Artículos científicos

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A tremor and slip event on the Cocos-Caribbean subduction zone as measured by a global positioning system (GPS) and seismic network on the Nicoya Peninsula, Costa Rica
(Universidad Nacional, Costa Rica, 2010-10-01) Outerbridge, Kimberly; Dixon, Timothy; Schwartz, Susan; Walter, Jacob; Protti, Marino; Gonzalez, Victor; Biggs, J; Thorwart, Martin; Rabbel, Wolfgang
In May 2007 a network of global positioning systems (GPS) and seismic stations on the Nicoya Peninsula, of northern Costa Rica, recorded a slow-slip event accompanied by seismic tremor. The close proximity of the Nicoya Peninsula to the seismogenic part of the Cocos-Caribbean subduction plate boundary makes it a good location to study such events. Several centimeters of southwest motion were recorded by the GPS stations over a period of several days to several weeks, and the seismic stations recorded three distinct episodes of tremor during the same time span. Inversion of the surface displacement data for the depth and pattern of slip on the plate interface shows peak slip at a depth of 25-30 km, downdip of the main seismogenic zone. Estimated temperatures here are ∼250°-300°C, lower than in other subduction zones where events of this nature have been previously identified. There may also be a shallower patch of slip at ∼6 km depth. These results are significant in that they are the first to suggest that slow slip can occur at the updip transition from stick slip to stable sliding, and that a critical temperature threshold is not required for slow slip. Tremor and low-frequency earthquake locations are more difficult to determine. Our results suggest they occur on or near the plate interface at the same depth range as the deep slow slip, but not spatially colocated. Copyright 2010 by the American Geophysical Union.
Constraints on inner forearc deformation from balanced cross sections, Fila Costeña thrust belt, Costa Rica
(Universidad Nacional, Costa Rica, 2007) Sitchler, Jason C.; Fisher, Donald M.; Gardner, Thomas W.; Protti, Marino
The Fila Costeña thrust belt in the forearc of Costa Rica is accommodating a significant portion of the convergence of the Cocos plate and Panama microplate. Geologic mapping of the thrust belt depicts a duplex with three horses that incorporate Eocene limestones and Oligocene to early Miocene clastics inboard of the subducting Cocos Ridge axis. By constructing a cross section at this location along a NE-SW trending transect perpendicular to the thrust belt, we constrain a shortening rate of approximately 40 mm/a and propose that as much as 50% of the total plate convergence rate is taken up in the inner forearc. The Eocene limestones at the base of the thrust sheets pinch out in both directions away from the onland projection of the Cocos Ridge axis owing to decrease in slip on faults and a lateral ramp in the basal décollement. The thrust belt terminates near the Panama border at the onland projection of the subducting Panama Fracture Zone. These observations suggest that shortening is propagating to the east with the migration of the Panama triple junction and the onset of shallow subduction of the thickened edge of the Cocos plate. The absence of similar features in the Nicaraguan forearc, where the subducting crust is older, subducts more steeply, and lacks incoming ridges and seamounts, indicates that deformation of the forearc basin in Costa Rica reflects greater couplin between converging plates inboard of the Cocos Ridge. Copyright 2007 by the American Geophysical Union.
Constraints on upper mantle anisotropy surrounding the Cocos slab from SK(K)S splitting
(Universidad Nacional, Costa Rica., 2010) Abt, David L; Fischer, Karen M.; Abers, Geoffrey A.; Protti, Marino; González, Victor; Strauch, Wilfried
SKS and SKKS splitting observations are used to constrain the pattern of mantle flow in the Central American subduction zone beneath Costa Rica and Nicaragua. After removing the effects of shallow wedge anisotropy on SK(K)S waveforms, a best fitting model of anisotropy beneath the Cocos Plate and in the deeper mantle wedge is determined. Fast polarization directions and model symmetry axis orientations in both regions (as well as the shallow wedge) are dominated by roughly arc-parallel azimuths and, therefore, are not consistent with sublithospheric mantle flow entrained by the subducting Cocos Plate or simple two-dimensional corner flow in the wedge. In conjunction with geochemical data and local S splitting tomography, the SK(K)S splitting observations and anisotropy models are consistent with flow to theWNW within the mantle wedge on the Caribbean side of the Cocos Plate, possibly drawn through a slab window beneath Panama and southern Costa Rica. Anisotropy in the Pacific mantle beneath the Cocos Plate is also best explained by flow with a component that is roughly parallel to the strike of the slab, although the absolute direction of this flow is not uniquely constrained. Copyright © 2010 by the American Geophysical Union.
Crustal structure along the southern Central American volcanic front
(Universidad Nacional, Costa Rica., 2018-08-20) MacKenzie, Laura; Abers, Geoffrey A.; Fischer, Karen M.; Syracuse, Ellen; Protti, Marino; Gonzalez, Victor; Strauch, Wilfried
Subduction alters continents several ways, including accretion, magmatic addition, mantle wedge serpentinization, and crustal differentiation. These changes affect seismic velocities, so characterizing upper plate crust establishes a baseline for composition and continental growth. Teleseismic P and PP arrivals from a temporary deployment of broadband seismometers in Central America have been used to estimate crustal thickness and Vp/Vs ratio from receiver functions and to image crust across the active arc. Crustal thickness ranges from 25 to 44 km with formal errors of 1.6–9.2 km. The thinnest crust (24.6 ±3.5 km) lies directly beneath the Nicaraguan arc, whereas the thickest crust lies in the Nicaraguan back arc (43.5 ± 2.5 km) and beneath the Costa Rican arc (37.9 ± 5.2 km). Crustal structure and Vp/Vs show sharp transitions at terrane boundaries. The Moho exhibits strong velocity contrasts throughout the study area of 0.5–1.0 km/s, even beneath arc and fore arc, precluding extensive serpentinization or ponded melt below the Moho. Crust is thicker beneath the Costa Rican arc, consistent with 10–23 km3/km/Ma crustal growth. The crust is thinner by 11–18 km beneath the large depression in central Nicaragua, with the thinnest crust beneath the arc. There, the relationship between thin crust, arc location, and deeper seismic velocities suggests that upper plate structure plays a critical role in focusing magma to the surface.
Detailed spatiotemporal evolution of microseismicity and repeating earthquakes following the 2012 Mw 7.6 Nicoya earthquake
(Universidad Nacional, Costa Rica., 2017) Yao, Dongdong; Walter, Jacob; Meng, Xiaofeng; Hobbs, Tiegan; Peng, Zhigang; Newman, Andrew V.; Schwartz, Susan Y.; Protti, Marino
We apply a waveform matching technique to obtain a detailed earthquake catalog around therupture zone of the 5 September 2012 moment magnitude 7.6 Nicoya earthquake, with emphasis on itsaftershock sequence. Starting from a preliminary catalog, we relocate ~7900 events using TomoDD to betterquantify their spatiotemporal behavior. Relocated aftershocks are mostly clustered in two groups. Thefirst isimmediately above the major coseismic slip patch, partially overlapping with shallow afterslip. The secondone is 50 km SE to the main shock nucleation point and near the terminus of coseismic rupture, in a zone thatexhibited little resolvable afterslip. Using the relocated events as templates, we scan through the continuousrecording from 29 June 2012 to 30 December 2012, detecting approximately 17 times more than templateevents. Wefind 190 aftershocks in thefirst half hour following the main shock, mostly along the plateinterface. Later events become more scattered in location, showing moderate expansion in both along-trench and downdip directions. From the detected catalog we identify 53 repeating aftershock clusters withmean cross-correlation values larger than 0.9, and indistinguishably intracluster event locations, suggestingslip on the same fault patch. Most repeating clusters occurred within thefirst major aftershock group. Veryfew repeating clusters were found in the aftershock grouping along the southern edge of the Peninsula,which is not associated with substantial afterslip. Our observations suggest that loading from nearby afterslipalong the plate interface drives spatiotemporal evolution of aftershocks just above the main shock rupturepatch, while aftershocks in the SE group are to the SE of the observed updip afterslip and poorly constrained.
A model of diffuse degassing at three subduction-related volcanoes
(Universidad Nacional, Costa Rica, 2000) Williams-Jones, G; Stix, J; Heiligmann, M; Charland, A; Sherwood Lollar, B; Arner, N; Gustavo Garzón, V; Barquero, J; Fernandez, E
Radon, CO2 and δ13C in soil gas were measured at three active subduction-related stratovolcanoes (Arenal and Poas, Costa Rica; Galeras, Colombia). In general, Rn, CO2 and δ13C values are higher on the lower flanks of the volcanoes, except near fumaroles in the active craters. The upper flanks of these volcanoes have low Rn concentrations and light δ13C values. These observations suggest that diffuse degassing of magmatic gas on the upper flanks of these volcanoes is negligible and that more magmatic degassing occurs on the lower flanks where major faults and greater fracturing in the older lavas can channel magmatic gases to the surface. These results are in contrast to findings for Mount Etna where a broad halo of magmatic CO2 has been postulated to exist over much of the edifice. Differences in radon levels among the three volcanoes studied here may result from differences in age, the degree of fracturing and faulting, regional structures or the level of hydrothermal activity. Volcanoes, such as those studied here, act as plugs in the continental crust, focusing magmatic degassing towards crater fumaroles, faults and the fractured lower flanks.
Behaviour of Polythionates in the Acid Lake of Poás Volcano: Insights into Changes in the Magmatic-Hydrothermal Regime and Subaqueous Input of Volatiles
(Springer, 2019) Martínez Cruz, María; van Bergen, Manfred J.; Takano, Bokuichiro; Fernández Soto, Erick; Barquero Hernández, Jorge
In this chapter, we document an extensive record of concentrations and speciation of polythionates (PTs: S4O62− , S5O62− , and S6O6 2−), which form in the warm (21–60 °C) and hyper-acidic (pH < 1.8) waters of the crater lake of Poás volcano (Costa Rica) through interaction with gaseous SO2 and H2S of magmatic origin. Our data set, together with earlier published results, covers the period 1980–2006 during which lake properties and behavior were marked by significant variations. Distinct stages of activity can be defined when combining PT distributions with geochemical, geophysical and field observations. Between 1985 and mid-1987, when fumarolic outgassing was centered on-shore, the total concentration of PTs in the lake was consistently high (up to 4,200 mg/kg). Mid-1987 was the start of a 7-year period of vigorous fumarolic activity with intermittent phreatic eruptions from the lake, which then dried out. Concentrations of PTs remained below or close to detection limits throughout this period. After mid-1994, when a new lake formed and fumarolic outgassing shifted to the dome, the total PT concentrations returned to relatively stable intermediate levels (up to 2,800 mg/kg) marking more quiescent conditions. Since early 1995, numerous weak fumarole vents started, opening up at several other locations in the crater area. During short intervals (November 2001–May 2002 and October 2003–March 2005), PTs virtually disappeared. After April 2005, PTs re-appeared in large amounts (up to more than 3,000 mg/kg) until February 2006, one month before the onset of the March 2006–2017 cycle of phreatic eruptions, when concentrations dropped and remained below 100 mg/kg. The observed behavior of PTs records changes in the input and SO2/H2S ratios of subaqueous fumaroles. The prevailing distribution of PTs is S4O62− > S5O62− > S6O62−, which is common for periods when total PT concentrations and SO2/H2S ratios of the gas influx into the lake are relatively high. PTs are virtually absent as a consequence of thermal or sulphitolytic breakdown during periods of strong fumarolic outgassing in response to shallow intrusion of fresh magma or fracturing of the solid envelope around a pre-existing body of cooling magma. They are also low in abundance or undetected during quiescent periods when subaqueous fumarolic output is weak and has low SO2/H2S ratios, resulting in a concentration sequence S5O62− > S4O62− > S6O62−. The onset of phreatic eruptions are preceded by an increase in PT concentrations, accompanied by a change in the dominance from penta-totetrathionate, and followed by a sharp drop in total PT content, up to several months before. Periods of phreatic eruptive activity that started in 1987 and 2006 followed these PT signals of increased input of sulfur-rich gas, in both cases possibly in response to shallow emplacement of fresh magma or hydrofracturing.
A model of degassing and seismicity at Arenal Volcano, Costa Rica
(Universidad Nacional, Costa Rica, 2001-08) Williams Jones, G; Stix, J; Heiligmann, M; Barquero, J; Fernandez, E
Arenal volcano is the most active volcano in Costa Rica and has emitted at least 1.3 Mt of SO2 since its reactivation in July 1968. Gas emissions from the volcano have been both by passive degassing and explosive eruptions, with passive degassing being dominant. Based on correlation spectrometry (COSPEC) measurements made during 1982, 1995 and 1996, the minimum average daily output is 130 ± 60 t d-1 SO2 emitted from Arenal. Arenal is extremely active, with tremor fluctuations showing a distinct correlation with Earth tides; decreased explosive activity and increased tremor appear to coincide with the maximum rate of change in Earth tides. This suggests that a system such as Arenal may be extremely sensitive to small changes in the confining pressure or stress regime of the conduit. The cyclic nature of explosive activity also may be caused by corresponding fluctuations in the extrusion rate of lava. At high extrusion rates, lava from the non-explosive conduit may overflow into the explosive conduit, temporarily blocking it with a resulting pressurisation of the system. Arenal is likely tapping a deep to mid crustal magma chamber and, unlike many volcanoes, there is a comparatively small difference between petrological and COSPEC SO2 estimates (0.41 vs. 1.3 Mt, respectively, since 1968), suggesting that Arenal is being continuously supplied by fresh magma. © 2001 Elsevier Science B.V. All rights reserved.
The next M-7 could occur within 5 to 10 years
(Observatorio Vulcanológico y Sismológico de Costa Rica, 2018) Chaves, Esteban; Muller, Cyril; Protti, Marino; Vega, Floribeth; Quintero, Ronnie
The article examines earthquake activity beneath the Osa and Burica Peninsulas in southern Costa Rica. Scientists use seismic and GPS monitoring to study how stress builds up along the boundary between the Cocos Plate and the Panama Block. The research analyzes the 2002 magnitude 6.2 Osa earthquake and shows that the region remains highly active, with ongoing deformation and seismic activity that may indicate the potential for future large earthquakes. Continuous monitoring is essential for improving earthquake hazard assessment and public safety.
Slow Slip and Inter‐transient Locking on the Nicoya Megathrust in the Late and Early Stages of an Earthquake Cycle
(Blackwell Publishing Ltd, 2020-11) Xie, Surui; Malservisi, Rocco; Protti, Marino; Dixon, Timothy; Jiang, Yan; Muller, Cyril
We analyzed continuous GPS data collected from 2002–2020 to characterize slow slipevents (SSEs) in and near the Nicoya Peninsula, Costa Rica. These data are bisected by the 5 September2012 Mw 7.6 earthquake. The displacement time series contain multiple signals, including plate convergence, plate interface locking, coseismic and postseismic deformation, seasonal oscillations, SSEs, and noise. GPS‐measured coseismic and postseismic displacements associated with the Mw 7.6 earthquake are modeled and removed by a step function plus multiple timescale relaxation processes with four characteristic times: 11, 94, 470, and 1,865 days. Seasonal oscillations are eliminated using a multichannel singular spectrum analysis (M‐SSA). Ten major SSEs (Mw > 6.6) are observed in the remaining time series, with a constant recurrence interval of 21.7 ± 2.6 months. SSEs occur in both shallow (~10 km) and deep (~35 km) portions of the plate interface, but the latter last longer and have larger magnitudes. There is minimum to no slow slip in the Mw 7.6 seismic rupture area and a persistent slow slip patch beneath the Nicoya Gulf entrance. Despite strong earthquake‐related stress perturbations, the inter‐SSE locking status on the megathrust is very similar between the late and early stages of the earthquake cycle and includes locked patches that ruptured in the 2012 earthquake or continue to rupture via SSEs. Some locked patches offshore south of the Nicoya Peninsula did not rupture in 2012, do not participate in SSEs, and may be indicative of supercycle behavior, that is, strain accumulation over several seismic cycles. These areas warrant heightened monitoring
Aerial strategies advance volcanic gas measurements at inaccessible, strongly degassing volcanoes
(American Association for the Advancement of Science, 2020-10-30) Liu, Emma; Bitetto, Marcello; Clarke, Robert; Edmonds, Marie; Hayer, Catherine; Nowicki, Scott; Schipper, C Ian; Aiuppa, Alessandro; Alan, Alfredo; Arellano, Santiago; Bobrowski, Nicole; Carn, Simon A.; Corrales, Ernesto; Moor, J. Maarten de; Díaz, Jorge Andrés; Fischer, Tobias P.; Freer, Jim E.; Fricke, G. Matthew; Galle, Bo O.; Itikarai, Ima; Jones, J.; Mason, Emily; Mulina, Kila; Rahilly, Kristen E; Rüdiger, Julian; Watson, I. Matthew; Gerdes, Gustav; Giudice, Gaetano; Gutmann, Alexandra; McCormick, Brendan; Richardson, Thomas
Volcanic emissions are a critical pathway in Earth’s carbon cycle. Here, we show that aerial measurements of volcanic gases using unoccupied aerial systems (UAS) transform our ability to measure and monitor plumes remotely and to constrain global volatile fluxes from volcanoes. Combining multi-scale measurements from ground-based remote sensing, long-range aerial sampling, and satellites, we present comprehensive gas fluxes—3760 ± [600, 310] tons day−1 CO2 and 5150 ± [730, 340] tons day−1 SO2—for a strong yet previously uncharac terized volcanic emitter: Manam, Papua New Guinea. The CO2/ST ratio of 1.07 ± 0.06 suggests a modest slab sediment contribution to the sub-arc mantle. We find that aerial strategies reduce uncertainties associated with ground-based remote sensing of SO2 flux and enable near–real-time measurements of plume chemistry and carbon isotope composition. Our data emphasize the need to account for time averaging of temporal variability in volcanic gas emissions in global flux estimates
El volcán Turrialba y Ovsicori en redes sociales
(Universidad Nacional de Costa Rica, 2015-06) Vega, Floribeth
Como instituto dedicado a la investigación sísmica y volcánica, la misión de Ovsicori (Observatorio Vulcanológico y Sismológico de Costa Rica) es documentar, analizar e interpretar los procesos sísmicos y volcánicos y divulgar el conocimiento resultante para contribuir con la prevención de riesgos y mitigación de los desastres que generan. En función de comunicar tal conocimiento a la población, y de aumentar el alcance de los contenidos informativos y educativos generados, en 2009 iniciamos nuestra aventura en las redes sociales, fundando, en setiembre de ese año, un perfil en la red social Twitter y, unos meses después, en abril de 2010, creamos un perfil en Facebook. Nuestro perfil en Twitter cuenta con más de 120.000 seguidores y en Facebook nos aproximamos a 300.000 “me gusta”. A través de esas dos redes, evacuamos dudas y proveemos documentos educativos, sencillos y atractivos, que facilitan al usuario entender nuestro trabajo y aprender sobre la actividad sísmica y volcánica en nuestro país y en el mundo.
Tomographic imaging of P- and S-wave velocity structure beneath Costa Rica
(Springer Nature, 1999) Yao, Z. S.; Quintero, Ronnie; Roberts, R. G.
45287 P-wave and 26813 S-wave arrival times from the data base of the Costa Rica network have been tomographically inverted to image the structure beneath Costa Rica. A regularized recursive least squares inverse method was used to produce the high resolution and minimum variance model parameter estimates. The first arrival times are calculated using a finite difference technique, which allows for flexible parameterization of the velocity model and easy inclusion of topography and source-receiver geometry. The P wave velocity structure and hypocenters are determined simultaneously, while the S wave velocity structure is determined using the relocated seismicity and an initial model derived from the P wave model assuming an average P to S wave velocity ratio of 1.78. The most prominent features in the inverted model are a low velocity structure under the volcanic chain in the center of the country, which is related to the hot material connected with the active volcanoes; and a high velocity zone in the mantle, which is related to the Cocos plate subducted under Costa Rica.
Animation Crustal Deformation in the Nicoya Peninsula Associated with the September 5th, 2012 Earthquake
(Universidad Nacional, Costa Rica, 2018) Hernandez Castro, F; Monge-Fallas, J; Mendez-Morales, M; Protti-Quesada, M
For the past fifteen years, the Volcanological and Seismological Observatory of Costa Rica (OVSICORI) in cooperation with American Universities, has been recording crustal defor mation data prior a potential earthquake in the Nicoya Peninsula, anticipation which came true on September 5th, 2012 with the occurrence of a 7.6 moment magnitude (Mw) earth quake. The historical importance of this earthquake is based on continuous monitoring of the Nicoya Peninsula before, during and after the earthquake, making it one of the best docu mented earthquake in history. The objective of this project is to visualize earthquake data in order to view displacement in two and three dimensions. Another goal is to make the method for showing the behavior of the crust during the earthquake, more intuitive. The target ques tion of the visualizations is only one: to show how the earths crust moved previous and dur ing the earthquake in each of the affected areas. We know of no other visualization that use a 3D environment to visualize one earthquake with actual data in this detail level
The Last Eighteen Years (1998–2014) of Fumarolic Degassing at the Poás Volcano (Costa Rica) and Renewal Activity
(Springer, 2019) Vaselli, Orlando; Tassi, Franco; Fischer, Tobias P; Tardani, Daniele; Fernández, Erick; Martínez, María del Mar; Moor, Marteen de; Bini, Giulio
This chapter reviews the geochemical and isotopic data from the fumarolic gas discharges collected in a discontinuous mode from 1998 to 2014 at Poás volcano. During this period, the “Tico” volcano experienced a renewed phreatic activity that started in 2006 after a couple of decades of relative quiescence. In January 2009, a 6.2 Mw earthquake hit the village of Cinchona, which is located a 4 km to the east of Poás. As the phreatic activity kept evolving, the hyperacidic lake (“Laguna Caliente”) dried out and the high-temperature fumaroles that previously were likely entering the lake were revealed, though not accessible. The pyroclastic dome that formed in the early fifties was destroyed at the beginning of 2017 by several relatively small phreatomagmatic (strombolian and vulcanian type) small-size eruptions. The risk of sudden phreatic and phreato-magmatic events prevented the direct sampling of the fumaroles and as a consequence, no geochemical data were sampled in the last three years. Nevertheless, interesting hints were recorded by the gas geochemistry before the 2006 phreatic activity and the 2009 Cinchona seismic events, mainly based on the temporal variations of the H2S/SO2, H2/H2O, H2/Ar, CO/CO2, CH4/CO2 and HCl/HF ratios. However, in most cases the geochemical record is not complete since the gas discharging vents migrated or stopped their activity and new fumaroles formed up to the recent visual observations.
Stress Field in Costa Rica, Central America
(2000) Quintero, Ronnie; Güendel, Federico
We have relocated 1658 earthquakes which occurred in Costa Rica, and its vicinity. These relocated earthquakes were then used to investigate the stress and orientation of fault planes within the study area. The analysis was made using the polarities of first motion P-waves. We found that the subduction zone for Costa Rica is mainly characterized by thrust faulting, with some areas also exhibiting a component of strike-slip motion. The intraplate Caribbean seismicity in central Costa Rica shows a predominant shallow left-lateral strike-slip faulting. In southern Costa Rica, the subduction of very young oceanic lithosphere beneath the Caribbean plate (i.e. Panama Block), enhanced by the collision and subduction of the Cocos Ridge, has produced a highly compressive stress regime. This highly compressive regime is characterized by strike-slip faults oriented in a NE-SW direction, extending all the way from the Pacific margin into the back-arc, connecting with the North Panama Deformed Belt.
Forearc carbon sink reduces long-term volatile recycling into the mantle
(Nature Publishing Group, 2019-04-25) Barry, Peter; Giovannelli, Donato; Schrenk, Matthew; Fattorini, Daniele; Manini, Elena; Nakagawa, Mayuko; Regoli, Francesco; smedile, francesco; Ballentine, Chris; Lloyd, Karen; Hummer, Daniel; Lopez, T.; Pratt, C. A.; Alpízar Segura, Y.; Battaglia, A.; Beaudry, P.; Bini, G.; Cascante, M.; d’ Errico, G.; di Carlo, M.; Fullerton, K.; Gazel, E.; González, G.; Halldórsson, Sæmundur Ari; Iacovino, K.; Kulongoski, J. T.; Martínez, M.; Miller, H.; Ono, S.; Patwardhan, S.; Ramírez, C. J.; Turner, S.; Vetriani, C.; Yücel, M.; Fischer, T. P.; Hilton, D. R.
Carbon and other volatiles in the form of gases, fluids or mineral phases are transported from Earth’s surface into the mantle at convergent margins, where the oceanic crust subducts beneath the continental crust. The efficiency of this transfer has profound implications for the nature and scale of geochemical heterogeneities in Earth’s deep mantle and shallow crustal reservoirs, as well as Earth’s oxidation state. However, the proportions of volatiles released from the forearc and backarc are not well constrained compared to fluxes from the volcanic arc front. Here we use helium and carbon isotope data from deeply sourced springs along two cross-arc transects to show that about 91 per cent of carbon released from the slab and mantle beneath the Costa Rican forearc is sequestered within the crust by calcite deposition. Around an additional three per cent is incorporated into the biomass through microbial chemolithoautotrophy, whereby microbes assimilate inorganic carbon into biomass. We estimate that between 1.2 × 108 and 1.3 × 1010 moles of carbon dioxide per year are released from the slab beneath the forearc, and thus up to about 19 per cent less carbon is being transferred into Earth’s deep mantle than previously estimated.
Terremoto del Valle de La Estrella: análisis sísmico, cascada de desastres y pérdidas económicas en valor presente (2020)
(Universidad Nacional, Costa Rica, 2021-04-21) Campos Durán, Daniela; Quintero Quintero, Ronnie; Abarca Rojas, Tatiana
Seismicity and focal mechanisms in the of North Panama Deformed Belt (NPDB) indicate a compressional environ-ment associated with the overthrusting of the Panama Block (PB) on the Caribbean plate; crustal PB strike-slip focal mechanisms are observed in the Talamanca and Central Volcanic Cordillera. The hypocenters reach maximum depths between 50-60 km at the foot of the Talamanca mountain range and are shallow near the Caribbean coast. The 1991, Valle de la Estrella earthquake (Mw 7.6) triggered aftershocks in an area of ~140x70 km; landslides and liquefaction were the secondary events that caused most damage and losses in infrastructure (housing, bridges, railroad network, road network and aqueducts); its effects were concentrated in coastal cities, such as Limón and Bocas del Toro. The economic losses in present 2020 value correspond to $3 433 266 937.41.
Volcano hazard and surveillance in Costa Rica
(Volcanica, 2021-03-04) Avard, Geoffroy; Mora, Mauricio; Bakkar, Henriette; Alvarado, Guillermo; Angarita, Mario; Cascante, Monserrat; Maarten de Moor, J.; Martínez, María; Muller, Cyril; Pacheco, Javier; Ruiz, Paulo; Soto, Gerardo
Costa Rica hosts ten volcanic complexes and is highly tectonically active due to its location at the interaction between the Cocos, Nazca, and Caribbean plates and the Panama microplate. Three of the five historically active volcanoes had frequent eruptions in 2019. The institutions in charge of monitoring the volcanoes of Costa Rica are the Observatorio Vulcanológico y Sismológico de Costa Rica from Universidad Nacional (OVSICORI-UNA) and the Red Sismológica Nacional (RSN: UCR-ICE that groups the Escuela Centroamericana de Geología from the Universidad de Costa Rica, and the Observatorio Sismológico y Vulcanológico de Arenal y Miravalles from the Instituto Costarricense de Electricidad; acronyms ECG, UCR, OSIVAM, and ICE). These institutions are focused on the most dangerous volcanoes, i.e. those closest to the Great Metropolitan Area (2.2 million inhabitants), which includes San José (the capital), and those near hydroelectrical and geothermal plants. In 2020, those institutions operated a network of. 59 seismic stations on volcanoes, 5 infrasound stations, 25 permanent GPS sites, 2 permanent DOAS, 3 permanent MultiGAS, 13 webcams, and performed systematic analyses in geochemistry and petrology laboratories. Those institutes routinely communicate results with the authorities in charge of crisis management nationally and internationally (Comisión Nacional de Prevención de Riesgos y Atención de Emergencias and Volcanic Ash Advisory Centre, respectively) and are always looking for more scientific collaborations.
Changing tectonic regimes in the central Costa Rica forearc between the Paleogene and the present: Insights from structural analysis and focal mechanisms
(Elsevier, 2021-01-04) Porras, Hernán; Mescua, José; Durán, Patrick; Cascante, Monserrat; Giambiagi, Laura; Muller, Cyril
We discuss the Cenozoic history of the Central Costa Rica forearc, between 10° and 9°30′N, based on geological mapping, fault slip data and seismological records.The temporal variability in the regional stress-field suggests a variable and complex deformation pattern. The first stage of deformation, from the Paleogene to early Miocene, was controlled by an extensional regime in the forearc. Afterwards, a change to orthogonal convergence triggered a contractional deformation and subsequent inversion of the sedimentary extensional basins in the middle-upper Miocene. Finally, a transpressive regime has been developed since the Pliocene.

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