Abstract

Northwest-directed motion of the Central American Forearc at ~14 mm/yr relative to the Caribbean plate is accommodated on margin normal and margin parallel fault systems within the Central American Volcanic Arc in Nicaragua. Proximity of faults to magmatic systems has historically led to magma-tectonic interactions. Here, we present two cases. The 1999 eruption of Cerro Negro volcano was preceded (~11 hrs) by four ~M5.2 earthquakes. Coulomb failure stress modeling indicates: 1) the earthquakes reduced normal stress on the Cerro Negro-Cerro La Mula volcanic alignment leading to magma migration and eruption along an ~100 m long fissure; and 2) triggered a regional sequence of aftershocks up to Ml4.6. The 2015-2016 eruption of Momotombo was preceded by the April 10, 2014 M_w 6.1 earthquake, which displaced the flank of the volcano southward by ~6 cm. Additionally, a sequence of earthquakes occurred northwest of the April 10, 2014 earthquake in 2016. We use GPS-derived co-seismic displacements and relocated earthquake aftershocks to study both the April 10, 2014 earthquake and the 2016 earthquake sequence. The earthquake dilated (10s of µStrain) and reduced the normal stress on the shallow magmatic system of Momotombo volcano, leading to magma injection, ascent, and eruption on December 1, 2015, after ~110 years of quiescence. In addition, the 2014 earthquake, increased the Coulomb Failure Stress on the faults that ruptured in 2016. In total, these sequences demonstrate the potential for cascading hazards.

Biography

Prof Dr Peter LaFemina received a BSc in Geoscience from Hartwick College, with an emphasis on tectonics and structural geology and an MSc in Geoscience from Florida International University where he studied changes in soil degassing at Telica and Cerro Negro volcanoes, Nicaragua. This was followed with a position as Research Scientist at the Center for Nuclear Waste Regulatory Analyses at Southwest Research Institute where he help develop potential field mapping techniques to investigate magmatism and tectonics, and the seismic and volcanic hazard assessments for critical facilities. He then received a PhD in Marine Geology and Geophysics at the University of Miami – Rosenstiel School of Marine & Atmospheric Sciences with an emphasis on investigating plate boundary zone deformation using space geodetic techniques. He was awarded the prestigious Walton Smith award for best PhD. After sixteen years as a Professor of Geosciences at The Pennsylvania State University, he moved to the Alfred Wegener Institute – Helmholtz Center for Polar & Marine Research and the University of Bremen. Today, he strives to improve our understanding of tectonic and magmatic processes at active plate boundaries and their impacts on society using terrestrial and satellite geodetic techniques through collaboration with students and national and international colleagues.