scholarly journals Throw-rate variations within linkage zones during the growth of normal faults: Case studies from the Western Volcanic Zone, Iceland

2020 ◽  
Vol 133 ◽  
pp. 103976
Author(s):  
Francesco Iezzi ◽  
Gerald Roberts ◽  
Joanna Faure Walker
Keyword(s):  
Case Studies ◽  
Normal Faults ◽  
Volcanic Zone ◽  
Linkage Zones

Unravelling rift development: a key study from the Northern Volcanic Zone of Iceland

2020 ◽  
Author(s):  
Elena Russo ◽  
Alessandro Tibaldi ◽  
Fabio Luca Bonali ◽  
Federico Pasquarè Mariotto ◽  
Páll Einarsson ◽  
...  
Keyword(s):  
Normal Faults ◽  
Volcanic Zone ◽  
The North ◽  
Rift Propagation ◽  
Extensive Field ◽  
Northern Volcanic Zone ◽  
Regional Tectonic ◽  
Aerial Vehicle ◽  
Mid Atlantic Ridge ◽  
Plate Separation

<p>Unravelling the kinematics, development and origin of the structures along a volcano-tectonic rift is of paramount importance for understanding plate separation, seismicity, volcanic activity and the associated hazards. Here, we focus on an extremely detailed survey of the Holocene deformation field along the Northern Volcanic Zone of Iceland, the northernmost point of emergence of the Mid-Atlantic Ridge. The study of this extremely dynamic rift is also useful for a better comprehension of how mid-oceanic ridges work. The study is based on extensive field and unmanned aerial vehicle surveys performed over the last four years, completed by about 6000 measures collected at 1633 sites on fault strike, dip and offset, and fracture strike, dip, dilation direction and dilation amount. The rift, named Theistareykir Fissure Swarm, is composed of N-S to NNE-SSW-striking normal faults and extension fractures affecting an area 8 km-wide and 34 km-long. The computed overall spreading direction is N111° averaged during Holocene times, with values of N125° to the north and N106° to the south. The kinematics is characterised by the presence of complex components of right-lateral and left-lateral strike-slip motions, with a strong predominance of right-lateral components along structures parallel and coeval to the rift zone. The surveyed 33 Holocene faults (696 sites of measurement) along the central part of the rift show two opposite directions of fault/rift propagation, based on fault slip profile analyses. We discuss the possible causes of these characteristics and analyse in detail the interaction of both faults and extension fractures with the WNW-ESE transform Tjornes Fracture Zone, and in particular with the parallel right-lateral Husavik-Flatey Fault in the central part of the rift, and the Grimsey Lineament to the north. We also assess the role of: i) repeated dyke intrusions from the magma chamber outward along the plate margin, ii) regional tectonic stresses, iii) mechanical interaction of faults, and iv) changes in the rheological characteristics of rocks.</p>

Advances in field data collection in volcano-tectonic sensitive areas: examples and results from the Northern Volcanic Zone of Iceland

2020 ◽  
Author(s):  
Fabio Luca Bonali ◽  
Alessandro Tibaldi ◽  
Federico Pasquaré Mariotto ◽  
Elena Russo ◽  
Noemi Corti
Keyword(s):  
Data Collection ◽  
Classical Field ◽  
Complete Picture ◽  
Tectonic Activity ◽  
Normal Faults ◽  
Volcanic Zone ◽  
Innovative Method ◽  
Fissure Swarm ◽  
Field Activity ◽  
Northern Volcanic Zone

<p>Classical field studies are vital for mapping and understanding volcano-tectonic processes, particularly for those that produce superficial deformation consequently to magmatic and tectonic activity. Unfortunately, very often, key outcrops are inaccessible due to harsh logistic conditions or their location in remote or dangerous areas. In the framework of the ILP Task Force II, we developed and tested modern and innovative methods aimed at overcoming these limitations in field research and data collection, that we combined with classical field mapping. Such methods have been used to provide a more complete picture of the deformation processes that have been taking place in the Theistareykir Fissure Swarm within the Northern Volcanic Zone of Iceland. This rift is characterized by the presence of huge normal faults, several extension fractures and volcanic centres. The modern methods we used derive from the use of UAVs (drones) combined with Structure from Motion (SfM) photogrammetry techniques. The first innovative method consists of analysing UAV-based SfM-derived high resolution orthomosaics and digital surface models where we collected hundreds of quantitative measurements of the amount of opening and opening direction of Holocene extension fractures and measurements of fault scarp height. The second and more innovative method we used is the Immersive Virtual Reality that can be applied to 3D digital outcrop models (DOMs), reconstructed with UAV-based SfM photogrammetry techniques; several sites within the Theistareykir Fissure Swarm have been reconstructed in the framework of the Italian Argo3D project. The reconstructed 3D DOMs were explored using different modalities: on foot, as is often the case during field activity, moving like a drone, above and around the target, as well as flying like an airplane. Thanks to these modes of exploration we were capable of better understanding the geometry of extension fractures, volcanic centres and normal faults. We also measured, in the virtual environment, the opening direction and the amount of dilation along the extensional fractures, the direction of magma-feeding fractures underlying cones and volcanic vents, as well as the amount of vertical offset along normal faults. The quantification and mapping of these features was accomplished through some tools tailored for virtual field activity in the framework of Italian Argo3D project and the Erasmus+ Key Action 2 2017-1-UK01-KA203-036719. Thanks to the merging of classical and modern approaches we are able of providing a complete picture related to the post-LGM deformation field affecting this part of the Icelandic rift, particularly focusing on the spreading direction and the stretch ratio across the whole Theistareykir Fissure Swarm.</p>

scholarly journals Velocity Modelling and Earthquake Relocation in  the Rotorua and Kawerau Geothermal Areas,  Taupo Volcanic Zone, New Zealand

2021 ◽  
Author(s):  
◽  
Daniel Clarke
Keyword(s):  
New Zealand ◽  
Cross Correlation ◽  
Seismic Velocity ◽  
Taupo Volcanic Zone ◽  
Normal Faults ◽  
Geothermal Systems ◽  
Time Data ◽  
Volcanic Zone ◽  
Arrival Times ◽  
Velocity Models

<p>We analyse catalogued phase arrival times and seismograms from two sets of earthquakes that occurred in and around the Rotorua and Kawerau geothermal systems in the Taupo Volcanic Zone, New Zealand. These data sets contain 504 and 1875 shallow (less than or equal to 20 km deep) earthquakes, respectively, and span the 21 year period between the beginning of 1984 and the end of 2004. We use arrival time data from these earthquakes to calculate reliable 1-D P- and S-wave seismic velocity models and accompanying station correction terms for Rotorua and Kawerau. These models are well constrained at depths of 4 to 15 km and are consistent with models obtained in seismic refraction studies for the same region. Using a combination of precise cross-correlation-derived and cataloguebased arrival times, we calculate accurate hypocentres for 155 and 400 earthquakes in Rotorua and Kawerau, respectively. These hypocentres are far less scattered than those in the earthquake catalogue. In Rotorua, the earthquakes cluster near the geothermally active parts of Rotorua City and also beneath the Mount Ngongotaha rhyolite dome. In Kawerau, the earthquakes align along northeast-trending lineations, consistent with the predominant alignment of faults within the region. Earthquakes in Okataina caldera to the southwest of Kawerau are tightly clustered, particularly beneath Puhipuhi Hill. We use cross-correlation to identify clusters of earthquakes in Rotorua and Kawerau based on the similarity of their recorded seismograms. Apart from two clusters in the northern part of Rotorua City, these are generally indicative of relatively short-lived bursts of activity within these regions. We compute composite focal mechanisms for four of these clusters, all of which indicate rupture on normal faults, consistent with the extensional tectonic regime of the Taupo Volcanic Zone.</p>

scholarly journals Velocity Modelling and Earthquake Relocation in  the Rotorua and Kawerau Geothermal Areas,  Taupo Volcanic Zone, New Zealand

2021 ◽  
Author(s):  
◽  
Daniel Clarke
Keyword(s):  
New Zealand ◽  
Cross Correlation ◽  
Seismic Velocity ◽  
Taupo Volcanic Zone ◽  
Normal Faults ◽  
Geothermal Systems ◽  
Time Data ◽  
Volcanic Zone ◽  
Arrival Times ◽  
Velocity Models

<p>We analyse catalogued phase arrival times and seismograms from two sets of earthquakes that occurred in and around the Rotorua and Kawerau geothermal systems in the Taupo Volcanic Zone, New Zealand. These data sets contain 504 and 1875 shallow (less than or equal to 20 km deep) earthquakes, respectively, and span the 21 year period between the beginning of 1984 and the end of 2004. We use arrival time data from these earthquakes to calculate reliable 1-D P- and S-wave seismic velocity models and accompanying station correction terms for Rotorua and Kawerau. These models are well constrained at depths of 4 to 15 km and are consistent with models obtained in seismic refraction studies for the same region. Using a combination of precise cross-correlation-derived and cataloguebased arrival times, we calculate accurate hypocentres for 155 and 400 earthquakes in Rotorua and Kawerau, respectively. These hypocentres are far less scattered than those in the earthquake catalogue. In Rotorua, the earthquakes cluster near the geothermally active parts of Rotorua City and also beneath the Mount Ngongotaha rhyolite dome. In Kawerau, the earthquakes align along northeast-trending lineations, consistent with the predominant alignment of faults within the region. Earthquakes in Okataina caldera to the southwest of Kawerau are tightly clustered, particularly beneath Puhipuhi Hill. We use cross-correlation to identify clusters of earthquakes in Rotorua and Kawerau based on the similarity of their recorded seismograms. Apart from two clusters in the northern part of Rotorua City, these are generally indicative of relatively short-lived bursts of activity within these regions. We compute composite focal mechanisms for four of these clusters, all of which indicate rupture on normal faults, consistent with the extensional tectonic regime of the Taupo Volcanic Zone.</p>

Corporate Sustainability: Challenge to Managerial Orthodoxies

2003 ◽  
Vol 9 (1) ◽  
pp. 2-11 ◽  
Author(s):  
Dexter Dunphy
Keyword(s):  
Case Studies ◽  
Corporate Sustainability ◽  
Central Place ◽  
Marked Contrast ◽  
Sustainability Management

ABSTRACTThis paper addresses the issue of corporate sustainability. It examines why achieving sustainability is becoming an increasingly vital issue for society and organisations, defines sustainability and then outlines a set of phases through which organisations can move to achieve increasing levels of sustainability. Case studies are presented of organisations at various phases indicating the benefits, for the organisation and its stakeholders, which can be made at each phase. Finally the paper argues that there is a marked contrast between the two competing philosophies of neo-conservatism (economic rationalism) and the emerging philosophy of sustainability. Management schools have been strongly influenced by economic rationalism, which underpins the traditional orthodoxies presented in such schools. Sustainability represents an urgent challenge for management schools to rethink these traditional orthodoxies and give sustainability a central place in the curriculum.

Short-Form Application of the Screening Test of Spanish Grammar and the Northwestern Syntax Screening Test to Latino Children

1978 ◽  
Vol 9 (4) ◽  
pp. 220-235
Author(s):  
David L. Ratusnik ◽  
Carol Melnick Ratusnik ◽  
Karen Sattinger
Keyword(s):  
New York ◽  
Case Studies ◽  
Metropolitan Area ◽  
Screening Test ◽  
Normative Data ◽  
Short Form ◽  
Latino Children ◽  
Data Application ◽  
York Metropolitan Area ◽  
Multiple Regression Technique

Short-form versions of the Screening Test of Spanish Grammar (Toronto, 1973) and the Northwestern Syntax Screening Test (Lee, 1971) were devised for use with bilingual Latino children while preserving the original normative data. Application of a multiple regression technique to data collected on 60 lower social status Latino children (four years and six months to seven years and one month) from Spanish Harlem and Yonkers, New York, yielded a small but powerful set of predictor items from the Spanish and English tests. Clinicians may make rapid and accurate predictions of STSG or NSST total screening scores from administration of substantially shortened versions of the instruments. Case studies of Latino children from Chicago and Miami serve to cross-validate the procedure outside the New York metropolitan area.

Case Studies for Telepractice in AAC

2014 ◽  
Vol 23 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Tanya Rose Curtis
Keyword(s):  
Service Delivery ◽  
Case Studies ◽  
Eye Gaze ◽  
Cognitive Impairments ◽  
Perceived Barriers ◽  
Computer Experience ◽  
Access Methods ◽  
Complex Communication Needs ◽  
Barriers To Service ◽  
Communication Needs

As the field of telepractice grows, perceived barriers to service delivery must be anticipated and addressed in order to provide appropriate service delivery to individuals who will benefit from this model. When applying telepractice to the field of AAC, additional barriers are encountered when clients with complex communication needs are unable to speak, often present with severe quadriplegia and are unable to position themselves or access the computer independently, and/or may have cognitive impairments and limited computer experience. Some access methods, such as eye gaze, can also present technological challenges in the telepractice environment. These barriers can be overcome, and telepractice is not only practical and effective, but often a preferred means of service delivery for persons with complex communication needs.

What Makes for Effective Online Treatment?

ASHA Leader ◽  
2013 ◽  
Vol 18 (1) ◽  
pp. 12-13
Author(s):  
Kristen Chmela
Keyword(s):  
Case Studies ◽  
Executive Director ◽  
Fluency Disorders ◽  
Online Treatment

In November, Kristen Chmela—executive director of the Chmela Fluency Center in Long Grove, Ill.—chatted with participants from ASHA’s online conference, Case Studies in Fluency Disorders. The Leader listened in.

Sign in / Sign up

Export Citation Format

Share Document