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Topic: Seismic moment

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Moment magnitude

Moment magnitude scale

Richter scale

Moment magnitude scale

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	Moment magnitude scale - Wikipedia, the free encyclopedia
		The moment magnitude scale (a successor to the Richter scale), was introduced in 1979 by Tom Hanks and Hiroo Kanamori and is used by seismologists to compare the energy released by earthquakes.
		The constants in the equation are chosen so that estimates of moment magnitude roughly agree with estimates using other scales such as the Richter magnitude scale.
		Therefore a seismic efficiency has to be chosen for a bomb that is quoted as a comparison.
	en.wikipedia.org /wiki/Moment_magnitude_scale (468 words)

	[No title]
		Applying the latter method provides estimates of the seismic moment rate which are a function of the two parameters of the earthquake size distribution and the earthquake occurrence rate.
		% This implies that the corner seismic moment depends neither on % the categories MNSK and Nishenko proposed, nor on the velocity % of the relative plate motion and the ratio % ($\perp\!/\!\parallel$) of the perpendicular/parallel % velocities, i.e., the corner moment is a more-or-less % universal constant.
		Seismic moment $M$ and tectonic moment rate $\dot M_T$ are measured in N m and N m/yr, respectively.
	moho.ess.ucla.edu /~kagan/momc.tex (11470 words)

	Dictionary of Meaning www.mauspfeil.net (Site not responding. Last check: 2007-10-15)
		For modern earthquakes, moment is usually estimated from recordings of earthquakes known as seismograms.
		For earthquakes that occurred in times before modern instruments were available, moment may be estimated from geologic estimates of the size of the fault rupture and the displacement.
		Seismic moment is the basis of the moment magnitude scale introduced by Hiroo Kanamori, which is often used to compare the size of different earthquakes.
	www.mauspfeil.net /Seismic_moment.html (219 words)

	Source Parameters and Moment Tensor Solutions (Site not responding. Last check: 2007-10-15)
		A double couple source is characterized by a moment tensor where one eigenvalue of the moment tensor vanishes (equivalent to the Null or B axis), and the sum of eigenvalues vanishes, i.e.
		The seismic moment tensor M has, in general, 6 independent components which follows from the condition that the angular momentum for the equivalent forces in the source must vanish.
		the scalar seismic moment) whose eigenvectors give the direction at the source of the tensional (positive) T axis and compressional (negative) P axis, respectively, while the zero eigenvalue is in the direction of the B (or null) axis of the double couple.
	seismo.um.ac.ir /education/Source%20Parameters%20and%20Moment%20Tensor%20Solutions.htm (2807 words)

	Influence of Near-source Velocity Heterogeneity on the Recovery of Isotropic Seismic Moment Tensors
		Moment tensors for input source mechanisms in the finite difference simulations are shown as well.
		To model the effects of LVC structure, E3D was used to calculate synthetic seismograms for a velocity model of the region derived from a local/teleseismic tomography P-wave model (H. Benz, written communication, 1999) (figure 20.1).
		While the NDC components of the seismic moment tensor remain difficult to resolve, the isotropic components of anomalous earthquakes in the LVC earthquake swarm of late 1997 and early 1998 appear to be real features of the source process.
	www.seismo.berkeley.edu /annual_report/ar99_00/node24.html (771 words)

	[No title]
		The fraction of seismic moment released as strike-slip earthquakes is approximately 50% for modern earthquakes and 75% for historical earthquakes.
		Scalar seismic moment, derived from the moment tensor, is used as a common scaling parameter in seismic hazard, such as the relationship between seismic moment and fault rupture length [e.g., Wells and Coppersmith, 1994].
		Regional moment tensor solutions are shown in Figures 4 through 10 along with the focal mechanisms which represent the major double couple of the deviatoric moment tensor.
	www.seismo.unr.edu /ftp/web/htdocs/students/Ichinose/RMTI (5673 words)

	Seismology
		Seismic waves produced by explosions have been used to map salt domes and other oil-bearing rocks, faults (cracks in deep rock), rock types, and long-buried giant meteor craters.
		Using seismic tomography with earthquake waves, the interior of the Earth has been completely mapped to a resolution of several hundred kilometers.
		In 2002, using high-resolution digital seismic records, some scientists have reported discovering several point sources of seismic noise that enter the Earth, move through it in a straight line at supersonic speeds, and then leave it.
	www.sciencedaily.com /encyclopedia/seismology (364 words)

	[No title]
		One major reason to study the seismic moment distribution is to compare it with estimates of tectonic deformation and draw appropriate conclusions.
		Although we cannot yet estimate the seismic moment for small earthquakes, acoustic emission events, and dynamics simulations nor directly compare their power-law exponent to large earthquake results, still the scale-invariance of these processes suggests that the power-law behaviour may be universal.
		Since global seismicity values may be influenced by a mixture of different earthquake populations, we compare the $\beta$-values for a set of zones which have a more homogeneous population (Kagan 1997; 1999).
	moho.ess.ucla.edu /~kagan/moms.tex (11537 words)

	ASC - Moment Magnitude Scale (Site not responding. Last check: 2007-10-15)
		Because fault geometry and observer azimuth are a part of the computation, moment is a more consistent measure of earthquake size than is magnitude, and more importantly, moment does not have an intrinsic upper bound.
		The seismic moment is related to fundamental parameters of the faulting process.
		Seismic moment was first determined for the 1964 Niigata, Japan earthquake by Keiiti Aki in 1966.
	www.asc-india.org /info/momag.htm (256 words)

	Seismology Article, Seismology Information (Site not responding. Last check: 2007-10-15)
		Seismic waves produced by explosions have been used to map salt domes and other oil-bearing rocks, faults (cracks in deep rock), rock types, andlong-buried giant meteor craters.
		For example, Chicxulub, the meteor that isbelieved to have killed the dinosaurs, was localized to central america by analyzing ejecta in the cretaceous boundary, and thenphysically proven to exist using seismic maps from oilexploration.
		Using seismic tomography with earthquake waves, the interiorof the Earth has been completely mapped to a resolution of several hundred kilometers.
	www.anoca.org /waves/earth/seismology.html (339 words)

	[No title] (Site not responding. Last check: 2007-10-15)
		Actual torsion: the moment resulting from the eccentricity between (1) the centers of mass at all floors above and including the given floor, and (2) the center of rigidity of the vertical seismic elements in the story below the given floor, and b.
		Accidental torsion: an accidental torsional moment produced by an artificial horizontal offset in the centers of mass, at all floors above and including the given floor, equal to a minimum of 5% of the horizontal dimension at the given floor level measured perpendicular to the direction of the applied load.
		The 1997 AISC Seismic Provisions permit such splices in the mid-height zone of columns based on the belief that large flexural demands, and in particular inelastic demands are unlikely to occur in this region.
	www.fema.gov /txt/hazards/earthquakes/nehrp/fema-350ch2.txt (10605 words)

	[No title] (Site not responding. Last check: 2007-10-15)
		As a result of these studies, and independent research conducted by others, it is now known that the typical moment-resisting connection detail employed in steel moment-frame construction prior to the 1994 Northridge earthquake, and depicted in Figure 1-1, had a number of features that rendered it inherently susceptible to brittle fracture.
		At this location, bending moments and shear forces in the beam must be transferred to the column through the combined action of the welded joints between the beam flanges and column flanges and the shear tab.
		The amount of strain demand placed on the connection elements of a steel moment frame is related to the span-to-depth ratio of the member.
	www.fema.gov /txt/hazards/earthquakes/nehrp/fema-350ch1.txt (4451 words)

	Fault slip and seismic moment of the 1700 Cascadia earthquake inferred from Japanese tsunami descriptions
		The 1700 Cascadia earthquake attained moment magnitude 9 according to new estimates based on effects of its tsunami in Japan, computed coseismic seafloor deformation for hypothetical ruptures in Cascadia, and tsunami modeling in the Pacific Ocean.
		The most likely earthquake, of moment magnitude 9.0, has 19 m of coseismic slip on an offshore, full-slip zone 1100 km long with linearly decreasing slip on a downdip partial-slip zone.
		Citation: Satake, K. Wang, and B. Atwater (2003), Fault slip and seismic moment of the 1700 Cascadia earthquake inferred from Japanese tsunami descriptions, J.
	www.agu.org /pubs/crossref/2003/2003JB002521.shtml (392 words)

	Richter Magnitude
		Both the magnitude and the seismic moment are related to the amount of energy that is radiated by an earthquake.
		It is only the amount radiated from the earthquake as seismic waves, which ought to be a small fraction of the total energy transfered during the earthquake process.
		For this moment is in units of dyne-cm, and energy is in units of ergs.
	www.seismo.unr.edu /ftp/pub/louie/class/100/magnitude.html (1477 words)

	UUSS - Glossary of Terms
		moment (earthquake) A measure of the energy released in an earthquake determined by strength of the fault and the area and amount of slip.
		Rayleigh wave A seismic surface wave involving elliptical motion in a vertical plane oriented in the direction of propagation of the wave.
		S wave A seismic body wave involving shear motion transverse to the direction of propagation of the wave.
	www.seis.utah.edu /qfacts/glossary.shtml (3403 words)

	Earthquake Hazards Program: xxx
		Although this program is still undergoing testing and "fine-tuning", in many cases an estimate of the moment tensor can be produced within 20 minutes of the arrival of the "gophered" broadband P-waveform data from the IRIS DMC.
		These data are merged with the USNSN dataset and used to refine the location and compute a body-wave moment tensor using a technique based on the theory of optimal filter design.
		Because of the growing number of broadband seismic stations with either real-time or dial-up capability, these preliminary solutions are usually very similar to those produced later, using data from the entire network.
	wwwneic.cr.usgs.gov /neis/FM/fast_moment.html (350 words)

	Automated Moment Tensor Software for Monitoring the Comprehensive Test Ban Treaty
		Although their epicenters and magnitudes can be determined fairly precisely, seismic moment tensor analysis can help in two ways.
		The maps in Figure 29.2 show the IMS stations used for the inversions, as well as the moment tensor solutions determined by the complete waveform inversion and the surface wave method, respectively.
		In both Figure 29.2 A and B, the solutions derived using two different velocity models are compared with the moment tensors given in the Harvard CMT and USGS catalogs.
	www.seismo.berkeley.edu /annual_report/ar01_02/node33.html (1371 words)

	references
		Seismic Hazard Assessment In Jordan And Its Vicinity.
		Seismic Interpretation Of The Stucture And Stratigraphy Of The Strait Of Hormuz.
		Seismicity Of The Eastern Mediterranean Region: Perspective From The Sinai Subplate.
	atlas.geo.cornell.edu /ctbt/references.html (14779 words)

	Earthquake Magnitude: SEISMIC MOMENT (M0), RADIATED ENERGY, AND MOMENT MAGNITUDE (M) (Site not responding. Last check: 2007-10-15)
		Such saturation, which is understood to arise from the scaling law of the seismic spectrum (Aki, 1967), occurs when the peak of the energy spectrum lies below the frequency range of the Wood-Anderson seismograph.
		One such scale, Mw, proposed by Kanamori (1977) is based on the seismic energy radiated in the form of elastic waves by the source.
		Another nearly equivalent magnitude scale, M, the moment magnitude, is based on the seismic moment, M0 = mu A u (Aki, 1966), where A is the area of the earthquake rupture surface, u is the average fault displacement, and mu is the shear modulus of the crustal volume containing the fault.
	www.johnmartin.com /earthquakes/eqsafs/safs_695.htm (311 words)

	Pre-Northridge Flaw [Seismic Structural Design Associates, INC.]
		Extensive finite element analyses and strain gage data from ATC-24 tests by Seismic Structural Design Associates, Inc. (SSDA) of this pre-Northridge connection made subsequent to the Northridge earthquake in 1994 and 1995 showed large stress and strain gradients horizontally across and vertically through the beam flanges and welds at the face of the column.
		It is these flange shear forces that produce a prying moment in the welds and flanges at the face of the column and at the weld access holes that led to the weld and flange fractures and to the column flange divot modes of connection fracture.
		In these notes it is stated that the large component of seismic shear, typically 50%, and its prying effects still exist in the beam flanges and welds of the SAC pre-qualified Reduced Beam Section (RBS), the WUF-W, and the WUF-B connections, which use the "standard" unreinforced flange connection (James Malley, p.
	www.ssda.net /flaw.htm (673 words)

	IASPEI Brochure
		Analysis of seismic waveform data has sought a relation between the duration of the nucleation phase and the seismic moment of an earthquake.
		Recordings of seismic waves provide the most comprehensive data set and the highest available spatial resolution for the investigation of the structure of the interior of the Earth and for constraining the properties of the materials at depth.
		Laboratory measurements of wave attenuation in mantle-like materials and the resulting velocity dispersion at seismic frequencies (0.001 to 10 Hz) are essential for interpreting seismic wave data in terms of the composition and properties of the interior of the Earth.
	www.iaspei.org /brochure/brochure.html (8803 words)

	Seismological Software Library - ORFEUS
		Seismic hazard analysis from Bender and Perkins, USGS Bulletin 1772, "SEISRISK III: A computer program for Seismic Hazard Estimation" Modifications by Roland LaForge.
		A seismic analysis system containing a complete set of programs and a simple database for analyzing earthquake data from analog and digital data.
		Seismic Application Package for managing and manipulating seismic data developed by the former IRIS Joint Seismic Program.
	www.orfeus-eu.org /links/softwarelib.htm (2767 words)

	BSL: Research Publications
		Pasyanos, M.E., Regional Moment Tensors and Structure of the Crust in Central and Northern California, Ph.D. Thesis, University of California, Berkeley, 1996.
		Bolt, B.A. and N. Gregor, Discrimination of a seismic source doublet in the Northridge, California earthquake of 17 January 1994, J. of Seism., 1, 29-37, 1997.
		Dreger, D., and A. Kaverina, Seismic remote sensing for the earthquake source process and near- source strong shaking: A case study of the October 16, 1999 Hector Mine earthquake, Geophys.
	seismo.berkeley.edu /seismo.publications.html (6218 words)

	European-Mediterranean Regional Centroid Moment Tensors (Site not responding. Last check: 2007-10-15)
		The seismic moment tensor is a complete description of the earthquake size and source geometry.
		The Centroid Moment Tensor (CMT) is a reliable method for calculating moment tensors, by which the Harvard Seismology Centroid-Moment Tensor Project systematically studies global seismicity.
		European-Mediterranean Regional Centroid Moment Tensors is a joint project between scientists from Istituto Nazionale di Geofisica e Vulcanologia (Rome, Italy) and Harvard University (Cambridge, MA, USA).
	www.ingv.it /seismoglo/RCMT (297 words)

	UC Berkeley Seismological Laborarory Moment Tensor Homepage (Site not responding. Last check: 2007-10-15)
		The BSL is operating two automated moment tensor methodologies under the Rapid Earthquake Data Integration (REDI) project.
		With these two methods, namely a surface wave spectral inversion and a three-component complete waveform inversion we determine preliminary (automatic) moment tensor solutions 6-9 minutes after the occurrence of an earthquake.
		After review the moment tensor is disseminated via the internet and by email.
	www.seismo.berkeley.edu /~dreger/mtindex.html (146 words)

	Guardian Unlimited Sport \| Formula one \| Formula one: Where do Ferrari go after Schumacher?
		The sight of Schumacher struggling at Monza of all places only added to the widespread sense of a man approaching the final stages of his career, and there is good reason to believe Ferrari are working hard behind the scenes to ensure a smooth succession to the throne when Schumacher finally hangs up his helmet.
		Most insiders now believe this seismic moment for the sport will happen at the end of next season and it is now clear that Raikkonen is at the top of Ferrari's list of replacements in 2007, with six-times MotoGP champion Valentino Rossi possibly earmarked as the Finn's No2.
		It is not simply his unmatched record of 84 grand prix victories which sets him apart but the unique relationship he has crafted with the Ferrari management.
	sport.guardian.co.uk /formulaone/story/0,10069,1561847,00.html (723 words)

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