Smithsonian Institution's Global Volcanism Network

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 30, no. 10, October 2005 (on the Internet at http://www.volcano.si.edu/). Edited by scientists at the Smithsonian, this Bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.     

Intertidal subsidence and collapse features on wave‐exposed,drift‐aligned sandy beaches subject to Amazon mud: Cayenne,French Guiana

Short‐lived collapse features affecting the intertidal sandy profile were observed on mud‐rich beaches in Cayenne. They were formed in packets of beach sand accumulating over thick (several metres) fluid to under‐consolidated foreshore mud, which adjusts to this sand loading by seaward and longshore migration of fluid mud and subsequent in situ mud dewatering, thus generating subsidence and deformation of the overlying sand sheet. These sandy collapse features required active longshore sand transport and were washed out by wave processes at each rising tide. They finally disappeared permanently as adjustment of the underlying mud enabled stabilization of the beach profile. Copyright © 2006 John Wiley & Sons, Ltd.     

CPT-based seismic stability assessment of a hazardous waste site

In areas of high seismicity, seismic stability often controls hazardous and solid waste landfill closure design. The undrained shear strength (S_u) of the waste mass is fundamental to seismic slope stability analyses. The value of S_u for hazardous waste fill is often difficult to characterize. The physical and chemical natures of the waste fill typically preclude laboratory testing of the materials. In certain cases, Cone Penetration Test (CPT) soundings can provide a viable technique for evaluation of S_u provided that the cone shear strength factor N_k can be established. If hazardous waste materials laboratory testing is not an option, N_k may be evaluated based upon results of non-intrusive in situ testing. This paper presents a case history of the seismic stability assessment of a hazardous waste site in which N_k was established from the results of non-intrusive Spectral Analysis of Surface Waves (SASW) soundings and empirical correlations to shear strength of soils. Generalization of the proposed methodology to other sites should be done with caution owing to variability among the parameters used in the analyses.     

Estimating Small-Area Populations by Age and Sex Using Spatial Interpolation and Statistical Inference Methods

The objective of this research is to compute population estimates by age and sex for small areas whose boundaries are different from those for which the population counts were made. In our approach, population surfaces and age‐sex proportion surfaces are separately estimated. Age‐sex population estimates for small areas and their confidence intervals are then computed using a binomial model with the two surfaces as inputs. The approach was implemented for Iowa using a 90 m resolution population grid (LandScan USA) and U.S. Census 2000 population. Three spatial interpolation methods, the areal weighting (AW) method, the ordinary kriging (OK) method, and a modification of the pycnophylactic method, were used on Census Tract populations to estimate the age‐sex proportion surfaces. To verify the model, age‐sex population estimates were computed for paired Block Groups that straddled Census Tracts and therefore were spatially misaligned with them. The pycnophylactic method and the OK method were more accurate than the AW method. The approach is general and can be used to estimate subgroup‐count types of variables from information in existing administrative areas for custom‐defined areas used as the spatial basis of support in other applications.     

Estimation of rock engineering properties using hardness tests

In engineering projects such as tunnels, dams, foundations, and slope stability, the strength and elastic properties of the intact rock affect both the project design and the construction operation. It is sometimes expensive and time consuming to perform direct tests to evaluate the engineering properties (such as strength, modulus of elasticity, and Poisson's ratio) of the intact rock. The purpose of this work is to investigate the relationships between the engineering properties of the intact rock and the different types of hardness (Schmidt, shore scleroscope, abrasion, and total hardness), which are relatively cheap and easy to evaluate. In this study, dolomite, dolomitic limestone, and shale rocks were used. For simplicity, linear statistical analyses were performed. The results show that there are good relationships between the engineering properties of the intact rock and its hardness. Also, the results of this study are compared well with the results obtained by other investigators conducted on different types of rocks.     

Zircon geochronology of basement rocks from the Pelagonian Zone,Greece: constraints on the pre-Alpine evolution of the westernmost Internal Hellenides

The Pelagonian Zone of Greece is the westernmost segment of the Internal Hellenides comprising widespread crystalline basement exposures of granites and orthogneisses. We dated these basement rocks in order to identify the major crust-forming episodes and to understand the evolutionary history of the area. In our study we investigated granites, gneisses, meta-rhyolites and mylonites from the major occurrences of the Pelagonian Zone. We applied single-zircon dating techniques such as Pb–Pb evaporation, conventional U–Pb and SHRIMP. The majority of the basement rocks gave Permo-Carboniferous intrusion ages, thus emphasizing the importance of this crust-forming event for the Internal Hellenides of Greece. Triassic intrusion ages were obtained, however, for a meta-rhyolite from the western Pelagonian Zone and two mylonites from the eastern Pelagonian Zone. These ages are interpreted to reflect magmatism accompanying early rifting that led to the subsequent opening of the Pindos Ocean to the west and the Meliata Ocean to the east of the Pelagonian Zone. The geochronological results demonstrate that the magmatic episodes during which most of the Pelagonian Zone crystalline basement formed are predominantly pre-Alpine in age.     

Smithsonian Institution’s Global Volcanism Network

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 31, no. 9, September 2006 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.     

Smithsonian Institution’s Global Volcanism Network

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 31, no. 10, October 2006 (on the Internet at http://www.volcano.si.edu/). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.     

Smithsonian Institution’s Global Volcanism Network

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 32, no. 3, March 2007 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.