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Observatorio Vulcanológico y Sismológico de Costa Rica

URI permanente para esta comunidadhttp://10.0.96.45:4000/handle/11056/14933

El Observatorio Vulcanológico y Sismológico de Costa Rica (OVSICORI) de la Universidad Nacional, es un instituto de investigación universitaria dedicado a la investigación de los volcanes, los sismos y otros procesos tectónicos, con el propósito de encontrar aplicaciones útiles a la sociedad que ayuden a mitigar los efectos adversos de esos fenómenos al desarrollo económico y social. Se trata de un observatorio, por cuanto una cantidad considerable de su esfuerzo va orientada a documentar la actividad sísmica, volcánica y la deformación cortical que, a su vez, retroalimenta a las actividades investigativas propias de un instituto de investigación universitaria.

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Teléfono: (506) 2562 4001 / (506) 2261 0611 / (506) 2261 0781

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  • Miniatura
    Ítem
    Aftershocks of the 2012 Mw 7.6 Nicoya, Costa Rica, earthquake and mechanics of the plate interface
    (Seismological Society of America (SSA), 2017-05-02) Chaves, Esteban; Duboeuf, Laure; Schwartz, Susan; Lay, Thorne; Kintner, Jonas
    Subduction of the Cocos plate beneath the Nicoya Peninsula, Costa Rica, generates large underthrusting earthquakes with a recurrence interval of about 50 yrs. The most recent of these events occurred on 5 September 2012 (Mw 7.6). A vigorous sequence of more than 6400 aftershocks was recorded by a local seismic network within the first four months after the mainshock. We determine locations and focal mechanisms for as many aftershocks as possible with M ≥1:5 occurring within the first nine days of the mainshock, all aftershocks with M ≥3 through the end of 2012, and all events with M ≥4 through the end of 2015. We determine faulting geometries using regional full waveform moment tensor (MT) inversion for the largest events (M ≥4) and P-wave first-motion polarities for smaller events, producing a mechanism catalog with 347 earthquakes. Sixty percent of these events are identified as underthrusting, and their locations are compared with spatial distributions of mainshock slip, afterslip, prior interplate seismicity, and slow-slip phenomena to better understand the mechanical behavior of the plate interface. Most of the aftershocks on the megathrust occur up-dip of the coseismic slip, where afterslip is large, and between coseismic slip and shallow slow-slip patches. The pattern of interplate seismicity during the interseismic period is similar to that for the aftershocks but does not extend to as great a depth. The coseismic slip extends even deeper than the interplate aftershocks, suggesting that the mainshock ruptured a strongly locked patch driving down-dip slip into the conditionally stable part of the deep plate interface that also hosts slow slip. About 80% of the aftershocks have one nodal plane oriented favorably to promote failure from static stress changes following the mainshock and early afterslip, whereas most others occur in regions of large afterslip.
  • Miniatura
    Ítem
    Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures
    (American Association for the Advancement of Science (AAAS), 2020) Lecocq, Thomas; Hicks, Stephen; Van Noten, Koen ; van wijk, kasper; Koelemeijer, Paula; De Plaen, Raphael; Massin, Frédérick; Hillers, Gregor; Anthony, Robert E.; Apoloner, Maria-Theresia; Arroyo-Solórzano, Mario; Assink, Jelle; Büyükakpınar, Pınar; Cannata, Andrea; Cannavo', Flavio; Carrasco, Sebastian; Caudron, Corentin; Chaves, Esteban; Cornwell, David; Craig, David; den Ouden, Olivier; Diaz, Jordi; Donner, Stefanie; Evangelidis, Christos; Evers, Läslo; Fauville, Benoit; Fernandez, Gonzalo; Giannopoulos, Dimitrios; Gibbons, Steven J.; Girona, Társilo; Grecu, Bogdan; Grunberg, Marc; Hetényi, György; Horleston, Anna; Inza, Adolfo; Irving, Jessica C.E.; Jamalreyhani, Mohammadreza; Kafka, Alan; Koymans, Mathijs R.; Labedz, Celeste; Larose, Eric; Lindsey, Nathaniel; McKinnon, Mika; Megies, Tobias; Miller, Meghan; Minarik, William; Moresi, Louis-Noel; Márquez Ramirez, Víctor H; Möllhoff, Martin; Nesbitt, Ian; Niyogi, Shankho; Ojeda, Javier; Oth, Adrien; Proud, Simon; Pulli, Jay; Retailleau, Lise; Rintamäki, Annukka E.; Satriano, Claudio; Savage, Martha; Shani-Kadmiel, Shahar; Sleeman, Reinoud; Sokos, Efthimios; Stammler, Klaus; Stott, Alexander; Subedi, Shiba; Sørensen, Mathilde Bøttger; Taira, Taka'aki; Tapia, Mar; Turhan, Fatih; van der Pluijm, Ben; Vanstone, Mark; Vergne, Jérôme; Vuorinen, Tommi; Warren, Tristram; Wassermann, Joachim; Xiao, Han
    Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the coronavirus disease 2019 (COVID-19) pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. Although the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This quiet period provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of human activities.
  • Miniatura
    Ítem
    The 27 February 2022 Lop Nor earthquake: detectability, location, and discrimination
    (Seismological Society of America (SSA), 2022) Gibbons, Steven J.; Chaves, Esteban; Fisk, Mark
    A seismic event with mb 4.8 (Mw 4.2) was detected close to the Chinese Lop Nor nuclear test site on 27 February 2022. Waveforms recorded at regional and far regional distances in central Asia indicate greater likeness with previous earthquakes in the region than with historical nuclear tests. We investigate signal-to-noise ratio (SNR) at regional and global stations, and find the best signals in central Asia and Alaska. Lower SNR at stations in China, Europe, and Australia is likely related to the radiation pattern. A joint probabilistic location of the 2022 event and well-constrained historical nuclear tests indicates an epicenter near 41.88° N and 88.10° E, about 25 km northwest of the tunnel portion of the test site. A moment tensor inversion using high-quality regional signals indicates a nearly deviatoric source with a 72% double couple and a reverse fault mechanism. The centroid depth is 20–25 km, consistent with depth phases recorded in Alaska. The observed faulting geometry and source composition for the 2022 Lop Nor event is consistent with previous earthquakes in the region and the spatial alignment of local geomorphological features, indicating tectonic and not anthropogenic origin.