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Landslide quantitative risk analysis of buildings at the municipal scale based on a rainfall triggering scenario
Publication . da Silva Pereira, Susana; Garcia, Ricardo A C; Zêzere, José; Oliveira, Sérgio; Silva, Márcio
A landslide quantitative risk analysis is applied the municipality of Santa
Marta de Penagui~ao (N of Portugal) to evaluate the risk to which the
buildings are exposed, using a vector data model in GIS.
Two landslide subgroups were considered: landslide subgroup 1 (event
inventory of landslides occurred on January 200)1; and landslide subgroup
2 (inventoried landslides occurred after the 2001 event until 2010). Seven
landslide predisposing factors were weighted and integrated using the
Information Value Method. The landslide susceptibility model was
independently validated and the model performance was expressed by
ROC curves.
The probability of landslide size was estimated using a probability density
function and the landslide hazard scenario was defined using the same
landslide rainfall-triggering event.
A vulnerability curve was constructed for each type of building considering
its structural properties and the proxy of landslide magnitude. The
economic value assigned for each building represents an approximated
cadastral value.
The landslide risk was computed for each building in vector format based
on a rainfall triggering scenario and two landslide magnitudes.
The probability of occurrence of small landslides is two orders of magnitude
higher than the probability of occurrence for large landslides, which
explains the higher risk generated by small landslides, despite of registering.
Evolución de la cubierta vegetal después de una perturbación por deslizamientos
Publication . Lopes, Luis; Neto, Carlos; Oliveira, Sérgio; Zêzere, José
La perturbación produce alteraciones en los ecosistemas afectando
la evolución por sucesión ecológica y, consecuentemente, es considerada
como uno de los principales factores que afectan al desarrollo de la vegetación.
Por ello, ejerce un papel crucial en el mantenimiento de la biodiversidad,
teniendo un papel ecológico muy importante a través de la creación de hábitats
complejos y únicos. Así, para la determinación del nivel de diferenciación
entre sectores internos de los deslizamientos en función de la vegetación, conjuntamente
con una evaluación de las alteraciones entre comunidades afectadas
y adyacentes, se han analizado mediante un muestreo estratiicado, tres
sectores del deslizamiento (cicatriz, cuerpo y pie), culminando en la identiicación
de 115 taxones. Las laderas inestables permiten el surgimiento de
especies endémicas donde el valor de conservación y la riqueza lorística es
máxima en la fase intermedia del proceso de recuperación iniciado con la perturbación.
La ocurrencia periódica de deslizamientos y consecuente regresión
sucesional se interpreta como positiva y necesaria.
A comparison between bivariate and multivariate methods to assess susceptibility to liquefaction-related coseismic surface effects in the Po Plain (Northern Italy)
Publication . Lanfredi Sofia, C.; Oliveira, Sérgio; Pereira, Susana; Zêzere, José; Corsini, A.
The two main events occurred during the 2012 seismic sequence on the
Po Plain in Northern Italy (May 20 Mw 5.9 and May 29 Mw 5.8) induced
widespread coseismic surface effects (CSEs), mostly liquefaction
phenomena, which caused severe damages. To prevent risks related to
CSE, an important non-structural measure is to assess locations
susceptible to liquefaction, which is usually done at site scale by means of
deterministic approaches in micro-zonation studies. This paper brings a
novel methodological contribution in the field of CSE susceptibility
mapping at regional scale, by testing and comparing bivariate (Weights of
Evidence) and multivariate (Logistic Regression) methods that, so far, have
not yet been used for such purpose. In a study area of 1480 km2
, the
computation used an inventory of CSE as supporting evidence and a set of
maps with geologic, geomorphic, hydrogeological and topographic
factors as causal variables. Both methods provided susceptibility maps
with a significant predictive capability and a fairly good spatial agreement
between each other. In conclusion, this application of data-driven spatial
modelling approaches indicates that such methods can be effectively
used for liquefaction susceptibility zonation at regional scale, which can
be of significant support for spatial planning over large areas.
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Fundação para a Ciência e a Tecnologia
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SFRH
Número da atribuição
SFRH/BPD/85827/2012