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Moderate mag. 5.9 earthquake - Java, Indonesia, on Friday, 21 May 2021 at 12:09 (GMT) - information

Mag. 5.9 earthquake - Java, Indonesia, on Friday, May 21, 2021, at 07:09 pm (GMT +7)

A strong magnitude 5.9 earthquake occurred in the Indian Ocean near the coast of  Indonesia in the late afternoon of Friday, May 21, 2021 at 7.09 pm local time (GMT +7). The quake had a moderate depth of 115 km (71 mi) and was felt over a large region.

Mag. 5.9 earthquake - Java, Indonesia, on Friday, May 21, 2021, at 07:09 pm (GMT +7) Mag. 5.9 earthquake - Java, Indonesia, on Friday, May 21, 2021, at 07:09 pm (GMT +7)
Moderate magnitude 5.9 earthquake at 115 km depth
21 May 12:12 UTC: First to report: VolcanoDiscovery after 3 minutes.
21 May 12:15: Now using data updates from EMSC
21 May 12:25: Now using data updates from BMKG
21 May 12:30: Epicenter location corrected by 4 km (2.5 mi) towards SSW.
Update Fri, 21 May 2021, 15:00

Strong but deep earthquake shakes Java and Bali

Location of this afternoon's quake under Java and locations of users who felt it
Location of this afternoon's quake under Java and locations of users who felt it
A strong magnitude 5.9 quake occurred this afternoon at 9.09 pm local time under the sea about 50 km from East Java's southern coast. Thanks to its great depth of 115 km, it did not cause shaking strong enough at the surface to cause any significant damage, but it was widely felt across most parts of Java and neighboring Bali as a light vibration lasting a few seconds.
Some users who sent us their reports could even feel both and distinguish between the primary and secondary seismic waves arriving with 10-20 seconds time difference.
Earthquakes at intermediate depth (70-300 km) occur frequently occur beneath Java. Most are the result of intraplate faulting within the slab of the Australian plate that subducting (sinking) in northeasterly direction into the mantle underneath Java.
Update Fri, 21 May 2021, 12:21

Significant 6.3 quake hits near Blitar, East Java, Indonesia

6.3 quake 21 May 7:09 pm (GMT +7)
6.3 quake 21 May 7:09 pm (GMT +7)
Just 12 minutes ago, a 6.3-magnitude earthquake struck near Blitar, East Java, Indonesia. The tremor was recorded early evening on Friday 21 May 2021 at 7:09 pm local time, at an intermediate depth of 123 km below the surface.
The event was filed by the European-Mediterranean Seismological Centre (EMSC), the first seismological agency to report it.
Our monitoring service identified a second report from the German Research Centre for Geosciences (GFZ) which listed the quake at magnitude 5.7.
Based on the preliminary seismic data, the quake was probably felt by many people in the area of the epicenter. It should not have caused significant damage, other than objects falling from shelves, broken windows, etc.
In Sumberpucung (pop. 35,300) located 64 km from the epicenter, Kepanjen (pop. 51,900) 70 km away, Blitar (pop. 132,400) 72 km away, Kedungwaru (pop. 80,300) 87 km away, Tulungagung (pop. 65,300) 88 km away, Malang (pop. 746,700) 88 km away, Batu (pop. 75,600) 97 km away, and Singosari (pop. 57,800) 98 km away, the quake should have been felt as light shaking.
VolcanoDiscovery will automatically update magnitude and depth if these change and follow up if other significant news about the quake become available. If you're in the area, please send us your experience through our reporting mechanism, either online or via our mobile app. This will help us provide more first-hand updates to anyone around the globe who wants to know more about this quake.
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Earthquake details

Date & timeMay 21, 2021 12:09:23 UTC
Local time at epicenterFriday, May 21, 2021, at 07:09 pm (GMT +7)
StatusPreliminary (automatic detection)
Magnitude5.9
Depth115 km
Epicenter latitude / longitude8.68°S / 112.31°E Indian Ocean, Indonesia
Seismic antipode8.68°N / 67.69°W Venezuela
Shaking intensityIV Light shaking near epicenter
Felt120 reports
Primary data sourceBMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia)
Nearest volcanoBratan (45 km / 28 mi)
Weather at epicenter at time of quakeScattered Clouds 27.5°C (81 F), humidity: 80%, wind: 6 m/s (12 kts) from ESE
Estimated seismic energy released4.5 x 1013 joules (12.4 gigawatt hours, equivalent to 10676 tons of TNT or 0.7 atomic bombs!) | about seismic energy
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Nearby places

The closest larger town where the quake might have been felt is Malang, a city with more than 750,000 inhabitants in Indonesia, in 86 km (53 mi) distance northeast of the epicenter. People likely experienced light shaking there. Several smaller towns and villages are located closer to the epicenter and might have experienced stronger shaking. In the capital of  Indonesia, Jakarta, 662 km (411 mi) away from the epicenter, the earthquake was probably felt as very weak shaking.
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
61 km (38 mi)
N of epicenter
Sumberpucung
(pop: 35,300)
IV: Light
East Java
67 km (41 mi)
N of epicenter
Blitar
(pop: 132,400)
IV: Light
East Java
68 km (42 mi)
NE of epicenter
Kepanjen
(pop: 51,900)
IV: Light
East Java
81 km (50 mi)
NW of epicenter
Kedungwaru
(pop: 80,300)
IV: Light
East Java
82 km (51 mi)
NW of epicenter
Tulungagung
(pop: 65,300)
IV: Light
East Java
86 km (53 mi)
NE of epicenter
Malang
(pop: 746,700)
IV: Light
East Java
93 km (58 mi)
N of epicenter
Batu
(pop: 75,600)
IV: Light
East Java
96 km (60 mi)
NE of epicenter
Singosari
(pop: 57,800)
IV: Light
East Java
166 km (103 mi)
N of epicenter
Surabaya
(pop: 2,374,700)
IV: Light
East Java
662 km (411 mi)
NW of epicenter
Jakarta
(pop: 8,540,100)
II: Very weak
Jakarta
Notes:
(*) Shaking intensity according to the Modified Mercalli Intensity Scale (MMI) and estimated using seismic models.

User-reports for this quake (123)

The first report about ground shaking reached us after only 5 minutes, before other agencies reported it. We received 122 reports for this quake.
User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
Contribute:
Leave a comment if you find a particular report interesting or want to add to it.
Flag as inappropriate.
Mark as helpful or interesting.
Send your own user report!
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Surabaya / Weak shaking (MMI III) / horizontal (sideways) swinging / 15-20 s : Sluggish shaking for surprisingly long time on 4th floor of mall building. Did not recognize as earthquake in the beginning. | 4 users found this interesting.  
  • Duduk dilantai terasa kencang gempanya
Denpasar, Bali / Light shaking (MMI IV) / 20-30 s : Was a long, slow roll that kept on going. No peaks, just steady. | 4 users found this interesting.  
  • Yes same here in Canggu Bali / long and slow shaking
Singaraja / Weak shaking (MMI III) / horizontal (sideways) swinging / very short : It was rather strong but only for a short moment | 3 users found this interesting.  
Canggu / Weak shaking (MMI III) / horizontal (sideways) swinging / 20-30 s : Seated on the couch in our second-story apartment, we noticed a continual, slight shaking for about 30 seconds. Our curtains and other hanging items moved slightly throughout. | One user found this interesting.  
Pererenan / Very weak shaking (MMI II) / 5-10 s : I felt that but hour is different - I experience that around 20:10 | 2 users found this interesting.  
Carat, Gempol, Pasuruan / Weak shaking (MMI III) / horizontal (sideways) swinging / 1-2 s : My desktop monitor sways horizontally maybe 1-2 seconds | 2 users found this interesting.  
Sleman / Weak shaking (MMI III) : Floor moving house lamps shaking | 2 users found this interesting.  
Blitar city / Light shaking (MMI IV) / both vertical and horizontal swinging / 10-15 s : The earthquake happened twice, the first on was small and after some seconds the bigger one was happened.  
Grajagan Pantai , Purwoharjo , Banyuwangi . / Very weak shaking (MMI II) / rattling, vibrating / 1-2 s : Felt a very light vibration and heard the roller door rattle then a deep shudder for about 3 seconds after .  
Denpasar / Very weak shaking (MMI II) / single lateral shake / 5-10 s : Just small shaking not everyone feel it | One user found this interesting.  
Bali south kuta / Weak shaking (MMI III) / rattling, vibrating / 1-2 s : Shaking like a heavy truck passing by , water in the gallon moved side ways ... | One user found this interesting.  
Singaraja / Light shaking (MMI IV) / horizontal (sideways) swinging / 10-15 s : The house was swaying for around 10 seconds. | One user found this interesting.  
Kulon progo / Light shaking (MMI IV) / rattling, vibrating / 10-15 s : It was scary but it only lasted for around 10-15 seconds | One user found this interesting.  
Bali / Light shaking (MMI IV) / horizontal (sideways) swinging / 5-10 s : Shaking | One user found this interesting.  
Pererenan / Weak shaking (MMI III) / rattling, vibrating / 5-10 s : Small gempa, just shaking the small flower pots | One user found this interesting.  
Ubud / Light shaking (MMI IV) / 2-5 s : Outdoor | One user found this interesting.  
Ubud / Light shaking (MMI IV) / vibration and rolling : Seemed like it went on for a while, but initial few jolts where unsure if it would build... | One user found this interesting.  
  • Stay Safe Everyone!!!
Sleman Yogyakarta / Very weak shaking (MMI II) / single vertical bump / 2-5 s : I felt my stomach vibrating and I saw the key's door swinging. | One user found this interesting.  
Sanur / Light shaking (MMI IV) / horizontal (sideways) swinging / 5-10 s : Short but sharp | One user found this interesting.  
Batu malang / Moderate shaking (MMI V) / rattling, vibrating / 2-5 s : Pretty strong shaking | One user found this interesting.  
Bali kerobokan / Weak shaking (MMI III) / single vertical bump / 2-5 s : Felt my bed shake | One user found this interesting.  
Ubud / Very weak shaking (MMI II) / rattling, vibrating / 2-5 s : Vibrating couch | One user found this interesting.  
Sibang kaja / Weak shaking (MMI III) / rattling, vibrating / 5-10 s : Light shaking house, felt underfoot | One user found this interesting.  
Surakarta / Light shaking (MMI IV) / single lateral shake / 1-2 s : I feel the shaking | One user found this interesting.  
Outside : The ground moving. | One user found this interesting.  
Keramas / Weak shaking (MMI III) / 20-30 s : Very light shaking that seemed to coming two waves over 20/30 seconds or so | One user found this interesting.  
Bali / Light shaking (MMI IV) / 20-30 s : Yes I feel | One user found this interesting.  
Denpasar, home / Moderate shaking (MMI V) / 10-15 s : It was felt around Kuta and Seminyak area | One user found this interesting.  
Blitar east java / Light shaking (MMI IV) / horizontal (sideways) swinging / 10-15 s : Mild earthquake felt | One user found this interesting.  
  • Stay Safe over there Everyone! Prayers for All
Seminyak / Light shaking (MMI IV) / horizontal (sideways) swinging / 5-10 s : I felt like my chair is moving , tv was moving and picture on the wall. | One user found this interesting.  
yogyakarta / Weak shaking (MMI III) / horizontal (sideways) swinging / 5-10 s : I live on the 3rd floor, so adjusted down the intensity. I certainly felt it up here!  
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What is Intensity and the Mercalli Intensity Scale?


The amount of shaking that occurs on the surface due to an earthquake is called the intensity. It is commonly measured on the so-called Modified Mercalli Intensity Scale (MMI) ranging from 1 (not felt) to 10 (extreme shaking), and given in Roman numerals as I,II,...IX, X, and often displayed with color codes ranging from light blue to dark red.
Earthquake intensity depends mainly on the magnitude and depth of the quake as well as the distance from the epicenter: The further away, the less shaking intensity occurs.
Read more about the MMI scale!

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
2021-05-21
Epicenter Agency
5.9 115 km
71 mi
12:09:23 Java, Indonesia BMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia)
5.7 108 km
67 mi
12:09:23 Java, Indonesia
34 km (21 mi) epicenter difference with BMKG
GFZ (German Research Centre for Geosciences)
5.8 114 km
71 mi
12:09:23 Indonesia: Near Surabaya
30 km (19 mi) epicenter difference with BMKG
RENASS (Réseau National de Surveillance Sismique (RéNaSS))
5.7 117 km
73 mi
12:09:23 JAVA, INDONESIA
37 km (23 mi) epicenter difference with BMKG
EMSC (European-Mediterranean Seismological Centre)
5.8 106 km
66 mi
12:09:23 33 km SSW of Sumberpucung, Indonesia
29 km (18 mi) epicenter difference with BMKG
USGS (United States Geological Survey)
5.8 116 km
72 mi
12:09:23 Java, Indonesia
24 km (15 mi) epicenter difference with BMKG
GeoAu (Geoscience Australia )

Seismograms

Seismic station: Kappang, Sulawesi, Indonesia (KAPI/II network) | Distance from quake: 917 km / 570 mi | Show on map | Station Info
Seismic station Kappang, Sulawesi, 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: 0.02-5.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool
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2 aftershocks for this quake

For this earthquake, 2 aftershocks have been detected so far. The strongest was a magnitude 4.5 quake that hit 2 weeks after the mainshock in 6.4 km (4 mi) distance, in Java, Indonesia, on Tuesday, Jun 8, 2021 on 12:28 am (Jakarta local time GMT +7).

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. 79 km2 (=31 sqare miles) as a first-order estimate. The length of the rupture zone thus was probably around 15 km (10 mi).
[More info]


Recorded aftershocks, latest first (2 quakes)

Date and Time GMTMag
Depth
DistanceRegionDetails
Jun 8, 2021 12:28 am (Jakarta)
3 years ago - felt
2 weeks after main shock
4.5

85 km
6.4 km (4 mi)
NE of main shock
Java, IndonesiaMore
May 21, 2021 07:31 pm (GMT +7)
3 years ago - felt
22 minutes after main shock
3.1

79 km
7.9 km (4.9 mi)
S of main shock
Java, IndonesiaMore
May 21, 2021 07:09 pm (GMT +7)
3 years ago - felt
5.9

115 km
0 km - This quakeIndian Ocean, 67 km S of Blitar, East Java, Indonesia
Main Shock (this quake)
More

Map of aftershocks

Previous quakes in the same area of this earthquake

Map of earlier quakes in the area of this quake

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