On Wednesday Evening a Strong M6.3 Earthquake struck in the Philippine Sea near Uwajima (Japan).

Written by Earthquakelist.org on April 17th, 2024. Last updated May 20th, 2024.

A strong MAG-6.3 earthquake struck in the Philippine Sea 18 kilometer from Uwajima, Japan in the evening of Wednesday April 17th, 2024. Earthquakes like this can cause significant economic damage and have a significant risk at casualties.

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Earthquake Summary

This earthquake hit under water in the Philippine Sea, right off the coast of Japan (4 mi offshore), 18 kilometer west of Uwajima in Ehime. The center of this earthquake had a quite shallow depth of 32 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time:	Apr 17, 2024 23:14 (Tokyo Time) - Apr 17, 2024 14:14 Universal Time.
Location:	18 km west of Uwajima, Ehime, Japan. Coordinates 33°15'1"N 132°21'53"E.
Map:	Map of area around epicenter. Click to open in Google Maps.
Magnitude:	MAG 6.3 Detected by 69 stations. Maximum Error Range ±0.037 .
Depth:	32 km (20 mi) A quite shallow depth.
Max. Intensity:	VIII Severe 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.

Significant impact predicted

The US Geographic Survey (USGS) describes the impact of this earthquake as follows:

Twelve people injured, nine homes damaged, several buildings damaged and landslides reported in the Ehime-Kochi-Oita area.

Based on scientific estimates by the USGS, the risk of high fatalities for this earthquake is classified at level YELLOW (significant). They expect an 50% likelyhood of between 0 and 1 fatalities, and a 90% chance that the number of fatalities falls no higher than 10.

The USGS classifies the economic impact of this earthquake at level YELLOW (significant). They expect an 36% likelyhood of between 10 and 100 million US Dollars in economic damage and impact, and a 96% chance that the economic impact of this earthquake falls between 1 and 10,000 million USD.

Roughly 20 million people exposed to shaking

An estimated 20 million 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.

An estimated 27,740 people were exposed to level VIII. At this level, severe shaking and likely moderate to heavy damage can be expected. The majority of people (roughly 17 million) live in an area exposed to level IV, where light shaking and likely no damage is expected. All exposure to shaking was within the borders of Japan .

Nearby towns and cities

This earthquake may have been felt in Japan . Uwajima in Ehime, Japan is the nearest significant place from the epicenter. The earthquake occurred 18 kilometer (11 mi) west of Uwajima. The intensity of shaking and damage in Uwajima is estimated to be around level VIII on the Modified Mercalli Intensity scale (severe shaking, likely moderate to heavy damage).

Multiple major population centers exist within 300km of the earthquake that struck today. Busan is located 369 km to the west-northwest (intensity unknown, possibly low). Hiroshima is located 128 km to the north and experienced an intensity of IV (light shaking, likely no damage). Osaka is located 331 km to the east-northeast (intensity unknown, possibly low).

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 VIII. 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

Shaking reported by 100 people in 3 countries

People that feel an earthquake may report their experience to the US Geographic Survey. Currently, 100 people have reported shaking in 55 places in 3 countries (Taiwan, Japan, Korea (South)).We keep updating this article as more ground reports become available. You may report that you felt this earthquake here.

Places with most reports:

• Iwakuni, Yamaguchi, Japan: 11 people.
• Uwajima, Ehime, Japan: 7 people.
• Ōsaka, Ōsaka, Japan: 5 people.
• Hiroshima, Hiroshima, Japan: 5 people.
• Pusan, Pusan, Korea (South): 4 people.
• Innoshima, Hiroshima, Japan: 3 people.
• Fuchū (E of Hiroshima), Hiroshima, Japan: 3 people.
• Tamano, Okayama, Japan: 3 people.
• Okayama, Okayama, Japan: 3 people.
• Kurashiki, Okayama, Japan: 3 people.

9 Aftershocks detected

After this earthquake struck, 9 smaller aftershocks occurred. At a distance of 1.1 km (0.7 mi) west-northwest of this earthquake, an aftershock struck 4 mins later. It measured a magnitude of 4.8

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 an unusually powerful earthquake

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 January 21st, 2022, when a 6.3 magnitude earthquake hit 66 km (41 mi) further south-southwest. An even stronger magnitude 7 earthquake struck on April 15th, 2016.

In total, 2 earthquakes with a magnitude of 6.3 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 5 years.

Low tsunami risk

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

Sources

Last updated 20/05/24 01:28 (). 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 us7000mcpi
2. European-Mediterranean Seismological Centre (EMSC): Earthquake 20240417_0000190
3. Geonames.org: World Cities Database
4. Google Maps: Static API
5. Earthquakelist.org: Historic Earthquakes Database

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