by Robert Marcos, photojournalist
Last week the University of Hawaiʻi at Mānoa released a study that reported that tectonic stress along the San Andreas and San Jacinto faults had reached its highest levels in 1,000 years.1
Key Findings of the Report
Critical State: The research, published in the Journal of Geophysical Research: Solid Earth, reveals that stress levels have accumulated to unprecedented heights because more than 160 years have passed since the region’s last major fault rupture. 2
The “Earthquake Gate”: Scientists identified the Cajon Pass—where the two fault lines intersect—as a critical junction. This area could either halt a rupture or facilitate a massive joint rupture across both systems simultaneously, creating a significantly more destructive earthquake than a single-fault event. 3
Impact Areas: A dual-fault rupture would severely threaten densely populated Southern California regions, including Los Angeles, San Bernardino, Riverside, and the Coachella Valley. 4
Expected Physical Damage
The San Andreas Fault bisects the city of Coachella. The section of the fault that extends through Coachella has a high probability of rupturing in the next 30 years. The resulting earthquake will be accompanied by extreme seismic shaking and lateral rupture of the ground that locally may exceed 20 feet. Other earthquake-induced hazards expected in the area include ground deformation due to liquefaction and slope failure. Earthquake scenarios indicate the infrastructure in the region will be damaged extensively by an earthquake on the San Andreas Fault. The water-distribution system especially will be hard-hit but other services, including the transportation network, will also be affected. The Coachella Canal is expected to be damaged by surface fault rupture and ground deformation, with the potential for significant flooding in the Coachella area.5
Hazards for Water Conveyance Systems
The All-American Canal and its 123-mile branch, the Coachella Canal, form a critical water delivery system for southern California’s desert agriculture. However, this infrastructure faces several severe structural, environmental, and public safety threats. 6
San Andreas Fault Proximity: The Coachella Canal directly crosses seismically active zones. Regional hazard models indicate that a major earthquake on the San Andreas Fault is expected to cause severe surface fault ruptures and ground deformation. 7
Catastrophic Flooding: Damage to the canal walls from an earthquake could instantly breach the concrete system, causing rapid, severe flash flooding in surrounding residential and agricultural areas of the Coachella Valley. 8
Immediate Drowning and Public Safety Hazards
The Deadly Trap”: The canals pose a massive public safety threat, with well over 140 recorded drownings in the Coachella Canal alone. While the water surface often looks calm, the internal currents are incredibly swift (moving at several feet per second) with powerful undertows. 9
Impassable Features: The canals feature steep, slick concrete walls that make it nearly impossible for a person or animal to climb out once they fall in. They also contain hidden underwater tunnels called “siphons” and automated water-delivery equipment that can trap and drown victims instantly. 10
Smuggler Exploitation: Because the All-American Canal runs parallel to the US – Mexico border, criminal cartels and human smugglers frequently force migrants into the dangerous currents to evade law enforcement, routinely resulting in fatalities. 11