M2.8 earthquake 17 km SSE of Machalí, Chile

Sunday, September 27, 1998, 13:05:56 UTC · 34.314°S, 70.556°W

A magnitude 2.8 earthquake struck 17 km SSE of Machalí, Chile on Sunday, September 27, 1998, 13:05:56 UTC, at a depth of 115.9 km (intermediate).

Magnitude: 2.8; Minor · md
Depth: 116 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

239 kg of TNT

That is about 1/63,000 of the Hiroshima bomb. A magnitude 5.0 releases about 1,995 times more energy.

Tectonic setting

225 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

116 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 M3.7 on October 8, 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 329 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 39 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 49,144 recorded deaths. The most severe:

1939M8.3
Chillan
25 Jan 1939 · 265 km away · intensity X
30,000 deaths$920 million damagetsunami
1861
Mendoza, San Luiz
20 Mar 1861 · 234 km away · intensity IX
14,000 deathsExtreme damage ($25M+)tsunami
1906M8.2
South Central
17 Aug 1906 · 198 km away · intensity XI
4,000 deaths$100 million damagetsunami
1965M7.3
Central
28 Mar 1965 · 221 km away
400 deaths$125 million damage
1928M7.6
Talca, Chillan, Santiago, San Fernando
1 Dec 1928 · 153 km away · intensity IX
279 deathsSevere damage ($5–24M)tsunami
1985M8.0
Central Coast, San Antonio, Valparaiso
3 Mar 1985 · 169 km away · intensity VIII
180 deaths$1.5 billion damagetsunami

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

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