Reviewed by USGSGuam29y ago
M6.5 earthquake 49 km N of Yigo Village, Guam
Wednesday, April 23, 1997, 19:44:28 UTC · 13.986°N, 144.901°E
A magnitude 6.5 earthquake struck 49 km N of Yigo Village, Guam on Wednesday, April 23, 1997, 19:44:28 UTC, at a depth of 100.8 km (intermediate). It is the strongest earthquake within 300 km since an M7.8 on August 8, 1993.
- Magnitude
- 6.5
- Strong · mwc
- Depth
- 101 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VI
- Strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured 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
100 km
from the nearest mapped plate boundary, between the Philippine Sea and Mariana plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
101 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 lists 4 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M6.0 on May 9, 1997. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 395 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.832 km S of Inarajan Village, GuamAugust 8, 1993 · 112 km S of this epicenter
- 7.0176 km ESE of San Jose Village, Northern Mariana IslandsMay 18, 1913 · 238 km E of this epicenter
- 7.098 km SSE of Inarajan Village, GuamDecember 9, 1909 · 176 km S of this epicenter
- 7.032 km NNE of Yigo Village, GuamOctober 26, 1912 · 19 km S of this epicenter
- 6.5112 km NE of Saipan, Northern Mariana IslandsJune 6, 1993 · 274 km NE of this epicenter
- 6.446 km ENE of Yigo Village, GuamOctober 29, 1936 · 47 km SE of this epicenter
- 6.3146 km WSW of Merizo Village, GuamNovember 24, 1917 · 210 km SW of this epicenter
- 6.3112 km ENE of Saipan, Northern Mariana IslandsJanuary 17, 1948 · 271 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1993M7.8
Tuman Bay, Apra Harbor
8 Aug 1993 · 112 km away · intensity IX
$250 million damagetsunami
- 1849M7.5
Guam
25 Jan 1849 · 173 km away · intensity IX
Severe damage ($5–24M)tsunami
- 1909M8.0
Guam
9 Dec 1909 · 166 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1892M7.5
Guam
16 May 1892 · 173 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1825
Ladrones Island
Apr 1825 · 173 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1834
Agana
May 1834 · 173 km away
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.