1,929 research outputs found
Slow-Growing and Extended-Duration Seismicity Swarms: Reactivating Joints or Foliations in the Cahuilla Valley Pluton, Central Peninsular Ranges, Southern California
Three prolific earthquake swarms and numerous smaller ones have occurred since 1980 in the Mesozoic igneous plutonic rocks of the Perris block of the Peninsular Ranges, Southern California. The major swarms occurred in 1980ā1981, 1983ā1984, and 2016ā2018, with the latest swarm still ongoing. These swarms have no clear mainshock, with the largest events of M_L 3.6, M_L 3.7, and M_w 4.4. Each successive swarm had larger cumulative seismic moment release with about 314 and 411 events of M ā„ 1.5, while the third swarm has produced about 451 events of M ā„ 1.5 (as of September 2018). The concurrent strikeāslip faulting occurred on north to northwest striking planes but with no orthogonal northeast trending seismicity alignments. These shallow swarms are probably driven by intrablock PacificāNorth America plate boundary stress loading of the two bounding major late Quaternary strikeāslip faults, the Elsinore and San Jacinto faults. The state of stress within the Cahuilla Valley pluton has a ~40Ā° angle between the maximum principal stress and the average trend of the swarms, suggesting that migrating pore fluid pressures aid in the formation and growth of zones of weakness. These swarms, which last more than 600 days each, exhibit clear bilateral spatial migration for distances of up to ~7ā8 km and reach their full length in about 20 months. The slow spatialātemporal development of the swarms corresponds to a fluid diffusivity of 0.006 to 0.01 m2/s, consistent with very low permeability rocks as expected for this block. There is no geodetic or other evidence for a slow slip event driving the swarms
Izobraževati med veliko transformacijo: Odnosnost in transformativno trajnostno izobraževanje
During this shifting of historical epochs, the āusual ways of doing thingsā is catalysing existential questions about the survival of humanity. Yet, it is precisely these points of severe disruption where the creation of something more complex and life-giving can evolve. In this article, we explore how the dominant Separation Paradigm has created the current disruptive socio-natural conditions. Individuals and societies steeped within the Separation Paradigm are unwittingly destructive, because they do not perceive, and thus unintentionally sever, the incomprehensibly relational nature of our universe. We summarise the overarching dynamics of the Separation Paradigm and critique how existent learning processes, including sustainability education, are reproducing the Separation Paradigm. A salve to the diverse manifestations of Separation, we describe multiple sources of the Relationality Paradigm as well as implications for relational ways of knowing and being, through an interweaving of theoretical and personal vignettes. Finally, we sketch the implications of a possible worldview transformation for educators and processes of education, particularly within transformative sustainability education.Velikanski zgodovinski premiki, ki jih doživljamo v tem Äasu, pod vpraÅ”aj postavljajo Ā»obiÄajen naÄin, kako poÄnemo stvariĀ«, in vodijo do eksistencialnih vpraÅ”anj o preživetju ÄloveÅ”tva. Prav obdobja velikanskih sprememb pa so tista, v katerih se lahko razvije nekaj kompleksnega in življenjsko pomembnega. V Älanku raziskujemo, kako je dominantna loÄevalna paradigma ustvarila trenutne razdiralne okoliÅ”Äine v naravi in družbi. Posamezniki in družbe so potopljeni v loÄevalno paradigmo in poslediÄno destruktivni, saj se ne zavedajo relacijske, odnosne narave naÅ”ega sveta. Obravnavamo vseobsegajoÄo dinamiko loÄevalne paradigme in pri tem kritiÄno opredelimo, kako obstojeÄi uÄni procesi, tudi izobraževanje o trajnosti, to paradigmo vedno znova reproducirajo. Kot možno reÅ”itev predstavimo odnosno paradigmo, pa tudi implikacije odnosnih naÄinov spoznavanja in bivanja, s prepletanjem teorije in osebnih zgodb. Ob koncu zariÅ”emo možnost za svetovnonazorsko transformacijo na podroÄju izobraževanja, zlasti v okviru transformativnega trajnostnega izobraževanja
What children know about the source of their knowledge without reporting it as the source
We argue that, amongst 3- to 5- year-olds, failure to report the source of knowledge recently acquired in answer to āHow do you knowā¦?ā is due to a specific failure to make a causal inference, in line with source monitoring theory but not fuzzy trace theory. In three Experiments, children (N = 37; 30; 59) identified a hidden toy by seeing, feeling, or by being told, having had two modes of access on each trial, one informative (e.g. seeing a toy identified by colour) and the other uninformative (e.g. being told the toyās colour by the Experimenter who had only felt it). Children who answered the know question wrongly nevertheless reported accurately who saw and who felt the toy, and what the well-informed player had said. They also realised when
the Experimenterās uninformative access implied their own knowledge was unreliable, suggesting precocious working understanding of knowledge sources
3D fault architecture controls the dynamism of earthquake swarms
The vibrant evolutionary patterns made by earthquake swarms are incompatible with standard, effectively two-dimensional (2D) models for general fault architecture. We leverage advances in earthquake monitoring with a deep-learning algorithm to image a fault zone hosting a 4-year-long swarm in southern California. We infer that fluids are naturally injected into the fault zone from below and diffuse through strike-parallel channels while triggering earthquakes. A permeability barrier initially limits up-dip swarm migration but ultimately is circumvented. This enables fluid migration within a shallower section of the fault with fundamentally different mechanical properties. Our observations provide high-resolution constraints on the processes by which swarms initiate, grow, and arrest. These findings illustrate how swarm evolution is strongly controlled by 3D variations in fault architecture
3D fault architecture controls the dynamism of earthquake swarms
The vibrant evolutionary patterns made by earthquake swarms are incompatible with standard, effectively two-dimensional (2D) models for general fault architecture. We leverage advances in earthquake monitoring with a deep-learning algorithm to image a fault zone hosting a 4-year-long swarm in southern California. We infer that fluids are naturally injected into the fault zone from below and diffuse through strike-parallel channels while triggering earthquakes. A permeability barrier initially limits up-dip swarm migration but ultimately is circumvented. This enables fluid migration within a shallower section of the fault with fundamentally different mechanical properties. Our observations provide high-resolution constraints on the processes by which swarms initiate, grow, and arrest. These findings illustrate how swarm evolution is strongly controlled by 3D variations in fault architecture
Activation of optimally and unfavourably oriented faults in a uniform local stress field during the 2011 Prague, Oklahoma, sequence
The orientations of faults activated relative to the local principal stress directions can provide insights into the role of pore pressure changes in induced earthquake sequences. Here, we examine the 2011 Mā5.7 Prague earthquake sequence that was induced by nearby wastewater disposal. We estimate the local principal compressive stress direction near the rupture as inferred from shear wave splitting measurements at spatial resolutions as small as 750 m. We find that the dominant azimuth observed is parallel to previous estimates of the regional compressive stress with some secondary azimuths oriented subparallel to the strike of the major fault structures. From an extended catalogue, we map ten distinct fault segments activated during the sequence that exhibit a wide array of orientations. We assess whether the five near-vertical fault planes are optimally oriented to fail in the determined stress field. We find that only two of the fault planes, including the Māāā5.7 main shock fault, are optimally oriented. Both the Mā4.8 foreshock and Māāā4.8 aftershock occur on fault planes that deviate 20ā29Ā° from the optimal orientation for slip. Our results confirm that induced event sequences can occur on faults not optimally oriented for failure in the local stress field. The results suggest elevated pore fluid pressures likely induced failure along several of the faults activated in the 2011 Prague sequence
Robust calling performance in frogs infected by a deadly fungal pathogen
Reproduction is an energetically costly behavior for many organisms, including species with mating systems in which males call to attract females. In these species, calling males can often attract more females by displaying more often, with higher intensity, or at certain frequencies. Male frogs attract females almost exclusively by calling, and we know little about how pathogens, including the globally devastating fungus, Batrachochytrium dendrobatidis, influence calling effort and call traits. A previous study demonstrated that the nightly probability of calling by male treefrogs, Litoria rheocola, is elevated when they are in good body condition and are infected by B.Ā dendrobatidis. This suggests that infections may cause males to increase their present investment in mate attraction to compensate for potential decreases in future reproduction. However, if infection by B.Ā dendrobatidis decreases the attractiveness of their calls, infected males might experience decreased reproductive success despite increases in calling effort. We examined whether calls emitted by L.Ā rheocola infected by B.Ā dendrobatidis differed from those of uninfected individuals in duration, pulse rate, dominant frequency, call rate, or intercall interval, the attributes commonly linked to mate choice. We found no effects of fungal infection status or infection intensity on any call attribute. Our results indicate that infected males produce calls similar in all the qualities we measured to those of uninfected males. It is therefore likely that the calls of infected and uninfected males should be equally attractive to females. The increased nightly probability of calling previously demonstrated for infected males in good condition may therefore lead to greater reproductive success than that of uninfected males. This could reduce the effectiveness of natural selection for resistance to infection, but could increase the effectiveness of selection for infection tolerance, the ability to limit the harm caused by infection, such as reductions in body condition
Induced earthquake families reveal distinctive evolutionary patterns near disposal wells
The timing of events in seismic sequences can provide insights into the physical processes controlling fault slip. In southern Kansas, the rate of earthquakes rose rapidly starting in 2013 following expansion of energy production into the area, demanding the disposal of large volumes of wastewater into deep wells. Seismicity catalogs that are complete to low magnitudes can provide insights into the physical processes that induce seismicity near wastewater disposal. We develop a catalog of over 130,000 earthquakes recorded in southern Kansas from midāMarch 2014 through December 2017 by applying a matched filter algorithm to an original catalog of 5,831 template earthquakes. Detections have nearly identical waveforms to their associated template event and represent slip on nearly coālocated sections of a fault. We select template events with at least 100 associated detections and examine the characteristics of these prolific families of earthquakes. We find that families located close (<10 km) to areas with significant volumes of injected fluids have nearāPoissonian interevent times and the families remain active over longer durations. Families farther from highāvolume injection wells show strong clustering of interevent times and shorter sequence durations. We conclude that increasing pore fluid pressures from nearby disposal of large volumes of wastewater is the primary driver of these long duration episodes, with earthquakeāearthquake interactions driving sequences at greater distance from the wells
Slow-Growing and Extended-Duration Seismicity Swarms: Reactivating Joints or Foliations in the Cahuilla Valley Pluton, Central Peninsular Ranges, Southern California
Three prolific earthquake swarms and numerous smaller ones have occurred since 1980 in the Mesozoic igneous plutonic rocks of the Perris block of the Peninsular Ranges, Southern California. The major swarms occurred in 1980ā1981, 1983ā1984, and 2016ā2018, with the latest swarm still ongoing. These swarms have no clear mainshock, with the largest events of M_L 3.6, M_L 3.7, and M_w 4.4. Each successive swarm had larger cumulative seismic moment release with about 314 and 411 events of M ā„ 1.5, while the third swarm has produced about 451 events of M ā„ 1.5 (as of September 2018). The concurrent strikeāslip faulting occurred on north to northwest striking planes but with no orthogonal northeast trending seismicity alignments. These shallow swarms are probably driven by intrablock PacificāNorth America plate boundary stress loading of the two bounding major late Quaternary strikeāslip faults, the Elsinore and San Jacinto faults. The state of stress within the Cahuilla Valley pluton has a ~40Ā° angle between the maximum principal stress and the average trend of the swarms, suggesting that migrating pore fluid pressures aid in the formation and growth of zones of weakness. These swarms, which last more than 600 days each, exhibit clear bilateral spatial migration for distances of up to ~7ā8 km and reach their full length in about 20 months. The slow spatialātemporal development of the swarms corresponds to a fluid diffusivity of 0.006 to 0.01 m2/s, consistent with very low permeability rocks as expected for this block. There is no geodetic or other evidence for a slow slip event driving the swarms
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