首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Understanding the Seismic Velocity Structure of Campi Flegrei Caldera (Italy): From the Laboratory to the Field Scale
Authors:S Vinciguerra  C Trovato  PG Meredith  PM Benson  C Troise  G De Natale
Institution:(1) HP-HT Laboratory Istituto Nazionale di Geofisica e Vulcanologia, sezione di Roma 1, Via di Vigna Murata 605, 00143 Rome, Italy;(2) Istituto Nazionale di Geofisica e Vulcanologia, sezione di Napoli, Via Diocleziano 328, 80124 Naples, Italy;(3) Department of Earth Sciences, University College London, Gower Street, London WC1E6BT London, United Kingdom
Abstract:We report laboratory measurements of P- and S-wave velocities on samples of tuff from Campi Flegrei (Italy), and a new tomographic velocity map of the Campi Flegrei caldera. Laboratory measurements were made in a hydrostatic pressure vessel during both increasing and decreasing effective pressure cycles. Selected samples were also thermally stressed at temperatures up to 600°C to induce thermal crack damage. Acoustic emission output was recorded throughout each thermal stressing experiment, and velocities were measured after thermal stressing. Laboratory P- and S-wave velocities are initially low for the tuff, which has an initial porosity of ~45%, but both increase by between 25 and 50% over the effective pressure range of 5 to 80 MPa, corresponding to a decrease of porosity of ~70%. Marked velocity hysteresis, due to inelastic damage processes, is also observed in samples subjected to a pressurization-depressurization cycle. Tomographic seismic velocity distributions obtained from field recordings are in general agreement with the laboratory measurements. Integration of the laboratory ultrasonic and seismic tomography data indicates that the tuffs of the Campi Flegrei caldera can be water or gas saturated, and shows that inelastic pore collapse and cracking produced by mechanical and thermal stress can significantly change the velocity properties of Campi Flegrei tuffs at depth. These changes need to be taken into account in accurately interpreting the crustal structure from tomographic data.
Keywords:Laboratory P- and S-wave velocities  tomographic velocity map  mechanical and thermal stresses
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号