Figure 2. This cross section is simplified from Tang et al. (2023) and depicts what’s happening underground at a location south of the April 2, 2024, magnitude 7.4 earthquake. Here, two thrust faults accommodate much of the 90 millimeters per year of tectonic contraction. This accommodation occurs by a combination of large earthquakes and aseismic creep (Thomas et al., 2014). Oddly, the faults join near the ground surface in the Longitudinal Valley, so as the Coast Range (to the east) and Central Range (to the west) are pushed upward, the triangular block between and beneath them is pushed downward. Just below the cross section, the Eurasian Plate is being subducted from the west, forming yet another surface on which large earthquakes can strike. Credit: Stein et al., 2024, CC BY-NC-ND 4.0