Constrained Moment Tensors: Source Models and Case Studies

2018 ◽  
pp. 213-231 ◽  
Author(s):  
Jan Šílený
Keyword(s):  
Case Studies ◽  
Moment Tensors ◽  
Source Models

Dense surface seismic data confirm non-double-couple source mechanisms induced by hydraulic fracturing

Geophysics ◽  
2016 ◽  
Vol 81 (6) ◽  
pp. KS207-KS217 ◽  
Author(s):  
Jeremy D. Pesicek ◽  
Konrad Cieślik ◽  
Marc-André Lambert ◽  
Pedro Carrillo ◽  
Brad Birkelo
Keyword(s):  
Hydraulic Fracturing ◽  
Seismic Data ◽  
P Wave ◽  
Source Modeling ◽  
Moment Tensors ◽  
Amplitude Data ◽  
Double Couple ◽  
Source Mechanisms ◽  
Source Models ◽  
Favorable Conditions

We have determined source mechanisms for nine high-quality microseismic events induced during hydraulic fracturing of the Montney Shale in Canada. Seismic data were recorded using a dense regularly spaced grid of sensors at the surface. The design and geometry of the survey are such that the recorded P-wave amplitudes essentially map the upper focal hemisphere, allowing the source mechanism to be interpreted directly from the data. Given the inherent difficulties of computing reliable moment tensors (MTs) from high-frequency microseismic data, the surface amplitude and polarity maps provide important additional confirmation of the source mechanisms. This is especially critical when interpreting non-shear source processes, which are notoriously susceptible to artifacts due to incomplete or inaccurate source modeling. We have found that most of the nine events contain significant non-double-couple (DC) components, as evident in the surface amplitude data and the resulting MT models. Furthermore, we found that source models that are constrained to be purely shear do not explain the data for most events. Thus, even though non-DC components of MTs can often be attributed to modeling artifacts, we argue that they are required by the data in some cases, and can be reliably computed and confidently interpreted under favorable conditions.

scholarly journals Relations between pressurized triaxial cavities and moment tensor distributions

2015 ◽  
Vol 58 (4) ◽  
Author(s):  
Claudio Ferrari ◽  
Maurizio Bonafede ◽  
Elisa Trasatti
Keyword(s):  
Boundary Element ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Moment Tensor ◽  
Cavity Surface ◽  
Moment Tensors ◽  
Fortran Code ◽  
Source Models ◽  
The Moment ◽  
Tensor Distributions

Pressurized cavities are commonly used to compute ground deformation in volcanic areas: the set of available solutions is limited and in some cases the moment tensors inferred from inversion of geodetic data cannot be associated with any of the available models. Two different source models (pure tensile source, TS and mixed tensile/shear source, MS) are studied using a boundary element approach for rectangular dislocations buried in a homogeneous elastic medium employing a new C/C++ code which provides a new implementation of the dc3d Okada fortran code. Pressurized triaxial cavities are obtained assigning the overpressure in the middle of each boundary element distributed over the cavity surface. The MS model shows a moment domain very similar to triaxial ellipsoidal cavities. The TS and MS models are also compared in terms of the total volume increment limiting the analysis to cubic sources: the observed discrepancy (~10%) is interpreted in terms of the different deformation of the source interior which provides significantly different internal contributions (~30%). Comparing the MS model with a Mogi source with the some volume, the overpressure of the latter must be ~37% greater than the former, in order to obtain the same surface deformation; however the outward expansion and the inner contraction separately differ by ~±10% and the total volume increments differ only by ~2%. Thus, the density estimations for the intrusion extracted from the MS model and the Mogi model are nearly identical.

Open source disaster recovery: Case studies of networked collaboration

First Monday ◽  
2006 ◽  
Author(s):  
Calvert Jones ◽  
Sarai Mitnick
Keyword(s):  
Open Source ◽  
Hurricane Katrina ◽  
Case Studies ◽  
Disaster Recovery ◽  
East Asian ◽  
The South ◽  
Disaster Victims ◽  
The World ◽  
Source Models ◽  
State Actors

Volunteers eager to help disaster victims have begun to draw on open source models of organization to mobilize and coordinate vast resources from around the world. This paper investigates two such groundbreaking efforts, involving responses to Hurricane Katrina and to the South East Asian tsunami. The study sheds light on how these organizations evolve so rapidly, how leaders emerge and confront challenges, and how interactions with traditional, more hierarchical disaster recovery efforts unfold. Lessons from these early efforts show how they can be improved, and also point to the need for more research on networked non–state actors that are playing increasingly prominent roles.

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.

Ethics: The Use of Case Studies in Ethics Education

2003 ◽  
Vol 13 (2) ◽  
pp. 22-24
Author(s):  
Cheryl D. Gunter
Keyword(s):  
Case Studies ◽  
Ethics Education

Case Studies of Sentence Complement Training and False Belief Performance

2005 ◽  
Vol 32 (Spring) ◽  
pp. 43-52
Author(s):  
Carol A. Miller ◽  
Sandy E. Verrilli
Keyword(s):  
Case Studies ◽  
False Belief

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.

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