February Geology and GSA Today media ...(ty currents. Hot pyroclastic flows are o...)

Date:1/22/2008

ty currents. Hot pyroclastic flows are one of the most dangerous volcanic phenomena and have been responsible for many fatalities. Famous examples include the eruption of Vesuvius with the destruction of Herculanium and Pompeii and the eruption of Mont Ple in Martinique that destroyed the town of St. Pierre, killing nearly all the inhabitants. Understanding how these flows behave is important in assessing volcanic hazards. One of the biggest problems has been obtaining temperature data from pyroclastic density currents. A major dome collapse of the Soufrire Hills volcano, Montserrat, on 26 December 1997, generated a devastating pyroclastic density current that destroyed vegetation and left a distinctive tar-like deposit on the surface that deposit included a range of charred, mainly herbaceous flowering plant axes and roots. Reflectance studies of these charcoalified plants provided minimum flow temperatures of 300-425 C, providing an estimate of pyroclastic density current characteristics. Scott et al. estimate flow-front current densities near the ground of 1.8 to 3 kilograms per cubic meter, using constraints from a mean flow speed of 90 meters per second estimated from seismic data. The mean temperature of the ash component is estimated as 400-610 C.

---

Caribbean chronostratigraphy refined with U-Pb dating of a Miocene coral
Rhawn Denniston et al., Department of Geology, Cornell College, Mount Vernon, Iowa 52314, USA. Pages 151-154.

Uplift of the Central American volcanic arc isolated the Caribbean and Pacific oceans approximately 3 million years ago, and changed the physiochemical characteristics of the Caribbean. In response, many shallow marine taxa experienced an increase in speciation. Quantifying these evolutionary rates requires having precise age constraints on the related sedimentary sequences, but such a well-defined chronology has been lacking. Denniston et al. refined the age of one sedimentary unit from the Dominican
'/>"/>

Contact: Ann Cairns acairns@geosociety.org 303-357-1056 Geological Society of America Source:Eurekalert

1 GOOD

Page: 1 2 3 4 5 6 7 8 9 10
Related biology news :

1. September Geology and GSA Today media highlights
2. October Geology and GSA Today media highlights
3. November GEOLOGY and GSA TODAY Media Highlights
4. December GEOLOGY and GSA TODAY media highlights
5. Heart of Herschel to be presented to media
6. Last chance for media to register for ECCO 14 -- the European Cancer Conference
7. Media highlights in the November issues of Biophysical Journal
8. Nanotechnology and the media: The inside story
9. Better protection for biomedial devices could result from Rutgers-Camden research
10. Media highlights in the Dec. 15 issue of Biophysical Journal
11. Immediate action needed to save corals from climate change