M4.4 earthquake 9 km SSE of Santa Cruz, Costa Rica

Friday, September 21, 2012, 06:37:02 UTC · 10.184°N, 85.538°W

A magnitude 4.4 earthquake struck 9 km SSE of Santa Cruz, Costa Rica on Friday, September 21, 2012, 06:37:02 UTC, at a depth of 44.8 km (shallow). USGS received 6 “Did You Feel It?” reports, with a maximum reported intensity of IV (light).

Magnitude: 4.4; Light · mb
Depth: 45 km; Shallow
Felt reports: 6; Max intensity IV
Est. shaking: —; No ShakeMap
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

60 tons of TNT

That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.

Tectonic setting

46 km

from the nearest mapped plate boundary, between the Panama and Caribbean plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

45 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

6 people reported feeling this earthquake to USGS; a per-place breakdown is not available 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 50 km

USGS lists 7 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.3 on October 10, 2012. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 425 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 52 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 12,071 recorded deaths. The most severe:

1972M6.2
Managua
23 Dec 1972 · 254 km away
10,000 deaths$3.0 billion damage
1930
Managua
31 Mar 1930 · 225 km away
1,000 deaths$15 million damage
1910M6.4
Cartago, San Jose
4 May 1910 · 170 km away
700 deathsSevere damage ($5–24M)
1992M7.6
Masachapa; Costa Rica
2 Sep 1992 · 269 km away
170 deaths$30 million damagetsunami
1991M7.6
Limon, Pandora; Panama
22 Apr 1991 · 276 km away · intensity X
90 deaths$510 million damagetsunami
1952
Costa Rica
30 Dec 1952 · 223 km away
29 deaths

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers