The July 6, 1912 earthquake
M7.2Mount McKinley (Denali) area, Alaska
A magnitude 7.2 earthquake 1.9 miles deep, centred in Denali Borough. The 31st strongest in Alaska’s record since 1900, and the strongest within 50 miles in the catalogue, which runs from 1900. 1 aftershock of magnitude 2.5 or more followed within 30 days.
The earthquake
- Magnitude
- 7.2
- surface-wave magnitude (ms)
- Depth
- 1.9 mi
- 3.0 km below the surface
- Local time
- Saturday, July 6, 1912
- 21:57 AST; 07:57 UTC on Jul 7, 1912
- In Alaska’s record
- 31st
- strongest of 124,625 since 1900
USGS ANSS Comprehensive Earthquake Catalog, event official19120707075738000 (“Mount McKinley (Denali) area, Alaska”). The USGS event page carries the ShakeMap, felt reports and the official summary.
Aftershocks
Earthquakes of magnitude 2.5 or more within 35 miles of the epicentre in the 30 days after.
1
Aftershocks in 30 days
6.4
Largest aftershock, Jul 8, 1912
0
On the first day
0
In the 7 days before
- The search radius is the surface rupture length expected for an earthquake of this magnitude (Wells and Coppersmith, 1994), at least 20 and at most 600 miles, so a great earthquake's sequence is counted along its whole fault.
- Before the modern seismic networks of the 1970s many small aftershocks went unrecorded, so early sequences read short.
Counties and cities within 50 miles
Distance from the epicentre to each county boundary (zero when inside) and to each city centre.
Counties
- Denali BoroughAK · inside
- Matanuska-Susitna BoroughAK · 29.1 mi
Earthquakes around the epicentre
1,921 earthquakes of magnitude 3 or more within 50 miles of this epicentre since 1973.
No earlier earthquake of magnitude 5 or more within 50 miles in the catalogue since 1900.
USGS ANSS Comprehensive Earthquake Catalog. Local time is the time zone of the county nearest the epicentre. Magnitudes are as the catalogue reports them.