Geothermal power is a growing energy source; however, efforts to increase production are tempered by concern over induced earthquakes. Although increased seismicity commonly accompanies geothermal production, induced earthquake rate cannot currently be forecast on the basis of fluid injection volumes or any other operational parameters. We show that at the Salton Sea Geothermal Field, the total volume of fluid extracted or injected tracks the long-term evolution of seismicity. After correcting for the aftershock rate, the net fluid volume (extracted-injected) provides the best correlation with seismicity in recent years. We model the background earthquake rate with a linear combination of injection and net production rates that allows us to track the secular development of the field as the number of earthquakes per fluid volume injected decreases over time.

Three‐dimensional near‐fault coseismic deformation fields from high‐resolution differential topography provide new information on the behavior of the shallow fault zone in large surface‐rupturing earthquakes. Our work focuses on the 16 April 2016 Mw 7.0 Kumamoto, Japan, earthquake, which ruptured ~40 km of the Futagawa‐Hinagu Fault Zone on Kyushu Island with an oblique strike‐slip mechanism and surface offset exceeding 2 m. Our differential lidar analysis constrains the structural style of strain accommodation along the primary fault trace and the surrounding damage zone. We show that 36 ± 29% and 62 ± 32% of the horizontal and vertical deformation, respectively, was accommodated off the principal fault trace. The horizontal strains of up to 0.03 suggest that the approximate elastic strain limit was exceeded over a ~250 m width in many locations along the rupture. The inelastic deformation of the fault volume produced the observed distributed deformation at the Earth's surface. We demonstrate a novel approach for calculating 3‐D displacement uncertainties, indicating errors of centimeters to a few decimeters for displacements computed over 50 m horizontal windows. Errors correlate with land cover and relief, with flatter agricultural land associated with the highest displacement uncertainty. These advances provide a framework for future analyses of shallow earthquake behavior using differential topography.

A key paradigm in seismology is that earthquakes release elastic strain energy accumulated during an interseismic period on approximately planar faults. Earthquake slip models may be further informed by empirical relations such as slip to length. Here, we use differential lidar to demonstrate that the Papatea fault—a key element within the 2016 Mw 7.8 Kaikōura earthquake rupture—has a distinctly nonplanar geometry, far exceeded typical coseismic slip-to-length ratios, and defied Andersonian mechanics by slipping vertically at steep angles. Additionally, its surface deformation is poorly reproduced by elastic dislocation models, suggesting the Papatea fault did not release stored strain energy as typically assumed, perhaps explaining its seismic quiescence in back-projections. Instead, it slipped in response to neighboring fault movements, creating a localized space problem, accounting for its anelastic deformation field. Thus, modeling complex, multiple-fault earthquakes as slip on planar faults embedded in an elastic medium may not always be appropriate.

The 1959 Mw ∼7.2 Hebgen Lake earthquake is among the largest continental normal faulting events recorded, as well as one of the earliest associated with a multifault rupture. Multimeter vertical slip was observed on three main, morphologically distinct strands: the Hebgen fault and southeastern section of the Red Canyon fault, which both follow sharp topographic rangefronts, and the Red Canyon fault Kirkwood Ridge section, which cuts steep topography in the footwall of the Hebgen fault. We augment early field, seismological, and geodetic studies by investigating the modern surface rupture using newly acquired airborne lidar topography. By estimating throw from scarp profiling of the ∼36.5 km primary surface rupture, we show both that peak 1959 slip occurred at a structurally mature part of the fault and that many 1959 slip minima are associated with clear structural complexities. Vertical slip often substantially exceeds throw measured at the fault free face immediately after the earthquake; the scarps do not conclusively express beveled forms characteristic of repeated slip and degredation, yet must in places capture both the 1959 earthquake (for which we estimate an average throw of 2.64 m) and one or two preceding latest Pleistocene–Holocene events known from trenching. This has wider, cautionary implications for interpreting paleo‐earthquake chronologies and deriving magnitudes from morphologically simple scarps. By comparing 1959‐only and multievent vertical displacement populations, and considering preliminary paleoseismic data, we suggest that large surface‐rupturing earthquakes on the Hebgen and Red Canyon faults involve highly variable slip distributions.

We investigate the 4 April 2010 M w 7.2 El Mayor-Cucapah (Mexico) earthquake using three-dimensional surface deformation computed from preevent and postevent airborne lidar topography. By profiling the E-W, N-S, and vertical displacement fields at densely sampled (∼300 m) intervals along the multisegment rupture and computing fault offsets in each component, we map the slip vector along strike. Because the computed slip vectors must lie on the plane of the fault, whose local strike is known, we calculate how fault dip changes along the rupture. A principal goal is to resolve the discrepancy between field-based inferences of widespread low-angle (<30 ∘ ) oblique-normal slip beneath the Sierra Cucapah, and geodetic and/or seismological models which support steeper (50 ∘ -75 ∘ ) faulting in this area. Our results confirm that low-angle slip occurred along a short (∼2 km) stretch of the Paso Superior fault-where the three-dimensional rupture trace is also best fit by gently inclined planes-as well as along shorter (∼1 km) section of the Paso Inferior fault. We also characterize an ∼8-km fault crossing the Puerta accommodation zone as dipping ∼60 ∘ NE with slip of ∼2 m. These results indicate that within the northern Sierra Cucapah, deep-seated rupture of steep faults (resolved by coarse geodetic models) transfers at shallower depths onto low-angle structures. We also observe a statistically significant positive correlation between fault dip and slip, with slip pronounced along steep sections of fault and inhibited along low-angle sections. This highlights the important role of local structural fabric in controlling the surface expression of large earthquakes.