13 resultados para strike-slip fault

em Digital Commons - Michigan Tech


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Understanding the geometry and kinematics of the major structures of an orogen is important to elucidate its style of deformation, as well as its tectonic evolution. We describe the temporal and spatial changes in the state of stress of the trans-orogen area of the Calama-Olacapato-El Toro (COT) Fault Zone in the Central Andes, at about 24°S within the northern portion of the Puna Plateau between the Argentina-Chile border. The importance of the COT derives principally from the Quaternary-Holocene activity recognized on some segments, which may shed new light on its possible control on Quaternary volcanism and on the seismic hazard evaluation of the area. Field geological surveys along with kinematic analysis and numerical inversion of ∼140 new fault-slip measurements have revealed that this portion of the COT zone, previously considered a continuous, long-lived lineament, in reality has been subjected to three different kinematic regimes: 1) a Miocene transpressional phase with the maximum principal stress (σ1) chiefly trending NNE-SSW; 2) an extensional phase that started by 9 Ma, with a horizontal NW-SE-striking minimum principal stress (σ3) – permutations between σ2 and σ3 axes have been recognized at two sites – and 3) a left-lateral strike-slip phase with a horizontal ∼E-W &sigma1 and ∼N-S σ3 dating to the Late Pliocene-Quaternary. Spatially, in the Quaternary, the left-lateral component decreases toward the westernmost tip of the COT, where it transitions to extension; this produced to a N-S horst and graben structure. Hence, even if transcurrence is still active in the eastern portion of the COT, as focal mechanisms of crustal earthquakes indicate, our study demonstrates that extension is becoming the predominant structural style of deformation, at least in the western region. These major temporal and spatial changes in the tectonic regimes are attributed in part to changes in the magnitude of the boundary forces due to subduction processes. The overall orogen-perpendicular extension might be the result of vertical stress larger than both the horizontal stresses induced by gravitational effect of a thickened crust.

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Within the Yellowstone National Park, Wyoming, the silicic Yellowstone volcanic field is one of the most active volcanic systems all over the world. Although the last rhyolite eruption occurred around 70,000 years ago, Yellowstone is still believed to be volcanically active, due to high hydrothermal and seismic activity. The earthquake data used in this study cover the period of time between 1988 and 2010. Earthquake relocations and a set of 369 well-constrained, double-couple, focal mechanism solutions were computed. Events were grouped according to location and time to investigate trends in faulting. The majority of the events has oblique, normal-faulting solutions. The overall direction of extension throughout the 0.64 Ma Yellowstone caldera looks nearly ENE, consistently with the direction of alignments of volcanic vents within the caldera, but detailed study revealed spatial and temporal variations. Stress-field solutions for different areas and time periods were calculated from earthquake focal mechanism inversion. A well-resolved rotation of σ3 was found, from NNE-SSW near the Hebgen Lake fault zone, to ENE-WSW near Norris Junction. In particular, the σ3 direction changed throughout the years in the Norris Junction area, from being ENE-WSW, as calculated in the study by Waite and Smith (2004), to NNE-SSW, while the other σ3 directions are mostly unchanged over time. The Yellowstone caldera was subject to periods of net uplift and subsidence over the past century, explained in previous studies as caused by expanding or contracting sills, at different depths. Based on the models used to explain these deformation periods, we investigated the relationship between variability in aseismic deformation and seismic activity and faulting styles. Focal mechanisms and P and T axes were divided into temporal and depth intervals, in order to identify spatial or temporal trends in deformation. The presence of “chocolate tablet” structures, with composite dilational faults, was identified in many stages of the deformation history both in the Norris Geyser Basin area and inside the caldera. Strike-slip component movement was found in a depth interval below a contracting sill, indicating the movement of magma towards the caldera.

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Tumult and Tragedy: Michigan’s 1913-14 Copper Strike chronicles one of the greatest upheavals in Michigan’s history. The determination, conflict, sorrow, and tragedy of this epic confrontation changed the Copper Country for decades and memories of conflict remain to this day. This traveling exhibit explores the story of this remarkable period in Michigan history.

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Tumult and Tragedy: Michigan’s 1913-14 Copper Strike chronicles one of the greatest upheavals in Michigan’s history. The determination, conflict, sorrow, and tragedy of this epic confrontation changed the Copper Country for decades and memories of conflict remain to this day. This traveling exhibit explores the story of this remarkable period in Michigan history.

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Tumult and Tragedy: Michigan’s 1913-14 Copper Strike chronicles one of the greatest upheavals in Michigan’s history. The determination, conflict, sorrow, and tragedy of this epic confrontation changed the Copper Country for decades and memories of conflict remain to this day. This traveling exhibit explores the story of this remarkable period in Michigan history.

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The purpose of this study is to take a closer look at media response in Finland concerning the 1913-14 Michigan Copper Strike and depict how the strike was presented in the Old Country and its main newspapers. I shall take a closer look at the 1913-14 issues of Työmies (social democrat), Helsingin Sanomat (liberal), and Uusi Suometar (conservative) for ideological views of the strike. Furthermore, and in terms of close reading and cross-referencing, how did these newspapers in Finland see the strike and the strike’s outcome? Editorial notes and letters from the public shall both be included. Special attention will be given to the notions of transnational solidarity between Finnish-American and Finnish labor activists.

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Labor Historian Marc Karson has singled out “labor priest” Peter E. Dietz as one of the strongest proponents for the active implementation of the Catholic Church’s 1890’s labor encyclical Rerum Novarum in the daily practice of American Catholics. Biographer Sister Mary Harrita Fox pointed out that in his work, Dietz “was particularly concerned over the role of the church in the copper strike in Upper Michigan.” This “particular concern” should be noted since the 1913 strike was one of the only disputes where Dietz went out of his way to visit and become actively involved. Why the keen interest? This presentation will review the impetus for the huge effort which brought Peter E. Dietz to the Copper Country and solely to that dispute alone, the resulting visit and report that he made concerning the strike, the important role he believed this visit and stance in the Copper Strike had in the future of the Church’s relationship to the US labor movement. The presentation will look at both what Dietz thought would occur as a result of his 1913 trip to the Keweenaw and what actually happened in this pivotal pre-World War One era event. The paper will put Father Peter E. Dietz and the Catholic Church into the larger frame of how religion has been viewed within the history of the Strike.

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In the Iron Range Strike of 1916, working-class wives picketed alongside their husbands in a conflict-ridden and dangerous setting. Mine deputies abused immigrant women on the picket lines and in their homes, with several disquieting reports receiving statewide attention in Minnesota. Many middle-class reformers in the Twin Cities grew sympathetic to the plight of northern mining families and became controversially involved the labor struggle. Some middleclass women worked alongside working-class wives and radical organizers from the Industrial Workers of the World (IWW). At the center of this gendered analysis is the cross-class cooperation between an upper-middle class woman, Lenora Austin Hamlin, a radical reformer, Elizabeth Gurley Flynn, and the story of a working-class housewife, Mikla Masonovich. This study will ask how authentic, prevalent, and unproblematic their stories of cross-class cohesive action actually were. In answering this, it will address and identify those factors that impeded women’s potential for unity. “Flash in the Pan” argues that as a result of both real and perceived differences, these networks of women remained isolated, inhibiting each from gaining sufficient power to work cohesively, and marginalizing their influence. Drawing upon a variety of sources, including media representations in newspapers, and archives of social, labor and women’s organizations, this regional study lends state-level insight into the larger gender-labor historiography.

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In the autumn of 1913, a small, remote Michigan mining community attracted national attention as miners and management found themselves embroiled in a conflict that would prove no easy victory for either side. The strike came as a shock to management, who, with the help of a nearly perfected paternal system, had come to expect a generally docile and compliant workforce. But what was even more shocking was the involvement of the miners’ wives in the strike effort, and the lengths they went to in order to keep men from crossing the picket line. This paper focuses on that effort, arguing that the women of the Michigan copper country developed strike strategies that were derived from their domestic experience, and justified their involvement through maternal arguments. However, these public actions allowed the management to disregard the respect and courtesy generally given to the domestic sphere as police and private agents perpetrated a number of home invasions in an attempt to break the strike. The involvement of women in male dominated labor disputes (mining, steel productions) has been largely ignored in the literature due to their indirect connection to the company as wives and not workers. This paper seeks to remedy this gap, and gain a better understanding of that indirect relationship. Sources include newspaper articles, private correspondence, public investigation records, and oral histories, found largely in the Michigan Tech Archives and Copper Country Historical Collections, Michigan Technological University, Michigan.

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In May of 1968, workers at the Kingston mine, a branch of the Calumet Division of Universal Oil Products walked off the site in protest of a safety issue involving a man-car. Knowing their contracts were due for negotiation in just a few months, the workers quickly returned, only to find themselves striking yet again just three months later, when negotiations failed. Requesting pay equal to that of the workers at the nearby White Pine mine was unacceptable to the heads of Universal Oil, the corporation which bought the long running Calumet & Hecla just a year earlier in 1968. The strike would last for nine months, ending in a total shutdown of all mining operations on the Keweenaw Peninsula, and bring an economic hardship to the area that would take decades to recover from. The Copper Strike of 1968-1969 is often forgotten, though extremely important to the story of the copper industry in Michigan, as well as to the United States. This paper has not yet been submitted.

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The 1913-14 Michigan copper strike is unlike many American labor actions of the period in that it did not include red flags or socialist anthems. Many of the most familiar photographs of the strike involve American flags, not red ones. Similarly, the songs mentioned in journalistic accounts of the strikers are American Civil War songs, not popular labor songs of the period. The few newly-written songs about the strike, published in the local newspapers, seem cautiously polite and espouse values such as patriotism, liberty and human rights. During a time when sections of the "friendly" press were concerned with labor presenting the correct image and avoiding unfavorable associations, the Copper Country strikers, and the W.F.M., seem to have been attempting to create a fresh narrative regarding what this strike was (and what it was not). This paper will consider elements of the Copper Country strike in the light of media coverage, prior to July 1913, of several American labor topics that might have influenced the way the strike was presented. Particular attention will be given to photographs, songs, and accounts from the 1912 Lawrence textile strike, as well as contemporaneous critiques of labor song lyrics. Most of this commentary will be drawn from the labor and socialist press, demonstrating that the 1913-14 Michigan copper strike occurred during a period in which the labor movement was struggling to craft and image that would display it as it wished to be seen. This paper has not yet been submitted.

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New volumetric and mass flux estimates have been calculated for the Kenya Rift. Spatial and temporal histories for volcanic eruptions, lacustrine deposition, and hominin fossil sites are presented, aided by the compilation of a new digital geologic map. Distribution of volcanism over time indicates several periods of southward expansion followed by relative positional stasis. Volcanism occurs throughout the activated rift length, with no obvious abandonment as the rift system migrated. The main exception is a period of volcanic concentration around 10 Ma, when activity was constrained within 2° of the equator. Volumes derived from seismic data indicate a total volume of c. 310,000 km3 (2.47 x 1010 kg/yr ), which is significantly more than the map-derived volumes found here or published previously. Map-based estimates are likely affected by a bias against recognizing small volume events in the older record. Such events are, however, the main driver of erupted volume over the last 5 Ma. A technique developed here to counter this bias results in convergence of the two volume estimation techniques. Relative erupted composition over time is variable. Overall, the erupted material has a mafic to silicic ratio of 0.9:1. Basalts are distinctly more common in the Turkana region, which previously experienced Mesozoic rifting. Despite the near equal ratio of mafic to silicic products, the Kenya Rift otherwise fits the definition of a SLIP. It is proposed that the compositions would better fit the published definition if the Turkana region was not twice-rifted. Lacustrine sedimentation post-dates initial volcanism by about 5 million years, and follows the same volcanic trends, showing south and eastward migration over time. This sedimentation delay is likely related to timing of fault displacements. Evidence of hominin habitation is distinctly abundant in the northern and southern sections of the Kenya Rift, but there is an observed gap in the equatorial rift between 4 and 0.5 million years ago. After 0.5 Ma, sites appear to progress towards the equator. The pattern and timing of hominid site distributions suggests that the equatorial gap in habitation may be the result of active volcanic avoidance.

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Rooted in critical scholarship this dissertation is an interdisciplinary study, which contends that having a history is a basic human right. Advocating a newly conceived and termed, Solidarity-inspired History framework/practice perspective, the dissertation argues for and then delivers a restorative voice to working-class historical actors during the 1916 Minnesota Iron Ore Strike. Utilizing an interdisciplinary methodological framework the dissertation combines research methods from the Humanities and the Social Sciences to form a working-class history that is a corrective to standardized studies of labor in the late 19th and early 20th centuries. Oftentimes class interests and power relationships determine the dominant perspectives or voices established in history and disregard people and organizations that run counter to, or in the face of, customary or traditional American themes of patriotism, the Protestant work ethic, adherence to capitalist dogma, or United States exceptionalism. This dissertation counteracts these traditional narratives with a unique, perhaps even revolutionary, examination of the 1916 Minnesota Iron Ore Strike. The intention of this dissertation's critical perspective is to poke, prod, and prompt academics, historians, and the general public to rethink, and then think again, about the place of those who have been dislocated from or altogether forgotten, misplaced, or underrepresented in the historical record. Thus, the purpose of the dissertation is to give voice to historical actors in the dismembered past. Historical actors who have run counter to traditional American narratives often have their body of "evidence" disjointed or completely dislocated from the story of our nation. This type of disremembering creates an artificial recollection of our collective past, which de-articulates past struggles from contemporary groups seeking solidarity and social justice in the present. Class-conscious actors, immigrants, women, the GLBTQ community, and people of color have the right to be remembered on their own terms using primary sources and resources they produced. Therefore, similar to the Wobblies industrial union and its rank-and-file, this dissertation seeks to fan the flames of discontented historical memory by offering a working-class perspective of the 1916 Strike that seeks to interpret the actions, events, people, and places of the strike anew, thus restoring the voices of these marginalized historical actors.