Reviewed by USGSPhilippines5y ago
M7.1 earthquake 60 km ENE of Pondaguitan, Philippines
Wednesday, August 11, 2021, 17:46:13 UTC · 6.475°N, 126.715°E
A magnitude 7.1 earthquake struck 60 km ENE of Pondaguitan, Philippines on Wednesday, August 11, 2021, 17:46:13 UTC, at a depth of 55.1 km (shallow). USGS received 153 “Did You Feel It?” reports, with a maximum reported intensity of IX (violent). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M7.2 on February 11, 2009.
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
- 7.1
- Major · mww
- Depth
- 55 km
- Shallow
- Felt reports
- 153
- Max intensity IX
- Est. shaking
- VII
- Very strong (ShakeMap)
- PAGER alert
- Green
- Impact estimate
- Tsunami
- Flag
- Check tsunami.gov
Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
674 kilotons of TNT
That is about 45 times the Hiroshima bomb. It released about 1,413 times the energy of a magnitude 5.0.
Tectonic setting
59 km
from the nearest mapped plate boundary, between the Philippine Sea and Sunda plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
55 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 |
|---|---|---|---|
| Davao, Southern Mindanao, Philippines | V · Moderate | 18 | 149 km |
| Alabel, Southern Mindanao, Philippines | VI · Strong | 6 | 175 km |
| Buayan, Southern Mindanao, Philippines | V · Moderate | 5 | 176 km |
| Tamisan, Southern Mindanao, Philippines | VII · Very strong | 4 | 82 km |
| Digos, Southern Mindanao, Philippines | V · Moderate | 4 | 163 km |
| Katangawan, Southern Mindanao, Philippines | IV · Light | 4 | 177 km |
| Malandag, Southern Mindanao, Philippines | V · Moderate | 3 | 172 km |
| Brasilisa, Caraga, Philippines | IV · Light | 3 | 393 km |
| Talisay, Southern Mindanao, Philippines | VII · Very strong | 2 | 91 km |
| Dahican, Southern Mindanao, Philippines | VI · Strong | 2 | 88 km |
| Camudmud, Southern Mindanao, Philippines | VI · Strong | 2 | 148 km |
| Lasang, Southern Mindanao, Philippines | VI · Strong | 2 | 155 km |
USGS PAGER estimate
Who was exposed to shaking
Modelled from the ShakeMap and population data. Alert level green: low likelihood of casualties and damage.
- VII · Very strong shaking
- 137,000 people
- VI · Strong shaking
- 806,000 people
- V · Moderate shaking
- 7.0 million people
- IV · Light shaking
- 13 million people
- III · Weak shaking
- 17 million people
- II · Weak shaking
- 2.8 million people
Estimated shaking in nearby towns
- BobonPopulation 4,500VII · Very strong
- PondaguitanPopulation 2,100VII · Very strong
- SurupPopulation 2,100VII · Very strong
- TamisanPopulation 2,900VII · Very strong
- LuzonPopulation 3,200VII · Very strong
- NanganPopulation 3,400VII · Very strong
- DavaocapitalPopulation 1.2 millionV · Moderate
- ButuancapitalPopulation 310,000IV · Light
After the main event
Aftershocks within 200 km
USGS lists 79 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.7 on August 12, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.195 km E of Sarangani, Philippines5y ago · 130 km S of this epicenter
- 4.296 km SSE of Pondaguitan, Philippines5y ago · 104 km S of this epicenter
- 4.3146 km SE of Pondaguitan, Philippines5y ago · 123 km SE of this epicenter
- 4.552 km S of Pondaguitan, Philippines5y ago · 84 km SW of this epicenter
- 4.270 km SE of Pondaguitan, Philippines5y ago · 69 km S of this epicenter
- 4.588 km ESE of Pondaguitan, Philippines5y ago · 48 km SE of this epicenter
- 4.4133 km ESE of Pondaguitan, Philippines5y ago · 92 km SE of this epicenter
- 4.469 km E of Sarangani, Philippines5y ago · 135 km SW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 1,680 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11924 Mindanao, Philippines EarthquakeApril 14, 1924 · 63 km W of this epicenter
- 8.01972 Mindanao, Philippines EarthquakeDecember 2, 1972 · 7 km SW of this epicenter
- 7.919 km WNW of Palimbang, PhilippinesAugust 16, 1976 · 298 km W of this epicenter
- 7.947 km ESE of Kalbay, PhilippinesMarch 14, 1913 · 138 km SW of this epicenter
- 7.877 km E of Baculin, PhilippinesMay 25, 1943 · 117 km NE of this epicenter
- 7.8161 km SE of Sarangani, PhilippinesApril 1, 1936 · 249 km S of this epicenter
- 7.774 km ENE of Barcelona, PhilippinesJuly 12, 1911 · 227 km N of this epicenter
- 7.6101 km SE of Sarangani, PhilippinesDecember 16, 1910 · 215 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 50 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 8,309 recorded deaths. The most severe:
- 1976M8.0
Mindanao: S
16 Aug 1976 · 291 km away · intensity VI
8,000 deaths$134 million damagetsunami
- 1913M7.8
Sangihe Island
14 Mar 1913 · 141 km away · intensity IX
138 deathsModerate damage ($1–5M)tsunami
- 1928M7.4
Cotabato,N Coast Of Illana Bay
19 Dec 1928 · 274 km away · intensity VII
97 deathsModerate damage ($1–5M)tsunami
- 2002M7.5
Mindanao
5 Mar 2002 · 277 km away
15 deaths$2 million damagetsunami
- 2019M6.8
Mindanao: Davao
15 Dec 2019 · 171 km away
13 deathsExtreme damage ($25M+)
- 2019M6.6
Mindanao: Cotabato, Davao
29 Oct 2019 · 189 km away
13 deathsSevere damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.