Wide-angle seismic constraints on the internal structure of Tenerife, Canary Islands
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We have used wide-angle seismic data to constrain the internal structure of Tenerife, Canary Islands, The experiment was designed as a seismic fan profile to detect azimuthal variations in the seismic structure of the volcanic edifice and its Ranks. Seismic energy was generated using a 75-1 airgun-array on board the RRS Charles Darwin fired every 40 s along a quasicircular profile around the island of Tenerife, centered on Teide volcano. We present the results obtained from the data recorded by five portable land stations distributed on the island. The travel-times indicate that the averaged P-wave velocity within the volcanic edifice is greater than 6 km/s. The observed travel-times were reduced to residual travel-times by removing the effects of variations in the bathymetry along the profile, variations in the shot-receiver distance, and from local heterogeneities. Negative residual travel-times up to 0.8 s in amplitude indicate that the southwestern part or Tenerife is characterized by a high P-wave velocity zone, coincident with a gravity maximum that was previously modeled as a high-density body forming the core of an old. large mafic volcano. We estimate velocities greater than 7.3 km/s within the anomalous body, suggesting that it represents an intrusive plutonic complex. This high-velocity, high-density body may have played an important role in the evolution of Tenerife, buttressing Las Canadas edifice acid preventing the occurrence of landslides in the southern and western areas of Tenerife. The bathymetric high between Tenerife and La Gomera is associated with travel-time delays up to 0.4 s, suggesting that it may be composed of large deposits of lava Rows and volcaniclastic materials, probably erupted from the shield massifs of Teno, Rogue del Conde, and La Gomera. The post-shield volcanic zones of Santiago and Dorsal rifts also seem to be characterized by moderate high P-wave velocities. (C) 2000 Elsevier Science B.V. Ail rights reserved.