83 Seismic velocities and densities of rocks

Velocity models and site effects at Kawah Ijen volcano and Ijen caldera (Indonesia) determined from ambient noise cross-correlations and directional energy density spectral ratios

“…It consists of clastic limestone interbedded with sandstone, clay and minor conglomerate (Sujanto et al, 1988). The average Vs velocity of such sedimentary layer at these depths is consistent with this interpretation (e.g., Christensen, 1982;Christensen et al, 2003).…”

“…Generally superficial volcanic stratums have very low Vs velocities (typically less than 500 m/s; i.e., Perrier et al, 2012;Christensen, 1982) due to the presence of ash and unconsolidated air-fall deposits. It may therefore rely with the most resent volcanic activity inside the caldera.…”

“…Indeed, stacked dispersion curves provide mean velocity models probed over several kilometers, while DEDHVRs give local velocity models. Therefore, DEDHVRs may highlight local high velocity body i.e., such as basaltic lava flows (e.g., Christensen, 1982). Therefore, these shallow deposits might be interpreted as the Holocene post-caldera deposits, resulting from the last volcanic activities inside the caldera (Sujanto et al, 1988).…”

Lithospheric structure in the North China craton constrained from Gravity Field Model (EGM 2008)

“…In constructing the forward model, we presented here a simplified model, especially for the crust. The P-wave velocity perturbation in our study area is about ±0.5% (Tian et al, 2009), and the corresponding density variation is about ±0.01 g/cm 3 , calculated from the Christensen's empirical equation (Christensen and Stanley, 2003). Therefore, the lateral density variation is rather small, we used the simplified model for the crust without considering the lateral variable nature of density.…”

Zona de cisalhamento de alta temperatura - o lineamento de Além Paraíba (RJ): petrotrama de plagioclásios-anisotropia sísmica-reologia da litosfera continental

“…As propriedades sísmicas dos principais minerais constituintes d.a crosta e manto superior podem ser encontradas em tabelas fornecidas por diferentes autores (Babuska, 1981;Christensen, 1982;Barruol, 1993 (Barruol, 1993 (Fig. 5.3) (Barruol, 1993) (Barruol, 1993 (Barruol, 1993 As ondas sísmicas se propagam mais rapidamente nos planos basais dos filossilicatos do que normal -aètes.…”