M4.7 earthquake 85 km W of Petrolia, CA

Saturday, August 29, 2026, 02:41:11 UTC · 40.450°N, 125.272°W

A magnitude 4.7 earthquake struck 85 km W of Petrolia, CA on Saturday, August 29, 2026, 02:41:11 UTC, at a depth of 10.0 km (shallow). USGS received 102 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M4.9 on August 6, 2026.

Tsunami flagUSGS sets this flag for large events in oceanic regions so tsunami warning centers review them. It does not by itself mean a tsunami occurred. Check tsunami.gov and local authorities for official messages.

Magnitude: 4.7; Light · mw
Depth: 10 km; Shallow
Felt reports: 102; Max intensity IV
Est. shaking: III; Weak (ShakeMap)
PAGER alert: Green; Impact estimate
Tsunami: Flag; Check tsunami.gov

Outlined circle: this earthquakeDashed circle: 50 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

194 tons of TNT

That is about 1/78 of the Hiroshima bomb. A magnitude 5.0 releases about 2 times more energy.

Tectonic setting

12 km

from the nearest mapped plate boundary, between the Pacific and Juan de Fuca plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

10 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
95503<br>0.213	II · Weak	17	104 km
95540<br>0.230	II · Weak	14	98 km
95501<br>0.248	II · Weak	11	102 km
95521<br>0.269	II · Weak	8	114 km
95589<br>0.285	III · Weak	6	118 km
95536<br>0.293	III · Weak	5	87 km
95519<br>0.302	II · Weak	4	118 km
95554<br>0.311	II · Weak	3	120 km
95562<br>0.320	III · Weak	2	96 km
95542<br>0.320	III · Weak	2	125 km
95528<br>0.320	II · Weak	2	116 km
95565<br>0.330	IV · Light	1	105 km

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No populated area was estimated to feel noticeable shaking.

After the main event

Aftershocks within 50 km

USGS lists 7 M2.5+ earthquakes within 50 km since this event; the largest was M2.7 on August 29, 2026. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 248 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 20 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 4 recorded deaths. The most severe:

2022M6.4
Humboldt County
20 Dec 2022 · 72 km away · intensity VIII
2 deaths$250 million damage
1954M6.6
Humboldt County
21 Dec 1954 · 124 km away
1 death$2 million damage
1932M6.5
Eureka
6 Jun 1932 · 89 km away · intensity VIII
1 deathModerate damage ($1–5M)
1992M7.1
Humboldt County: Ferndale, Petrolia
25 Apr 1992 · 81 km away · intensity VIII
$75 million damagetsunami
2010M6.5
Off Coast Northern
10 Jan 2010 · 54 km away
$43 million damage
1980M7.2
North Coast
8 Nov 1980 · 113 km away · intensity VII
$2 million damage

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers