caa a22 4500 475826019 CHVBK 20180406123828.0 cr unu---uuuuu 170329e20000201xx s 000 0 eng 10.1007/s004450050001 doi (NATIONALLICENCE)springer-10.1007/s004450050001 Physical volcanology and structural development of Cerro Azul Volcano, Isabela Island, Galápagos: implications for the development of Galápagos-type shield volcanoes [Elektronische Daten] [Terry Naumann, Dennis Geist] 3: ) erupted from circumferential vents near the summit. These flows are nearly an order of magnitude smaller in volume than the predominantly aa flows erupted from radial eruptive fissures near the break in slope (0.06-0.1 km3). The differences in volume and flow morphology with altitude are due to slower eruption rates from summit vents than from flank vents, which, in turn, are attributable to the different heights the magmas must ascend from shallow reservoirs. These observations support the contention that the steep upper flanks were constructed by the buildup of short lava flows rather than by the structural deformation of originally gently dipping flanks. In addition to the higher eruption rates, a subdued lower flank geometry is promoted by the deposition of lava deltas onto the shallow Galápagos platform on the western, northern, and eastern flanks of the volcano. 40Ar/39Ar geochronology and volume estimates show that, despite their morphologic differences, the growth of the western Galápagos shields has been nearly synchronous, precluding an evolutionary model for their development. The wide variations in elevation, volume, area, and the distribution of slope angles among the western volcanoes can be linked instead to different long-term eruption rates and, to a lesser degree, the position of each volcano relative to the edge of the Galápagos platform. Springer-Verlag Berlin Heidelberg, 2000 Caldera nationallicence Eruption rate nationallicence Galápagos nationallicence Hydrovolcanism nationallicence Ocean island nationallicence Morphology nationallicence Shield volcano nationallicence Naumann Terry Department of Geology, University of Alaska, Anchorage, AK 99508, USA e-mail: aftrn@uaa.alaska.edu Fax: +1-907-7866850, US aut Geist Dennis Department of Geology and Geological Engineering, University of Idaho, Moscow, ID 83844, USA, US aut https://doi.org/10.1007/s004450050001 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s004450050001 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Naumann Terry Department of Geology, University of Alaska, Anchorage, AK 99508, USA e-mail: aftrn@uaa.alaska.edu Fax: +1-907-7866850, US aut NATIONALLICENCE 700 1- Geist Dennis Department of Geology and Geological Engineering, University of Idaho, Moscow, ID 83844, USA, US aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer