The San Diego Area Took the Largest EQ in 120 Years! Big Deal or Not?

stock here: I guess it is kind of a big deal. But if you expand the area out to the true fault line and up there have been much larger quakes, but usually in sparely populated areas.

At the far bottom A-Eye gave me some 3D modeling work that was done after the 7.2 Landers Earthquake in 1992. It’s fairly interesting, yet their ability to predict quakes is amazingly inadequate.

Below is since 1905, 5.0 and up

Yes, the 1992 Landers earthquake caused significant damage, although the area it struck was relatively sparsely populated, which limited the impact compared to what might have occurred in a more urban area.
Key Facts:

Date: June 28, 1992

Magnitude: 7.3

Location: Near Landers, Southern California (San Bernardino County)

Damage Overview:
Type Description
Buildings Over 1,000 structures were damaged. The worst hit were unreinforced masonry buildings, mobile homes, and older wood-frame structures.
Infrastructure Roads cracked, power lines were downed, and water lines were broken. Highway 247 buckled in places.
Utilities Widespread power outages and disruption of water service occurred in many desert communities.
Ground Rupture Surface faulting occurred along several faults, with ruptures extending over 50 miles. Maximum offsets were over 18 feet in some locations.
Casualties 1 person died (a heart attack attributed to the quake), and over 400 were injured.
Aftershocks Thousands followed, including the M6.5 Big Bear earthquake just 3 hours later, which caused additional damage.
Notable Impacts:

The Marine Corps Air Ground Combat Center at Twentynine Palms sustained structural damage.

Parts of Joshua Tree and Yucca Valley experienced shaking that damaged homes and businesses.

Scientists and emergency response agencies used the event as a major case study in interconnected fault systems and triggered seismicity.

Seismic modeling of the 1992 Landers earthquake has significantly advanced our understanding of complex fault interactions and rupture dynamics.​
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1. Dynamic Rupture Modeling on Nonplanar Faults

Researchers employed three-dimensional boundary integral equation methods to simulate the Landers earthquake’s rupture process. By incorporating realistic, nonplanar fault geometries—including bends and branches—they successfully reproduced key features such as spontaneous rupture transfer between faults, slip distribution patterns, and rupture propagation without assuming lateral heterogeneity in fault properties. ​
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2. Co-Seismic Slip Distribution

A model derived from GPS-based surface displacement data revealed that most slip occurred within the upper 10–12 km of the crust. Significant slip was concentrated on the Johnson Valley, Homestead Valley, Emerson, and Camp Rock faults. This model aligned well with observed surface displacements and highlighted the complexity of multisegment fault ruptures. ​
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3. Physics-Based Dynamic Simulations

High-performance computing facilitated the development of dynamic rupture models that integrated fault geometry, stress conditions, and material properties. These simulations provided insights into rupture speed, energy release, and ground motion patterns, enhancing our ability to predict strong ground motions in similar tectonic settings. ​

4. Bayesian Inversion Techniques

Advanced Bayesian inversion methods combined multiple data sources to produce detailed co-seismic slip models. This approach offered a probabilistic framework to assess uncertainties in fault behavior and rupture characteristics, contributing to more robust seismic hazard assessments. ​
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These seismic modeling efforts have not only deepened scientific understanding of the Landers earthquake but also informed seismic hazard assessments and preparedness strategies in tectonically active regions.