Seismic source analysis of two anomalous earthquakes in Northern Chile

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F22%3A00560472" target="_blank" >RIV/67985530:_____/22:00560472 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0895981122002371" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0895981122002371</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jsames.2022.103948" target="_blank" >10.1016/j.jsames.2022.103948</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Seismic source analysis of two anomalous earthquakes in Northern Chile

Popis výsledku v původním jazyce

Northern Chile is a seismically very active region driven by subduction of the Nazca plate beneath the South American plate. Anomalous focal mechanisms were reported by international agencies for two recent earth-quakes with magnitudes larger than Mw 6. The September 11, 2020, Mw 6.2 Loa River earthquake occurred in the forearc under the Coastal Cordillera and had a strike-slip mechanism, while most common regional seismicity is characterised by NS-oriented, trench-parallel, thrust mechanisms, consistent with the subduction geometry. The June 3, 2020, Mw 6.8 San Pedro de Atacama earthquake occurred at intermediate depth with a normal faulting mechanism. In this case, the anomalous behavior involves the NW-SE striking of the focal mechanism, which deviate from the typical NS orientation in the region. In this study we reconstruct the rupture geometry for these two earthquakes by means of moment tensor inversion, rupture directivity analysis and aftershock dis-tribution. Seismological results are discussed in the frame of the spatial and temporal distribution of local seismicity, which are analyzed using clustering techniques. Our results show that both earthquakes reveal the activation of seismogenic structures in the continental crust or within the subducting oceanic crust close to the subduction interface. The Loa River earthquake occurred at the base of the continental crust, at the contact with the slab. This finding highlights the role of seismicity associated with crustal faults in the South American plate, which poses a secondary seismic hazard for the region, alongside the seismicity directly associated with the subduction zone. The San Pedro de Atacama earthquake, in turn, occurred within the subducting slab. Its anomalous mechanism may indicate a local anomaly in the geometry of the subducting slab.

Název v anglickém jazyce

Seismic source analysis of two anomalous earthquakes in Northern Chile

Popis výsledku anglicky

Northern Chile is a seismically very active region driven by subduction of the Nazca plate beneath the South American plate. Anomalous focal mechanisms were reported by international agencies for two recent earth-quakes with magnitudes larger than Mw 6. The September 11, 2020, Mw 6.2 Loa River earthquake occurred in the forearc under the Coastal Cordillera and had a strike-slip mechanism, while most common regional seismicity is characterised by NS-oriented, trench-parallel, thrust mechanisms, consistent with the subduction geometry. The June 3, 2020, Mw 6.8 San Pedro de Atacama earthquake occurred at intermediate depth with a normal faulting mechanism. In this case, the anomalous behavior involves the NW-SE striking of the focal mechanism, which deviate from the typical NS orientation in the region. In this study we reconstruct the rupture geometry for these two earthquakes by means of moment tensor inversion, rupture directivity analysis and aftershock dis-tribution. Seismological results are discussed in the frame of the spatial and temporal distribution of local seismicity, which are analyzed using clustering techniques. Our results show that both earthquakes reveal the activation of seismogenic structures in the continental crust or within the subducting oceanic crust close to the subduction interface. The Loa River earthquake occurred at the base of the continental crust, at the contact with the slab. This finding highlights the role of seismicity associated with crustal faults in the South American plate, which poses a secondary seismic hazard for the region, alongside the seismicity directly associated with the subduction zone. The San Pedro de Atacama earthquake, in turn, occurred within the subducting slab. Its anomalous mechanism may indicate a local anomaly in the geometry of the subducting slab.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10507 - Volcanology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of South American Earth Sciences

ISSN

0895-9811

e-ISSN

1873-0647

Svazek periodika

119

Číslo periodika v rámci svazku

November

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

11

Strana od-do

103948

Kód UT WoS článku

000857430600003

EID výsledku v databázi Scopus

2-s2.0-85136602244