【正文】 ep topography exposed to rock fall hazard, the flow fronts were relatively accessible. Hence, ground based images could be acquired of the flow front and distal channel regions and the data used in this paper were collected on 27 September 2004.Visible images were acquired with a Canon EOS 300D (30722048 effective pixels) fitted with a fixedfocus 28 mm lens, the imaging geometry of which had been precalibrated in a laboratory (Robson et al. 1999). Thermal images were obtained with a FLIR ThermaCAM S40 which provides a horizontal field of view of 24176。3% (increased exitance for distant objects and decreased exitance for closer objects) with respect to the ‘globally’ corrected image (for a measured relative humidity of 75%).The bination of a known surface, camera orientation and sensor imaging geometry allows orthorectification of the thermal images and hence geo referencing of the data. An example is shown in Fig. 3. Note that, for this image, some important regions of the flow are occluded by the irregular topography of flow areas closer to the camera. This could be avoided by using less oblique images (. data acquired from a helicopter) or by bining images from different terrestrial positions. Some distortion is evident in the uppermost area of the imaged channel (to the north), where rectification errors from problems at the edge of the surface model are pounded by the oblique viewing angle.Although these issues will be addressed in future work, flow features can be easily identified in the current rectified data. For example, using the parallel lineations of elevated exitance to delineate the active regions of the channel (as opposed to the levees), at a viewing range of ~310 m, the western channel branch has a width of m, which narrows to ~9 m as the flow passes over a region of steeper gradient at a range of ~260 m (Fig. 3). This pares with an average channel width of 17 m and maxima and minima of 37 and 2 m respectively, determined from laser altimeter data collected earlier in the eruption (Mazzarini et ). For this channel section, the exitance measured from the central region of the flow is ~700–1,700 W m?2(corresponding to a black body temperature of 200–290176。C. In this image, 39 pixels were saturated and, with the exception of only a few, these were observing the flowfront nearest the camera. However, they represent % of the imaged front and similar images, taken using the 500–1,500176。C and relative humidity, 75%).Axes scales are meters with respect to the camera position. Areas of surface which are occluded for this camera orientation plot in black. Their angular nature is a result of defining their extent using the triangulation of the surface model.Summary1. Multiphoto closerange photogrammetric techniques have been successfully applied to visible and thermal images of lava flows collected using groundbased Cameras.2. The visible images have been used to generate topographic data and to assist registration of the thermal imagery.3. The bination of known imaging geometry and topographic data allows observation distances to be calculated and hence relevant atmospheric attenuation corrections to be applied to each pixel in the thermal images.4. Photogrammetric orthorectification and geo referencing of the thermal images provides quantitative results for further analysis of lavaflow development (. Channel migration, transition from channel to tube morphology, the effect of flow fronts constraining advance rates)and for bination with other image datasets.Acknowledgements This work was supported by the Royal Society. We thank S. Calvari, J. Dehn, D. 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