Crustal movement and stress rates in the Southern Basin and Field

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The Basin and Range Province in North America is home to some of the most extreme environments on the continent, including Death Valley. Stretching from the Wasatch Mountains in Utah to the Sierra Nevada in California and to northwestern Mexico, this region experiences near-constant drought and intense summer heat.

The basin and range province is also seismically active. For example, the 1887 Sonoran earthquake in the southern basin and range caused severe damage and dozens of deaths. However, deformation rates in the southern basin and ridge are difficult to determine due to the lack of small faults and infrequent seismic events. Moreover, the San Andreas and Gulf of California fault systems adjacent to the Pacific and North American plate boundaries could mask stress rates in the southern basin and field.

In a new paper, Broermann et al. The deformation was detected in a large area including Arizona, New Mexico, southern parts of Utah and Colorado, within the Southern Basin and the Colorado mountain range. The authors observed crustal motion using the EarthScope Plate Boundary Observary. An array of GPS sensors, seismometers, and other instruments monitor the seismology and underlying plate tectonics of North America. The authors used the data to develop models of cortex surface velocity and stress rates in the study area. They conclude that stress accumulated in the crust is the primary driver of future continental earthquakes.

The authors separated the effects of plate boundary and fluctuating effects of seismic and seismic distortion on stress rates in the region. The results revealed three distinct regions with unique characteristics: a western region, an eastern region, and the inner massif of the Colorado Plateau. Each region varies in the rate of stress and movement it experiences, which can affect the likelihood of future earthquakes. For example, the western region has higher stress rates and an approximately east-west major axis. In contrast, the eastern region has lower stress rates and a west-southwest orientation axis.

The highest stress in the study area includes southwestern Arizona, an extension with scattered faults and low seismicity. The high stress rate in the region may indicate the potential for large-scale earthquakes in the future, although stress accumulation may be reduced by other processes. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2020JB021355, 2021)

– Aaron Seder, science writer

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