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Cascading Hazards in a Migrating Forearc-Arc System: Earthquake and Eruption Triggering in Nicaragua

Feb 13, 2023, 13:15 Uhr
MARUM Seminar
MARUM Seminar room 2070

Peter Christopher LaFemina

Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven

Strain partitioning in the Central American convergent margin between the subducting Cocos Plate and Caribbean Plate is accommodated along the Middle America Trench and faults in the forearc-arc regions. In Nicaragua northwest-directed (margin parallel) forearc motion occurs on northeast (margin normal) and northwest (margin parallel) trending faults within the arc. The proximity of active faults and magmatic systems has historically led to magma-tectonic interactions. We investigate the active tectonics of Nicaragua, including a triggered sequence of earthquakes and a volcanic eruption. We use GPS-derived co-seismic displacements and relocated earthquake aftershocks to study the April 10, 2014 (Mw 6.1), September 15, 2016 (Mw 5.7), and September 28, 2016 (Mw 5.5) as a triggered sequence of earthquakes on faults that accommodate forearc motion.

Peter Christopher LaFemina
Peter Christopher LaFemina

Our analyses and modeling indicate that the April 10, 2014 earthquake ruptured a previously unmapped margin parallel right-lateral strike-slip fault in Lago de Managua (Xolotlan) and that the September 2016 earthquakes ruptured mapped arc-normal, left-lateral and oblique-slip faults. The April 10, 2014 earthquake promoted failure of the September 2016 earthquake faults by imparting static Coulomb failure stress changes of 0.02 MPa to 0.07 MPa. Additionally, the September 15, 2016, earthquake promoted failure (static Coulomb failure stress change of 0.08 MPa to 0.1 MPa) on a sub-parallel fault that ruptured five hours after the mainshock. The April 10, 2014 earthquake displaced the flank of Momotombo volcano ~6 cm coseismically and dilated (10s of µStrain) the shallow magma system of Momotombo Volcano, which led to magma injection, ascent, and eruption on December 1, 2015, after ~100 years of quiescence. In total, this sequence represents the potential for cascading hazards in a forearc-arc system, with earthquake and magmatic triggering over short spatial (10’s km) and temporal (yrs) scales.