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An exceptional data set documents surface deformation before, during and after the earthquake that struck northeastern Japan in March 2011. But models for assessing seismic and tsunami hazard remain inadequate. See Letter p.373

A new catalogue of slow-slip events on the Cascadia megathrust shows that a cubic moment–duration scaling law is likely, with scaling properties strikingly similar to regular earthquakes.

Seismotectonic studies seek to provide ways of assessing the timing, magnitude and spatial extent of future earthquakes. Numerical simulations of seismic and aseismic fault slip in a fully dynamical numerical model open the possibility of predicting a fault system’s seismic rupture patterns from observations of its slip properties.

In 2011, a modest earthquake in southern Spain seriously damaged the city of Lorca. Analysis of surface deformation suggests that the quake was caused by rupture of a shallow fault patch brought closer to failure by the pumping of water from a nearby aquifer.

In March 2005 the Sunda megathrust earthquake, with a moment magnitude of 8.6, occurred. Concern was then focused further south on the Mentawai area, where large earthquakes had occurred in 1797 (magnitude 8.8) and 1833 (magnitude 9.0). On 12 September 2007, a magnitude 8.4 earthquake occurred, followed by a magnitude 7.9 earthquake 12 hours later. This paper shows that these earthquakes ruptured only a fraction of the area ruptured in 1833 and conclude that the stress state on the portion of the Sunda megathrust that ruptured in 1797 and 1833 was probably not adequate for the development of a single major large rupture in 2007, meaning that the potential for a large megathrust event in the Mentawai area thus remains high.

Faults are generally assumed to be more complicated at the surface than at depth. Analysis of the 2010 El Mayor–Cucapah earthquake, in contrast, reveals that the surface trace is nearly straight but the fault must be highly segmented at depth, thus the characteristics of this earthquake could not have been anticipated from surface geology.

This study shows that the contrast in tectonic regime between primarily strike-slip faulting in northern Tibet and dominantly normal faulting in southern Tibet requires mechanical coupling between the upper crust of southern Tibet and the underthrusting Indian crust. Such coupling is inconsistent with the presence of active ‘channel flow’ beneath southern Tibet, and indicates that the Indian crust retains its strength as it underthrusts the plateau.

Slip on a subduction megathrust can occur during an earthquake or aseismically. The size, location and frequency of earthquakes that a megathrust can generate depend on where and when aseismic creep is taking place, and what fraction of the long-term slip it accounts for. Here this issue is addressed by looking at the central Peru megathrust, and specifically at the Pisco earthquake of 2007. The findings show that aseismic creep accounts for 50–70% of the slip budget on the seismogenic portion of the megathrust.

Faults are unlocked by earthquakes. Analysis of seismic data from the 2015 Nepal earthquake shows that only part of the Main Himalayan Thrust fault was unzipped by the quake, leaving much of the fault locked and ready to slip in a future event.

The February 2023 Kahramanmaraş earthquake doublet reveals how pre-stress and local stress heterogeneity influence fault ruptures, with key insights into rupture kinematics, fault geometry, and stress interactions along complex fault systems.

Analysis of the sub-seasonal patterns of river migration reveals that permafrost reduces erosion rates and suggests that full permafrost thaw may lead to a 30–100% increase in the migration rates of Arctic rivers.

The Earth’s mantle viscosity is studied following a deep earthquake located near the bottom of the upper mantle, and a weak layer is detected that is consequential to the understanding of mantle dynamics.

Thirty years of geothermal heat production at Coso in California depleted shear stresses within the geothermal reservoir, which changed its faulting style and inhibited aftershocks from the 2019 Ridgecrest earthquake.

A transition from rate-weakening to rate-strengthening frictional behaviour with increasing slip rate could explain the observed diversity of slow slip events on faults, according to numerical simulations.

The authors here investigate in the 2019 Ridgecrest earthquakes in Searles Valley, California. Based on geodetic and seismological data, the authors separate the event into two earthquakes (Mw 6.5 and 7.1) and produce kinematic slip models of the event.

There is increasing evidence that the seismicity of large Himalayan earthquakes can be bimodal, but the underlying mechanisms are unclear. Here, the authors present a model and show that the bimodal seismicity results from a relatively higher friction and a non-planar geometry of the Himalayan megathrust.