306 people reported shaking from a 4.9 earthquake 9 km north of Delta, Baja California, near Mexicali

At 18:27 UTC on November 3, 2026, which was 10:27 a.m. in Baja California, a magnitude 4.9 earthquake struck 9 km north of Delta, Baja California. The U.S. Geological Survey counted 306 people who reported shaking through its citizen felt-report system. The epicenter lies roughly 35 to 40 kilometers southeast of central Mexicali, by straight-line distance from the published coordinates.

Help yourself and the planet: The Cool Down makes it easy to help yourself while helping the planet, with smart, simple changes to save more and waste less in your everyday life.

Get The Cool Down →

We may earn a commission if you sign up.

Alert levels stayed at the bottom of the scale. The agency rated the likelihood of damage as low with a green alert, and its landslide and liquefaction alerts were green as well.

Magnitude 4.89 at 15.6 kilometers depth

The USGS event page lists the quake as M 4.9, 9 km N of Delta, B.C., MX, and the reviewed solution from the Southern California network puts it at moment magnitude 4.89, latitude 32.4308 north and longitude 115.1797 west, at a depth of 15.59 kilometers. That solution used 71 phases from 57 stations with an azimuthal gap of 55 degrees. A separate solution from the agency’s national center, based on 116 phases from 107 stations, came out slightly lower at Mww 4.8 and shallower at 10.45 kilometers.

The magnitude-sorted USGS feed for the period beginning November 2 carries the same event with the same 4.89 value and the felt-report count of 306, alongside the alert color of green. The detailed record adds the source mechanics: a scalar moment of 2.401 times 10 to the 16th newton-meters, and a preliminary focal mechanism with one nodal plane striking 346 degrees and dipping 59 degrees, the other striking 245 degrees and dipping 72 degrees. Both planes show a mix of sideways and vertical slip, the pattern expected along the oblique plate boundary here. The record does not name a fault.

The agency’s ShakeAlert early warning system also appears in the record: the event is flagged as confirmed and activated for the quake. The record carries an aftershock forecast product as well, though the forecast figures themselves sit in a separate file.

306 felt reports and shaking near intensity 5

The 306 figure comes from the agency’s felt-report project, a citizen science effort in which people who experienced an earthquake describe what they noticed and how much damage they saw. Those answers are turned into maps of shaking. A count of 306 is a count of submitted responses, not of everyone who felt the ground move, because only a fraction of people in a shaken area ever fill in a form.

The reports averaged a community intensity of 5.4. Instrument-based estimates landed close by: the automatic ShakeMap from the Southern California network gave a maximum intensity of 4.98, the reviewed ShakeMap from the California Geological Survey gave 4.73, and the PAGER impact system listed a maximum of 5.0. Intensity 5 on the Modified Mercalli scale is generally described as moderate shaking that most people indoors notice, with objects rattling, which fits a magnitude 4.9 event at mid-crustal depth.

The ground-failure model, which estimates landslides and liquefaction, found a population exposure of zero for the event. Together with the green PAGER alert, that zero means the agency’s models expected no population to face damaging ground failure.

Mexicali and the Laguna Salada fault system’s 2010 quake

Seismologists watching this stretch of the border have a larger reference point. The USGS summary of the April 4, 2010 earthquake records a magnitude 7.2 event at 22:40 UTC about 50 km south-southeast of Mexicali, on a strike-slip segment that coincides with the southeastern part of the Laguna Salada fault system. Two people died and at least 233 were injured in the Mexicali area. The rupture began with east-down motion on faults at the eastern edge of the Sierra El Mayor and then ran northwest with oblique, right-lateral slip. Field geologists from the Mexican research center CICESE found surface rupture that offset Highway 2 by about 1.2 meters, and the agency called it the largest earthquake in the area since 1892, and its aftershock zone overlaps the section believed to have ruptured that year.

The same summary places the area in a plate boundary made of northwest-trending strike-slip faults separated by pull-apart basins, parallel to the San Andreas system, with the Pacific plate moving northwest relative to North America at about 1.8 inches per year. It also recalls the 1940 Imperial Valley earthquake, near magnitude 7, on the Imperial fault, and a magnitude 7.0 to 7.2 event on the Cerro Prieto fault in 1934. Nothing in the 2026 record ties the new quake to any of those faults.

The unresolved piece is the aftershock picture. A reviewed 4.9 at roughly 15 kilometers depth can be followed by smaller events in the days ahead, and the agency has published a forecast product for the sequence. Its numbers, not the 306 felt reports, will show whether this was a stand-alone jolt or the start of a busier stretch. The 306 count reflects the feed as read on November 3, and the USGS page lets people submit felt reports for a recent event, so the tally can change.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

Help yourself and the planet: Get The Cool Down →

We may earn a commission if you sign up.