Intense seismic activity in the U.S.: record of tremors between January 29 and 30

In the United States, earthquakes are recurring natural phenomena that affect various regions of the country. During the last 24 hours recorded by the United States Geological Survey (USGS), significant seismic events were documented and monitored by geology experts. Friday, January 30, and Thursday, January 29, were days of considerable tectonic activity, with earthquakes of varying magnitudes scattered across national territories and adjacent regions.

Overview: How many earthquakes were recorded and where

The USGS interactive mapping platform documented a total of 27 seismic movements in North America and the Caribbean with magnitudes greater than 2.5 during this period. Of these events, nine occurred within U.S. territory and its associated areas, mainly concentrated in Alaska, island territories, and western and central states.

The strongest recorded tremor was a magnitude 4.2 located eight kilometers from Black Eagle in Montana, representing the most notable event during this seismic sequence. This event highlights the persistence of tectonic activity in specific regions of the country.

Detected earthquakes in order of intensity and geographic distribution

Main event — Montana:

• Location: 8 kilometers northeast of Black Eagle
• Magnitude: 4.2
• Date and time: January 29, 19:41 UTC (12:41 PM in Helena)

Moderate tremors in Alaska and the Southwest:

Alaska recorded most of the events, distributed as follows:

• 74 kilometers north of Yakutat: magnitude 3.7 (January 29, 22:59 UTC)
• 94 kilometers north of Yakutat: magnitude 3.5 (January 29, 18:37 UTC)
• 61 kilometers east of Sand Point: magnitude 3.5 (January 29, 21:01 UTC)
• 59 kilometers southeast of Sand Point: magnitude 3.3 (January 29, 20:25 UTC)
• 40 kilometers east of Pedro Bay: magnitude 3.0 (January 30, 02:07 UTC)
• 194 kilometers southeast of Akutan: magnitude 3.1 (January 30, 02:02 UTC)
• 23 kilometers west of Akhiok: magnitude 2.8 (January 30, 11:52 UTC)
• 28 kilometers northwest of Happy Valley: magnitude 2.6 (January 30, 11:44 UTC)
• 47 kilometers northwest of Valdez: magnitude 2.6 (January 29, 15:16 UTC)
• 64 kilometers southeast of Adak: magnitude 2.6 (January 29, 13:21 UTC)
• 288 kilometers southwest of Adak: magnitude 3.8 (January 29, 12:57 UTC)

Southwest zone — Oregon:

• 259 kilometers southwest of Pistol River, Oregon: magnitude 3.5 (January 30, 05:30 UTC, corresponding to 9:30 PM on January 29 in Salem)

Central region — Colorado, New Mexico, and Texas:

Colorado experienced two earthquakes:

• 29 kilometers south of Weston: magnitude 2.8 (January 30, 11:06 UTC)
• 32 kilometers southwest of Segundo: magnitude 2.5 (January 30, 11:06 UTC)

New Mexico:

• 32 kilometers north of Cimarrón: magnitude 3.9 (January 30, 07:20 UTC)

Texas recorded three events:

• 12 kilometers west of Stanton: magnitude 2.7 (January 30, 07:25 UTC)
• 35 kilometers northwest of Toyah: magnitude 2.5 (January 29, 18:32 UTC)
• 10 kilometers southeast of Pearsall: magnitude 2.6 (January 29, 17:02 UTC)

Puerto Rico and Caribbean region:

• 5 kilometers east-southeast of Maricao, Puerto Rico: magnitude 3.1 (January 30, 07:53 UTC)
• 133 kilometers northeast of Vieques, Puerto Rico: magnitude 3.3 (January 29, 16:41 UTC)

Other events:

• 5 kilometers northwest of Malmstrom Air Force Base, Montana: magnitude 2.7 (January 30, 00:46 UTC)
• 104 kilometers southeast of McCarthy, Alaska: magnitude 3.1 (January 29, 18:36 UTC)

The threat of the Big One and the San Andreas Fault

The San Andreas Fault is a crucial geological structure extending approximately 1,300 kilometers across California, delineating the boundary between the Pacific Plate and the North American Plate. This zone represents an area of constant seismic movement and is under continuous scientific surveillance.

Experts warn of the possibility of a megathrust earthquake of magnitude 8 or higher, colloquially known as the “Big One.” An event of this magnitude could cause widespread devastation across large territories, particularly affecting densely populated urban areas like Los Angeles and San Francisco, where millions of people would face significant risks.

Historically, two major earthquakes have marked this region: the 1906 San Francisco earthquake, which reached magnitude 7.8, and the 1857 Fort Tejon earthquake, with magnitude 7.9. These events, documented by USGS archives, provide perspective on the potential destructive capacity of future seismic movements.

In response to these threats, California authorities continuously conduct emergency drills, evaluate structural safety protocols, and run public education campaigns. These initiatives aim to prepare the population for preventive actions before an earthquake, safe conduct during the event, and response procedures afterward. Public awareness is essential to minimize risks and safeguard lives should another significant quake shake the region.