Moment magnitude scale

Hanks, T. and Kanomoi, H. A moment magnitude scale. Journal of Geophysical Research 84(B5) (1979), 2348-2350. 

Moment Magnitude Scale for measuring earthquake size based on the amount of energy released. 

On April 6, 2009, an earthquake of 6.3 moment magnitude scale (MMS) struck central Italy with its epicenter near L Aquila (42°21 N 13°24 E). The earthquake caused damages to a relevant number of buildings in the city of L Aquila several buildings collapsed, and about 1,500 people were injured, and about 300 people died, making this event the deadliest earthquake to hit Italy since the 1980 Irpinia earthquake. 

Gutenberg B, Richter CF (1956) Magnitude and energy of earthquakes. Annali di Geofisica 9 1-15 Hanks C, Kanamori H (1979) A moment magnitude scale. 

Hanks TC, Kanamori H (1979) A moment magnitude scale. J Geophys Res 84 2348-2350 Hsu Y-J, Yu S-B, Simons M, Kuo L-C, Chen H-Y (2009) ftiterseismic crustal deformation in the Taiwan plate boundary zone revealed by GPS observations, seismicity, and earthquake focal mechanisms. Tectonophysics 479 4-18... 

In order to examine the suitability of the predictive model class in Equation (6.75) and to propose the most suitable one, model class candidates are constructed. Here, predictive model classes are considered in a similar functional form of Equation (6.75) but to include different combinations of terms in different model classes. Eirst of all, the constant b is necessary to serve as a scaling factor of the PGA for any model class so all model classes contain b. As will be discussed later in Section 6.5.3.1 that only strong-motion records with moment magnitude M > 3.5 are utilized, Mq = 3.5 is taken in this study. Eor the site properties, the terms b Gs and bjGc are either included or excluded together in a model class. Therefore, there are 2 = 32 model class candidates, namely Ci, C2, , C32. 

Several sources and projects define the earthquake magnitude in different ways. Day (2002) and Youd et al. (2001) differentiate between the local magnitude (Ml), the surface wave magnitude (Mg) and the moment magnitude (My, ). The latter (M ) is defined as Mg in Eurocode, and best represents the energy associated with the earthquake. However it is concluded that below a value of 7 the magnitude are reasonably close to one another and there is no need to identify which scale is meant in design specifications. 

Body waves Calibration functions Earthquake size Earthquake strength Magnitude scale Richter scale Seismic energy Seismic moment Standardization of measurements Surface waves Wave attenuation... 

Earthquake Magnitude Estimation, Fig. 3 Theoretical source spectra of radiated displacement (fe/t) and velocity amplitudes (right) scaled to seismic moment Mo. respectively seismic moment rate dMo/dt in relation to the praiod ranges within which the lASPEl (2013) standard magnitudes are measured (see section Magnitude Scales and the... 

Earthquake Magnitude Estimation, Fig. 15 Average relationships of different common types of magnitude scales with respect to the non-saturating moment magnitude Mw Mjma is determined by the Japanese... 

By contrast, historical earthquakes only can be explored by macroseismic analyses, and intensi is the only parameter that allows an estimate of the earthquake size to be made. Experience gained from the macroseismic analyses of instrumental events led to the development of empirical relationships in order to approximately estimate the moment magnitude (Mw) of historical events from earthquake intensity distribution. As a result, instrumental records are in the best case available from the first half of the twentieth century however, historical intensity analyses (extended in some regions back to the sixth to seventh century B.C.) are behind most of the seismic hazard analyses, seismic-building codes, and nuclear regulatory guides worldwide. Therefore, the use and refinement of intensity scales in earthquake analysis is stiU, and will continue to be, imperative to the society. 

When a chain has lost the memory of its initial state, rubbery flow sets in. The associated characteristic relaxation time is displayed in Fig. 1.3 in terms of the normal mode (polyisoprene displays an electric dipole moment in the direction of the chain) and thus dielectric spectroscopy is able to measure the relaxation of the end-to-end vector of a given chain. The rubbery flow passes over to liquid flow, which is characterized by the translational diffusion coefficient of the chain. Depending on the molecular weight, the characteristic length scales from the motion of a single bond to the overall chain diffusion may cover about three orders of magnitude, while the associated time scales easily may be stretched over ten or more orders. 

Let the approach of the moment of a natural disaster be characterized by vector. v, that gets into some cluster of multi-dimensional phase space Xy. In other words, converting our verbal portrait to quantitative estimation of this process, we introduce a generalized characteristic I t) of a natural disaster and identify it by calibrated scale E, for which we postulate the presence of relationships of type E] < S2, Ej > S2, or E] = E2. This means that there always exists a value of I(t) = p which determines when a natural catastrophe of a given type can be expected E —> p =/ (S), where / is conversion of the notion of natural disaster into a number. As a result, magnitude 6 = I t) — p determines the expected time interval before the catastrophe occurs. 

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