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(a) Azimuthal variation of the radial component of synthetic receiver functions for a model of a dipping layer over a half-space. The model has an interface at 25 km depth, dipping 20° toward N40°E. We used Vp = 6.3 km/ s, Vp/Vs of 1.80, and a constant ray parameter of 0.06. Note the absence of the PpPp phase (shaded region) along the strike of the dipping interface. (b) Along-strike receiver functions for the same velocity model in Figure 4a but varying dip angle. Note that the Ps amplitude is not very sensitive to the dip angle.
Source publication
1] The Central American subduction zone in northern Costa Rica shows along-strike variations in both the incoming and overriding plates. By analyzing the subducting oceanic Moho (M1) and the upper plate Moho (M2) with receiver functions, we investigate the variability in the hydration state of the subducting Cocos Plate and the nature of crustal te...
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Context 1
... receiver functions were computed by applying the deconvolution procedure (section 4.1) on the synthetic responses. [27] In the presence of a dipping interface, stacking to create an average receiver function risks misin- terpretation of the structure as Ps and multiples may show a strong azimuthal variation in timing, amplitude, and polarity [e.g., Cassidy, 1992;Hayes and Furlong, 2007] (Figure 4). We analyzed the azimuthal behavior of synthetic receiver functions to search for the direction at which the complica- tions are minimized. ...
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... performed this analysis by creating synthetic receiver functions using a dip- ping interface with the appropriate orientation for our study region. We found that receiver functions along the strike of the dipping interface are similar to a flat interface case, particularly for the Ps phase and the absence of PpPp phases that are observed at other back azimuths (Figure 4a). In addition, the Ps amplitude of receiver functions along the strike is not very sensitive to changes in the dip angle (Figure 4b). ...
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... found that receiver functions along the strike of the dipping interface are similar to a flat interface case, particularly for the Ps phase and the absence of PpPp phases that are observed at other back azimuths (Figure 4a). In addition, the Ps amplitude of receiver functions along the strike is not very sensitive to changes in the dip angle (Figure 4b). These observations motivated us to stack our observed receiver functions along the strike of the subducting Cocos Plate for individual stations located in the Nicoya Peninsula, in order to compare the Ps amplitude between stations. ...
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Citations
... Mann and Burke (1984) reviewed the neotectonic development of the Caribbean Plate using earthquake focal mechanism solutions, faulting, and volcanic activity. Receiver function analysis has been used to study the crustal structure of the local region of the Caribbean (Niu et al., 2007;Linkimer et al., 2010). Investigators have also attempted to image the velocity structure of the subsurface Caribbean using surface waves or teleseismic P-waves, etc., and different mantle velocity models have been proposed successively (e.g., Miller et al., 2009;Bezada et al., 2010;Harris et al., 2018;Braszus et al., 2021). ...
... The northwest Caribbean plate is separated from the Cocos plate by the Middle America Trench (Mann et al., 2006;Linkimer et al., 2010;see Fig. 1A) and from the North American plate by a variably transpressional to transtensional strike-slip boundary that includes the Motagua Suture Zone and Cayman Trough (Mann et al., 2006;Ratschbacher et al., 2009). The southern boundary is somewhat more complicated by incipient subduction of the Caribbean plate beneath the North Panama Deformed Belt (Camacho et al., 2010) and the transition to the Caribbean-South American plate boundary along the South Caribbean Deformation Front (Mantilla-Pimiento et al., 2009). ...
The recycling of water into the Earth’s mantle via hydrated oceanic lithosphere is believed to have an important role in subduction zone seismicity at intermediate depths. Hydration of oceanic lithosphere has been shown to drive double planes of intermediate-depth, Wadati-Benioff zone seismicity at subduction zones. However, observations from trenches show that pervasive normal faulting causes hydration ~25 km into the lithosphere and can explain neither locations where separations of 25–40 km between Wadati-Benioff zone planes are observed nor the spatial variability of the lower plane in these locations, which suggests that an additional mechanism of hydration exists. We suggest that intraplate deformation of >50-m.y.-old lithosphere, an uncommon and localized process, drives deeper hydration. To test this, we relocated the 25 November 2018 6.0 MW Providencia, Colombia, earthquake mainshock and 575 associated fore- and aftershocks within the interior of the Caribbean oceanic plate and compared these with receiver functions (RF) that sampled the fault at its intersection with the Mohorovičić discontinuity. We examined possible effects of velocity model, initial locations of the earthquakes, and seismic-phase arrival uncertainty to identify robust features for comparison with the RF results. We found that the lithosphere ruptured from its surface to a depth of ~40 km along a vertical fault and an intersecting, reactivated normal fault. We also found RF evidence for hydration of the mantle affected by this fault. Deeply penetrating deformation of lithosphere like that we observe in the Providencia region provides fluid pathways necessary to hydrate oceanic lithosphere to depths consistent with the lower plane of Wadati-Benioff zones.
... In a typical subduction zone, we expect to see a Moho associated with the overriding plate, and a deeper Moho for the subducting slab. This is observed in northern Costa Rica by Linkimer et al. (2010); where they introduce a nomenclature that will be followed in this paper: The deeper Moho within the subducting plate is called M1, and the shallower Moho of the overriding plate is called M2. For a flat slab scenario, we expect to see only the M1 boundary with an increase in impedance because the upper plate and subducting plate are coupled and the impedance of the lower crust should be similar to the impedance of the oceanic subducting crust. ...
... The seismological constraints on the crustal thickness throughout Costa Rica range ∼27-42 km in northern Costa Rica (Deshon et al., 2006;Linkimer et al., 2010;MacKenzie et al., 2008;Protti et al., 1996). In central to southern Costa Rica the depth to the upper plate Moho has been imaged by receiver function analysis (Dzierma et al., 2011) to be 30-40 km, whereas tomographic models place it at ∼30 km (Dinc et al., 2010), and active source imaging shows it to be 40 km beneath the volcanic front (Hayes et al., 2013). ...
... To provide calibration for our methodology, we generated receiver functions for a long-running seismic site, JTS, in northern Costa Rica ( Figure S4). This site was investigated in Linkimer et al. (2010) where the authors identified phases from the crust-mantle boundaries within both the overriding and the subducting plates. We observe the same phases with respect to time and back-azimuth, giving confidence that our procedures yield results consistent with previous work. ...
Past studies of southern Costa Rica have generated a multitude of tectonic scenarios to account for different data sets. Flat slabs, detached slabs, and slab windows have been proposed to address the uplift of the Cordillera de Talamanca (CT), cessation of volcanism, and absence of deep seismicity beneath southern Costa Rica. In this study, we investigate the crust and the upper mantle along the southwest flank of the CT using the receiver function methodology. We observe two regional positive P‐to‐S converted pulses at delay times of ∼2–4 s and ∼5–8 s. The first likely represents a gradational crust‐mantle boundary of the upper plate. The second represents a similar impedance increase ∼50–60 km deep that extends from central Costa Rica to Panama. Compared to well‐located seismicity, this boundary is offset to the NE from the Cocos plate Benioff zone beneath northern CT, and remains observable through a gap in seismicity farther to the southeast. This offset makes it difficult to interpret this feature as related to the presently subducting lithosphere. Instead, we propose that the 50–60 km deep boundary marks the Moho of a lithospheric fragment left behind under the CT in the course of Panama Triple Junction migration through Costa Rica over the last 10 Ma. Our interpretation accounts for the geophysical, geochemical, structural, and geomorphic observations in the literature explaining the complex geodynamic scenario observed in southern Costa Rica.
... Our results identify a region of clear and regionally similar rock fabric beneath the Central American isthmus. Crustal thickness estimates in central and southern Costa Rica do not exceed 40 km (Linkimer et al., 2010;Hayes et al., 2013), which is insufficient to produce delays of ∼1 s with realistic values of anisotropy (Long and Silver, 2009). ...
Surrounded by subducting slabs and continental keels, the upper mantle of the Pacific is largely prevented from mixing with surrounding areas. One possible outlet is beneath the southern part of the Central American isthmus, where regional observations of seismic anisotropy, temporal changes in isotopic composition of volcanic eruptions, and considerations of dynamic topography all suggest upper mantle flow from the Pacific to the Caribbean. We derive new constraints on the nature of seismic anisotropy in the upper mantle of southern Costa Rica from observations of birefringence in teleseismic shear waves. Fast and slow components separate by ~1 s, with faster waves polarized along the 40°–50° (northeast) direction, near-orthogonally to the Central American convergent margin. Our results are consistent with upper mantle flow from the Pacific to the Caribbean and require an opening in the lithosphere subducting under the region.
... Pichler y Weyl (1975) ya habían sugerido que la corteza basáltica en Costa Rica se fue transformado gradualmente a corteza continental típica, por el emplazamiento de magmas silícicos. Esto es consistente con la observación de que las velocidades del norte de Costa Rica, así como que el espesor mayor de la corteza superior a la que se habría esperado, es similar a las velocidades y el espesor de la corteza continental en Guanacaste, entre 42 km bajo el volcán Miravalles, a unos 36,7±2,4 km hacia los extremos de la cordillera (Linkimer et al., 2010y Lücke, 2012. ...
... Los magmas del vulcanismo del Pleistoceno se originaron por un alto grado (21-32%) de fusión parcial del manto (tipo MORB) en la cuña astenosférica (Malavassi, 1991), a unos 110 km de profundidad bajo los volcanes (Lücke & Arroyo, 2015), con cierta asimilación de sedimentos oceánicos (Feigenson y Carr, 1993y Herrstrom et al., 1995. Seguidamente, se tuvo el estancamiento de los magmas en ascenso en la base de la corteza (34-42 km de profundidad; Linkimer et al., 2010y Lücke, 2012 2018). Muchos lahares también ocurrieron en ambos volcanes, disparados por vulcanismo, sismos y lluvias torrenciales; sin embargo, los últimos en el Rincón de la Vieja fueron provocados por erupciones surseyanas históricas en el siglo XX y lo que se lleva del XXI. ...
... Along the southwestern edge of the continental Chortís block, the Santa Rosa accretionary complex defines an intra-oceanic subduction zone with CLIP basement extending south of this belt (Escuder-Viruete & Baumgartner, 2014 Hauff, & Klügel, 2008;Sanchez, Mann, Emmet, 2016). Linkimer, Beck, Schwartz, Zandt, and Levin (2010) used a receiver function analysis to refine the terrane boundaries between the Chortís and Chorotega blocks. They suggest that the boundary between the Mesquito Oceanic terranes (Chortís block) and the Chorotega block corresponds with the western part of the Trans-isthmic fault system merging towards the northeast with the Hess Escarpment ( Figure 3). ...
... The northwestern part of the North Costa Rican arc segment probably belongs structurally to the Chortís block (e.g. Baumgartner et al., 2008;Geldmacher et al., 2008;Hauff et al., 2000;Linkimer et al., 2010;Weinberg, 1992) and is underlain by an assemblage of older accreted island arc rocks and/or relics of oceanic plateaus, aseismic oceanic ridges and seamounts that differ geochemically from the CLIP basalts (Alvarado, Denyer, & Sinton, 1997;Baumgartner et al., 2008;Buchs et al., 2013;Geldmacher et al., 2008;Hauff et al., 2000). ...
en Southern Central America is a Late Mesozoic/Cenozoic island arc that evolved in response to the subduction of the Farallón Plate beneath the Caribbean Plate in the Late Cretaceous and, from the Oligocene, the Cocos and Nazca Plates. Southern Central America is one of the best studied convergent margins in the world. The aim of this paper is to review the sedimentary and structural evolution of arc‐related sedimentary basins in southern Central America, and to show how the arc developed from a pre‐extensional intra‐oceanic island arc into a doubly‐vergent, subduction orogen. The Cenozoic sedimentary history of southern Central America is placed into the plate tectonic context of existing Caribbean Plate models. From regional basin analysis, the evolution of the southern Central American island arc is subdivided into three phases: (i) non‐extensional stage during the Campanian; (ii) extensional phase during the Maastrichtian‐Oligocene with rapid basin subsidence and deposition of arc‐related, clastic sediments; and (iii) doubly‐vergent, compressional arc phase along the 280 km long southern Costa Rican arc segment related to either oblique subduction of the Nazca plate, west‐to‐east passage of the Nazca–Cocos–Caribbean triple junction, or the subduction of rough oceanic crust of the Cocos Plate. The Pleistocene subduction of the Cocos Ridge contributed to the contraction but was not the primary driver. The architecture of the arc‐related sedimentary basin‐fills has been controlled by four factors: (i) subsidence caused by tectonic mechanisms, linked to the angle and morphology of the incoming plate, as shown by the fact that subduction of aseismic ridges and slab segments with rough crust were important drivers for subduction erosion, controlling the shape of forearc and trench‐slope basins, the lifespan of sedimentary basins, and the subsidence and uplift patterns; (ii) subsidence caused by slab rollback and resulting trench retreat; (iii) eustatic sea‐level changes; and (iv) sediment dispersal systems.
Abstract
ja 中央アメリカ大陸南部は中生代後期から新生代までの島弧にその起源がある. この論文の研究目的は, この地域の堆積盆地の堆積過程や構造発達史に関する先行研究をレビューし, この地域が海洋島弧からどのようにして現在のような造山帯になったかを明らかにすることである. 中央アメリカ大陸南部の発達過程は応力場の違いによって, 3段階に分けることができる. 1)カンパニアンの間は中央アメリカ大陸南部の応力場は張力場ではなかった. 2)マーストリヒチアンから漸新世までの間の応力場は張力場になり, この地域は急激に沈降し, 島弧起源の砕屑岩が堆積した. 3)新第三紀から現在までの応力場は圧縮場で, 造山活動が活発であった. 島弧起源の堆積盆地の構造を決めたのは次の4つの因子である. 1)沈み込むプレートの沈み込み角度と形状, 2)海溝が島弧から遠ざかることによる沈降, 3)海水面変動, 4)堆積物供給システム.
... Following Zellmer et al. (2016), we have used the computer code MELTS (Ghiorso and Sack, 1995;Smith and Asimow 2005) to model the adiabatic decompression of a water "supersaturated" melts ascending from the crust mantle transition (located at 40 km depth, below the Miravalles-Guayabo caldera, according to Linkimer et al., 2010). This approach is based on the fact that liquidus temperatures depend on melt chemistry and on the H2O content within the melt. ...
The Miravalles-Guayabo caldera is located in the Guanacaste Cordillera and its genesis and evolution is related with the geodynamic setting of northwestern Costa Rica. The development of a N-S graben, and related NE-trending fracture zones, was essentially coeval with caldera forming eruptions and the multiple collapses which dismembered earlier volcanoes. The lavas of the Miravalles-Guayabo Complex (MGC) are two-pyroxene calc-alkaline andesites and basaltic andesites with subordinate high alumina basalts and rare dacites. Interstitial matrix glasses span from andesite (in basalts) to dacite (in andesite s.l.) and rhyolite (in dacite) that overlap the bulk chemical compositions of the lavas. REE patterns and spider diagrams show typical features of a subduction-related volcanism at convergent plate boundaries with spiked incompatible-element patterns, negative anomalies for Nb and Ti in spider diagrams, enrichment in LILE (with the exclusion of Sr) and LREE, and relative depletion in HFSE. The geochemical signatures of the MGC volcanic rocks are essentially consistent with recent petrogenetic models. Thermobarometric estimates suggest that basaltic and magmas equilibrated with their phenocrystic phases at 1080–1120 °C, and pressures ranges of 380–430 MPa, whereas andesitic melts are confined at 200–230 MPa and temperatures of 1050–1070 °C. In turn, amphibole-biotite dacites equilibrated at 240–290 MPa and temperatures of 920–950 °C approaching water saturated conditions (with H2O contents up to 5.7–7.2 wt%). Thermobarometry indicate that contiguous andesitic-dacitic magma lenses are stored within the subvolcanic region at depths below 10 km, whereas basaltic magmas are stored and degas at slightly higher depths (up to ~15 km). Single eruptions associated with the emplacement of lava flows seem to be related to the tapping of portions of single magma lenses during minor unrest episodes. Conversely, caldera forming eruptions involved the ejection of differentiated rhyolitic pumices (of La Ese member) and likely occurred during recharge and pressurization of this heterogeneous reservoir under critical stress conditions.
... Several papers address active tectonics and active fault mapping (e.g., Montero and Dewey, 1982;Morales, 1985;Montero, 1994;Montero et al., 2013Montero et al., , 2017Araya et al., 2015, to name just a few). Other contributions are related to ground acceleration, intensities, and hazards (e.g., Climent et al., 2008;Linkimer, 2008a,b;Benito and Torres, 2010;Benito et al., 2012), volcanic seismicity ( Mora et al., 2006), and the structure of the Costa Rican margin ( Arroyo et al., 2009Arroyo et al., , 2014Linkimer et al., 2010;Lücke, 2014;Lücke and Arroyo, 2015;Araya et al., 2016). ...
The National Seismological Network of Costa Rica (RSN) is a joint effort between the University of Costa Rica (UCR) and the Costa Rican Institute of Electricity (ICE). In this article, we briefly describe its history, contributions, and seismic catalog. We also address recent developments, such as the expansion of the station network, the improvement on earthquake locations, and the use of new communication channels to share earthquake information. The RSN seismic catalog contains almost 123,000 earthquakes recorded since 1974. The geographical distribution of the local seismicity highlights plate boundaries as well as regions located along the inland projection of several bathymetric highs in the Cocos plate. In 2015, 70 new short-period seismometers were installed to provide a new configuration with higher station density in central Costa Rica. Also, earthquake locations were improved by integrating routines from the SeisComP, EarthWorm, and SEISAN software packages. Additionally, several tools for disseminating earthquake information were developed, for example, an application for smartphones released in 2015 and a new website created in 2017. The RSN is also using Facebook and Twitter to engage and educate nonscientific audiences.
... As expected, many of the major crustal features observed in the inversion are visible at all the ten sites. It has been observed that significant variations in amplitude and arrival times of Moho Pms and other converted phases exhibits at the IIGS station with respect to back azimuth, which suggests that there may be presence of dipping structures or anisotropic medium (Zheng et al. 2005;Linkimer et al. 2010). The highly seismically active Dauki fault lies in the south of the SP. ...
It is noticed that few geophysical studies have been carried out to decipher the crustal structure of southwestern part of the Northeast India comprising of Tripura fold belt and Bengal basin as compared to the Shillong plateau and the Brahmaputra basin. This region has a long history of seismicity that is still continuing. We have determined first-order crustal features in terms of Moho depths (H) and average VP/VS ratios (κ) using H-κ stacking technique. The inversion of receiver functions data yields near surface thick sedimentary layer in the Bengal basin, which is nearly absent in the Shillong plateau and Tripura fold belt. Our result suggests that the crust is thicker (38–45 km) in the Tripura fold belt region with higher shear-wave velocity in the lower crust than the Shillong plateau. The distribution of VP/VS ratio indicates heterogeneity throughout the whole region. While low to medium value of Poisson’s ratio (1.69–1.75) indicates the presence of felsic crust in the Shillong plateau of the extended Indian Archean crust. The medium to high values of VP/VS ratio (> 1.780) in the Bengal basin and the Tripura fold belt region represent mafic crust during the formation of the Bengal delta and the Tripura fold belt creation in the Precambrian to the Permian age. The depth of the sediments in the Bengal basin is up to 8 km on its eastern margin, which get shallower toward its northeastern and southeastern margins.
... Rojas et al., 1993a,b,c;Güendel and Protti, 1998;Montero, 1999b;Fernández et al., 2007), and focal mechanisms (Dziewonski et al., 1981;Güendel and Protti, 1998;Montero, 1999b;Fernández et al., 2007;Mann et al., 2007;Camacho et al., 2010). For the geophysical studies, we use crustal structure studies (Flueh and von Huene, 2007;Mann et al., 2007;MacKenzie et al., 2008;Dzierma et al., 2010;Linkimer et al., 2010;Hayes et al., 2013), including gravimetric maps (Weyl, 1980;Cuevas et al., 2003;Lücke et al., 2010). The seismicity of Central America has been studied, by several researchers, by Molnar and Sykes (1969), Burbach et al. (1984), White and Harlow (1993), Protti et al. (1994), Rojas et al. (1993a), Ambraseys andAdams (2001), LaFemina et al. (2002), Camacho et al. (2010), among several others. ...
Central America is one of the most active seismic zones in the World, due to the interaction of five tectonic plates (North America, Caribbean, Coco, Nazca and South America), and its internal deformation, which generates almost one destructive earthquakes (5.4. ≤. Mw. ≤. 8.1) every year. A new seismological zonation for Central America is proposed based on seismotectonic framework, a geological context (tectonic and geological maps), geophysical and geodetic evidence (gravimetric maps, magnetometric, GPS observations), and previous works. As a main source of data a depurated earthquake catalog was collected covering the period from 1522 to 2015. This catalog was homogenized to a moment magnitude scale (Mw). After a careful analysis of all the integrated geological and seismological information, the seismogenic zones were established into seismic areas defined by similar patterns of faulting, seismicity, and rupture mechanism. The tectonic environment has required considering seismic zones in two particular seismological regimes: a) crustal faulting (including local faults, major fracture zones of plate boundary limits, and thrust fault of deformed belts) and b) subduction, taking into account the change in the subduction angle along the trench, and the type and location of the rupture. The seismicity in the subduction zone is divided into interplate and intraplate inslab seismicity. The regional seismic zonation proposed for the whole of Central America, include local seismic zonations, avoiding discontinuities at the national boundaries, because of a consensus between the 7 countries, based on the cooperative work of specialists on Central American seismotectonics and related topics.
