Unusually powerful M4.0 Earthquake struck on Thursday Afternoon near San Antonio in The United States.

Written by Earthquakelist.org on September 14th, 2023. Last updated November 13th, 2023.

In the early afternoon of Thursday September 14th, 2023, an unusually powerful MAG-4.0 earthquake hit under land 45 miles from San Antonio in The United States. The USGS has indicated there is a potential risk at tsunami's following this earthquake. Another country near the epicenter is Mexico.

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Earthquake Summary

The earthquake struck on land in The United States, 45 miles (72 km) east-southeast of San Antonio in Texas. The center of this earthquake had a very shallow depth of 3 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time:	Sep 14, 2023 01:50PM (Chicago Time) - Sep 14, 2023 18:50 Universal Time.
Location:	45 mi ESE of San Antonio, Texas, The United States. Coordinates 29°4'31"N 97°51'53"W.
Map:	Map of area around epicenter. Click to open in Google Maps.
Magnitude:	MAG 4.0 Detected by 8 stations. Maximum Error Range ±0.045 .
Depth:	3 mi (5 km) A very shallow depth.
Max. Intensity:	V Moderate On the Modified Mercalli Scale.
Tsunami Risk:	Potential tsunami risk The USGS has indicated there is a potential risk at tsunami's following this earthquake. Always stay cautious - More info here.

Potential tsunami risk

There is a potential tsunami risk in the aftermath of this earthquake, immediately evacuate to higher grounds away from coastal areas and monitor advice from local authorities. The US Geographic Survey organization has indicated a potential risk for tsunami's following this earthquake.

Tsunami Risk Factors

Minimal impact predicted

Based on scientific estimates by the US Geographic Survey (USGS), the risk of high fatalities for this earthquake is classified at level GREEN (low). They expect an 65% likelyhood of between 0 and 1 fatalities, and a 96% chance that the number of fatalities falls no higher than 10.

The USGS classifies the economic impact of this earthquake at level GREEN (low). They expect an 65% likelyhood of between 0 and 1 million US Dollars in economic damage and impact, and a 96% chance that the economic impact of this earthquake falls no higher than 10 million USD.

Roughly 7.3 million people exposed to shaking

This earthquake may have been felt by around 7.3 million people. That is the expected population size of the area exposed to a level of shaking of II or higher on the Modified Mercalli scale according to the USGS.

The highest earthquake impact level for this earthquake is V, which corresponds with moderate shaking and very light damage. Roughly 0 people are expected to be exposed to this level. Intensity level III was experienced by the majority of people (around 5.8 million). In their region, weak shaking and probably no damage can be expected. All exposure to shaking was within the borders of Mexico .

Nearby towns and cities

2 countries can be found within 300km of the epicenter of this earthquake: The United States and Mexico .

Located 35 miles (56 km) south of the epicenter of this earthquake, Seguin (Texas, The United States) is the nearest significant population center. Seguin experienced an earthquake intensity (MMI Scale) of roughly III. That level implies weak shaking and probably no damage.

Multiple large cities are in proximity of today's earthquake. San Antonio is located 45 mi to the west-northwest and experienced an intensity of III (weak shaking, probably no damage). Houston is located 158 mi to the east-northeast (intensity unknown, possibly low). Austin is located 83 mi to the north and experienced an intensity of III (weak shaking, probably no damage).

An overview of nearby towns and cities is available in the overview below. If places don't have intensity data available, it likely means the experienced impact in those places was fairly small.

Overview of nearby places

Earthquake Intensity Map

The maximum intensity (MMI Scale) caused by this earthquake is V. The map below shows in which areas this earthquake was the most and least impactful. It is based on data from the US Geographic Survey.

I Not felt

II Weak

III Weak

IV Light

V Moderate

VI Strong

VII Very Strong

VIII Severe

IX Violent

X Extreme

Aftershocks detected

Since this main shock, 1 smaller aftershock was detected. Just 17 hrs after this main shock, an earthquake measuring MAG-3 was detected 4 mi (6 km) southwest of this earthquake.

Before this earthquake struck, 3 smaller foreshocks occurred. Roughly 3 days before this earthquake, a foreshock measuring MAG-3.2 was detected nearby this earthquake.

Overview of foreshocks and aftershocks

More earthquakes coming?

Earthquakes can create aftershocks. These are generally at least 1 magnitude lower than any main shock, and as time passes the chance and strength of aftershocks decreases.

In only six percent of cases, significant earthquakes are followed by a larger main shock, making the current earthquake a foreshock. While the chance of this happening is not so large, it is adviced to maintain cautiousness in the hours and days following a major earthquake.

This is the strongest earthquake in 5 years

Earthquakes of this strength are not so common in the region, but it's not the first time. This is the strongest earthquake to hit since May 1st, 2018, when a 4 magnitude earthquake hit 12 mi (19 km) further southwest. That was also the heaviest earthquake to hit the region in the past 10 years.

In total, 1 earthquake with a magnitude of 4 or higher have been registered within 300km (186 mi) of this epicenter in the past 10 years. This comes down to an average of once every 10 years.

Sources

Last updated 13/11/23 08:48 (). As more information on this earthquake becomes available this article will be updated. This article is automatically composed based on data originating from multiple sources.

1. US Geographic Society (USGS): Earthquake tx2023sbec
2. European-Mediterranean Seismological Centre (EMSC): Earthquake 20230914_0000168
3. Geonames.org: World Cities Database
4. Google Maps: Static API
5. Earthquakelist.org: Historic Earthquakes Database

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