A dense GPS network deployed in Ecuador reveals a highly heterogeneous pattern of interseismic coupling confined in the first 35 km depth of the contact between the subducting oceanic Nazca plate and ...the North Andean Sliver. Interseismic models indicate that the coupling is weak and very shallow (0–15 km) in south Ecuador and increases northward, with maximum found in the rupture areas of large (Mw>7.0) megathrust earthquakes that occurred during the 20th century. Since the great 1906 Mw=8.8 Colombia–Ecuador earthquake may have involved the simultaneous rupture of three to six asperities, only one or two asperities were reactivated during the large seismic sequence of 1942 (Mw=7.8), 1958 (Mw=7.7), 1979 (Mw=8.2) and 1998 (Mw=7.1). The axis of the Carnegie Ridge, which is entering the subduction zone south of the Equator, coincides well with the location of a 50 km wide creeping corridor that may have acted as persistent barrier to large seismic ruptures. South of this creeping region, a highly locked asperity is found right below La Plata Island. While this asperity may have the potential to generate an Mw∼7.0–7.5 earthquake and a local tsunami, until now it is unknown to have produced any similar events. That region is characterized by the presence of slow slip events that may contribute significantly to reduce the long-term moment deficit accumulated there and postpone the failure of that asperity. At the actual accumulation rate, a characteristic recurrence time for events such as those in 1942, 1958 and 1979 is 140±30 yr, 90±20 yr, 153±80 yr respectively. For the great 1906 event, we find a recurrence time of at least 575±100 yr, making the great 1906 earthquake a rare super cycle event.
•We model heterogeneous interseismic coupling along the Ecuadorian subduction zone.•The ruptures of large megathrust earthquakes correlate with discrete locked asperities.•Subduction of geomorphologic features promotes creeping on the megathrust interface.
The high energy consumes have generated the need of developing higher efficiency devices, in this sense flameless combustion is a great alternative. The design of flameless combustion systems by ...means of Computational Flow Dynamics simulation is an alternative value to reduce costs, however it required an adequate model selection. In the present study a capability evaluation of standard and realizable versions of k-e turbulence model was carried out. Experimental measurements of temperature and chemical species were performed in combustion chamber of a regenerative furnace in order to compare this with numerical data and in this way determinate the performance and the incidence of the selected models. The realizable version shows better results regarding at changes of flow direction and recirculation patterns inside the furnace.
The aim of this paper is to investigate the effects of replacing natural gas with synthetic gases on the combustion stability and the combustion pollutants of a surface-stabilized combustion burner. ...We evaluated three synthetic gases with high hydrogen contents ranging from 60% H2 to 75% H2. The experimental study was carried out under different input power conditions (300 to 500 kW/m2) and equivalence ratios. The results obtained in this work indicate that combustion stability of natural gas in a surface-stabilized combustion burner is significantly affected by the addition of synthetic gases, which in this case was held constant to obtained equimolar mixtures of synthetic gas and natural gas. This result seems to be explained by the variations of some important combustion properties, mainly the laminar burning velocity and the adiabatic flame temperature. On the other hand, it was found that CO emissions slightly decrease with increasing H2 concentration. This behavior is attributed to the increase of the OH radical.
The aim of this work was determined turbulent burning velocities of air-syngas-methane flames at sub-atmospheric conditions using the angle method and Schlieren imaging. We analyzed a high hydrogen ...content syngas that can be obtained with a Conoco-Phillips coal gasification process. Equivalence ratios evaluated here correspond to lean combustion conditions: 0.8-1.0. Experiments were carried out at room temperature of 297 K and 849 mbar. The chemical-turbulence interaction was evaluated considering geometric parameters, laminar flame properties, and turbulence length scales. It was found that the turbulent burning velocity and the ratio between turbulent and laminar burning velocities increases with the turbulence intensity. Additionally, the addition of syngas to methane increases the laminar and turbulent burning velocity.
The Quito Fault System (QFS) extends over 60 km along the Interandean Depression in northern Ecuador. Multidisciplinary studies support an interpretation in which two major contemporaneous fault ...systems affect Quaternary volcanoclastic deposits. Hanging paleovalleys and disruption of drainage networks attest to ongoing crustal deformation and uplift in this region, further confirmed by 15 years of GPS measurements and seismicity. The resulting new kinematic model emphasizes the role of the N‐S segmented, en echelon eastward migrating Quito Fault System (QFS). Northeast of this major tectonic feature, the strike‐slip Guayllabamba Fault System (GFS) aids the eastward transfer of the regional strain toward Colombia. These two tectonic fault systems are active, and the local focal mechanisms are consistent with the direction of relative GPS velocities and the regional stress tensor. Among active features, inherited N‐S direction sutures appear to play a role in confining the active deformation in the Interandean Depression. The most frontal of the Quito faults formed at the tip of a blind thrust, dipping 40°W, is most probably connected at depth to inactive suture to the west. A new GPS data set indicates active shortening rates for Quito blind thrust of up to 4 mm/yr, which decreases northward along the fold system as it connects to the strike‐slip Guayllabamba Fault System. The proximity of these structures to the densely populated Quito region highlights the need for additional tectonic studies in these regions of Ecuador to generate further hazard assessments.
Key Points
Neotectonics of Quito faults are studied by a multidisciplinary approach
Our kinematic model defines a N‐S fold system migrating eastward
The GPS rate for QFS is 4 mm/yr, suggesting a deficit of crustal seismicity
The Tungurahua volcano, in Ecuador, has been experiencing a substantial activity period since 1999, with several eruptions, including those of 2006 and 2008. We use a persistent scatterers approach ...to analyze a time series of Envisat synthetic aperture radar (SAR) data over the period 2003–2009, to investigate surface deformation in the region of the volcano. We measure a continuous large‐scale uplift with a maximum line of sight displacement rate of about 8 mm/yr, which is the first evidence of a sustained inflation in the Andes for an active volcano encompassing several eruptions. We model this signal as magma emplacement in a permanent storage zone at 11.5 km below sea level, with a net inflow rate of 7 million m3/yr. The paroxysmal eruptions in 2006 and 2008 did not seem to disrupt this long‐term signal. However, we observe significant deformation during the 2006 eruption consistent with an additional intrusion of 4.5 million m3 of magma.
Key Points
We use PS‐InSAR method to detect volcanic deformation at Tungurahua volcanoWe measure large‐scale and long‐term inflation at Tungurahua volcanoWe model the deformation and estimate magma emplacement and inflation rate
The Colombia–Ecuador subduction zone is an exceptional natural laboratory to study the seismic cycle associated with large and great subduction earthquakes. Since the great 1906 Mw = 8.6 ...Colombia–Ecuador earthquake, four large Mw > 7.5 megathrust earthquakes occurred within the 1906 rupture area, releasing altogether a cumulative seismic moment of ∼35% of the 1906 seismic moment. We take advantage of newly released seismic catalogs and global positioning system (GPS) data at the scale of the Colombia–Ecuador subduction zone to balance the moment deficit that is building up on the megathrust interface during the interseismic period with the seismic and aseismic moments released by transient slip episodes. Assuming a steady-state interseismic loading, we found that the seismic moment released by the 2016 Mw = 7.8 Pedernales earthquake is about half of the moment deficit buildup since 1942, suggesting that the Pedernales segment was mature to host that seismic event and its postseismic afterslip. In the aftermath of the 2016 event, the asperities that broke in 1958 and 1979 both appears to be mature to host a large Mw > 7.5 earthquakes if they break in two individual seismic events, or an Mw∼7.8–8.0 earthquake if they break simultaneously. The analysis of our interseismic-coupling map suggests that the great 1906 Colombia–Ecuador earthquake could have ruptured a segment of 400 km-long bounded by two 80 km wide creeping segments that coincide with the entrance into the subduction of the Carnegie ridge in Ecuador and the Yaquina Graben in Colombia. These creeping segments share similar frictional properties and may both behave as strong seismic barriers able to stop ruptures associated with great events like in 1906. Smaller creeping segments are imaged within the 1906 rupture area and are located at the extremities of the large 1942, 1958, 1979, and 2016 seismic ruptures. Finally, assuming that the frequency–magnitude distribution of megathrust seismicity follows the Gutenberg–Richter law and considering that 50% of the transient slip on the megathrust is aseismic, we found that the maximum magnitude subduction earthquake that can affect this subduction zone has a moment magnitude equivalent to Mw ∼8.8 with a recurrence time of 1,400 years. No similar magnitude event has yet been observed in that region.
We studied single neutral pion production via muon antineutrino charged-current interactions in plastic scintillator (CH) using the MINERvA detector exposed to the NuMI low-energy, wideband ...antineutrino beam at Fermilab. Measurement of this process constrains models of neutral pion production in nuclei, which is important because the neutral-current analog is a background for appearance oscillation experiments. Furthermore, the differential cross sections for π0 momentum and production angle, for events with a single observed π0 and no charged pions, are presented and compared to model predictions. These results comprise the first measurement of the π0 kinematics for this process.
ANTARES is a neutrino detector based on a three-dimensional grid of photomultipliers tubes (PMT's) arranged in several detection lines anchored to the seabed at depth of 2.5km in the Mediterranean ...Sea (40km off the Toulon coast in France), its main physics goal is the reconstruction and identification of high energy neutrinos of extra-terrestrial origin. The PMT's register the Cherenkov light induced by relativistic charged leptons produced by the interaction of neutrinos with material in the detector surroundings. The propagation of Cherenkov light strongly depends on the optical properties of the sea water, the understanding of which is crucial in order to achieve the expected detector performance. To reach the ANTARES physics goals, good time and positioning calibration systems are required.
The ANTARES optical beacon system consists of a set of pulsed light sources strategically located throughout the detector. The system is mainly used for time calibration but can also be used as a tool to study the water optical properties and their stability. In this contribution we will present the current status of our measurements of the group velocity and transmission length of light carried out between 2008 and 2011. A set of water models strategically defined will be discussed as well as some preliminary results concerning track reconstruction parameters.
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