M3.8 earthquake 22 km WNW of Villa Basilio Nievas, Argentina

Friday, November 20, 1998, 04:17:51 UTC · 31.455°S, 68.942°W

A magnitude 3.8 earthquake struck 22 km WNW of Villa Basilio Nievas, Argentina on Friday, November 20, 1998, 04:17:51 UTC, at a depth of 100.0 km (intermediate).

Magnitude: 3.8; Minor · md
Depth: 100 km; Intermediate
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

8 tons of TNT

That is about 1/1,992 of the Hiroshima bomb. A magnitude 5.0 releases about 63 times more energy.

Tectonic setting

353 km

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

Depth: intermediate

100 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 50 km

USGS lists 9 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.4 on December 11, 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 401 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 32 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 24,987 recorded deaths. The most severe:

1861
Mendoza, San Luiz
20 Mar 1861 · 150 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
1944M6.9
San Juan Province
15 Jan 1944 · 43 km away · intensity IX
10,000 deaths$100 million damage
1965M7.3
Central
28 Mar 1965 · 238 km away
400 deaths$125 million damage
1920M6.7
Mendoza
17 Dec 1920 · 71 km away · intensity VIII
400 deathsSevere damage ($5–24M)
1971M7.8
Central
9 Jul 1971 · 243 km away · intensity IX
83 deaths$236 million damagetsunami
1977M7.5
San Juan Province: Mendoza
23 Nov 1977 · 111 km away · intensity IX
65 deaths$80 million damage

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

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