Puerto Vallarta, Jalisco — The Jalisco State Civil Protection and Firefighters Unit (UEPCBJ) reported a spike in seismic activity off the state’s coast, recording 12 earthquakes along the Rivera Fracture in just 24 hours. Three quakes registered at or above magnitude 5.4, while the rest fell between magnitudes 4.3 and 5.4.
Most events struck late Tuesday and into early Wednesday at the northwest end of the Rivera Fracture, a right-lateral transform fault that runs parallel to the Jalisco coast. Seismometers placed by the Jalisco State Seismic Network (Resjal) detected three moderate shocks measuring 5.8, 5.9, and 5.4, along with nine smaller tremors. All occurred roughly 375 kilometers offshore, near the maritime zones of Tomatlán, Cihuatlán, and La Huerta.
“In this last period alone, 12 earthquakes have been recorded, including three moderate magnitude events of 5.8, 5.9, and 5.4, as well as several more with magnitudes between 4.3 and 5.4,” said UEPCBJ Director Erika Martínez. She added that none of the quakes triggered tsunami warnings or coastal alerts, given their depth and distance from shore.
Geologists note that the Rivera Fracture lies at the boundary of the Rivera and Pacific tectonic plates. The fault moves horizontally, carrying one plate past the other. Scientists have monitored it for decades and describe its behavior as “persistent,” with occasional bursts of activity followed by lulls.
The National Seismological Service (SSN) corroborated Resjal’s data, confirming that the recent swarm matches the fault’s typical pattern. “We see clusters like this every few years,” said SSN seismologist Luis Ortega. “They reflect stress release along the plate boundary. Unless the pattern changes dramatically, coastal communities remain safe.”
State Civil Protection spokesperson Carlos Vega reminded residents that the events pose no direct threat to Jalisco’s shoreline. “All indicators show these quakes occur too far offshore to cause damage or generate tsunamis,” he said. Vega urged businesses and families to focus on routine preparedness: secure heavy furniture, keep emergency kits, and know evacuation routes just as a precaution.
Local fishermen reported feeling mild vibration onboard their vessels but noted no damage. “We heard the radio chatter and felt two jolts, but everything stayed calm,” said captain Mariana López, who operates a charter near La Huerta. “We keep an eye on alerts, but this one didn’t worry us.”
The UEPCBJ’s scientific team runs continuous monitoring stations across Jalisco’s coast. They feed real-time data to Resjal and the SSN, ensuring any abnormal shifts trigger immediate review. Earlier this year, the team upgraded three ocean-bottom sensors to improve quake localization and magnitude estimates.
Experts stress that understanding the Rivera Fracture’s rhythm helps communities plan for future events. While most quakes occur too far offshore to harm people, a significant shift closer to shore could pose risks. To guard against that, the Jalisco State Civil Protection and Fire Department holds quarterly drills simulating offshore tremors and minor tsunami scenarios.
Since 2022, Resjal has logged five similar swarms along the Rivera Fracture, each lasting two to three days. Those clusters never escalated into major hazards. Still, scientists track every event to refine their models.
Residents along the Jalisco coast may notice increased chatter online about this latest swarm, but officials stress that the quake count alone doesn’t signal an escalation. Instead, they view it as a normal uptick in long-term regional seismicity. “We expect these swarms every few years,” said geologist Adriana Pérez of the University of Guadalajara. “They remind us of the tectonic forces at work, but they don’t spell danger for beach towns.”
For now, the UEPCBJ will keep its monitoring gear active and update the public if conditions change. Visitors planning coastal trips should use official channels for the latest information. As always, the best defense lies in awareness and preparation, not panic.
Puerto Vallarta, Jalisco — The Jalisco State Civil Protection and Firefighters Unit (UEPCBJ) reported a spike in seismic activity off the state’s coast, recording . . .
