Fast changes along the trench make Central America an excellent target for the study of subduction zone processes Marino Protti Observatorio Vulcanológico y Sismológico de Costa Rica Universidad Nacional - OVSICORI-UNA Agenda ◆ Tectonic setting of Central America ◆ Seismic sources in Central America ◆ Upper plate deformation ◆ Geometry of the Wadati-Benioff Zone ◆ Large subduction earthquakes in the region ◆ Characteristics of the subducting plate ◆ Future research ◆ LACSC 2016 TECTONIC PLATES REGIONAL TECTONIC SETTING Seismicity of Central America 1900-2015 (M>5) Seismicity of Central America 1900-2015 (M>7) A coastal microplate by Lyon-Caen et al., 2006 Sliver motion from Alvarado et al., 2010 Sliver motion from Feng et al., 2012 Pull-apart interpretation for the Gulf of Fonseca (Alvarado et al., 2010) Regional sliver(?) (Franco et al., 2012) Tectonic Setting of Costa Rica 1992 . Nicaragua Hess Nicaragua-Papagayo 11o segment Escarpment 1916 Costa Caribbean 1900 Rica Sea o 10 1939 Limon 1950 1916 Nicoya segment Panama Thrust 1990 Belt 1991 ODP Leg 170 Pacific Cobano-Herradura 1916 9 o Middle segment Ocean Quepos-Sierpe North American segment 1941 American Trench 1904 Panama Plate 1983 Osa-Burica segment o Caribbean Plate 8 Cocos Plate Cocos ? Ridge Panama Fracture Panama Nazca Block Plate 100 km Zone 87 o 86 o 85 o 84 o 83 o 82o Nicaragua vs S Costa Rica Age of the Oceanic Cocos Plate From Barckhausen Correlation between the age and geometry of the subducting Cocos plate Parallel-to-the-trench mantle flow C Protti Seismogenic zone and most recent earthquakes Seismic coupling (Feng et. al., May 2012) September 5th, 2012 Mw=7.6 Nicoya Earthquake Inversion done by Lujia Feng in Singapore only 2 hours after the earthquake Before and after High rate (5 Hz) displacement seismograms (m) There is more sexappeal for the MAT Drilling the seismogenic zone Some issues to think about ◆ Where are the hidden faults under big cities? (extensive volcanic deposits and lahars) ◆ Can we characterized the seismic coupling off shore Central America? ◆ What’s the potential for a major earthquake along the Hess scarpment? ◆ How the sliver motion behaves over an megathrust earthquake cycle? ◆ How local fault motion is controlled by coupling and failure of the subduction megathrust? Central America Regional Network ◆ Managua, Nicaragua (June 4-5 2015) ◆ Hotel Neruda 6:30 PM (reunión preparatoria). Latin America and Caribbean Seismological Commission (LACSC) (IASPEI-IUGG) Regional Assembly 2016 June 20-23, San José, Costa Rica https://www.youtube.com/watch?v=QbhCpfxsod8 Muchas gracias .