138 (3-4), pp Sahetepy-Engel S T M and A J L Harris, 2008, Thermal structure and heat loss at the summit crater of an active lava dome, Bulletin of Volcanology DOI /s Sahetepy-Engel S T M, L P Flynn, A J L Harris, G J Bluth, W I Rose and O Matías, 2004, Surface temperature and spectral measurements at Santiaguito Lava Dome, Guatemala, Geophysical Res Lett 31: L19610 EW S N 100°C 0°C Jan 11, 2008 EW S N EW S N NS E W NS E W NS E W Summary Points: Santiaguito heat flow is about 42 MJ/s in This rate is equivalent to an extrusion rate of about 0.1 m 3 /s and is apparently decreasing. Helicopter Image Min T surf Lava Flow Max T surf Lava FlowAverages Temperature (°C) Area (m 2 )79, pixels T air (°C)16.5 q rad (x 10 3 J s -1 m -2 ) q free (x 10 3 J s -1 m -2 ) q surf (x 10 3 J s -1 m -2 ) Q rad (MJ s -1 ) Q free (MJ s -1 ) Q surf (MJ s -1 ) In between eruptions 1 and 2 Right before eruption 2 Right after eruption 2 Area (m 2 ) 28,223 T air (°C)8.76 q rad average (x 10 3 J s -1 m- 2) q free average (x 10 3 J s -1 m- 2) q surf average (x 10 3 J s -1 m- 2 ) Q rad (MJ s -1 ) Q free (MJ s -1 ) Q surf (MJ s -1 )