M3.6 earthquake 70 km WNW of La Ligua, Chile

Friday, March 20, 1998, 07:56:59 UTC · 32.270°S, 71.951°W

A magnitude 3.6 earthquake struck 70 km WNW of La Ligua, Chile on Friday, March 20, 1998, 07:56:59 UTC, at a depth of 31.5 km (shallow).

Magnitude: 3.6; Minor · md
Depth: 32 km; Shallow
Felt reports: 0; Did You Feel It?
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

4 tons of TNT

That is about 1/3,975 of the Hiroshima bomb. A magnitude 5.0 releases about 126 times more energy.

Tectonic setting

75 km

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

Depth: shallow

32 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

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 50 km

USGS lists 19 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.3 on April 1, 1998. 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 449 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 42 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 4,778 recorded deaths. The most severe:

1906M8.2
South Central
17 Aug 1906 · 81 km away · intensity XI
4,000 deaths$100 million damagetsunami
1965M7.3
Central
28 Mar 1965 · 72 km away
400 deaths$125 million damage
1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 99 km away · intensity VIII
180 deaths$1.5 billion damagetsunami
1971M7.8
Central
9 Jul 1971 · 75 km away · intensity IX
83 deaths$236 million damagetsunami
1822M8.5
Valparaiso, Quillota, Concon, Aconcagua
20 Nov 1822 · 81 km away · intensity XI
72 deathsExtreme damage ($25M+)tsunami
1943M8.2
Illapel
6 Apr 1943 · 169 km away
11 deathsLimited damage (under $1M)tsunami

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

Nearby trackers