Shallow M5.6 Earthquake struck on Monday Night in the South China Sea 127km from Laoag (The Philippines).

Written by Earthquakelist.org on April 27th, 2025. Last updated May 19th, 2025.

A shallow and significant M5.6 earthquake struck in the South China Sea 127 kilometer from Laoag, The Philippines in the night of Monday April 28th, 2025. Shaking may have been felt by a total of 3.2 million people.

Earthquake Summary

This earthquake hit under water in the South China Sea, 29 kilometers (18 mi) off the coast of The Philippines, 127 kilometer north-northeast of Laoag in Ilocos. The center of this earthquake had a very shallow depth of 18 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time:	Apr 28, 2025 01:18AM (Manila Time) - Apr 27, 2025 17:18 Universal Time.
Location:	127 km NNE of Laoag, Ilocos, The Philippines. Coordinates 19°12'24"N 121°9'23"E.
Map:	Map of area around epicenter. Click to open in Google Maps.
Magnitude:	MAG 5.6 Detected by 58 stations. Maximum Error Range ±0.041 .
Depth:	18 km (11 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 3.2 million people exposed to shaking

The USGS has published a report estimating the number of people exposed to this earthquake. Acoording to their analysis, roughly 3.2 million have been exposed to shaking at an MMI level of II or higher.

An estimated 20 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 2.8 million). In their region, weak shaking and probably no damage can be expected. All exposure to shaking was within the borders of The Philippines .

People	MMI Level	Shaking	Damage
0	I	Not noticable	None
57,220	II	Very weak	None
2,790,000	III	Weak	Probably none
307,300	IV	Light	Likely none
20	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 The Philippines . Located 107 kilometer (66 mi) north-northwest of the epicenter of this earthquake, Aparri (Cagayan Valley, The Philippines) is the nearest significant population center. The intensity of shaking and damage in Aparri is estimated to be around level IV on the Modified Mercalli Intensity scale (light shaking, likely no damage).

Major cities near this earthquake: Laoag is located 127 km to the south-southwest and experienced an intensity of III (weak shaking, probably no damage). Tuguegarao is located 187 km to the south-southeast and experienced an intensity of III (weak shaking, probably no damage). Santiago is located 283 km to the south (intensity unknown, possibly low).

A complete list of nearby places is included below. Estimated intensity data (MMI) sourced from a shake-map published by the US Geographic Survey is shown where available (cities without data probably experienced little impact).

Overview of nearby places

Cities and Towns around the epicenter of this earthquake.
Distance	Place	Intensity (MMI)
107 km (66 mi) SSE from epicenter	Aparri Cagayan Valley, The Philippines.	IV Light
127 km (79 mi) SSW from epicenter	Laoag Ilocos, The Philippines.	III Weak
129 km (80 mi) SSW from epicenter	San Nicolas Ilocos, The Philippines.	III Weak
142 km (88 mi) SSW from epicenter	Batac City Ilocos, The Philippines.	III Weak
182 km (113 mi) SSE from epicenter	Solana Cagayan Valley, The Philippines.	III Weak
187 km (116 mi) SSE from epicenter	Tuguegarao Cagayan Valley, The Philippines.	III Weak
195 km (121 mi) S from epicenter	Tabuk Cordillera, The Philippines.	III Weak
199 km (124 mi) SSW from epicenter	Vigan Ilocos, The Philippines.	III Weak
208 km (129 mi) SSE from epicenter	Cabagan Cagayan Valley, The Philippines.	III Weak
237 km (147 mi) SSE from epicenter	Roxas Cagayan Valley, The Philippines.
242 km (150 mi) SSE from epicenter	Ilagan Cagayan Valley, The Philippines.
262 km (163 mi) SSW from epicenter	Santa Maria Ilocos, The Philippines.
262 km (163 mi) S from epicenter	San Mateo Cagayan Valley, The Philippines.
264 km (164 mi) SSW from epicenter	Tagudin Ilocos, The Philippines.
264 km (164 mi) S from epicenter	Mankayan Cordillera, The Philippines.
272 km (169 mi) S from epicenter	Ramon Cagayan Valley, The Philippines.
276 km (171 mi) SSE from epicenter	Alicia Cagayan Valley, The Philippines.
277 km (172 mi) S from epicenter	Diadi Cagayan Valley, The Philippines.
283 km (176 mi) S from epicenter	Santiago Cagayan Valley, The Philippines.
299 km (186 mi) S from epicenter	Solano Cagayan Valley, The Philippines.

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 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 4 people

People that feel an earthquake may report their experience to the US Geographic Survey. Currently, 4 people have reported shaking in 3 places, all within Philippines.We keep updating this article as more ground reports become available. You may report that you felt this earthquake here.

Places with most reports:

Namuac, Cagayan Valley, Philippines: 2 people.
Bangui, Ilocos, Philippines: 1 person.
Cabugao, Ilocos, Philippines: 1 person.

2 Aftershocks detected

This main shock was followed by 2 smaller aftershocks. Just 9 hrs after this main shock, an earthquake measuring MAG-3.2 was detected 5 km (3 mi) north-northeast of this earthquake.

This main shock was prefaced by 2 smaller foreshocks. A 5.5 magnitude earthquake hit 24 mins earlier nearby.

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 3.0	6 hrs earlier Apr 27, 2025 07:48PM (Manila Time)	69 km (43 mi) N from Main Shock.
Foreshock	M 5.5	24 mins earlier Apr 28, 2025 12:54AM (Manila Time)	7 km (4 mi) W from Main Shock.
Main Shock This Earthquake	M 5.6	Apr 28, 2025 01:18AM (Manila Time)	-
Aftershock	M 3.2	9 hrs later Apr 28, 2025 09:54AM (Manila Time)	5 km (3 mi) NNE from Main Shock.
Aftershock	M 3.0	2 days later Apr 30, 2025 04:25AM (Manila Time)	16 km (10 mi) NNE 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.

It's always adviced to be cautious of the risk of a larger shock following any significant earthquake, however this risk is fairly small. There is a roughly 94 percent change that no larger main shock will follow in the days following this earthquake.

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

Earthquakes like this are common in the region

Earthquakes of this strength occur quite regularly in the region. This is the strongest earthquake to hit since December 3rd, 2024, when a 5.7 magnitude earthquake hit 87 km (54 mi) further south-southwest. An even stronger magnitude 7 earthquake struck on July 27th, 2022.

In total, 10 earthquakes with a magnitude of 5.6 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 year.

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 5.6. Earthquakes of this strength are unlikely to trigger a tsunami.	This earthquake occurred at a depth of of 18 km (11 mi). Earthquakes this shallow could trigger a tsunami.

Sources

Last updated 19/05/25 19:48 (). This article contains currently available information about the earthquake and is automatically composed. We continue to update this article up to a few days after the earthquake occurred.