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Mag. 4.2 earthquake - Aru Sea, 79 km northwest of Pulau Warilau Island, Maluku, Indonesia, on Saturday, Sep 21, 2019, at 03:29 am (Jayapura time)

A moderate magnitude 4.2 earthquake occurred under the sea 81 km (50 mi) from  Indonesia in the early morning of Saturday, Sep 21, 2019 at 3.29 am local time (Asia/Jayapura GMT +9). The quake had a very shallow depth of 15 km (9 mi) and was not felt (or at least not reported so).

Mag. 4.2 earthquake - Aru Sea, 79 km northwest of Pulau Warilau Island, Maluku, Indonesia, on Saturday, Sep 21, 2019, at 03:29 am (Jayapura time) Mag. 4.2 earthquake - Aru Sea, 79 km northwest of Pulau Warilau Island, Maluku, Indonesia, on Saturday, Sep 21, 2019, at 03:29 am (Jayapura time)

Moderate magnitude 4.2 earthquake at 15 km depth

20 Sep 18:40 UTC: First to report: BMKG after 11 minutes.
Sep 21 10:40: Magnitude recalculated from 4.3 to 4.2.
Hypocenter depth recalculated from 10.0 to 15.0 km.

Earthquake details

Date & timeSep 20, 2019 18:29:24 UTC
Local time at epicenterSaturday, Sep 21, 2019, at 03:29 am (Asia/Jayapura GMT +9)
StatusPreliminary (automatic detection)
Depth15.0 km
Epicenter latitude / longitude4.75°S / 134.19°E Indonesia
Seismic antipode4.75°N / 45.81°W
Shaking intensityLight shaking near epicenter
Felt0 reports
Primary data sourceBMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia)
Estimated seismic energy released1.3 x 1011 joules (35 megawatt hours, equivalent to 30.1 tons of TNT) | about seismic energy
Interactive map
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Nearby places

The closest larger town where the quake might have been felt is Tual, a town with 89,000 inhabitants in Indonesia, in 187 km (116 mi) distance southwest of the epicenter. People likely experienced very weak shaking there.
The following table shows some of the places that might have been affected (or not) by the shaking.
Distance Place Max. shaking intensity(*) Region Country
187 km (116 mi)
SW of epicenter
(pop: 89,000)
II: Very weak
212 km (132 mi)
NE of epicenter
(pop: 43,900)
II: Very weak
217 km (135 mi)
NW of epicenter
(pop: 320)
II: Very weak
(*) Shaking intensity according to the Modified Mercalli Intensity Scale (MMI) and estimated using seismic models.

User-reports for this quake

There are no user reports for this quake yet.

If you felt it, be the first to report it!
User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
There are no user reports for this quake.

Compare Quake Data

Data for the same earthquake as reported by different agencies

The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.
Mag Depth Time GMT
Epicenter Agency
4.2 15 km
9.3 mi
18:29:24 Irian Jaya Region, Indonesia BMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia)
4.3 10 km
6.2 mi
18:29:23 Near S Coast Of Papua, Indonesia
1.1 km (0.7 mi) epicenter difference with BMKG
EMSC (European-Mediterranean Seismological Centre)
(*) A depth given as 10 km often means that the the depth of the quake could not determined with sufficient accuracy.


Seismic station: Jayapura, Indonesia (JAY/PS network) | Distance from quake: 764 km / 475 mi | Show on map | Station Info
Seismic station Jayapura, Indonesia: vertical movement plot around time of quake (source: IRIS/BUD)
Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.2-5.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool
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Aftershocks for this quake

No aftershocks have been recorded so far. When aftershocks are detected, we will update this section.

What are aftershocks?

Larger earthquakes (above magnitude 5 or so) such as this one are usually followed by smaller ones known as aftershocks that occur in the same area during the days, weeks, months or even years after the main shock.
[More info]

What about this quake?

Based on its magnitude, the fault that was active during the quake likely ruptured beneath a surface of approx. 2 km2 (=1 sqare miles) as a first-order estimate. The length of the rupture zone thus was probably around 2 km (1 mi).
[More info]

Recorded aftershocks, latest first (0 quake)

Date and Time GMTMag
Sep 21, 2019 03:29 am (Jayapura)
4 years ago

15 km
0 km - This quakeAru Sea, 79 km NW of Pulau Warilau Island, Maluku, Indonesia
Main Shock (this quake)

Map of aftershocks

Earthquake statistics

Average number of earthquakes

Based on data from the past 10 years and our earthquake archive back to 1900, there are about 310 quakes on average per year in the area near the epicenter of this quake (within 100 km/61 mi):
  • Mag. 7 or higher: 0.02 quakes per year (or 1 quake every 41.7 years)
  • Mag. 6 or higher: 0.13 quakes per year (or 1 quake every 7.5 years)
  • Mag. 5 or higher: 2.2 quakes per year
  • Mag. 4 or higher: 11.9 quakes per year
  • Mag. 3 or higher: 21.9 quakes per year
  • Mag. 2 or higher: 22 quakes per year
The area where this quake occurred has a very high level of seismic activity. It has had at least 3 quakes above magnitude 7 since 1900, which suggests that larger earthquakes of this size occur infrequently, probably on average approximately every 40 to 45 years.

Number of quakes per year

Previous quakes in the same area of this earthquake

Map of earlier quakes in the area of this quake

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Map to embed or share

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