5/28/2015 — Earthquake swarm strikes West Coast Dormant Volcano near San Diego – Baja California MX

A new swarm of earthquakes has developed near a dormant volcano in South California / North Mexico along the Mexicali border region.

The volcano in question is a dormant Butte named “Cerro Prieto”.  Clearly this volcano has a recent eruptive past (geologically speaking).

baja california dormant volcano cerro prieto earthquake may 28 2015


A closeup view of the volcano shows black basalt , and igneous rock fanning out from the cone of the butte.

Compared to other dormant butte volcanoes in the area, this cone appears to have erupted in the past few hundred years or less.

cerro prieto 1

Above: Cerro Prieto butte volcano located in Baja California / North Mexico. Seeing multiple earthquakes develop nearby this location (May 28, 2015).


This dormant volcanic movement in Baja California follows other movement which occurred at another series of dormant volcanoes up the West coast over the past few days.

Noteworthy earthquake activity occurred yesterday (May 27, 2015) in Northern, and Southern California.  Both sets of earthquakes near obvious volcanic locations.

black butte may 27 2015

Above: Black Butte volcano located in Northern California. May 27, 2015 saw earthquake activity near these dormant volcanic buttes.


This past week a series of earthquakes occurred along the West coast at dormant volcanoes.

The movement became obvious a few days ago, when a 5.4M (4.8 magnitude revised) earthquake struck at a series of dormant volcanic buttes near Las Vegas, Nevada.

In addition to this current activity, yesterday we saw another dormant volcano show movement in Baja California / North Mexico, just South of this Cerro Prieto earthquake epicenter.

This makes TWO dormant volcanoes in Baja Mexico struck in approximately 24 hours time, which is a fair amount of activity to see in a short burst of a few hours.

Seeing dormant volcanoes show movement in such a cluster (only across California into Baja) means the greater area is under pressure, and should watch for larger movement in the near term (next 3-5 days or less).


Information on the new swarm of earthquakes at Cerro Prieto Volcano from the USGS:


Magnitude/uncertainty 3.5 ml± 0.2
Location/uncertainty 32.239°N 115.276°W± 0.9 km
Depth/uncertainty 11.6 km± 1.0
Origin Time 2015-05-28 12:13:41.720 UTC
Number of Stations 23
Number of Phases 25
Minimum Distance 20.18 km (0.18°)
Travel Time Residual 0.23 sec
Azimuthal Gap 119°
FE Region Baja California, Mexico (45)



Magnitude/uncertainty 3.3 ml± 0.2
Location/uncertainty 32.236°N 115.289°W± 1.1 km
Depth/uncertainty 3.8 km± 3.2
Origin Time 2015-05-28 12:04:00.220 UTC
Number of Stations 25
Number of Phases 29
Minimum Distance 20.37 km (0.18°)
Travel Time Residual 0.3 sec
Azimuthal Gap 93°
FE Region Baja California, Mexico (45)


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