Source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude ( M ), surface rupture length, subsurface rupture length, downdip rupture width, rupture area, and maximum and average displacement per event. The resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment, moment magnitude, subsurface rupture length, downdip rupture width, and average surface displacement. Each source parameter is classified as reliable or unreliable, based on our evaluation of the accuracy of individual values. Only the reliable source parameters are used in the final analyses. In comparing source parameters, we note the following trends: (1) Generally, the length of rupture at the surface is equal to 75% of the subsurface rupture length; however, the ratio of surface rupture length to subsurface rupture length increases with magnitude; (2) the average surface displacement per event is about one-half the maximum surface displacement per event; and (3) the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement. Thus, for most earthquakes in this data base, slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface. Log-linear regressions between earthquake magnitude and surface rupture length, subsurface rupture length, and rupture area are especially well correlated, showing standard deviations of 0.25 to 0.35 magnitude units. Most relationships are not statistically different (at a 95% significance level) as a function of the style of faulting: thus, we consider the regressions for all slip types to be appropriate for most applications. Regressions between magnitude and displacement, magnitude and rupture width, and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area. The large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data. Separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions. Regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults, and to estimate the expected surface displacement along a fault for a given size earthquake.

New Empirical Relationships among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement

This essential reference for graduate students and researchers provides a unified treatment of earthquakes and faulting as two aspects of brittle tectonics at different timescales. The intimate connection between the two is manifested in their scaling laws and populations, which evolve from fracture growth and interactions between fractures. The connection between faults and the seismicity generated is governed by the rate and state dependent friction laws - producing distinctive seismic styles of faulting and a gamut of earthquake phenomena including aftershocks, afterslip, earthquake triggering, and slow slip events. The third edition of this classic treatise presents a wealth of new topics and new observations. These include slow earthquake phenomena; friction of phyllosilicates, and at high sliding velocities; fault structures; relative roles of strong and seismogenic versus weak and creeping faults; dynamic triggering of earthquakes; oceanic earthquakes; megathrust earthquakes in subduction zones; deep earthquakes; and new observations of earthquake precursory phenomena.

The Mechanics of Earthquakes and Faulting

Empirical relations involving seismic moment M_o, magnitude M_S, energy E_S and fault dimension L (or area S) are discussed on the basis of an extensive set of earthquake data (M_S ≧ 6) and simple crack and dynamic dislocation models. The relation between log S and log M_o is remarkably linear (slope ∼ 2/3) indicating a constant stress drop Δσ; Δσ = 30, 100 and 60 bars are obtained for inter-plate, intra-plate and “average” earthquakes, respectively. Except for very large earthquakes, the relation M_S ∼ (2/3) log M_o ∼ 2 log L is established by the data. This is consistent with the dynamic dislocation model for point dislocation rise times and rupture times of most earthquakes. For very large earthquakes M_S ∼ (1/3) log M_o ∼ log L ∼ (1/3) log E_S. For very small earthquakes M_S ∼ log M_o ∼ 3 log L ∼ log E_S. Scaling rules are assumed and justified. This model predicts log E_S ∼ 1.5 M_S ∼ 3 log L which is consistent with the Gutenberg-Richter relation. Since the static energy is proportional to σL^3, where σ is the average stress, this relation suggests a constant apparent stress ησ where η is the efficiency. The earthquake data suggest ησ ~ 1/2 Δσ. These relations lead to log S ∼ M_S consistent with the empirical relation. This relation together with a simple geometrical argument explains the magnitude-frequency relation log N ∼ − M_S.

/pdf/theoretical-basis-of-some-empirical-relations-in-seismology-1e9arnhgn6.pdf

Theoretical basis of some empirical relations in seismology

Summary Examination of more than 100 fault plane solutions for earthquakes within the Alpide belt between the Mid-Atlantic ridge and Eastern Iran shows that the deformation at present occurring is the result of small continental plates moving away from Eastern Turkey and Western Iran. This pattern of movement avoids thickening the continental crust over much of Turkey by consuming the Eastern Mediterranean sea floor instead. The rates of relative motion of two of the small plates involved, the Aegean and the Turkish plates, are estimated, but are only within perhaps 50 per cent of the true values. These estimates are then used to reconstruct the geometry of the Mediterranean 10 million years ago. The principal difference from the present geometry is the smooth curved coast which then formed the southern coast of Yugoslavia, Greece and Turkey. This coast has since been distorted by the motion of the two small plates. Similar complications have probably been common in older mountain belts, and therefore local geological features may not have been formed by the motion between major plates. A curious feature of several of the large shocks for which fault plane solutions could be obtained for the main shock and one major aftershock was that the two often had different mechanisms.

Active tectonics of Mediterranean region

http://goldrock.persiangig.com/Document/Active%20Tectonics.pdf

Active Tectonics of the Mediterranean Region

Preface Acknowledgements Definitions Transliteration Chronology 1. Macroseismic data from historical sources 2. Macroseismic data from field studies 3. Case histories 4. Instrumental data 5. Earthquake history of Persia Notes References Index.

A history of Persian earthquakes

A large and uniform dataset is used to find equations for the prediction of absolute spectral acceleration ordinates in Europe and adjacent areas, in terms of magnitude, source-distance and site geology. The dataset used is shown to be representative of European strong motion in terms of the attenuation of peak ground acceleration. The equations are recommended for use in the range of magnitudes from M s 4.0 to 7.5 and for source-distances of up to 200 km.

Prediction of horizontal response spectra in europe

SUMMARY This paper summarizes evidence for surface faulting in historical and recent earthquakes in the Eastern Mediterranean region and in the Middle East. Such information is particularly important for studies of active tectonics and for palaeoseismology. We have found 78 cases of faulting pre-1900 and 72 post-1900, some of which show that faults that have apparently been inactive this century had already ruptured before 1900. For some cases faulting could not have been predicted from 20th century activity, and in others it could have been expected, but has not been observed during the instrumental period. The data are suYcient to allow the derivation of relationships between magnitude and rupture length.

/pdf/faulting-associated-with-historical-and-recent-earthquakes-458ulp05ld.pdf

Faulting associated with historical and recent earthquakes in the Eastern Mediterranean region

This article presents equations for the estimation of horizontal strong ground motions caused by shallow crustal earthquakes with magnitudes Mw ≥ 5 and distance to the surface projection of the fault less than 100km. These equations were derived by weighted regression analysis, used to remove observed magnitude-dependent variance, on a set of 595 strong-motion records recorded in Europe and the Middle East. Coefficients are included to model the effect of local site effects and faulting mechanism on the observed ground motions. The equations include coefficients to model the observed magnitude-dependent decay rate. The main findings of this study are that: short-period ground motions from small and moderate magnitude earthquakes decay faster than the commonly assumed 1/r, the average effect of differing faulting mechanisms is not large and corresponds to factors between 0.8 (normal and odd) and 1.3 (thrust) with respect to strike-slip motions and that the average long-period amplification caused by soft soil deposits is about 2.6 over those on rock sites. Disappointingly the standard deviations associated with the derived equations are not significantly lower than those found in previous studies.

/pdf/equations-for-the-estimation-of-strong-ground-motions-from-20394ygorw.pdf

Equations for the Estimation of Strong Ground Motions from Shallow Crustal Earthquakes Using Data from Europe and the Middle East: Horizontal Peak Ground Acceleration and Spectral Acceleration

N. N. Ambraseys

Papers

A history of Persian earthquakes

Prediction of horizontal response spectra in europe

Faulting associated with historical and recent earthquakes in the Eastern Mediterranean region

Equations for the Estimation of Strong Ground Motions from Shallow Crustal Earthquakes Using Data from Europe and the Middle East: Horizontal Peak Ground Acceleration and Spectral Acceleration

Some characteristic features of the Anatolian fault zone