M7.0 Earthquake 30 km E of Ishinomaki, Japan — March 20, 2021
2021-03-20 09:09:43 UTC (2021-03-20) · approx. 6:09 PM UTC+9 local
Felt by 409 people across surrounding communities. Maximum shaking intensity MMI 7.0 (severe).
On March 20, 2021 at 09:09 UTC, a magnitude 7.0 shallow crustal earthquake struck 30 km E of Ishinomaki, Japan, at a depth of 43.0 km and coordinates 38.4515°, 141.6477°. The earthquake was reported felt by 409 peopleacross surrounding communities, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 7.0 (severe). The USGS PAGER system issued a yellow alert level for this event, indicating local impact possible. The nearest populated place is Ishinomaki (population 117,233).
Physical scale: An earthquake of magnitude 7.0 releases seismic energy equivalent to roughly 477 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 41 km — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Japan, a region characterized by the intersection of four tectonic plates — Pacific, Philippine Sea, Eurasian, and North American — creating multiple subduction zones. The nearest mapped fault system is the Japan Trench. View all earthquakes in Japan.
Learn more: Magnitude scale · Aftershock sequences
Nearest Populated Places
What the Shaking Felt Like
At MMI 7.0 (severe), people in the most strongly affected areas would have experienced: Very strong shaking. Difficult to stand. Damage to weak structures; slight damage to well-built structures. Furniture broken. Fallen plaster and loose bricks.
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 409 citizen responses 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 | 11,561,334 |
| MMI 4 | light | 41,479,824 |
| MMI 5 | moderate | 2,255,205 |
| MMI 6 | strong | 2,134,305 |
| MMI 7 | very strong | 50,423 |
Earthquake Details
141.6477°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 7.0 earthquake near Ishinomaki, Japan?
The magnitude 7.0 earthquake that struck 30 km E of Ishinomaki, Japan on March 20, 2021 at 09:09 UTC had a depth of 43.0 km. It was felt by 409 people with maximum shaking intensity of MMI 7.0 (severe). For context, this was a strong earthquake capable of causing significant damage.
Where did the earthquake occur?
The earthquake epicenter was located at 38.4515°, 141.6477°, which is 30 km E of Ishinomaki, Japan. The nearest populated place is Ishinomaki (population 117,233). View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 7.0 earthquakes can continue for months to years and gradually diminish over time.
Has Japan had earthquakes this big before?
The largest recorded earthquake in Japan was the M9.1 Tohoku earthquake of March 11, 2011. Today's magnitude 7.0 event is significantly smaller than that historical record.
Actions
Location
Authoritative source: USGS event page (event ID: us7000dl6y). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, March 20, 2021). M7.0 Earthquake 30 km E of Ishinomaki, Japan — March 20, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000dl6y/