An Integrated Approach to Seismic Event Location: 1. Evaluating How Method of Location Affects the Volume of Groups of Hypocenters

When seismic events occur in spatially compact clusters, the volume and geometric characteristics of these clusters often provides information about the relative effectiveness of different location methods, or about physical processes occurring within the hypocentral region. This report defines and explains how to determine the convex polyhedron of minimum volume (CPMV) surrounding a set of points. We evaluate both single-event and joint hypocenter determination (JHD) relocations for three rather different clusters of seismic events: 1) nuclear explosions from Mururoa relocated using P and PKP phases reported by the ISC, 2) intermediate depth earthquakes near Bucaramanga, Colombia, relocated using P and PKP phases reported by the ISC, and 3) shallow earthquakes near Vanuatu (formerly, the New Hebrides), relocated using P and S phases from a local station network. This analysis demonstrates that different location methods markedly affect the volume of the CPMV, however, volumes for JHD relations are �not always smaller than volumes for single-event relocations.Phillips Laboratory, Directorate of Geophysics, Air Force Material Command, Hanscom Air Force Base, MassachusettsInstitute for Geophysic

Cliff's Nodes Concerning Plotting Nodal Lines for P, Sh, and Sv

The purpose of this technical report is to provide background� information for a Fortran program package CliffsNodes.PShSv for plotting focal mechanisms and nodal lines.Institute for Geophysic

Croatian Regional Strategy in the Framework of the EU Accession Process

A limitation on the implementation of modern regional policy in Croatia is the inherited doctrine of the reconstruction of war affected areas. This doctrine is no longer appropriate to the needs of new regional policy, which must be formulated in the context of EU accession. This is especially important considering that the EU emphasizes that member states must be in a position to withstand competitive pressures in the single market as a key condition for accession. In this context, regional policy will be closely tied into the accession strategy. A major objective will be to prepare for the introduction of EU cohesion policy and the Structural Funds. The pre-accession funds will contribute to that effort. The situation in Croatia today is that while “balanced regional development†is one of seven key government priorities, there is no clear definition of what this means. There is a fragmented listing of regions deemed to have special problems without, on the face of it, any coherent profile of those development needs. The National Strategy for Regional Development will seek to address these issues. The implications, therefore, for approach to the analysis of regional policy in Croatia today is that we concentrate essentially upon three main fields of enquiry from two perspectives – top-down and bottom-up. These are: • Assessment of the overall policy framework for regional development, including the current legal framework in particular policies, legal acts and regulations which affect the development of those parts of the country which can be loosely termed “assisted areasâ€. • Assessment of the institutional and administrative capacity in place. • Appraisal of the types of regional development instruments currently deployed and their effectiveness in dealing with development needs at national, regional and local level. The strategy sets the context for balanced regional development both at national and sub-national level as well as draws attention to development needs of the ‘assisted areas’ as well as counties highlighting their different development profiles. It brings together the main analytical parts – policy framework, institutional context and finally an assessment of the existing development interventions. This is followed by a SWOT analysis before moving to a set of conclusions and next steps which will frame the strategic rationale behind the strategy. The paper is linked to the project Strategy and Capacity Building for Regional Development (CARDS 2002 Programme for Croatia): Analysis Section for Strategy.

Conformal Field Theory and Geometry of Strings

What is quantum geometry? This question is becoming a popular leitmotiv in theoretical physics and in mathematics. Conformal field theory may catch a glimpse of the right answer. We review global aspects of the geometry of conformal fields, such as duality and mirror symmetry, and interpret them within Connes' non-commutative geometry. Extended version of lectures given by the 2nd author at the Mathematical Quantum Theory Conference, Vancouver, Canada, August 4 to 8, 1993Comment: 44 pages, latex file, 5 references adde

Location and Felt Reports for the 25 April 2010 mbLg 3.9 Earthquake Near Alice, Texas: Was it Induced by Petroleum Production?

This study examines seismograms and felt reports for the 25 April 2010 Alice, Texas, earthquake and explores its possible relationship with gas and oil production in the Stratton field. We identified P arrivals at seven broadband stations situated within similar to 100 km of the epicentral region and determined a location of 27.72 degrees N, 97.95 degrees W, about 11 km east of the location reported by the National Earthquake Information Center but coincident with the region of highest intensity (modified Mercalli intensity V-VI) felt reports. We compare arrivals for observed secondary P and S arrivals with predictions from a published Gulf Coast velocity model. At nearby stations, the secondary arrivals are much stronger than primary arrivals; the arrival times and the presence of high-amplitude phases traveling at the Love-wave velocity of the uppermost model layer suggest the focal depth was shallow, 3 km or less. This places the 2010 hypocenter approximately along the mapped trace of the Vicksburg fault zone and at the depth of the Frio formation, the principal productive member in the Stratton field, which has produced at least 2.7 trillion cubic feet of gas and about 100 million barrels of oil since production commenced in 1938. We conclude it is plausible, although not proven definitively, that production in the Stratton field contributed to the occurrence of the 2010 Alice earthquake and an earlier similar earthquake that occurred on 24 March 1997.Ewing-Worzel Summer FellowshipU.S. Geological Survey (USGS), Department of the Interior, under USGS G12AP20001Institute for Geophysic

The regional variation of new technology based firms in Austria

During the last two decades the role of new business start-ups has gained a growing interest both from regional economics as well as from (regional) economic policy. It was recognized that not only the large Galbraithian enterprise is the driving force in processes like employment growth or structural economic change, but also small and often new or young firms are playing an active role. In the 1980s so called new technology based firms (NTBFs) gained considerable attention. It has been argued that the Schumpeterian entrepreneur is an important force for the implementation of new ideas into the market place, often via the formation of NTBFs. In our paper we analyse the structure and the regional variation of new business formation in the high technology sector in Austria. Using a definition based upon the OECD we differentiate the high tech sector in (i) top technology, (ii) higher technologies and (iii) technology orientated services. We demonstrate the relative importance of these groups for the total population of new business start-ups in Austria in the time period ot 1990-1994 as well as for certain sub-populations like manufacturing and services. The main part of our paper discusses the regional variation of NTBFs using the framework of the well known urban incubator hypothesis. It is expected that metropolitan and urban regions have a higher orientation towards high tech (what means the proportion of NTBFs) than the rural or hinterland regions. An additional part of our paper deals with the question wether NTBFs play an important role in the process of structural change of regional economies as has been postulated by various authors during the last couple of years.

Magnetohydrodynamics of Chiral Relativistic Fluids

We study the dynamics of a plasma of charged relativistic fermions at very high temperature $T\gg m$, where $m$ is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magneto-hydrodynamical description of the evolution of such a plasma. We show that, as compared to conventional MHD for a plasma of non-relativistic particles, the hydrodynamical description of the relativistic plasma involves new degrees of freedom described by a pseudo-scalar field originating in a local asymmetry in the densities of left-handed and right-handed fermions. This field can be interpreted as an effective axion field. Taking into account the chiral anomaly we present dynamical equations for the evolution of this field, as well as of other fields appearing in the MHD description of the plasma. Due to its non-linear coupling to helical magnetic fields, the axion field significantly affects the dynamics of a magnetized plasma and can give rise to a novel type of inverse cascade

A Cluster Expansion for Dipole Gases

We give a new proof of the well-known upper bound on the correlation function of a gas of non-overlapping dipoles of fixed length and discrete orientation working directly in the charge representation, instead of the more usual sine-Gordon representation.Comment: 8 pages, Late

Remembering today tomorrow: exploring the human-centred design of digital mementos

This paper describes two-part research exploring the context for and human-centred design of ‘digital mementos’, as an example of technology for reflection on personal experience(in this case, autobiographical memories). Field studies into families’ use of physical and digital objects for remembering provided a rich understanding of associated user needs and human values, and suggested properties for ‘digital mementos’ such as being ‘not like work’, discoverable and fun. In a subsequent design study, artefacts were devised to express these features and develop the understanding of needs and values further via discussion with groups of potential ‘users’. ‘Critical artefacts’(the products of Critical Design)were used to enable participants to envisage broader possibilities for social practices and applications of technology in the context of personal remembering, and thus to engage in the design of novel devices and systems relevant to their lives. Reflection was a common theme in the work, being what the digital mementos were designed to afford and the mechanism by which the design activity progressed. Ideas for digital mementos formed the output of this research and expressed the designer’s and researcher’s understanding of participants’ practices and needs, and the human values that underlie them and, in doing so, suggest devices and systems that go beyond usability to support a broader conception of human activity