Central Costa Rica Research Articles

Tourist crossing: examining the intersection of wildlife tourism attractions & animal welfare in Costa Rica

ABSTRACT Wildlife tourism attractions (WTAs) are key actors in promoting ecotourism and animal welfare. This field note focuses on the Toucan Rescue Ranch (TRR), a wildlife rescue and rehabilitation nonprofit organization based in central Costa Rica, and its efforts to promote animal welfare through education and outreach. TRR's key ecotourism challenges and achievements – particularly around wildlife protections and coalition building are explored. The article concludes with reflections on the future opportunities facing ecotourism regarding animal welfare regionally, as well as the tourism industry more broadly. These findings were gleaned from discussions with TRR staff during a physical visit as well as during Zoom calls in 2023.

On the status of Helicops wettsteini Amaral, 1929, a senior synonym of Hypsiscopus murphyi (SERPENTES: Homalopsidae).

We redescribe the name-bearing types of Helicops wettsteini Amaral, 1929, a species described from central Costa Rica. However, while Helicops wettsteini has been considered in the literature a synonym of Hypsiscopus plumbeus (previously Enhydris plumbea), we present here morphological evidence for considering Helicops wettsteini a synonym of the recently described species Hypsiscopus murphyi Bernstein, Voris, Stuart, Phimmachak, Seateun, Sivongxay, Neang, Karns, Andrews, Osterhage, Phipps & Ruane, 2022, which hence becomes a junior subjective synonym of Hypsiscopus wettsteini (Amaral, 1929).

Genetic inference of orchid colonization of a Costa Rican lava flow

AbstractThe dispersal and colonization of plant populations allow species to occupy novel habitats, migrate, and undergo range shifts in response to changing environmental factors and, as such, are fundamental ecological processes for ensuring the long‐term persistence of species. Natural landscape disturbance often generates habitats available for colonization. Patterns of colonization and population expansion can be inferred from the levels and partitioning of genetic variation of plant populations with known disturbance histories, such as recent volcanic eruptions. We sampled and mapped 496 individuals from two populations of the colonizing terrestrial orchid, Sobralia chrysostoma, on the 1992 lava flow of Volcán Arenal in central Costa Rica. We used neutral co‐dominant markers to genotype individuals and estimate population genetic statistics. Both populations had high mean levels of genetic diversity (P = 100%; AP = 3.31; He = 0.259) suggesting that the lava flow was colonized by numerous individuals that likely originated from multiple source populations. However, significant spatial genetic structure (SGS) was only present in one population at the smallest distance class (≤2 m) and was low (r = 0.032). That these large and genetically diverse populations had such low SGS and an absence of SGS, respectively is contrary to expectations and differs significantly from the pattern in Epidendrum radicans (Orchidaceae), with which S. chrysostoma is growing sympatrically. Our results suggest that these two populations either consist primarily of immigrant individuals or that seeds produced in situ dispersed over longer distances, thereby producing larger seed shadows and greater overlap of seed shadows.

Modeled Forest Conversion Influences Humid Tropical Watershed Hydrology More than Projected Climate Change

In the humid tropics, forest conversion and climate change threaten the hydrological function and stationarity of watersheds, particularly in steep terrain. As climate change intensifies, shifting precipitation patterns and expanding agricultural and pastoral land use may effectively reduce the resilience of headwater catchments. Compounding this problem is the limited long-term monitoring in developing countries for planning in an uncertain future. In this study, we asked which change, climate or land use, more greatly affects stream discharge in humid tropical mountain watersheds? To answer this question, we used the process-based, spatially distributed Soil Moisture Routing model. After first evaluating model performance (Ns = 0.73), we conducted a global sensitivity analysis to identify the model parameters that most strongly influence simulated watershed discharge. In particular, peak flows are most influenced by input model parameters that represent shallow subsurface soil pathways and saturation-excess runoff while low flows are most sensitive to macropore hydraulic conductivity, soil depth and porosity parameters. We then simulated a range of land use and climate scenarios in three mountain watersheds of central Costa Rica. Our results show that deforestation influences streamflow more than altered precipitation and temperature patterns through changes in first-order hydrologic hillslope processes. However, forest conversion coupled with intensifying precipitation events amplifies hydrological extremes, reducing the hydrological resilience to predicted climate shifts in mountain watersheds of the humid tropics. This finding suggests that reforestation can help mitigate the effects of climate change on streamflow dynamics in the tropics including impacts to water availability, flood pulses, channel geomorphology and aquatic habitat associated with altered flow regimes.

Nitrate Legacy in a Tropical and Complex Fractured Volcanic Aquifer System

AbstractNitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3− and Cl− concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl− and moderate NO3−/Cl− ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl− ratios and Cl− concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively.

Soundscape structure in forests surrounded by protected and productive areas in central Costa Rica

Ecosystems are under a multitude of pressures, including land-use change, overexploitation, pollution, and climate change. Most studies, resources, and conservation efforts are allocated to protected areas, while anthropogenic activities in their surroundings may affect them in ways that are poorly understood. We evaluated soundscape structure in forests surrounded by protected or productive areas in central Costa Rica. We sampled soundscapes in 91 recording sites in Grecia Forest Reserve and Poas Volcano National Park, and surrounding areas with productive activities (predominantly agricultural and urban). We classified sampling sites into three clusters according to landscape entropy, forest amount, and fragmentation surrounding recording points: more fragmented, more conserved, and intermediate. The conserved cluster showed higher acoustic diversity or entropy, but lower acoustic complexity, shorter duration of sounds in all frequency ranges, and lower amount of energy in the biological frequency bands than the fragmented cluster. We additionally found a positive significant relationship between the amount of forest and acoustic entropy or diversity indices, but a negative relationship with acoustic activity or energy indices. Indices, such as spectral and temporal entropy, the entropy of spectral variance, and total entropy, seemed to be a better fit than acoustic complexity and bioacoustic indices as indicators of habitat conservation in this study. Acoustic indices revealed that the surrounding matrices of protected areas have an impact on acoustic environments. We encourage researchers and decision-makers to carefully interpret acoustic indices when evaluating habitats showing a higher value in acoustic energy or activity because this might not necessarily reflect either a high level of biodiversity or habitat conservation. Also, we highlight the importance of preserving undisturbed forested matrices around protected areas, as they are important for maintaining acoustic diversity.

Evidence for Caribbean plate subduction in southern Costa Rica

AbstractNestled between the Cocos, Nazca, Caribbean, and South American plates, the Panama microplate represents an area of rapidly evolving tectonics throughout the past ~10 m.y. Past and current studies have observed a notable amount of seismicity throughout this region, in particular the Caribbean coast of Costa Rica, which experienced a Mw 7.7 earthquake in 1991 CE. We investigated the crust and upper mantle structure of this region using the receiver function methodology and report two results: (1) first-order lateral constraints on the position of the Panama microplate boundary near the intersection between the Central Costa Rica Deformed Belt (onshore) and North Panama Deformed Belt (offshore), and (2) an impedance contrast south and east of these belts, supporting that the Caribbean plate currently subducts beneath the Panama microplate. Observed local seismicity is a consequence of the recently (ca. 14 Ma) initiated Caribbean plate subduction beneath the overlying Panama microplate. Our results are also consistent with a doubly convergent subduction margin dominating southern Costa Rica tectonics, uplifting the Talamanca Cordillera, and causing the cessation of southern Costa Rica volcanism over the past ~10 m.y.

The first record of Mexiconnus Jałoszyński in Costa Rica with description of a new species (Coleoptera, Staphylinidae, Scydmaeninae)

To date, Mexiconnus Jałoszyński was a monotypic genus known to occur in Chiapas, Mexico. The sole species, M. mexicanus (Franz), was unique among Stenichnini in having strongly broadened protarsi with a conspicuous setal cushion on the ventral side of the protarsomere 1. A new species, M. triops sp. n., is described, based on a male collected in central Costa Rica. In contrast to the type species of the genus, the male of M. triops is wingless, microphthalmous and depigmented, a set of features that suggest a possible endogean life habit.

Magmatic and Tectonic Domains of Central Costa Rica and the Irazú‐Turrialba Volcanic Complex Revealed by Ambient Noise Tomography

AbstractThe Central America Volcanic Arc runs from Guatemala to Panama, locally interrupted in Costa Rica after the twin‐system Irazú‐Turrialba Volcanic Complex, at the onset of the Talamanca Cordillera. A marked geological discontinuity characterizes the transition between the volcanic arc and this continental mountain range. To shed light on the spatial and structural relationships between active tectonics and volcanism, we deployed a temporary network consisting of 20 broadband seismic stations around the Irazú‐Turrialba Volcanic Complex that integrated the national seismic networks maintained by Costa Rican institutes. From the seismic records, we extract cross‐correlation functions and Rayleigh wave group‐velocity dispersion curves to perform two ambient noise tomographies at a regional and local scale. From this, we derive two models that point out the magmatic and tectonic features of the southern part of the Central American Volcanic Arc and of the Irazú‐Turrialba Volcanic Complex. The regional‐scale tomographic inversion suggests that such a volcanic complex shares a common reservoir at about 5–7 km depth that is fed by a sub‐vertical region, departing from at least 12 km depth. From here magmas appear to be transported upwards and stored in separate reservoirs below each volcanic edifice. Our study establishes an improved understanding of the spatial relationship between tectonic features and distribution of magmatic reservoirs underpinning the plumbing system of the Irazú‐Turrialba volcanic complex.

Application of Scenario Earthquakes for Analysis of Seismically Triggered Landslide Hazard: A Case Study in Costa Rica

In this study, we demonstrate the capabilities of hypothetical scenario earthquakes as a new tool for assessment of hazards associated with earthquake-triggered landslides. Costa Rica offers an ideal environment for demonstrating the utility of scenario earthquakes due to its diverse tectonic environments and associated widespread seismic hazard, rugged topography, and high landslide susceptibility. We investigate the relative influence of landslide proxies such as topographic slope, peak ground velocity (PGV), and compound topographic index (CTI), and earthquake source parameters such as magnitude and depth, on predicted landslide probability and fatality. We examine five distinct tectonic environments, including subduction events beneath the (1) Nicoya and (2) Osa peninsulas respectively, (3) intraplate earthquakes beneath the Central Volcanic Range (CVR) and (4) the Central Costa Rica Deformed Belt (CCRDB), and (5) back-arc thrust events on the eastern Caribbean coast. Our results demonstrate that the slope, PGV, and CTI thresholds necessary to produce landslide probabilities greater than 10% vary by tectonic environment. In all cases, we observe magnitude to be the primary control on the predicted maximum landslide probability and overall areal landslide coverage. We validate model predictions with observed landslide inventories from the 2009 Cinchona and 1991 Limon earthquakes, demonstrating a good fit, where over 70% of landslides occurring in zones of greater than 20% probability. We also use a global model of landslide impact to predict exposure and fatality ranges for each scenario earthquake of this study, revealing that moderate-sized earthquakes in the CCRDB and CVR and large subduction megathrust earthquakes each pose a significant hazard to Costa Rica’s population.

Phylogenomics Reveals the Evolutionary History of Phytolacca (Phytolaccaceae).

Phytolacca is the largest genus of Phytolaccaceae. Owing to interspecific hybridization, infraspecific variation, and apparent weak genetic control of many qualitative characters, which have obscured boundaries between species, the classification and phylogenetic relationships of this genus are unclear. Native Phytolacca is disjunctly distributed in America, eastern Asia, and Africa, and the biogeographic history of the genus remained unresolved. In this study, we used the whole chloroplast genome and three markers (nrDNA, rbcL, and matK) to reconstruct phylogenetic relationships within Phytolacca, analyze divergence times, and infer biogeographic histories. The phylogenetic results indicate that Phytolacca is monophyletic, which is inconsistent with the infrageneric classification based on morphology. According to the divergence time estimation, Phytolacca began to diversify at approximately 20.30 Ma during the early Miocene. Central America, including Mexico, Costa Rica, and Colombia, is the center of species diversity. Biogeographical analysis indicated five main dispersal events and Phytolacca originated from Central and South America. Birds may be the primary agents of dispersal because of the fleshy fruiting of Phytolacca. This study extended sampling and added more genetic characteristics to infer the evolutionary history of Phytolacca, providing new insights for resolving the classification and elucidating the dispersal events of Phytolacca.

Human-wildlife conflict in indigenous communities of the Nairi Awari Indigenous Territory of East Central Costa Rica

Abstract. Sáenz-Bolaños C, Fuller TK, Sievert L, Carrillo E. 2022. Human-wildlife conflict in indigenous communities of the Nairi Awari Indigenous Territory of East Central Costa Rica. Biodiversitas 23: 2238-2244. Human-wildlife conflict is essential for conservation because it is necessary to maintain the balance of requirements needed by humans and wildlife. Indigenous territories are not exempt from interactions with wildlife, and in this study, we focus on one indigenous territory of the Cabécar Indigenous Group of Costa Rica called Nairi Awari. We wanted to know which are the most common wildlife species, which interactions with these species the Nairi Awari consider negative, and what are the possible solutions to these interactions. To do this, we administered 24 semi-structured questionnaires to indigenous people from March-August 2019. The results showed 16 species as “problematic animals”, the jaguar (Panthera onca) being the most common, followed by hawks. Of the six problem categories identified, predation on poultry was the most cited category, but it raised fewer negative feelings among respondents than some other problems. Possible solutions to pig or cow predation, problems which most maddened respondents, included improved management (48%), scaring animals (12%), and killing big cats (16%). It is important to understand these perceptions in order to address future management to benefit conservation and human welfare. In particular, there is potential to work in the long term to improve the management of domestic animals.

Deciphering complex groundwater age distributions and recharge processes in a tropical and fractured volcanic multi‐aquifer system

AbstractGroundwater recharge in highly fractured volcanic aquifers in the humid tropics remains poorly understood. In this region, rapid demographic growth and unregulated land use change are resulting in extensive surface water pollution and a large dependency on groundwater extraction. Here we present a multi‐tracer approach including δ18Oδ2H, 3H/3He dating, and noble gases (NG) within the most prominent multi‐aquifer system of central Costa Rica, with the objective to assess dominant groundwater recharge mechanisms and age distributions. We sampled wells and large springs across an elevation gradient from 868 to 2421 m asl. Our results indicate relatively young apparent ages ranging from 0.0 ± 3.2 up to 43.5 ± 7.6 years within the unconfined aquifer system. Helium isotopes (R/Ra up to 5.4) indicate a dominant signal from the upper mantle and preclude 3H/3He dating in 50% of the samples. Potential recharge elevations (based on NG and δ18O) ranged from ~1350 to 2670 m asl. NG‐derived recharge temperatures ranged from 11.0°C to 19.4°C. Recharge estimates varied from 129 ± 78 to 1605 ± 196 mm/yr with a mean value of 642 ± 117 mm/yr, representing 20.1 ± 4.0% of the total mean annual rainfall as effective recharge. The shallow unconfined aquifer is characterized by young and rapidly infiltrating water, whereas the deeper aquifer units have relatively older water (>60 years). These results are intended to guide the delineation and mapping of critical recharge areas in mountain headwaters to enhance water security and sustainability in the most important headwater dependent systems of Costa Rica.

Extraregional Migratory Flows in Transit as Complex Unbounded Emergency (Risk): Conceptual Challenges and Empirical Lessons in Costa Rica

Recent migratory flows transiting through Central America have led to unprecedented institutional and humanitarian responses across the sub-region. Between 2015 and 2016, the small Central American countries and Costa Rica in particular experienced at least two major “migration waves,” triggered by thousands of “extraregional migrants” in transit from Cuba, Haiti, and many countries from Asia and Africa who became stranded for months in Central America. The article examines how these recent and unusual migratory flows led to novel state responses, including the use of disaster risk management principles and operational mechanisms. Based on empirical data from Costa Rica, the article explores how the concept and notion of complex unbounded emergency (risk) may be appropriate in understanding the practical implications of this new migratory reality in terms of disaster risk reduction and management. It aims to shed new insights on the complexities of extraregional migratory flows, which are likely to continue into the foreseeable future.

Damsel in distress: is the nomenclature of Lachesis melanocephala Solórzano & Cerdas, 1986 (Serpentes, Viperidae) in need of rescue?

The neotropical viperid snake genus Lachesis Daudin, 1803 accomodates four venomous species that occur in forested areas from Central America, in Nicaragua and Costa Rica, to most of South America, southwards into southeastern Brazil and Bolivia (Campbell & Lamar 2004). This genus is unique among neotropical crotalines in having a high number of ventrals, dorsal, and cephalic scales, while also being oviparous (Campbell & Lamar 2004). Lachesis melanocephala Solórzano & Cerdas, 1986 is a large-sized viper, distributed from the Pacific coast of southwestern Costa Rica to northwestern Panama (Campbell & Lamar 2004). This species reaches up to 2.4 meters of total length, and can be diagnosed based on its uniformly black dorsal head pattern and inconspicuous postocular black stripe (Fig. 1; Campbell & Lamar 2004).

Stable isotopic characterization of nitrate wet deposition in the tropical urban atmosphere of Costa Rica

Increasing energy consumption and food production worldwide results in anthropogenic emissions of reactive nitrogen into the atmosphere. To date, however, little information is available on tropical urban environments where inorganic nitrogen is vastly transported and deposited through precipitation on terrestrial and aquatic ecosystems. To fill this gap, we present compositions of water stable isotopes in precipitation and atmospheric nitrate (δ18O-H2O, δ2H-H2O, δ15N-NO3-, and δ18O-NO3-) collected daily between August 2018 and November 2019 in a tropical urban atmosphere of central Costa Rica. Rainfall generation processes (convective and stratiform rainfall fractions) were identified using stable isotopes in precipitation coupled with air mass back trajectory analysis. A Bayesian isotope mixing model using δ15N-NO3- compositions and corrected for potential 15N fractionation effects revealed the contribution of lightning (25.9 ± 7.1%), biomass burning (21.8 ± 6.6%), gasoline (19.1 ± 6.4%), diesel (18.4 ± 6.0%), and soil biogenic emissions (15.0 ± 2.6%) to nitrate wet deposition. δ18O-NO3- values reflect the oxidation of NOx sources via the ·OH + RO2 pathways. These findings provide necessary baseline information about the combination of water and nitrogen stable isotopes with atmospheric chemistry and hydrometeorological techniques to better understand wet deposition processes and to characterize the origin and magnitude of inorganic nitrogen loadings in tropical regions.

Response of a hydrothermal system to escalating phreatic unrest: the case of Turrialba and Iraz\xfa in Costa Rica (2007\u20132012)

This study presents the first hydrogeochemical model of the hydrothermal systems of Turrialba and Irazú volcanoes in central Costa Rica, manifested as thermal springs, summit crater lakes, and fumarolic degassing at both volcanoes. Our period of observations (2007–2012) coincides with the pre- and early syn-phreatic eruption stages of Turrialba volcano that resumed volcanic unrest since 2004, after almost 140 years of quiescence. Peculiarly, the generally stable Irazú crater lake dropped its level during this reawakening of Turrialba. The isotopic composition of all the discharged fluids reveals their Caribbean meteoric origin. Four groups of thermal springs drain the northern flanks of Turrialba and Irazú volcanoes into two main rivers. Río Sucio (i.e. “dirty river”) is a major rock remover on the North flank of Irazú, mainly fed by the San Cayetano spring group. Instead, one group of thermal springs discharges towards the south of Irazú. All thermal spring waters are of SO4-type (i.e. steam-heated waters), none of the springs has, however, a common hydrothermal end-member. A water mass budget for thermal springs results in an estimated total output flux of 187 ± 37 L/s, with 100 ± 20 L/s accounted for by the San Cayetano springs. Thermal energy release is estimated at 110 ± 22 MW (83.9 ± 16.8 MW by San Cayetano), whereas the total rock mass removal rate by chemical leaching is ~ 3000 m3/year (~ 2400 m3/year by San Cayetano-Río Sucio). Despite Irazú being the currently less active volcano, it is a highly efficient rock remover, which, on the long term can have effects on the stability of the volcanic edifice with potentially hazardous consequences (e.g. flank collapse, landslides, phreatic eruptions). Moreover, the vapor output flux from the Turrialba fumaroles after the onset of phreatic eruptions on 5 January 2010 showed an increase of at least ~ 260 L/s above pre-eruptive background fumarolic vapor fluxes. This extra vapor loss implies that the drying of the summit hydrothermal system of Turrialba could tap deeper than previously thought, and could explain the coincidental disappearance of Irazú’s crater lake in April 2010.

Spatial variability of the b-value and seismic potential in Costa Rica

Costa Rica is a seismically active region located in a subduction zone. Combining earthquake data from the National Seismological Network and several Central American catalogs from 1522 to 2020, we present a new estimation for the Gutenberg-Richter relationship. The seismic catalog compiled with ~122,000 earthquakes was studied by calculating the magnitude of completeness (Mc) and by applying a space-time window declustering method. The residual catalog and a previously proposed seismic zonation were used to determine the b-value, the maximum magnitude (Mmax), and the mean recurrence interval (MRI). Our results show a temporal and geographic variation in the Mc, decreasing from 7.0 since 1793 to 3.0 since 1995, and with the lowest estimate (2.5) in Central Costa Rica. The b-values of 0.85 for the entire catalog and ~0.83 for the interplate zones, are similar to other regions worldwide with young subducting slabs. There is a general trend of higher and more variable b-values among the upper-plate (average 0.90) and intraslab (1.14) zones as compared to the interplate regions (0.85). The upper-plate variability is explained in terms of the diversity in geological units and faulting style, whereas in the interplate and the subducting slab is connected to the stress level imposed by different seafloor morphologies and hydration states along the margin. Our data suggest a seismic potential of moment magnitude (Mw) 7.9–8.0 for the Nicoya and Southern Nicaragua interplate zones and for the Limon region. The Gutenberg-Richter distribution shows that a Mw 7.0 has a longer MRI for the intraslab zones (~72 years) than for the subduction interplate region (~15 years) and plate and microplate boundaries (~40–45 years). Interplate earthquakes have occurred recently (1991 Mw 7.7 and 2012 Mw 7.6) but no major intraslab since 1948 (Mw 7.0).

Albinism in a Yellow-bellied Earth Snake (Geophis godmani Boulenger, 1894) (Serpentes: Dipsadidae) from Central Costa Rica

Anomalous pigmentations have been reported in several groups of reptiles. Among these, albinism is one of the most striking aberrations of body coloration. This pigmentary anomaly is caused by the absence of melanin in the integument. Many cases of albinism have been reported in snakes, primarily in species with cryptozoic habits, and several reports are available for the Dipsadidae family from South America. Geophis is one of the most diverse genera in this family, with 50 species distributed mainly in Mesoamerica. The Yellow-bellied Earth Snake (Geophis godmani) is known only from the mountain ranges of Costa Rica and western Panama. In September, 2020 we encountered an albino individual of the Yellow-bellied Earth Snake at Palmira de Zarcero, Alajuela province, Costa Rica. Here we report on this finding and discuss possible consequences of albinism in snakes. Snakes affected by albinism have red eyes and a yellow or pink coloration due to the presence of xanthophores and erythrophores. As a result, aspects such as thermoregulation can be affected, and jeopardize the snake's survival. However, some individuals can have traits that potentially preclude the negative effects of albinism. These characteristics would allow for the survival of individual snakes to the adult stage, such as the albino individual of Geophis godmani we found in central Costa Rica.

Changing tectonic regimes in the central Costa Rica forearc between the Paleogene and the present: Insights from structural analysis and focal mechanisms

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.