Written by on . Last updated April 16th, 2024.

In the late afternoon of Sunday March 31st, 2024, a shallow and significant MAG-5.5 earthquake hit in the South Pacific Ocean 158 kilometer from Nuku‘alofa, Tonga. Roughly 90 thousand people may have felt this earthquake.

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Earthquake Summary

This earthquake hit under water in the South Pacific Ocean, 147 kilometers (91 mi) off the coast of Tonga, 158 kilometer north-northwest of Nuku‘alofa in Tongatapu. The center of this earthquake had a very shallow depth of 10 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time: Mar 31, 2024 04:01PM (Tongatapu Time)
- Mar 31, 2024 03:01 Universal Time.
Location: 158 km NNW of Nuku‘alofa, Tongatapu, Tonga.
Coordinates 19°54'55"S 175°58'20"W.
Map: Map of area around epicenter.
Map of area around epicenter. Click to open in Google Maps.
Magnitude: MAG 5.5
Detected by 12 stations. Maximum Error Range ±0.089 .
Depth: 10 km (6 mi)
A very shallow depth.
Max. Intensity:
IV
Light

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 90 thousand people exposed to shaking

An estimated 90 thousand have been exposed to shaking (An MMI or Modified Mercalli Intensity level II or higher) as a result of this earthquake according scientific estimates published by the USGS.

The highest earthquake impact level for this earthquake is III, which corresponds with weak shaking and probably no damage. Roughly 93,260 people are expected to be exposed to this level.

People in 2 countries have been exposed to shaking. In Tonga , around 90 thousand people, with impact levels up to III (weak shaking, probably no damage).

People MMI Level Shaking Damage
0
I
Not noticable None
0
II
Very weak None
93,260
III
Weak Probably none
0
IV
Light Likely none
0
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 Tonga . The closest significant population center near the earthquake is Nuku‘alofa in Tongatapu, Tonga. Nuku‘alofa is located 158 kilometer (98 mi) north-northwest of the epicenter. Nuku‘alofa experienced an earthquake intensity (MMI Scale) of roughly III. That level implies weak shaking and probably no damage.

Overview of nearby places

Distance Place Intensity (MMI)
158 km (98 mi)
SSE from epicenter
Nuku‘alofa

Tongatapu, Tonga.
III
Weak
Cities and Towns around the epicenter of this earthquake.

Earthquake Intensity Map

The graph below overlays a map of the region around the epicenter with earthquake intensity data provided by the US Geographic Survey. The highest intensity level detected for this earthquake is IV.

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.

Aftershocks detected

Before this earthquake struck, 8 smaller foreshocks occurred. Roughly 10 hrs before this earthquake, a foreshock measuring MAG-5.3 was detected nearby this earthquake.

Overview of foreshocks and aftershocks

Classification Magnitude When Where
Foreshock M 4.5 12 hrs earlier
Mar 31, 2024 03:32AM (Tongatapu Time)
24 km (15 mi)
ENE from Main Shock.
Foreshock M 4.9 12 hrs earlier
Mar 31, 2024 03:38AM (Tongatapu Time)
37 km (23 mi)
NE from Main Shock.
Foreshock M 5.3 10 hrs earlier
Mar 31, 2024 05:44AM (Tongatapu Time)
15 km (9 mi)
N from Main Shock.
Foreshock M 5.2 9 hrs earlier
Mar 31, 2024 06:35AM (Tongatapu Time)
24 km (15 mi)
N from Main Shock.
Foreshock M 4.6 8 hrs earlier
Mar 31, 2024 08:00AM (Tongatapu Time)
16 km (10 mi)
NNE from Main Shock.
Foreshock M 4.5 5 hrs earlier
Mar 31, 2024 10:32AM (Tongatapu Time)
32 km (20 mi)
NW from Main Shock.
Foreshock M 4.4 5 hrs earlier
Mar 31, 2024 10:33AM (Tongatapu Time)
47 km (29 mi)
NNW from Main Shock.
Foreshock M 4.8 5 hrs earlier
Mar 31, 2024 11:07AM (Tongatapu Time)
12 km (7 mi)
NW from Main Shock.
Main Shock
This Earthquake
M 5.5 Mar 31, 2024 04:01PM
(Tongatapu Time)
-
Detected MAG2.5+ earthquakes within within 100km (62 mi), that occurred in the three days before and after the main shock.

More earthquakes coming?

Aftershocks are usually at least 1 order of magnitude less strong than main shocks. The more time passes, the smaller the chance and likely strength of any potential aftershocks.

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 March 2nd, 2024, when a 5.8 magnitude earthquake hit 258 km (160 mi) further west-southwest. An even stronger magnitude 7.1 earthquake struck on November 1st, 2014.

In total, 140 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 26 days.

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 10 km (6 mi). Earthquakes this shallow could trigger a tsunami.

Sources

Last updated 16/04/24 04:58 (). 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 us7000m90u
  2. European-Mediterranean Seismological Centre (EMSC): Earthquake 20240331_0000029
  3. Geonames.org: World Cities Database
  4. Google Maps: Static API
  5. Earthquakelist.org: Historic Earthquakes Database

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