M5.5 Earthquake 189 km W of Oula Xiuma, China — May 21, 2021
2021-05-21 18:13:01 UTC (2021-05-21) · approx. 1:13 AM UTC+7 local
Maximum shaking intensity MMI 6.6 (very strong).
On May 21, 2021 at 18:13 UTC, a magnitude 5.5 shallow crustal earthquake struck 189 km W of Oula Xiuma, China, at a depth of 10.0 km and coordinates 34.4808°, 99.0805°. The USGS PAGER system issued a yellow alert level for this event, indicating local impact possible. The nearest populated place is Changmahe (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.
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
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 | 607,422 |
| MMI 4 | light | 59,576 |
| MMI 5 | moderate | 5,047 |
| MMI 6 | strong | 3,395 |
| MMI 7 | very strong | 9 |
Earthquake Details
99.0805°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 5.5 earthquake near Oula Xiuma, China?
The magnitude 5.5 earthquake that struck 189 km W of Oula Xiuma, China on May 21, 2021 at 18:13 UTC had a depth of 10.0 km. For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at 34.4808°, 99.0805°, which is 189 km W of Oula Xiuma, China. The nearest populated place is Changmahe (population 0).
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.
Actions
Location
Authoritative source: USGS event page (event ID: us6000ef4i). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, May 21, 2021). M5.5 Earthquake 189 km W of Oula Xiuma, China — May 21, 2021. Retrieved February 4, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000ef4i/