M5.5 Earthquake in the Flores region, Indonesia — August 15, 2023
2023-08-15 03:54:02 UTC (2023-08-15) · approx. 11:54 AM UTC+8 local
Felt by 1 person across nearby locations. Aftershock of the M5.6 mainshock.
On August 15, 2023 at 03:54 UTC, a magnitude 5.5 intermediate depth earthquake struck in the Flores region, Indonesia, at a depth of 173.0 km and coordinates -8.3786°, 121.4462°. The earthquake was reported felt by 1 personacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 3.7 (light). The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. This earthquake was detected by 105 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 466, placing it among routine seismic activity. The nearest populated place is Nila Dua (population 0).
Physical scale: An earthquake of magnitude 5.5 releases seismic energy equivalent to roughly 3 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 3.8 km — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.6 mainshock that occurred 6 days ago 67 km NNW of Ende, Indonesia. Since the mainshock, the USGS has recorded 39 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
The epicenter is located in Indonesia, a region characterized by the convergence of the Indo-Australian, Eurasian, and Philippine Sea plates, forming the Sunda-Banda arc system. The nearest mapped fault system is the Sunda megathrust. View all earthquakes in Indonesia.
Learn more: Magnitude scale · Aftershock sequences
Nearest Populated Places
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 1 citizen response to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Population exposure (USGS PAGER)
Estimated population that experienced each level of shaking. Based on the USGS PAGER rapid impact assessment, which combines ShakeMap output with global population grids.
| Shaking intensity (MMI) | Description | Population exposed |
|---|---|---|
| MMI 3 | weak | 1,875,320 |
| MMI 4 | light | 629,662 |
Earthquake Details
121.4462°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 5.5 earthquake in the Flores region, Indonesia?
The magnitude 5.5 earthquake that struck in the Flores region, Indonesia on August 15, 2023 at 03:54 UTC had a depth of 173.0 km. It was felt by 1 person with maximum shaking intensity of MMI 3.7 (light). For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at -8.3786°, 121.4462°, which is in the Flores region, Indonesia. The nearest populated place is Nila Dua (population 0). View all earthquakes in Indonesia.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.5 earthquakes can continue for days to weeks and gradually diminish over time.
Is this the same earthquake as the M5.6 one earlier?
No. This magnitude 5.5 earthquake is an aftershock of the larger magnitude 5.6 mainshock that occurred earlier 67 km NNW of Ende, Indonesia. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Indonesia had earthquakes this big before?
The largest recorded earthquake in Indonesia was the M9.1 Indian Ocean earthquake of December 26, 2004. Today's magnitude 5.5 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000l005). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, August 15, 2023). M5.5 Earthquake in the Flores region, Indonesia — August 15, 2023. Retrieved October 27, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000l005/