We develop new empirical scaling laws for rupture width $W$, rupture length $L$, rupture area $A$, and average slip $D$, based on a large database of rupture models. The database incorporates recent earthquake source models in a wide magnitude range ($Mw$ 5.4–9.2) and events of various faulting styles. We apply general orthogonal regression, instead of ordinary least‐squares regression, to account for measurement errors of all variables and to obtain mutually self‐consistent relationships. We observe that $L$ grows more rapidly with $Mw$ compared to $W$. The fault‐aspect ratio ($L/W$) tends to increase with fault dip, which generally increases from reverse‐faulting, to normal‐faulting, to strike‐slip events. At the same time, subduction‐interface earthquakes have significantly higher $W$ (hence a larger rupture area $A$) compared to other faulting regimes. For strike‐slip events, the growth of $W$ with $Mw$ is strongly inhibited, whereas the scaling of $L$ agrees with the $L$‐model behavior ($D$ correlated with $L$). However, at a regional scale for which seismogenic depth is essentially fixed, the scaling behavior corresponds to the $W$ model ($D$ not correlated with $L$). Self‐similar scaling behavior with $Mw−log10A$ is observed to be consistent for all the cases, except for normal‐faulting events. Interestingly, the ratio $D/W$ (a proxy for average stress drop) tends to increase with $Mw$, except for shallow crustal reverse‐faulting events, suggesting the possibility of scale‐dependent stress drop. The observed variations in source‐scaling properties for different faulting regimes can be interpreted in terms of geological and seismological factors. We find substantial differences between our new scaling relationships and those of previous studies. Therefore, our study provides critical updates on source‐scaling relations needed in seismic–tsunami‐hazard analysis and engineering applications.

Our theoretical model of rupture arrest indicates that most of the injection-induced earthquakes have been self-arrested.

Many studies have modeled the Tohoku tsunami of March 11, 2011 as being due entirely to slip on an earthquake fault, but the following discrepancies suggest that further research is warranted. (1) Published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40 m measured along the coast of the Sanriku district in the northeast part of Honshu Island. (2) Published models cannot reproduce the timing and high-frequency content of tsunami waves recorded at three nearshore buoys off Sanriku, nor the timing and dispersion properties of the waveforms at offshore DART buoy #21418. (3) The rupture centroids obtained by tsunami inversions are biased about 60 km NNE of that obtained by the Global CMT Project.\ud \ud Based on an analysis of seismic and geodetic data, together with recorded tsunami waveforms, we propose that, while the primary source of the tsunami was the vertical displacement of the seafloor due to the earthquake, an additional tsunami source is also required. We infer the location of the proposed additional source based on an analysis of the travel times of higher-frequency tsunami waves observed at nearshore buoys. We further propose that the most likely additional tsunami source was a submarine mass failure (SMF—i.e., a submarine landslide). A comparison of pre- and post-tsunami bathymetric surveys reveals tens of meters of vertical seafloor movement at the proposed SMF location, and a slope stability analysis confirms that the horizontal acceleration from the earthquake was sufficient to trigger an SMF. Forward modeling of the tsunami generated by a combination of the earthquake and the SMF reproduces the recorded on-, near- and offshore tsunami observations well, particularly the high-frequency component of the tsunami waves off Sanriku, which were not well simulated by previous models. The conclusion that a significant part of the 2011 Tohoku tsunami was generated by an SMF source has important implications for estimates of tsunami hazard in the Tohoku region as well as in other tectonically similar regions.\u

Large dynamic stresses near earthquake rupture fronts may induce an inelastic response of the surrounding materials, leading to increased energy absorption that may affect dynamic rupture. We systematically investigate the effects of off‐fault plastic energy dissipation in 2‐D in‐plane dynamic rupture simulations under velocity‐and‐state‐dependent friction with severe weakening at high slip velocity. We find that plasticity does not alter the nature of the transitions between different rupture styles (decaying versus growing, pulse‐like versus crack‐like, and subshear versus supershear ruptures) but increases their required background stress and nucleation size. We systematically quantify the effect of amplitude and orientation of background shear stresses on the asymptotic properties of self‐similar pulse‐like ruptures: peak slip rate, rupture speed, healing front speed, slip gradient, and the relative contribution of plastic strain to seismic moment. Peak slip velocity and rupture speed remain bounded. From fracture mechanics arguments, we derive a nonlinear relation between their limiting values, appropriate also for crack‐like and supershear ruptures. At low background stress, plasticity turns self‐similar pulses into steady state pulses, for which plastic strain contributes significantly to the seismic moment. We find that the closeness to failure of the background stress state is an adequate predictor of rupture speed for relatively slow events. Our proposed relations between state of stress and earthquake source properties in the presence of off‐fault plasticity may contribute to the improved interpretation of earthquake observations and to pseudodynamic source modeling for ground motion prediction.