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The Raton Basin of Southern Colorado and Northern New Mexico experienced a significant increase in seismicity over the last several decades, including two M5+ earthquakes. The increase in seismicity started soon after an increase in wastewater disposal associated with coal‐bed methane production. Twenty‐nine wastewater injection wells have operated in the Basin, with several high‐rate injectors located within a kilometer of the most seismically active regions. We developed a pore pressure model to investigate the relationship between pore pressure diffusion and onset of induced seismicity, with an emphasis on the Trinidad fault zones. Our model indicates that sufficient pore pressure increase had accumulated on the northern extent of the Trinidad fault zone to induce seismicity at the time of early‐stage seismic activity. The hydrogeologic architecture of the Basin played a key role in controlling pore pressure perturbation. The basal sedimentary interval with moderately low diffusivity restricted vertical pore pressure diffusion, creating a substantial lag time between wells becoming active and the expression of perturbation in the fault zones. The spatiotemporal relationship between early‐stage seismicity and wastewater injection in conjunction with modeled pore pressures suggests that the early‐stage seismicity in the Raton Basin was likely triggered by pore pressure diffusion. Plain Language Summary: In the Raton Basin, coal‐bed methane production sparked the need for deep wastewater disposal starting in 1994. Prior to wastewater injection few earthquakes were recorded within its boundaries but a large increase in earthquakes has been recorded over the last several decades. Pore pressure increase, caused by the deep wastewater injection, is thought to be the reason for the increase in local earthquakes. We developed a model to estimate pore pressure increases on several fault zones that have recently exhibited increased earthquake frequency. We found that wastewater injection produced increases in pore pressure on the fault zones large enough to cause earthquakes. This suggests that increased seismicity is, at least in part, the result of pore pressure change caused by deep wastewater injection. Key Points: Pore pressure change between 0.007 and 0.03 MPa initiates the onset of induced seismicity on the Trinidad fault zoneThe basal sedimentary interval restricted pore pressure diffusion, limiting the impact of high‐rate injection wells in the short termThe depth varying permeability of crystalline basement effects the manner and magnitude of pore pressure diffusion into basement faults [ABSTRACT FROM AUTHOR]

The 2019 Ridgecrest earthquake sequence manifested as one of the most complex fault surface ruptures observed in California in modern times. The M6.4 foreshock and M7.1 mainshock occurred on an intricate network of orthogonal and sub‐parallel faults resulting in observable surface displacement and surface rupture captured by geodetic data. Here we present the application of a high‐resolution 3D finite element model (FEM) approach to invert for the detailed fault slip of the entire sequence using complex rheology and fused coseismic Global Navigation Satellite System (GNSS) data with Sentinel‐1 differential interferometric synthetic aperture radar and pixel offset data. The heterogeneous FEM and the fused geodetic data set of pixel offsets, interferograms, and GNSS data results in our optimal inversion solution. This preferred solution is a complex, high‐resolution non‐planar slip model of both the M6.4 and M7.1 events that features three main regions of large slip (6.9+ m), with depths ranging from 2 to 10 km. The regions of slip are bounded by the mainshock hypocenter and the mainshock aftershocks and appear to be related to spatially varying rheological properties. We successfully reproduce a localized region of observed subsidence in the northern portion of the primary fault through the inclusion of a curved fault strand with a significant dip‐slip component. The curved fault strand is the site of our maximum slip of 7.4 m at a depth of 4.2 km. The results demonstrate a robust fit from a more complete, detailed model for the entire seismogenic zone with reasonable computational cost, providing new insights into the governing rheologic and structural processes. Plain Language Summary: The 2019 Ridgecrest, California earthquake sequence consisted of two main earthquakes: the M6.4 foreshock and the M7.1 mainshock. Understanding the structure and behavior of the faults responsible for these earthquakes is important to earthquake hazard and forecasting. We construct a complex 3D model representing the earth's interior at the location of the Ridgecrest earthquake using triangular building blocks. By combining Global Positioning System and different microwave remote sensing data, we produce a detailed map of how the ground deformed, even close to the faults. We use this deformation map to fine tune our 3D model and determine in which direction and by how much the faults moved during the M6.4 and M7.1 earthquakes. We find that the faults had large movement of almost 7 m in three regions at depths of 2–10 km. The largest movement of 7.4 m occurs north of the mainshock at an offshoot of the main fault where our mapped deformation shows the ground sinking. The locations of large fault movement coincide with regions of low aftershock activity and particular earth material. Key Points: High resolution finite element model with complex rheology and fused synthetic aperture radar‐Global Navigation Satellite System data produces a more complete fault slip model at all depthsMagnitude and extent of maximum slip regions surrounding the hypocenter persist for both homogeneous and heterogeneous rheology typesMaximum slip is bounded by mainshock hypocenter, aftershocks, decreased Poisson's ratio bodies, and the seismogenic zone [ABSTRACT FROM AUTHOR]