December 9, 1909 Earthquake: Guam, US Territories
A magnitude 8 earthquake struck Guam, US Territories on December 9, 1909 at 23:28 UTC, 100 km below the surface. It caused a tsunami.
Map
Where it struck, with the other significant earthquakes within 200 km. Circles are sized and colored by magnitude; select one for its page.
The earthquake
- Date
- December 9, 1909
- Time
- 23:28 UTC
- Place
- Guam, US Territories
- Magnitude
- 8
- Focal depth
- 100 km (62 mi)
- Intensity
- 8 on the Modified Mercalli scale
- Tsunami
- Yes: the tsunami it caused
- Epicenter
- 12.500° N, 145.000° E
- Country
- US Territories
The toll
- Damage
- Moderate (about $1 to $5 million)
Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.
What the record says
NCEI’s account, from the sources it cites.
At 9 a.m. on December 10th there were two shocks lasting twenty seconds of which the second was the more severe. Direction of the shocks SE-NW. In Agaña [Hagåtña] pratically all the east and west walls of native mortar houses were badly cracked. Several fissures opened in the ground from one of which, near the river, came a large flow of water. The river bed sank in several places. The passing wave could been distinctly as it crossed the plaza, and the station ship in the harbor reported having felt the shock. No damage of importance was done in the other towns on the island. (reference #2519)
Destructive earthquake. (reference #1072)
Reference #1060 lists epicenter Dec 9, 1909, 2330 UTC, 13N, 145E (Northern Mariana Islands), moderate damage.
Reference #1085 lists epicenter Dec 9, 1909, 2328 UTC, 12.5N 145E (Northern Mariana Islands), depth 100 km, magnitude 8.
Other significant earthquakes nearby
Within 200 km, the deadliest first.
More
Significant earthquakes of 1909The 1900sEvery quake the USGS located in 1909Recent earthquakes near hereThis day in weather history
Sources
Significant earthquakes from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI earthquake 2894.