On Monday Morning a Shallow M5.5 Earthquake struck in the South Pacific Ocean near Copiapó (Chile).

Written by Earthquakelist.org on September 11th, 2023. Last updated November 9th, 2023.

In the morning of Monday September 11th, 2023, a shallow and significant M5.5 earthquake hit in the South Pacific Ocean 86 kilometer from Copiapó, Chile. Around 300 thousand people have been exposed to shaking.

Earthquake Summary

This earthquake hit under water in the South Pacific Ocean, 23 kilometers (14 mi) off the coast of Chile, 86 kilometer west-northwest of Copiapó in Atacama. The center of this earthquake had a very shallow depth of 21 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time:	Sep 11, 2023 10:37 (Santiago Time) - Sep 11, 2023 13:37 Universal Time.
Location:	86 km WNW of Copiapó, Atacama, Chile. Coordinates 27°10'9"S 71°10'34"W.
Map:	Map of area around epicenter. Click to open in Google Maps.
Magnitude:	MAG 5.5 Detected by 14 stations. Maximum Error Range ±0.083 .
Depth:	21 km (13 mi) A very shallow depth.
Max. Intensity:	V Moderate On the Modified Mercalli Scale.
Tsunami Risk:	Low tsunami risk Earthquakes under MAG-6.5 do not usually cause tsunami's. Always stay cautious - More info here.

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 300 thousand people exposed to shaking

The USGS has published a report estimating the number of people exposed to this earthquake. Acoording to their analysis, roughly 300 thousand have been exposed to shaking at an MMI level of II or higher.

An estimated 10 people were exposed to level V. At this level, moderate shaking and very light damage can be expected. Intensity level III was experienced by the majority of people (around 270 thousand). In their region, weak shaking and probably no damage can be expected.

People in 2 countries have been exposed to shaking. Roughly 300 thousand people were exposed to shaking in Chile , with level V (moderate shaking, very light damage) as the highest recorded. Shaking was experienced by inhabitants of Argentina too.

People	MMI Level	Shaking	Damage
0	I	Not noticable	None
6,350	II	Very weak	None
274,300	III	Weak	Probably none
22,650	IV	Light	Likely none
10	V	Moderate	Very light
0	VI	Strong	Light
0	VII	Very Strong	Moderate
0	VIII	Severe	Moderate to heavy
0	IX	Violent	Heavy
0	X	Extreme	Very heavy

Nearby towns and cities

This earthquake may have been felt in Chile . The closest significant population center near the earthquake is Copiapó in Atacama, Chile. Copiapó is located 86 kilometer (53 mi) west-northwest of the epicenter. The intensity of shaking and damage in Copiapó is estimated to be around level III on the Modified Mercalli Intensity scale (weak shaking, probably no damage).

Overview of nearby places

Cities and Towns around the epicenter of this earthquake.
Distance	Place	Intensity (MMI)
86 km (53 mi) ESE from epicenter	Copiapó Atacama, Chile.	III Weak
142 km (88 mi) NE from epicenter	Diego de Almagro Atacama, Chile.	III Weak
162 km (101 mi) SSE from epicenter	Vallenar Atacama, Chile.	III Weak

Earthquake Intensity Map

The intensity in shaking and damage by this earthquake is illustrated through the map below. The highest intensity measured for this earthquake is V.

I Not felt

II Weak

III Weak

IV Light

V Moderate

VI Strong

VII Very Strong

VIII Severe

IX Violent

X Extreme

Earthquake Intensity Map based on Shakemap Data provided by USGS.

Shaking reported by 1 person

People that feel an earthquake may report their experience to the US Geographic Survey. Currently, 1 person has reported shaking in one place in Chile.We keep updating this article as more ground reports become available. You may report that you felt this earthquake here.

Places with most reports:

Copiapó, Atacama, Chile: 1 person.

13 Aftershocks detected

Since this main shock, 13 smaller aftershocks were detected. At a distance of 7 km (4 mi) south-east of this earthquake, an aftershock struck 2 days later. It measured a magnitude of 4.5

Before this earthquake struck, 2 smaller foreshocks occurred. Roughly 1 day before this earthquake, a foreshock measuring MAG-3.3 was detected nearby this earthquake.

Overview of foreshocks and aftershocks

Detected MAG2.5+ earthquakes within within 100km (62 mi), that occurred in the three days before and after the main shock.
Classification	Magnitude	When	Where
Foreshock	M 3.3	1 day earlier Sep 10, 2023 01:39 (Santiago Time)	6 km (4 mi) SSW from Main Shock.
Foreshock	M 2.6	7 hrs earlier Sep 11, 2023 03:34 (Santiago Time)	10 km (6 mi) WNW from Main Shock.
Main Shock This Earthquake	M 5.5	Sep 11, 2023 10:37 (Santiago Time)	-
Aftershock	M 2.6	19 mins later Sep 11, 2023 10:56 (Santiago Time)	8 km (5 mi) SSW from Main Shock.
Aftershock	M 2.6	1 hr later Sep 11, 2023 12:00 (Santiago Time)	2 km (1.2 mi) SE from Main Shock.
Aftershock	M 3.0	4 hrs later Sep 11, 2023 14:40 (Santiago Time)	12 km (7 mi) SW from Main Shock.
Aftershock	M 2.8	6 hrs later Sep 11, 2023 16:17 (Santiago Time)	13 km (8 mi) SW from Main Shock.
Aftershock	M 3.6	7 hrs later Sep 11, 2023 17:35 (Santiago Time)	12 km (7 mi) E from Main Shock.
Aftershock	M 2.7	10 hrs later Sep 11, 2023 21:03 (Santiago Time)	9 km (5 mi) E from Main Shock.
Aftershock	M 2.7	12 hrs later Sep 11, 2023 22:17 (Santiago Time)	14 km (8 mi) ENE from Main Shock.
Aftershock	M 2.6	17 hrs later Sep 12, 2023 04:06 (Santiago Time)	3 km (2.1 mi) N from Main Shock.
Aftershock	M 2.9	19 hrs later Sep 12, 2023 05:56 (Santiago Time)	9 km (5 mi) E from Main Shock.
Aftershock	M 2.5	22 hrs later Sep 12, 2023 08:57 (Santiago Time)	42 km (26 mi) E from Main Shock.
Aftershock	M 3.0	2 days later Sep 13, 2023 00:47 (Santiago Time)	5 km (2.9 mi) S from Main Shock.
Aftershock	M 4.5	2 days later Sep 13, 2023 21:50 (Santiago Time)	7 km (4 mi) SE from Main Shock.
Aftershock	M 3.5	3 days later Sep 14, 2023 09:20 (Santiago Time)	20 km (13 mi) SSE from Main Shock.

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.

Read: How to Stay Safe during an Earthquake (cdc.gov).

Earthquakes like this happen often in the region

Earthquakes of this strength are very common in the region. This is the strongest earthquake to hit since April 4th, 2023, when a 5.9 magnitude earthquake hit 36 km (22 mi) further south-east. An even stronger magnitude 6.9 earthquake struck on November 11th, 2015.

In total, 36 earthquakes with a magnitude of 5.5 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 3 months.

Low tsunami risk

DISCLAIMER: We strongly suggest to closely monitor advice from local authorities with regards to tsunami risks. Our analysis is based on automatically collected data from external sources, and these might contain mistakes. In addition, earthquakes can cause landslides that may lead to a tsunami, or be a followed by another, potentially stonger, earthquake.

Based on early data it appears this earthquake was not strong enough (lower than MAG-6.5) to be likely to cause destructive tsunami's. However this earthquake appeared to have hit at a shallow depth under sea, so stay cautious and monitor advice from local authorities.

Tsunami Risk Factors

Factor	Under Sea?	MAG-6.5 or stronger?	Shallow depth?
Explanation	Almost all tsunami's are caused by earthquakes with their epicenter under sea or very near the sea. However stay cautious in coastal areas as earthquakes on land may cause landslides into sea, potentially still causing a local tsunami.	Under MAG 6.5: Very unlikely to cause a tsunami. MAG 6.5 to 7.5: Destructive tsunami's do occur, but are uncommon. Likely to observe small sea level changes. MAG 7.6+: Earthquakes with these magnitudes might produce destructive tsunami's.	Most destructive tsunami's are caused by shallow earthquakes with a depth between 0 and 100km under the surface of the earth. Deeper tsunami's are unlikely to displace to ocean floor.
This Earthquake	This earthquake appears to have struck under the sea.	Not this earthquake. This earthquake had a magnitude of 5.5. Earthquakes of this strength are unlikely to trigger a tsunami.	This earthquake occurred at a depth of of 21 km (13 mi). Earthquakes this shallow could trigger a tsunami.

Sources

Last updated 09/11/23 14:18 (). 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.