Reviewed by USGSWashington21d ago
M3.8 earthquake 20 km E of Castle Rock, Washington
Saturday, September 5, 2026, 11:09:28 UTC · 46.246°N, 122.642°W
A magnitude 3.8 earthquake struck 20 km E of Castle Rock, Washington on Saturday, September 5, 2026, 11:09:28 UTC, at a depth of 17.7 km (shallow). USGS received 1,025 “Did You Feel It?” reports, with a maximum reported intensity of IV (light).
- Magnitude
- 3.8
- Minor · ml
- Depth
- 18 km
- Shallow
- Felt reports
- 1,025
- Max intensity IV
- Est. shaking
- IV
- Light (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
6 tons of TNT
That is about 1/2,368 of the Hiroshima bomb. A magnitude 5.0 releases about 75 times more energy.
Tectonic setting
234 km
from the nearest mapped plate boundary, between the Juan de Fuca and North American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
18 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.
| Place | Intensity | Reports | Distance |
|---|---|---|---|
| 98632<br>0.090 | III · Weak | 228 | 37 km |
| 98626<br>0.090 | III · Weak | 178 | 23 km |
| 98674<br>0.102 | III · Weak | 72 | 37 km |
| 98611<br>0.112 | III · Weak | 58 | 26 km |
| 98629<br>0.137 | III · Weak | 40 | 44 km |
| 98625<br>0.148 | III · Weak | 35 | 29 km |
| 98649<br>0.186 | III · Weak | 23 | 21 km |
| 98604<br>0.190 | III · Weak | 22 | 54 km |
| 98601<br>0.199 | III · Weak | 20 | 42 km |
| 98607<br>0.203 | II · Weak | 19 | 72 km |
| 98675<br>0.224 | III · Weak | 15 | 54 km |
| 98645<br>0.224 | II · Weak | 15 | 21 km |
USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS has not published any M2.5+ earthquake within 50 km since this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 41 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.8The 2001 Nisqually, Washington EarthquakeFebruary 28, 2001 · 101 km N of this epicenter
- 6.74 km WNW of Roy, WashingtonApril 13, 1949 · 85 km N of this epicenter
- 6.71 km ENE of Dash Point, WashingtonApril 29, 1965 · 121 km N of this epicenter
- 6.1Puget Sound region, WashingtonNovember 13, 1939 · 129 km N of this epicenter
- 5.88 km N of Satsop, WashingtonJuly 3, 1999 · 111 km NW of this epicenter
- 5.8Puget Sound area, WashingtonFebruary 15, 1946 · 117 km N of this epicenter
- 5.738 km NNE of Amboy, WashingtonMay 18, 1980 · 35 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 77 recorded deaths. The most severe:
- 1980M5.2
Mt St Helens
18 May 1980 · 35 km away · intensity V
61 deaths$2.0 billion damagetsunami
- 1949M7.0
Washington
13 Apr 1949 · 102 km away · intensity VIII
8 deaths$25 million damagetsunami
- 1965M6.6
Seattle
29 Apr 1965 · 131 km away · intensity VIII
7 deaths$28 million damage
- 2001M6.8
Olympia, Seattle, Tacoma
28 Feb 2001 · 101 km away · intensity VIII
1 death$2.0 billion damage
- 1993M5.6
Washington-Oregon Border
25 Mar 1993 · 135 km away · intensity VII
$28 million damage
- 1700M9.0
Cascadia Subduction Zone
27 Jan 1700 · 230 km away
Severe damage ($5–24M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.