Matching Items (4)

Kartika: An Indo-American Journey

Description

This podcast explores the life of Cendraini, growing up in the developing country of Indonesia as well as her eventual immigration to America. It delves into prominent topics and history

This podcast explores the life of Cendraini, growing up in the developing country of Indonesia as well as her eventual immigration to America. It delves into prominent topics and history of Indonesia in regards to Cen's life. The podcast focuses on family, and how no matter the challenges that life may bring, family will be there for you.

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Created

Date Created
  • 2021-05

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Transitions in eruption style at silicic volcanoes: from stable domes to pyroclastic flows and explosive plumes

Description

Silicic volcanoes produce many styles of activity over a range of timescales. Eruptions vary from slow effusion of viscous lava over many years to violent explosions lasting several hours. Hazards

Silicic volcanoes produce many styles of activity over a range of timescales. Eruptions vary from slow effusion of viscous lava over many years to violent explosions lasting several hours. Hazards from these eruptions can be far-reaching and persistent, and are compounded by the dense populations often surrounding active volcanoes. I apply and develop satellite and ground-based remote sensing techniques to document eruptions at Merapi and Sinabung Volcanoes in Indonesia. I use numerical models of volcanic activity in combination with my observational data to describe the processes driving different eruption styles, including lava dome growth and collapse, lava flow emplacement, and transitions between effusive and explosive activity.

Both effusive and explosive eruptions have occurred recently at Merapi volcano. I use satellite thermal images to identify variations during the 2006 effusive eruption and a numerical model of magma ascent to explain the mechanisms that controlled those variations. I show that a nearby tectonic earthquake may have triggered the peak phase of the eruption by increasing the overpressure and bubble content of the magma and that the frequency of pyroclastic flows is correlated with eruption rate. In 2010, Merapi erupted explosively but also shifted between rapid dome-building and explosive phases. I explain these variations by the heterogeneous addition of CO2 to the melt from bedrock under conditions favorable to transitions between effusive and explosive styles.

At Sinabung, I use photogrammetry and satellite images to describe the emplacement of a viscous lava flow. I calculate the flow volume (0.1 km3) and average effusion rate (4.4 m3 s-1) and identify active regions of collapse and advance. Advance rate was controlled by the effusion rate and the flow’s yield strength. Pyroclastic flow activity was initially correlated to the decreasing flow advance rate, but was later affected by the underlying topography as the flow inflated and collapsed near the vent, leading to renewed pyroclastic flow activity.

This work describes previously poorly understood mechanisms of silicic lava emplacement, including multiple causes of pyroclastic flows, and improves the understanding, monitoring capability, and hazard assessment of silicic volcanic eruptions.

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Agent

Created

Date Created
  • 2016

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Neotectonics of Java, Indonesia: crustal deformation in the overriding plate of an orthogonal subduction system

Description

Shallow earthquakes in the upper part of the overriding plate of subduction zones can be devastating due to their proximity to population centers despite the smaller rupture extents than

Shallow earthquakes in the upper part of the overriding plate of subduction zones can be devastating due to their proximity to population centers despite the smaller rupture extents than commonly occur on subduction megathrusts that produce the largest earthquakes. Damaging effects can be greater in volcanic arcs like Java because ground shaking is amplified by surficial deposits of uncompacted volcaniclastic sediments. Identifying the upper-plate structures and their potential hazards is key for minimizing the dangers they pose. In particular, the knowledge of the regional stress field and deformation pattern in this region will help us to better understand how subduction and collision affects deformation in this part of the overriding plate. The majority of the upper plate deformation studies have been focused on the deformation in the main thrusts of the fore-arc region. Study of deformation within volcanic arc is limited despite the associated earthquake hazards. In this study, I use maps of active upper-plate structures, earthquake moment tensor data and stress orientation deduced from volcano morphology analysis to characterize the strain field of Java arc. In addition, I use sandbox analog modeling to evaluate the mechanical factors that may be important in controlling deformation. My field- and remotely-based mapping of active faults and folds, supplemented by results from my paleoseismic studies and physical models of the system, suggest that Java’s deformation is distributed over broad areas along small-scale structures. Java is segmented into three main zones based on their distinctive structural patterns and stress orientation. East Java is characterized by NW-SE normal and strike-slip faults, Central Java has E-W folds and thrust faults, and NE-SW strike-slip faults dominate West Java. The sandbox analog models indicate that the strain in response to collision is partitioned into thrusting and strike-slip faulting, with the dominance of margin-normal thrust faulting. My models test the effects of convergence obliquity, geometry, preexisting weaknesses, asperities, and lateral strength contrast. The result suggest that slight variations in convergence obliquity do not affect the deformation pattern significantly, while the margin shape, lateral strength contrast, and perturbation of deformation from asperities each have a greater impact on deformation.

Contributors

Agent

Created

Date Created
  • 2016

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Faith, moral authority, and politics: the making of progressive Islam in Indonesia

Description

Several Islamic organizations have experience major changes in their theological frames and political identities away from fundamentalist and revivalist theological orientation to one that embraces a progressive Islamic theology that

Several Islamic organizations have experience major changes in their theological frames and political identities away from fundamentalist and revivalist theological orientation to one that embraces a progressive Islamic theology that synthesizes these norms with classical Islamic teachings. What are the factors that explain these theological changes? What are the causal mechanisms that help to promote them? Using the moral authority leadership theory, I argue that Islamic groups would be able to change their theological frames and political identities if the changes are promoted by religious leaders with 'moral authority' status, who are using both ideational and instrumental strategies to reconstruct the theological frames of their organizations. In addition to moral authority leadership, intermediary variables that also affect the likelihood of a theological change within Islamic groups are the institutional culture of the organization - the degree of tolerance for non-Islamic theological teachings - and the relationship between the Islamic group and the state. This study is a comparative historical analysis of two Indonesian Islamic groups: the Nahdlatul Ulama (NU) and the Muhammadiyah. It finds that the NU was able to successfully change its theological positions due to the presence of a charismatic moral authority leader, the tolerant institutional culture within the organization, and the ability of the organization to ally with the Suharto regime, allowing the reform to be institutionalized with little intervention from the regime. On the other hand, theological reform within the Muhammadiyah was not successful due to the lack of a leader with moral authority status who could have led the reforms within the organization, as well as to the dominance of a revivalist institutional culture that does not tolerate any challenges to their interpretation of Islamic theology. The analysis makes theoretical contributions on the role of religious leadership within Islamic movements and the likelihood of Islamic groups to adopt liberal political norms such as democracy, religion-state separation, and tolerance toward religious minorities. It identifies the mechanisms in which theological change within Islamic group become possible.

Contributors

Agent

Created

Date Created
  • 2012