2025 East Java earthquake

2025 East Java earthquake

USGS ShakeMap
Surabaya Malang Situbondo Jember
UTC  time	2025-09-30 16:49:42
ISC  event	67423940
USGS-ANSS	ComCat
Local date	30 September 2025
Local time	23:49:42 WIB (UTC+7)
Magnitude	Mw 6.0
Depth	242 km (150 mi) (USGS) 11 km (7 mi) (BMKG)
Epicenter	7°14′24″S114°10′12″E / 7.240°S 114.170°E / -7.240; 114.170
Type	Thrust
Areas affected	East Java, Bali, Indonesia
Max. intensity	MMI VI (Strong)
Tsunami	No
Aftershocks	160+ ≥3.0 Mw  [1] Mw 4.5 on 1 October 2025 (strongest) [2]
Casualties	6 injured

On 30 September 2025, at 23:49:49 WIB (16:49:42 UTC), an earthquake with a magnitude of 6.0 struck the Sumenep Regency, East Java. ^[3] the epicenter located off at the bottom of the sea near Sapundi Island. The earthquake affected most of the area in East Java, Bali, and Lombok with the strongest earthquake shocks was on Sapudi Island.

Earthquake

The Meteorology, Climatology, and Geophysical Agency (BMKG) recorded that the earthquake had a magnitude of 6.5 M_w  but was later revised to a magnitude of 6.0. ^[4] The epicenter of the earthquake was on the seabed with coordinates of 7.25 S and 114.22 E, or if drawn in a straight line it was 50 kilometers southeast of Sumenep Regency at a depth of 11 km (6.8 mi). ^[5] While the United States Geological Survey reported an earthquake magnitude of 6.0 M_w  with a depth of 24.2 km (15.0 mi). Several aftershocks occurred with magnitudes above M_w  3.0. The strongest aftershock with a magnitude of 4,5 M_w  on 1 October, 00:15 WIB (UTC+7) Modified Mercalli intensity scale estimated at VI (strong) by BMKG. ^[6]

According to the Director of Earthquakes and Tsunami at BMKG, Daryono, the earthquake was categorized as a shallow earthquake. ^[7] The source of the earthquake is associated with the extension of the offshore fault of the Kendeng Zone or Madura Strait Back Arc Thrust, with a thrust fault mechanism. ^[8]

Other impacts

On 29 September, the Al-Khoziny Islamic Boarding School collapsed, and traps dozens of the students (santri) inside the building. The collapse occurred approximately 200 kilometers from the earthquake's epicenter. This seismic event significantly hampered ongoing rescue operations at the collapsed Islamic boarding school. According to Mohammad Syafii, Head of the National Search and Rescue Agency, the earthquake has compacted the debris, thus reducing the space for the trapped victims. He noted that the gaps between the debris that were originally 50 centimeters wide were now only 10 centimeters, increasing the difficulty of access for survivors. ^[9] The earthquake also raised concerns about the structural integrity of remaining buildings, as tremors from the quake could potentially cause further collapse. ^[9]

References

1. Muhammad Refi Sandi (1 October 2025). "BMKG: 166 Kali Gempa Susulan Guncang Sumenep, 6 Orang Luka dan Ratusan Rumah Rusak" (in Indonesian). iNews . Retrieved 1 October 2025.
2. ANSS. "M 4.5 - 32 km SE of Kalianget, Indonesia 2025". Comprehensive Catalog. U.S. Geological Survey.
3. ANSS. "M 6.0 - 32 km SE of Kalianget, Indonesia 2025". Comprehensive Catalog. U.S. Geological Survey.
4. "Penyebab Gempa Sumenep Magnitudo 6,0" (in Indonesian). Detik.com. 1 October 2025. Retrieved 1 October 2025.
5. "Gempa Bumi M 6,5 Guncang Sumenep Madura, Kedalaman 11 Km" (in Indonesian). CNBC Indonesia. 30 September 2025. Retrieved 1 October 2025.
6. "BMKG ShakeMap: Pusat gempa berada di laut 50 km Tenggara Sumenep - Jawa Timur". BMKG (in Indonesian). 30 September 2025. Retrieved 30 September 2025.
7. Bimo Kresnomurti (1 October 2025). "Apa Penyebab Gempa Sumenep 6,0 SR Terjadi? Ini Penjelasan BMKG" (in Indonesian). Kontan . Retrieved 1 October 2025.
8. "BMKG: Sumenep miliki catatan bencana gempa merusak yang panjang" (in Indonesian). AntaraNews. 1 October 2025. Retrieved 1 October 2025.
9. Marsi, Federica. "Rescuers race to save survivors of Indonesia school collapse as quake hits". Al Jazeera . Retrieved 5 October 2025.