Observations made in Gale Crater by instruments on the MSL Curiosity Rover show that the diurnal amplitude of the surface pressure is increased and the depth of the Convective Boundary Layer (CBL) is decreased relative to other lander locations on flatter regions of Mars (Haberle et al., 2014; Moores et al., 2015). Mesoscale modeling studies of Gale Crater suggest that crater circulations produce these effects. Tyler & Barnes (2013) show that local upslope/downslope flows along the crater rim and Mt. Sharp amplify the diurnal pressure cycle. These same flows are thought to be at least partly responsible for the suppression of the CBL because upward air flow at the rim and in the center (due to Mt. Sharp) forces subsidence over the lowest regions of the crater during the day. Regional flows, largely due to the location of Gale near the dichotomy boundary, may also play a role in shaping the circulation internal to the crater. Whether the behavior of the CBL and the amplified diurnal pressure cycle are phenomena observed in craters morphologically different from Gale (i.e. bowl-shaped, irregular, degraded) is not yet understood. We will explore these questions by characterizing the behavior of these processes as they are shaped by the morphology of craters greater than 100 km in diameter. We use the NASA Ames Mars Global Circulation Model (GCM) that now utilizes the NOAA/GFDL cubed-sphere finite-volume dynamical core to examine ~100 craters of varying size and shape from a database of known Martian craters (Robbins & Hynek, 2014). Run at 7.5 km resolution, the GCM is capable of resolving surface winds, temperature, and pressure inside craters of this size allowing for the analysis of dozens of craters simulated at various seasons and within the context of synoptic and global-scale phenomena.

Currently available soil volumetric water content (VWC) sensors have several drawbacks that pose certain challenges for implementation on large scale for farms. Such issues include cost, scalability, maintenance, wires running through fields, and single-spot resolution. The development of a passive soil moisture sensing system utilizing Radio Frequency Identification (RFID) would allay many of these issues. The type of passive RFID tags discussed in this paper currently cost between 8 to 15 cents retail per tag when purchased in bulk. An incredibly cheap, scalable, low-maintenance, wireless, high-resolution system for sensing soil moisture would be possible if such tags were introduced into the agricultural world. This paper discusses both the use cases as well as examines one implementation of the tags. In 2015, RFID tag manufacturer SmarTrac started selling RFID moisture sensing tags for use in the automotive industry to detect leaks during quality assurance. We place those tags in soil at a depth of 4 inches and compared the moisture levels sensed by the RFID tags with the relative permittivity (εr) of the soil as measured by an industry-standard probe. Using an equation derived by Topp et al, we converted to VWC. We tested this over a wide range of moisture conditions and found a statistically significant, correlational relationship between the sensor values from the RFID tags and the probe’s measurement of εr. We also identified a possible function for mapping vales from the RFID tag to the probe bounded by a reasonable margin of error.

Persistent Scatterer Interferometry (PSI) is a novel remote sensing technique for monitoring land deformation on large scale. It is economic and can be used for detection of land surface deformation in the past given that the sensor should have passed over the area. The millimetric precision of the technique makes it very useful. One of its application is monitoring of slow moving landslides. In this study we have focused upon monitoring of slow moving landslides in Tehri region of Uttarakhand state of India. This area is landslide prone. Its susceptibility to landslide has increased due to construction of artificial reservoir in the region. The variation in reservoir drawdown level can be cited as one of the reasons. In this study we have applied Persistent Scatterer Interferometry on the stack of 20 Single Look Complex (SLC) scenes of Envisat satellite of European Space Agency. We have performed time-series analysis for period starting from 12 May 2008 to 26 July 2010. The methodology consists of selection of master image, coregistration of other slave images to master image, calculation of amplitude stability index, generation of reflectivity map. After this 19 interferograms were generated. On basis of this selection of Persistent Scatterers (PS) is done. After that estimation and removal of Atmospheric Phase Screen (APS) was done. In the end calculation of time-series displacement of PSs is performed. From this analysis we are able to identify the spatial location of slow moving landslides. In this study we have identified PSs having nearly 40 mm/year of velocity. Detected areas showing land movement away from the line of sight of satellite, can be found on the rim of reservoir as well as areas 4 kilometres interior, away from the boundary of reservoir. These areas are located near roads and places where anthropogenic interference is there.

We analyze peridotites from a wide range of tectonic settings to investigate relationships between olivine lattice preferred orientation (LPO) and deformation conditions in naturally deformed rocks. These samples preserve the five olivine LPO types (A through E-type) that rock deformation experiments have suggested are controlled by water content, temperature, stress magnitude, and pressure. The naturally deformed specimens newly investigated here (65 samples) and compiled from an extensive literature review (445 samples) reveal that these factors may matter less than deformation history and/or geometry. Some trends support those predicted by experimentally determined parametric dependence, but several observations disagree — namely that all LPO types are able to form at very low water contents and stresses, and that there is no clear relationship between water content and LPO type. This implies that at the low stresses typical of the mantle, LPO type more often varies as a function of strain geometry. Because olivine LPO is primarily responsible for seismic anisotropy in the upper mantle, the results of this study have several implications. These include (1) the many olivine LPO types recorded in samples from individual localities may explain some of the complex seismic anisotropy patterns observed in the continental mantle, and (2) B-type LPO – where olivine’s “fast axes” align perpendicular to flow direction – occurs under many more conditions than traditionally thought. This study highlights the need for more experiments, and the difficulty in using olivine LPO in naturally-deformed peridotites to infer deformation conditions.

Carbonate drift deposits in the Santaren Channel, on the Marion Plateau and in the Inner Sea of the Maldives were cored and dated by ODP and IODP expeditions. The ages based on biostratigraphy of these drifts are 11.4 Ma (Marion Drift), 12.3 Ma (Santaren Drift) and 12.9 Ma (Maldives Inner Sea), indicating a near simultaneous onset of the Florida, East Australia and Indian Ocean Currents that are all part of the global ocean current system. The Himalayan tectonics started with the collision of the Indian continent with Asia about ~50 Ma ago and continues today. The uplift of the Himalaya and Tibetan Plateau was not steady and not consistent across the mountain belt. The uplift of the southern and central Tibetan Plateau occurred from 40–35 Ma, at the northern Tibetan plateau at approximately 25–20 Ma, and at the northeastern to eastern Tibetan plateau at ~15 Ma. Significant increases in altitude of the entire Tibetan plateau are thought to have occurred about 10–8 Ma agoor more recently, some 3 myrs after the onset of the modern Indian Ocean monsoon-driven circulation system that is dated at 12.9 Ma. This sudden onset or intensification is puzzling in light of the continuous uplift of the Himalaya and Tibetan Plateau. If a linkage between tectonics and climate exists, the uplift must have stepped over a threshold that caused the climate to change dramatically. The near simultaneous onset of the global ocean circulation and the intensification of the monsoon is strong evidence that a combination of factors caused the sudden climate change. It is likely that onset of the intense monsoon is the combined result of the tectonic configuration, consisting of the Himalayan uplift but also the closing of the Tethyan seaway, and progressive glaciation on Antarctica.

Essential Biodiversity Variables (EBVs) are state variables that lie between primary measurements and high-level indicators, and are necessary for assessment of the health and prognosis of Earth’s biosphere. EBVs represent the complete spectrum of biological diversity from genes to ecosystems, and so are based on observations which themselves are highly diverse, and typically human-collected or analyzed. What is now sorely needed are structured dictionaries of biological measurements that data collectors, curators and nascent biodiversity programs can reference at all stages of planning and data organization. Similarly, analysts working with data defined according to these measurement dictionaries, require assurance that their results are comparable across scales and institutions. Full understanding of primary measurements will ideally require machine-readable, interpretable, and interoperable descriptions of the measurement contents, collection methods, data-typing, dimensions and associated units for physical quantities, and specification of appropriate temporal and spatial scales, plus the relationships among those attributes and facets of the ecosystem. Formal ontologies, i.e. vocabularies built using modern Semantic Web technologies, now provide the ideal tools and protocols for structuring and operationalizing EBV primary measurements. Here we illustrate an approach to apply these to existing data sets (both primary and harmonized intermediates) using community-accepted measurement ontologies under development. Such techniques can streamline the discovery and integration of observations, assist with calibration/validation checks required for automated or remote data collection, and enable rigorous structured definitions for modeled or remotely-sensed EBVs as these are developed.

Conventionally, radar-based nowcasting methods have been conducted by shifting or extrapolating the most recent estimated precipitation field along the estimated motion field to lead times up to 3 hr. However, such methods assume that these fields do not evolve during the lead-time period. A more recent nowcasting approach is the short-term ensemble prediction system known as STEPS. STEPS aims to filter small spatial scales of rain as they have an expected short life-time compared to large spatial scales. Besides, it perturbs the precipitation field during extrapolation so that the prediction uncertainties related to the evolution of precipitation is considered, resulting in an ensemble nowcast. In this work, the configuration, implementation, and performance of STEPS are studied for its radar-based ensemble nowcasting application in Germany. Attention is given to the spatial localization (i.e., the adjustment of parameters that control the spatio-temporal evolution of precipitation in large domains). For such purpose, the capability of STEPS is analyzed using multiple rain events collected by the German radar network. Preliminary analysis regarding the spatial scale filtering of STEPS (without perturbation) shows an improvement against conventional extrapolation of 20 to 30 % on the critical success index starting at lead times of 30 min at a rainfall threshold of 0.1 mm hr-1. In terms of the spatial structure, STEPS (without perturbation) provides a consistent nowcast for lead times up to 3 hr. Although small spatial structures are filtered, the spatial structure at scales of 32 km or larger is maintained. The skill of a probabilistic nowcast (STEPS with perturbation) was also analyzed. It is shown that for the probability of exceeding the 5.0 mm hr-1 threshold, the predictability of the nowcast is compromised for lead times on the order of 1 hr. However, the capability of identifying rain and non-rain areas is still valuable: the hit rates are still larger than the false alarm rates. Our preliminary results highlight aspects needed in the configuration of STEPS such as the evolution model and the perturbation model. In this manner, this study can serve as a basis for an improved nowcasting system in Germany and as a reference for forecasters to understand the characteristics of the examined nowcast system.

Geotechnical engineering and geology faculty at Drexel and Villanova Universities and a graduate teaching assistant collaborated with an environmental hydrogeologist from a local civil engineering firm to develop a field trip for their undergraduate engineering geology courses. At Villanova, Geology for Engineers is required for all civil and environmental engineering students. Similarly, at Drexel, Geologic Principles for Infrastructure & Environmental Engineering is a required course for all civil, architectural and environmental engineering students. The learning goal of both courses is to have students understand how basic topics in geology and geomorphology apply to civil and environmental engineering practice. The field trip focuses on the core elements of the courses: the importance of rock type on engineering properties, the effects of plate tectonics and weathering on rocks, and the interaction of human activity with the lithosphere and hydrosphere. The team selected Wissahickon Valley Park as the location for the field trip because it provides a dynamic stream ecosystem within a geologically diverse setting that has been highly impacted by urban development of the surrounding City of Philadelphia. The engineering aspects bring novelty into an established practice of classical geology field trips. In addition to examining outcrops and evidence of geologic processes, the students were required to critically identify engineering issues associated with the infrastructure in the valley, storm water management, and the impact of development on the stream valley. From anonymous surveys disseminated after the first offering of the field trip, students indicated the trip had enriched their learning experience, improved their ability to apply basic geology knowledge in a real-world context, and increased their interest in how rock, soil, water, and climate play roles in infrastructure engineering. Without exception, the students agreed that the field trip should be offered again. This presentation will describe the development of the collaboration between the educators and practitioners, the resulting field trip and materials that have been adopted at both universities. We will also update the surveys’ results from two more trips of the fall of 2018.

The prediction of natural disasters in general and earthquakes, in particular, is becoming increasingly critical in providing early warnings and mitigating catastrophes’ effects. This study investigates relations between earthquakes and ionospheric disturbances. Based on analyzing TEC disturbances, we search for the impact of the earthquake-related seismic waves on the ionosphere. The study is designed as cross-sectional investigations, in which the global earthquakes are randomly collected by the cluster sampling method. We use data of 54 permanent GNSS (Global Navigation Satellite Systems) stations and global earthquakes with magnitudes (Mw) from 4.0 to 9.0 in the period from 2006 to March 2020. The selected data ensure strict conditions such as accuracy, the distance from the GNSS stations to the epicenter, and the depth of hypocenter. Probability and statistics are applied to filter, classify and analyze data. The results indicate that TEC fluctuations at the regions occurring earthquakes with magnitudes greater than 6.0 Mw are significant. These TEC anomalies appear from 30 minutes to around two hours before the mainshocks, and the oscillations remain from five to eight minutes. These TEC variations occur from five to eleven days before the great earthquakes. The results reveal the relations between ionospheric anomalies and earthquake-related seismic waves. The findings are the base to filter TEC anomalies generated by earthquakes in building ionospheric models. The study also opens up a prospect for GNSS applications in studying TEC anomalies linked to earthquake precursors as well.

The author presents an iterative approach to describing a data set, such as a paleoclimatic proxy or a model output, in terms of automata of successively higher order. The automata reflect dynamics acting on successively longer timescales and larger spatial scales. The method uses the computed probability density function from reconstructed state space portraits, over successive overlapping windows in time, of the record of magnetic susceptibility of loess and paleosols at Luochuan, central China. Areas of consistently high probability across several time windows represent areas of quasistability, which are used as the predictive and successor states of a succession of Markov Chains that characterize the variability of the strength of the East Asian paleomonsoon at different time scales. Seven metastable states are thus identified, forming four Markov Chains, which show a marked increase in complexity of behavior of the paleomonsoon system throughout the Quaternary. A higher-order automaton is suggested by the sequence of Markov Chains, suggesting differing cycles of dynamic behaviour in the Early and Late Quaternary.

The Miocene epoch, spanning 23.03-5.33Ma, was a dynamic climate of sustained, polar amplified warmth. Miocene atmospheric CO2 concentrations are typically reconstructed between 300-600ppm and were potentially higher during the Miocene Climatic Optimum (16.75-14.5Ma). With surface temperature reconstructions pointing to substantial midlatitude and polar warmth, it is unclear what processes maintained the much weaker-than-modern equator-to-pole temperature difference. Here we synthesize several Miocene climate modeling efforts together with available terrestrial and ocean surface temperature reconstructions. We evaluate the range of model-data agreement, highlight robust mechanisms operating across Miocene modelling efforts, and regions where differences across experiments result in a large spread in warming responses. Prescribed CO2 is the primary factor controlling global warming across the ensemble. On average, elements other than CO2, such as Miocene paleogeography and ice sheets, raise global mean temperature by ~ 2℃, with the spread in warming under a given CO2 concentration (due to a combination of the spread in imposed boundary conditions and climate feedback strengths) equivalent to ~1.2 times a CO2 doubling. This study uses an ensemble of opportunity: models, boundary conditions, and reference datasets represent the state-of-art for the Miocene, but are inhomogeneous and not ideal for a formal intermodel comparison effort. Acknowledging this caveat, this study is nevertheless the first Miocene multi-model, multi-proxy comparison attempted so far. This study serves to take stock of the current progress towards simulating Miocene warmth while isolating remaining challenges that may be well served by community-led efforts to coordinate modelling and data activities within a common analysis framework.

Atmospheric photoelectrons are central to the production of planetary ionospheres. They are created by photoionization of the neutral planetary atmosphere by solar EUV and soft X-ray irradiance. They provide the energy to heat the thermosphere. Thermalized photoelectrons permeate magnetospheres creating polarization electric fields and plasma waves as they interact with ions to maintain charge neutrality. Energetic photoelectrons (>1 eV) have a distinctive energy spectral shape as first revealed in data from the Atmosphere Explorer satellites. Energetic photoelectrons escaping the ionosphere follow local magnetic fields illuminating the planet’s magnetic topology. Current models using state-of-the-art EUV observations accurately capture their production and transport. However, in spite of 60 years of space research the electron thermalization processes occurring below 1 eV at low altitudes in planetary thermospheres are not understood quantitatively. Results from event analysis of data from the Mars Atmosphere and Volatile Evolution (MAVEN) mission are not consistent with current models of photoelectron thermalization. The lack of quantitative understanding reflects the complexity of the physics and the lack of a large data base of simultaneous neutral, ion, and electron densities and temperatures in lower planetary thermospheres Introduction:

Although many suggest that future diets should include more plant-based proteins, animal-sourced foods are unlikely to completely disappear from our diet. Grasslands yield a notable part of the world’s animal protein production, but thus far, there is no global insight into the relationship between current livestock stocking densities and the availability of grassland forage resources. This inhibits acting upon concerns over the negative effects of overgrazing in some areas and utilising the potential for increasing production in others. Previous research has examined the potential of sustainable grazing but lacks generic and observation-based methods needed to fully understand the opportunities and threats of grazing. Here we provide a novel framework and method to estimate global livestock carrying capacity and relative stocking density, i.e. the reported livestock distribution relative to the estimated carrying capacity. We first estimate the aboveground biomass that is available for grazers on grasslands and savannas based on the MODIS Net Primary Production (NPP) approach on a global scale. This information is then used to calculate reasonable livestock carrying capacities, using slopes, forest cover and animal forage requirements as restrictions. With this approach, we found that stocking rates exceed the forage provided by grasslands in northwestern Europe, midwestern United States, southern China and the African Sahel. In this study, we provide the highest resolution global datasets to date. Our results have implications for prospective global food system modelling as well as national agricultural and environmental policies. These maps and findings can assist with conservation efforts to reduce land degradation associated with overgrazing and help identify undergrazed areas for targeted sustainable intensification efforts.

The El Niño-Southern Oscillation (ENSO) phenomenon is the main mechanism forcing climate variability in tropical South America in several timescales, impacting the life cycles of disease vectors and host/vector relationships. The dengue is a vector-borne disease with great socioeconomic impact in Colombia, being the arbovirus with the highest mortality. In this analysis, we related the records of Dengue cases registered in Colombia in the period 2007-2017 and the series of sea surface temperature anomalies in the Niño 3.4 region. Furthermore, we studied the effect of the ENSO on precipitation, relative humidity, maximum and minimum air temperature, and wind velocity in Colombia to understand the impact of the ENSO in the dengue incidence. The effect of the ENSO on climatic variables spatially varies. During the warm (cold) phase, i.e., El Niño (La Niña), the maximum and minimum air temperature increase (decrease) throughout the country, but in the Amazonian region, it is less likely to occur. During El Niño the mean rainfall decreases, except in the Orinoquía region where it can increase. In the Pacific and Caribbean regions, rainfall is more likely to decrease in this phase of the ENSO, while surface radiation increases in the Andean region. Wind speed increases in the Andean, Caribbean and Pacific regions, and decreases in the Orinoquía and Amazonian regions. El Niño phase intensifies the incidence rate of Dengue in the Andean, Caribbean, and Pacific regions (correlation between 0.3 and 0.8 with 95% of confidence for lags between 1 and 14 months approximately) and La Niña in the Amazonian and Orinoquía regions (correlation between 0.2 and 0.5 with 95% of confidence for lags between 10 and 20 months approximately). The above should be explained by the decreasing in rainfall and increasing on temperature and wind velocity (less relative humidity) in the Andean, Caribbean and Pacific regions, and the increase in radiation in the Andean region during El Niño. On the other hand, during La Niña, rainfall decreases in the Orinoquía region and decreases on the temperature are unlike in the Amazonian region.

Triple collocation is an established technique for retrieving linear calibration coefficients and observation error variances of a physical quantity observed simultaneously by three different observation systems. The formalism is extended to an arbitrary number of systems, and representativeness errors and associated cross-covariances are included in a natural way. It is applied to quadruple collocations of ocean surface vector winds from two scatterometers (ASCAT-A, ASCAT-B, or ScatSat), buoy measurements, and NWP model forecasts. There are fifteen possible sets of quadruple collocation equations, twelve of which are solvable for the essential variables (calibration coefficients, observation error variances, and common variance) as well as two additional error covariances, each set leading to a different solution. A remarkable property of the quadruple collocation equations is proven: when the two additional error covariances from a particular solution are used to correct the corresponding observed covariances, all sets yield the same solution. Therefore the quadruple collocation equations by themselves give no information on the representativeness errors involved; these have to be estimated using other methods. The spreading in the solutions is a measure of the accuracy of the underlying error model. Variation of the scale at which the spatial variances are evaluated yields an optimal scale of 100 to 200 km. For the datasets used in this study the error in the scatterometer error variances is 0.03 to 0.05 ms-1, more than expected on statistical grounds. A more precise determination requires an error model better describing the data.

Dengue virus (DENV) is an endemic disease in the hot and humid low-lands of Colombia. We characterize diverse temporal and spatial patterns of monthly series of dengue incidence in diverse regions of Colombia during the period 2007-2017 at different spatial scales, and their association with indices of El Niño/Southern Oscillation (ENSO) and local climatic variables. For estimation purposes, we use linear analysis tools including lagged cross-correlations (Pearson test), cross wavelet analysis (wavelet cross spectrum, and wavelet coherence), as well as a novel nonlinear causality method, PCMCI, that allows identifying common causal drivers and links among high dimensional simultaneous and time-lagged variables. Our results evidence the strong association of DENV cases in Colombia with ENSO indices and with local temperature and rainfall data. El Niño (La Niña) phenomenon is related to the intensification (weakening) of dengue cases at the national level and in most regions and departments, with maximum correlations occurring at shorter time lags in the Pacific region, closer to the Pacific Ocean. This association is mainly explained by the ENSO-driven increase in temperature and decrease in rainfall, especially in the Andes and Pacific regions. The influence of ENSO is not stationary (there is a reduction of DENV cases since 2005) and local climate variables vary in space and time, and thus it is not easy to extrapolate results from one site to another. The association between DENV and ENSO varies at national and regional scales when data are disaggregated by seasons, being stronger in DJF and weaker in SON. Specific regions (Pacific and Andes) control the overall relationship between dengue dynamics and ENSO at national scale, and the departments of Antioquia and Valle del Cauca determine those of the Andes and Pacific regions, respectively. Cross wavelet analysis indicates that the ENSO-DENV relation in Colombia exhibits a strong coherence in the 12 to16-months frequency band, which denotes the frequency locking between the annual cycle and the interannual (ENSO) timescales. Results of nonlinear causality metrics reveal the complex concomitant effects of ENSO and local climate variables (Fig. 1), offering new insights to develop early warning systems for DENV in Colombia.

To understand the influence of the Sun on Earth's system, long and accurate measurements of solar irradiance are a prerequisite. The available direct measurements of solar irradiance since 1978 are clearly not sufficient for this purpose. This stimulated development of models used to reconstruct past solar irradiance variations from alternative observations. The main driver of the irradiance variations on time scales of days to millennia is the evolution of the solar surface magnetic field in form of dark sunspots and bright faculae and network. Therefore, models require input data describing the contributions of these various magnetic regions on the Sun at earlier times. Unfortunately, records that can be used to describe the facular and network contributions are barely longer than the direct irradiance measurements. Thus, irradiance reconstructions to earlier periods have to rely on sunspot data alone. Data that have hardly been used for solar irradiance reconstructions until now are full-disc solar observations in the Ca II K line. Such data exist since 1892 from various observatories and include all the needed information describing faculae and the network. However, they are plagued by a bunch of various problems and artefacts, and recovering the non-linear response of the photographic material to the radiation is non-trivial since the required information is usually missing, too. We have developed a method to process Ca II K observations from various sources and demonstrated the higher accuracy achieved by our method compared to other techniques presented in the literature. Here we use the carefully reduced Ca II K observations from multiple archives to reconstruct solar irradiance variations.

he boundary between the North American and Caribbean plates cuts EW across the island of Hispaniola. Relative motion on this part of the plate boundary is transpressional and tectonic deformation is partitioned between a NW-SE fold-and-thrust belt and two E-W left-lateral faults 150 km apart. The southern fault, the Enriquillo-Plantain Garden Fault (EPGF), is well defined in western Haiti but looses its morphological expression as it nears Lake Azuei in eastern Haiti. Since the sedimentation rate is high for this 20 km-long lake, Holocene deformation should be recorded in its upper stratigraphy and bottom morphology. To test this hypothesis, we analyzed 200 km of subbottom (CHIRP) profiles collected in 2017 that imaged the upper 2 - 10 m of sediments. This dataset is complemented with other sonar data, including 140 km of echosounder profiles (Moknatian et al., Rem. Sensing 2017) and 65 km of CHIRP profiles (Wang et al., Tectonics 2018). Morphological and stratigraphic information extracted from the combined dataset are compiled into a detailed geological map, which reveals: 1) Gas-charged sediments occur across most of the flat lake floor. However, where the gas front is deeper, the CHIRP data show the rhythmic stratigraphy characteristic of turbidites; 2) Turbidite beds fold up along the edges of the lake floor, documenting the ongoing deformation of the basin margins; 3) In the southern part of the lake, en echelon folds are trending EW, a trend compatible with fault-propagation folds developing ahead of a S-dipping oblique-slip EPGF. We find no evidence of fault scarp or stratigraphic offset in that same area, as might be expected from a sub-vertical EPGF; 4) Deeper penetration seismic reflection profiles acquired concurrently with the CHIRP reveal that the west side of the lake is occupied by a NW-trending monoclinal fold, possibly the expression of a SW-dipping blind thrust fault at depth. Vertical faults across that monocline are associated with subtle breaks in slope. Careful mapping of these slope breaks shows that these faults strike NW-SE, subparallel to the monocline; 5) A < 2 kyr-old paleoshoreline is uplifted 1-2 m across the monocline and soft-sediment deformation suggestive of liquefaction also affects that area. A large earthquake on the presumed underlying blind thrust fault could explain these two features.