Shallow M5.5 Earthquake struck on Sunday Evening 172km from Bontang in Indonesia.

Written by Earthquakelist.org on September 15th, 2024. Last updated September 18th, 2024.

A shallow and significant M5.5 earthquake struck under land 172 kilometer from Bontang in Indonesia in the evening of Sunday September 15th, 2024. Shaking may have been felt by a total of 1.3 million people.

Earthquake Summary

The earthquake struck on land in Indonesia, 172 kilometer (107 mi) north-east of Bontang in East Kalimantan. The center of this earthquake had a very shallow depth of 11 km. Shallow earthquakes usually have a larger impact than earthquakes deep in the earth.

Date and Time:	Sep 15, 2024 21:08 (Makassar Time) - Sep 15, 2024 13:08 Universal Time.
Location:	172 km NE of Bontang, East Kalimantan, Indonesia. Coordinates 1°20'15"N 118°27'41"E.
Map:	Map of area around epicenter. Click to open in Google Maps.
Magnitude:	MAG 5.5 Detected by 25 stations. Maximum Error Range ±0.062 .
Depth:	11 km (7 mi) A very shallow depth.
Max. Intensity:	VII Very Strong On the Modified Mercalli Scale.
Tsunami Risk:	Tsunami very unlikely While this was a shallow earthquake in a coastal area, it appears to have occurred under land (3 km from the sea) with a magnitude that is usually not strong enough to 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 100% likelyhood of between 0 and 1 million US Dollars in economic damage and impact.

Roughly 1.3 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 1.3 million have been exposed to shaking at an MMI level of II or higher.

Very strong shaking and likely moderate damage may have been experienced by an estimated 190 people. At VII, it is the highest MMI level this earthquake has caused. Intensity level III was experienced by the majority of people (around 1.1 million). In their region, weak shaking and probably no damage can be expected. All exposure to shaking was within the borders of Indonesia .

People	MMI Level	Shaking	Damage
0	I	Not noticable	None
21,760	II	Very weak	None
1,099,000	III	Weak	Probably none
205,700	IV	Light	Likely none
6,100	V	Moderate	Very light
1,010	VI	Strong	Light
190	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 Indonesia . Located 172 kilometer (107 mi) north-east of the epicenter of this earthquake, Bontang (East Kalimantan, Indonesia) is the nearest significant population center. The intensity of shaking and damage in Bontang is estimated to be around level III on the Modified Mercalli Intensity scale (weak shaking, probably no damage).

Multiple large cities are in proximity of today's earthquake. Samarinda is located 251 km to the southwest (intensity unknown, possibly low). Palu is located 295 km to the south-southeast (intensity unknown, possibly low). Loa Janan is located 262 km to the southwest (intensity unknown, possibly low).

The table below provides an overview of all places in proximity of today's earthquake. Where available, the estimated intensity on the Modified Mercalli Intensity Scale in each place is included. Places where this information is omitted likely experienced little impact.

Overview of nearby places

Cities and Towns around the epicenter of this earthquake.
Distance	Place	Intensity (MMI)
172 km (107 mi) SW from epicenter	Bontang East Kalimantan, Indonesia.	III Weak
240 km (149 mi) NNW from epicenter	Tarakan North Kalimantan, Indonesia.
251 km (156 mi) SW from epicenter	Samarinda East Kalimantan, Indonesia.
262 km (163 mi) SW from epicenter	Loa Janan East Kalimantan, Indonesia.
295 km (183 mi) SSE from epicenter	Palu Central Sulawesi, Indonesia.

Earthquake Intensity Map

The maximum intensity (MMI Scale) caused by this earthquake is VII. 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

Earthquake Intensity Map based on Shakemap Data provided by USGS.

Shaking reported by 3 people

People that feel an earthquake may report their experience to the US Geographic Survey. Currently, 3 people have reported shaking in 2 places in Indonesia.We keep updating this article as more ground reports become available. You may report that you felt this earthquake here.

Places with most reports:

Tanjung Redeb, Kalimantan Timur, Indonesia: 2 people.
Bontang, Kalimantan Timur, Indonesia: 1 person.

6 Aftershocks detected

Since this main shock, 6 smaller aftershocks were detected. Just 31 mins after this main shock, an earthquake measuring MAG-4 was detected 13 km (8 mi) west-southwest of this earthquake.

In the days before this main shock, 1 smaller foreshock was detected. A 4 magnitude earthquake hit 2 hrs 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 4.0	2 hrs earlier Sep 15, 2024 19:28 (Makassar Time)	3 km (1.9 mi) S from Main Shock.
Main Shock This Earthquake	M 5.5	Sep 15, 2024 21:08 (Makassar Time)	-
Aftershock	M 4.0	31 mins later Sep 15, 2024 21:39 (Makassar Time)	13 km (8 mi) WSW from Main Shock.
Aftershock	M 3.6	2 hrs later Sep 15, 2024 23:16 (Makassar Time)	10 km (6 mi) SW from Main Shock.
Aftershock	M 3.0	3 hrs later Sep 15, 2024 23:52 (Makassar Time)	11 km (7 mi) SSW from Main Shock.
Aftershock	M 2.5	3 hrs later Sep 16, 2024 00:06 (Makassar Time)	17 km (11 mi) SSW from Main Shock.
Aftershock	M 3.1	4 hrs later Sep 16, 2024 00:54 (Makassar Time)	16 km (10 mi) SSW from Main Shock.
Aftershock	M 3.1	5 hrs later Sep 16, 2024 01:38 (Makassar Time)	22 km (14 mi) SSW 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 are common in the region

Earthquakes of this strength occur quite regularly in the region. This is the strongest earthquake to hit since September 9th, 2023, when a 6 magnitude earthquake hit 208 km (129 mi) further south-east. An even stronger magnitude 7.5 earthquake struck on September 28th, 2018.

In total, 9 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 year.

Tsunami very unlikely

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.

While MAG-6.5+ earthquakes may cause tsunami's, it appears that the epicenter of this earthquake hit under land. In addition, the reported depth is deeper than 100km, making the risk of a tsunami even less likely. However always 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 on land near a coastal area (3 km from 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 11 km (7 mi). Earthquakes this shallow could trigger a tsunami.

Sources

Last updated 18/09/24 12:38 (). This article is automatically generated based on available data. We keep checking multiple sources for additional information. This article gets updated as new details on this earthquake become available.