M4.0 earthquake 6 km NW of Petrinja, Croatia

Thursday, January 7, 2021, 11:06:46 UTC · 45.483°N, 16.242°E

A magnitude 4.0 earthquake struck 6 km NW of Petrinja, Croatia on Thursday, January 7, 2021, 11:06:46 UTC, at a depth of 9.5 km (shallow). USGS received 2 “Did You Feel It?” reports, with a maximum reported intensity of III (weak).

Magnitude: 4.0; Light · mb
Depth: 10 km; Shallow
Felt reports: 2; Max intensity III
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

15 tons of TNT

That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.

Tectonic setting

711 km

from the nearest mapped plate boundary, between the Eurasian and African plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: shallow

10 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
Bestovje, Zagreb, Croatia	III · Weak	1	49 km
Zagreb, Grad Zagreb, Croatia	II · Weak	1	42 km

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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.4 on January 15, 2021. 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 117 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 1,170 recorded deaths. The most severe:

1976M6.5
Ne, Balkans Nw: Slovenia: Nw
6 May 1976 · 249 km away · intensity X
978 deaths$3.6 billion damage
1763M6.2
Gyor; Czechoslovakia: Komarom
28 Jun 1763 · 288 km away · intensity IX
83 deathsLimited damage (under $1M)
1943
Bosnia-Herzegovina
29 Jan 1943 · 144 km away
19 deathsLimited damage (under $1M)
1930M6.0
Senigallia
30 Oct 1930 · 281 km away · intensity IX
18 deathsSevere damage ($5–24M)tsunami
1969M6.0
Bosnia-Herzegovina: Banja Luka
26 Oct 1969 · 105 km away · intensity VIII
14 deaths$50 million damage
1976M6.0
Northeastern
15 Sep 1976 · 253 km away · intensity IX
11 deathsModerate damage ($1–5M)

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

Nearby trackers