Reviewed by USGSCalifornia109y ago
M6.5 earthquake 52 km WNW of Big Lagoon, California
Monday, July 15, 1918, 00:23:12 UTC · 41.325°N, 124.720°W
A magnitude 6.5 earthquake struck 52 km WNW of Big Lagoon, California on Monday, July 15, 1918, 00:23:12 UTC, at a depth of 15.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 6.5
- Strong · mw
- Depth
- 15 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (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
85 kilotons of TNT
That is about 6 times the Hiroshima bomb. It released about 178 times the energy of a magnitude 5.0.
Tectonic setting
35 km
from the nearest mapped plate boundary, between the Juan de Fuca and North American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
15 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
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
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 PAGER estimate is available for this event.
After the main event
Aftershocks within 100 km
USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 9 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.5235 km W of Port Orford, OregonAugust 5, 1910 · 272 km NW of this epicenter
- 6.4187 km W of Trinidad, CaliforniaDecember 31, 1915 · 139 km W of this epicenter
- 6.4off the coast of Northern CaliforniaJune 10, 1917 · 298 km SW of this epicenter
- 6.3237 km WSW of Ferndale, CaliforniaMay 6, 1915 · 233 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1865
Fort Humboldt, Eureka
1 Oct 1865 · 41 km away · intensity IX
Moderate damage ($1–5M)
- 1873M6.7
Northern
23 Nov 1873 · 96 km away · intensity VIII
Limited damage (under $1M)tsunami
- 1871M5.9
Humboldt County
2 Mar 1871 · 112 km away · intensity VII
Limited damage (under $1M)
- 1898
N Coast,Mendocino County
14 Apr 1898 · 266 km away · intensity X
Limited damage (under $1M)
- 1851
Northern
13 Nov 1851 · 273 km away
tsunami
- 1855
Northern
20 Mar 1855 · 77 km away · intensity V
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.