PACAYA'S 1961-2008 ACTIVITY: NEW DRAFT OF A 3D VOLCANOLOGICAL MAP

Pacaya's current eruption has now lasted nearly 50 years, with open vent activity marked by extrusion of high Al basalt which has led to a pile of lava flows with generally decreasing length, concentrated in an assymetical conical feature (Mackenney Cone) on the western flank of a pre-existing cone and leading to a total volume change of about 0.21 +/- 0.05 km3, an average extrusion rate of 0.17 +/- 0.04 m3/s (KS Durst et al., Bull Volcanol, in press).

The map was compiled from aerial photos of different dates, satellite imagery and especially field observations by many, including Dr Alfredo Mackenney, who has made weekly visits for nearly all of the whole eruption. The complexity of the lava sequences and their concentration near the Mackenney cone has led to most mapped units being buried by subsequent ones, so that the map has the challenge of how to effectively depict growth in 3 dimensions. All layers of the map are georectified into a GIS and a 2006 orthophoto is used to define most of the current surface. The map is presented in draft form, with hopes for ideas which can lead to an effective presentation format.