On 8 September 2023 at 23:11 DST (22:11 UTC), an earthquake with a moment magnitude of 6.8–6.9 and maximum Mercalli intensity of IX ( Violent) struck Morocco's Marrakesh–Safi region. Listen to the shaking of the Landers Earthquake captured by seismometers in Parkfield, CA and Long Valley Caldera near Mammoth Lakes, CA.Main shock and aftershocks in Al Haouz Province, Marrakesh-Safi region – M 2.0 or greater ( map data)ģ1☀4′23″N 8☂4′25″W / 31.073°N 8.407°W / 31.073 -8.407 Listen to the shaking of the Landers Earthquake captured by seismometers in Parkfield, CA and Long Valley Caldera near Mammoth Lakes, CA. ![]() Lessons, Lore, and Legacies of the 1992 Landers Earthquake Where Earthquakes Hide in the Desert by Austin Elliot Scientific overview of the earthquake from Southern California Earthquake Data Center, including photos of the fault rupture. ScienceĪrticles from CALIFORNIA GEOLOGY™ magazine about the earthquake sequence and its effects, including numerous photos. These scientific developments continue to contribute directly to improved understanding of seismic hazard in southern California and beyond. Thanks to modern data availability and innovative analysis, the Landers earthquake, and the large earthquakes that followed, contributed important lessons to our understanding of earthquake ruptures and the complex interactions between earthquakes and faults. Thus, from 1992 onward, the eastern part of California has been especially seismically active. The Ridgecrest earthquakes in particular generated another bounty of data from monitoring networks that have grown more sophisticated since 1992. Then in 2019, the Ridgecrest area to the north of Landers was jolted by a M6.4 earthquake on 4 July, followed by a M7.1 earthquake on 5 July. On 16 October 1999, the M7.1 Hector Mine earthquake-another complex large earthquake in a remote part of the Mojave desert-struck to the west/northwest of the Landers rupture. ![]() Those aftershocks tapered off over time, but in the decades that followed, it became clear that the Joshua Tree-Landers-Big Bear sequence was only the beginning of a period of heightened regional activity in the area known as the Eastern California Shear Zone. The Landers mainshock was followed by many thousands of recorded aftershocks. Using the wealth of data it generated, the Landers sequence had many important lessons for earthquake science, lessons regarding the potentially complex nature of large earthquake ruptures, and how earthquakes trigger other earthquakes at both near and far distances. Seismology is a data-driven science, often fueled by observations of notable earthquakes. Over the weeks, months, and years that followed, researchers exploited the rich data sets collected from traditional networks, boots-on-the-ground mapping, portable instruments, and remote sensing imagery. In spite of these limitations, the Landers earthquake produced a bounty of new data. The launch of the USGS Did You Feel It? system was still seven years away (although observations of the earthquake can now be contributed retroactively!). Researchers rushed to their offices to analyze the quake, relying on paper topo maps to interpret data and plan fieldwork. The triggered earthquakes, which occurred at distances of up to 1250 kilometers (17 source dimensions) from the Landers mainshock, were confined to areas of persistent seismicity and strike-slip to normal faulting” -David Hill et al., Science, v 260, issue 5114, 1617-1623Ĭomputer technologies were relatively limited in 1992: with the web barely in its infancy, researchers had less sophisticated tools than they do now to analyze data and share results. Hough, USGS)įrom the earliest observations onward, it became clear that this was a complex sequence that included the primary mainshock (the M 7.3 Landers earthquake), a large foreshock (the M 6.1 Joshua Tree earthquake), many aftershocks including the M6.3 Big Bear event, and distant events that scientists dubbed remotely triggered earthquakes: “The magnitude 7.3 Landers earthquake of 28 June 1992 triggered a remarkable sudden and widespread increase in earthquake activity across much of the western United States. Shaking at this location was likely especially strong due to the proximity to the surface rupture and the local topography, which is known to amplify shaking. ![]() Structures in the desert near the town of Landers did, however, sustain serious damage. Damage from the Landers earthquake was relatively light given the magnitude (7.3) because the strongest shaking was concentrated in a relatively remote part of the Mojave Desert.
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