ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

We have focused our studies on the potential of caldera
collapse events as a triggering mechanism for the initiation
of landslides in Tenerife. Using a Geographic Information
System (Gis) we have analysed various geological and
morphologic models established by field geology, subaerial
and submarine geophysical data and remote sensing information.
Supplementary data on dyke trends, eruption
vents and extension of pyroclastic deposits has been linked
to the models and improved our understanding of the volcanic
influence during the genesis of the island. The information
obtained has been incorporated into a numerical
model, which simulates a caldera collapse with its phases
of pre-eruption tumescence, vertical collapse and associated
explosive eruptions. We have calculated the stability of
the volcano flank including the horizontal stresses in the
changing stress field, the fractures inside the up doming
area and the seismicity produced by the vertical collapse.
The results of Gis and numerical models indicate that fracturing,
horizontal tensile stress and seismicity caused by
caldera collapse can surpass the stabilising forces of a volcano
flank and trigger a landslide. Therefore we propose
that the caldera collapse events have also triggered large
landslides on the previously weakened slopes of the Las
Cafiadas edifice.
TAMAs HuszAR 1, ADAM KERTESZ 1, DENES L6CZY 1,
KATALIN MOLNAR 1 & JANOS MIKA 2
Simulation of possible climate change effects on
soil water content
1 Geographical Research Institute, Hungarian Academy of Sciences,
p.o. box 64, H-I062 Budapest, Hungary
2 Hungarian Meteorological Service, p.o. box 39, H-1675,
Budapest, Hungary
The Epic (Erosion Productivity Impact Calculator - Sharpley
and Williams, 1990) is applied to estimate soil water
content consequences of the expected regional climate
changes in a typical subcatchment, the Pecsely basin (24
km"), selected for study on the northern catchment of Lake
Balaton, according to climate scenarios (Mika, 1988). The
study is based on the soil hydrology parameters included
in Epic model, exhibiting relatively fast response to the climate
variations. To specify regional climate scenarios for
Hungary with a coarsely time resolution, two approaches
are employed. The simpler one is the use of a geographical
analogy which presumes correspondence of differences in
monthly variance and even the daily behaviour to the established
differences in the long-term means that correspond
to the scenario. Based on this concept, climate data of Pa-
pa (N of Lake Balaton) were selected as geographical analogues
for the expected changes in the Pecsely basin, also
considering the necessary similarities in the non-climatological
conditions. The second approach is a search for statistical
connections between semiannual and monthly anomalies,
and also between monthly anomalies and daily statistics
within the same month. For generating daily weather
sequences, the built-in generator of the Epic is used. Results
of the two approaches are compared. Climate differences
generate considerable variation both in the soil
water content and transpiration. Another source of variation
is crop-rotation, responsible for the half of standard
deviations.
JAMES R. HOOPER 1
& DAVID B. PRIOR 2
Sea floor engineering geomorphology: some recent
achievements and future directions
1Fugro-McClelland Marine Geosciences, Houston, Texas, USA
2 College of Geosciences, Texas A&M University, USA
The development of coastal and offshore resources, such
as oil and gas and minerals, involves sea floor engineering
in remote, complex, and sometimes hazardous environments.
New mapping technology is revealing that the
world's ocean floors exhibit wide variety of relief, sediment
properties, and active geologic processes such as erosion,
faulting, fluid expulsion and landslides. Optimum engineering
design and construction practice require detailed surveys
of sea floor geomorphology, and geologic conditions
on the sea bed and to various depths beneath it, combined
with geotechnical properties of the sediments, and oceanographic
information. Integrated site survey models attempt
to predict conditions and process frequencies and magnitudes
relevant to the engineering design lifetimes of sea
floor installations such as cables, pipelines, production
plafforms, as well as supporting coastal infrastructure such
as jetties, wharves, bridges and harbours. Proper engineering
solutions also contribute to sustainable development
policy objectives by avoiding or minimising risk of adverse
environmental impacts, particularly in coastal areas, where
geoscience and engineering data are key inputs to Coastal
Zone Management. Recent use of deep water areas for oil
and gas production, pipelines and cable routes are also
showing that the «frontier» regions beyond the continental
shelves contain exciting, exotic and enigmatic geomorphological
features and processes. Safe and cost-effective engineering
use of these regions are requiring new technial and
conceptual advances towards better understanding of sea
floor geomorphology - tasks which have barely begun.
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