Scenario-based probabilistic hazard assessment for explosive events at the San Salvador volcanic complex, El Salvador
Por:
Aravena, Alvaro, Bevilacqua, Andrea, Neri, Augusto, Gabellini, Pietro, Ferres, Dolors, Escobar, Demetrio, Aiuppa, Alessandro, Cioni, Raffaello
Publicada:
1 jun 2023
Resumen:
We present a scenario-based, probabilistic hazard assessment for the San
Salvador volcanic complex (SSVC), a volcanic field located in the
vicinity of San Salvador that includes the El Boquer ` on stratovolcano
and 25 monogenetic vents. We define a set of likely eruption scenarios
for tephra fallout and pyroclastic density currents (PDCs). The eruption
scenarios range from violent Strombolian eruptions with a significant
uncertainty in source position to sub-Plinian and Plinian activity fed
from the central cone. The adopted methodology is mainly based on
numerical modeling using Tephra2 (adopting the software TephraProb) to
study tephra fallout and the branching box model and the branching
energy cone model (adopting the programs BoxMapProb 2.0 and ECMapProb
2.0) to describe inertial and frictional PDCs, respectively. Despite the
dominant W-WSW-trending winds, numerical results show that Plinian
eruptions at El Boquer ` on volcano are able to deposit thick tephra
layers in the metropolitan area of San Salvador city, likely reaching
mass loads of the order of 100 kg/m2 (conditional probability of 50%).
The simulated sub-Plinian events highlight the seasonal influence of
wind patterns. In fact, the conditional probability of significant
tephra sedimentation in San Salvador city is strongly reduced when
eruptions occur during the rainy season. Numerical modeling of violent
Strombolian eruptions is performed considering uncertainty in vent
position. Results show that the conditional probability of depositing
tephra mass loads higher than 10 kg/m2 at a given point reaches a
maximum value of-7% on the NW flank of the volcano, at about 8 km from
the central crater. On the other hand, very low conditional
probabilities (<1%) are obtained for San Salvador city for any relevant
threshold (10 kg/m2 or more) of tephra mass load during violent
Strombolian events. Regarding PDCs, results show that those produced
during large-scale Plinian erup-tions are able to invade significant
areas of the volcano surroundings, including San Salvador city. PDCs
generated from the partial collapse of a sub-Plinian eruption column
exhibit maximum inundation probabilities on the N, W and S flanks of the
volcano. Cerro El Picacho exerts a significant shield effect on the
propagation of these PDCs, with low inundation probabilities for San
Salvador city (<3%). Finally, coupling published vent opening
probability maps and numerical modeling of small-scale PDCs yields
maximum inundation probabilities on the NW flank of the volcano,
reaching maximum conditional probabilities of the order of-10% and
values of about 5% near the village of Nuevo Sitio del Nin similar to
o.
Filiaciones:
Aravena, Alvaro:
Facultad de Ciencias Básicas, Universidad Católica del Maule, Talca, Chile
Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, Clermont-Ferrand, France
Univ Catolica Maule, Fac Ciencias Basicas, Talca, Chile
Univ Clermont Auvergne, Lab Magmas & Volcans, CNRS, IRD,OPGC, Clermont Ferrand, France
Bevilacqua, Andrea:
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy
Ist Nazl Geofis & Vulcanol, Sez Pisa, Pisa, Italy
Neri, Augusto:
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy
Ist Nazl Geofis & Vulcanol, Sez Pisa, Pisa, Italy
Gabellini, Pietro:
Dipartimento di Scienze della Terra, Università degli studi di Firenze, Florence, Italy
Univ Firenze, Dipartimento Sci Terra, Florence, Italy
Ferres, Dolors:
Escuela Nacional de Ciencias de la Tierra, UNAM, Ciudad de México, Mexico
UNAM, Escuela Nacl Ciencias Tierra, Ciudad de Mexico, Mexico
Escobar, Demetrio:
Dirección del Observatorio Ambiental, MARN, San Salvador, El Salvador
MARN, Direcc Observ Ambiental, San Salvador, El Salvador
Aiuppa, Alessandro:
Dipartimento di Scienze della Terra e del Mare, Università degli studi di Palermo, Palermo, Italy
Univ Palermo, Dipartimento Sci Terra & Mare, Palermo, Italy
Cioni, Raffaello:
Dipartimento di Scienze della Terra, Università degli studi di Firenze, Florence, Italy
Univ Firenze, Dipartimento Sci Terra, Florence, Italy
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