SOUTHERN CALIFORNIA, Sept. 14 (Our California Times) — Dozens of small earthquakes rattled parts of South Los Angeles over slightly more than 18 hours, according to earthquake records attributed to the U.S. Geological Survey. The events were recorded from about 8 p.m. Friday to about 2:30 p.m. Saturday, with reported magnitudes ranging from 1.0 to 2.7.
The activity was concentrated near Lennox and Westmont. Reports also named nearby Hawthorne and Inglewood, and residents in communities including Crenshaw, Huntington Park, Bell, West Adams, Mid-City and Gardena reported light shaking.
The sequence drew attention because it occurred near the Newport-Inglewood Fault Zone, a major fault system in the Los Angeles region. But the available information does not confirm that a mapped segment of that fault produced the earthquakes, and it does not establish that the swarm changed the region’s earthquake risk.
How many earthquakes occurred?
The count depends on which area and time period are included. Accounts citing USGS records described the activity as “dozens” of earthquakes. Other reports gave counts of 90 or 93 events, while broader counts mentioned more than 60 or more than 80 earthquakes in the Los Angeles region.
Those figures may not describe exactly the same group of earthquakes. The available reports do not show whether the counts used identical geographic boundaries, time windows, magnitude thresholds or versions of the USGS earthquake catalog.
For the Lennox and Westmont cluster, the reported magnitudes ran from 1.0 to 2.7. Earthquakes of that size are generally small, although an earthquake’s effects can vary depending on its depth, distance from buildings and local ground conditions.
What is an earthquake swarm?
An earthquake swarm is a group of earthquakes that occurs in a concentrated area over a relatively short period. Unlike a typical sequence dominated by one large mainshock followed by smaller aftershocks, a swarm may contain many small events without one clearly dominant earthquake.
The reported South Los Angeles activity fits the basic description of a swarm because many small events were recorded close together in time and location. That description does not, by itself, identify the fault that generated the earthquakes or predict what will happen next.
Was the Newport-Inglewood Fault Zone responsible?
The earthquakes were reported near the Newport-Inglewood Fault Zone, which runs through the Los Angeles region and continues toward Newport Beach before extending offshore, according to a Temblor background analysis based on USGS data.
The fault zone is described as a strike-slip system. In a strike-slip earthquake, blocks of Earth’s crust move mainly sideways past one another.
Proximity does not prove that the earthquakes occurred on that fault. One account specifically noted that the responsible fault or underground structure had not been confirmed. The information available for this event does not identify a named seismologist, a published analysis of the sequence or a direct determination of its fault plane.
Does the swarm signal a larger earthquake?
The available information does not support a specific forecast. A cluster of small earthquakes can be scientifically notable without providing a reliable indication that a larger earthquake is imminent.
No peer-reviewed study of this particular swarm, named research team, statistical analysis or confidence estimate was identified in the available material. As a result, the reported event count and location describe what was recorded, but they do not establish a cause-and-effect relationship between the swarm and any future earthquake risk.
A separate report mentioned a magnitude 3.2 earthquake near Compton days earlier, also near the fault zone. The available information does not include a direct USGS record or other official source confirming that event, so its relationship to the Lennox and Westmont sequence remains unestablished.
What is known about the effects?
Residents in several South Los Angeles communities reported light shaking. The available accounts do not establish injuries, property damage, an official hazard assessment or a change in earthquake forecasts tied to the swarm.
The clearest finding is narrower: USGS-attributed records show a concentrated burst of small earthquakes in the Lennox-Westmont area over a period of slightly more than 18 hours. The records place the activity near the Newport-Inglewood Fault Zone, but they do not, by themselves, identify the exact underground structure involved or demonstrate that the sequence altered the broader seismic hazard.
