Relationships between earthquakes, hurricanes, and landslides in Costa Rica
Fecha
2019-06-03
Tipo
artículo de datos
Autores
Quesada Román, Adolfo
Fallas López, Berny
Hernández Espinoza, Karina María
Stoffel, Markus
Ballesteros Cánovas, Juan Antonio
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Resumen
Landslides are a common natural hazard in Costa Rica,
recurrently triggered by seismicity and extraordinary rainfall.
Here, we investigate the coalescence of both processes and their
ability to trigger massive landslides and debris flows in Costa Rica.
The study focuses on Miravalles Volcano, affected by an earthquake
of 5.4 Mw on July 2, 2016, and by intense rainfalls related to
Hurricane Otto only 4 months later, on November 24, 2016. During
the passage of Hurricane Otto, ~300 mm of rain were recorded in
the study region. We use logistic general linear regression models
(GLM) to represent the statistical relationships between the factors
controlling landslides (such as epicenter distance, rainfall during
Hurricane Otto, altitude, and slope). The compound 2016 event
triggered 942 landslides, of which 62% were located within 3–6 km
from the Bijagua earthquake epicenter, and on the eastern, southeastern,
and southern slopes of Miravalles Volcano, i.e., in the zone
where the density of local faults is highest and rainfall reached
maximal values during the hurricane. The statistical analysis supports
the existence of coupled earthquake-hurricane dynamics
with higher landslide densities close to the epicenter and at sites
receiving larger rainfall totals, but also showing higher slopes and
altitudes. Debris flows affected an area of ~27 km2 and moved
down the river systems, leaving eight casualties around the volcano
and ca. 103 million US$ of losses in Upala and Bagaces. Results
of this study can be useful for the assessment and understanding
of geological and hydrometeorological hazards in Costa Rica and
other tropical countries.
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GEOMORPHOLOGY, CYCLONES, Debris flows, Compound events, CENTRAL AMERICA