Earthquakes and Volcanic Eruptions - John Seach

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Earthquakes are able to disturb volcanic systems. In 1992 an earthquake in Landers, Southern California triggered deformation in the active Long Valley caldera. An article in Nature (29th October 1998 p 888-90) discussed this phenomenon. The conclusion was that large earthquakes (> magnitude 7) were able to trigger volcanic eruptions within a radius of 750 km.

Volcanic Eruptions Triggered by Earthquakes

Year

Volcano

Earthquake Magnitude

2007

8.1

2002

Nyiragongo

4.8

2002

Yasur

7.3

1996

Karymsky

6.7

1994

Suoh

7.2

1986

Atka

7.7

1974

Gaua

7.2

1939

Kavachi

8.1

1939

Bagana

7.9

1934

Pinacate Peaks

7.1

1920

Villarrica

7.4

1914

Aso

7.0

1913

Ambrym

8.1

1913

Awu

8.3

1899

Wrangell

8.3

1868

Cotopaxi

7.0

1854

Alaid

7.0

1837

Osorno

8.0

1837

Villarrica

8.0

1835

Yanteles

8.1

1835

Minchinmavida

8.1

1822

Villarrica

8.5

1822

San Jose

8.5

1737

Villarrica

7.7

1730

Villarrica

8.7

1587

Guagua Pichincha

7.7

 

Nyiragongo (2002)
On 4 January 2002, an earthquake measuring 4.8 on the Richter scale struck the area near Nyiragongo volcano. Two weeks later Nyiragongo erupted resulting in half a million evacuees!

Yasur Volcano (2002)
On January 3, 2002 a magnitude 7.3 earthquake hit Vanuatu. Two days later Yasur volcano increased its eruptive activity. On January 16, 2002 the Vanuatu Red Cross was preparing evacuation plans for part of the island of Tanna due to the contaminated water supplies and increased ash fall.

California (1992)
Southern California's largest earthquake since 1952, M 7.5 occurred on 28 June 1992. It appeared to trigger seismicity at several volcanic centers in California.
The earthquake was centered roughly 200 km E of Los Angeles.  Marked increases in microseismicity were observed at Lassen Peak, Medicine Lake caldera, and the Geysers. No earthquakes were observed at Shasta, but the lack of operating stations on the volcano limited the capability to observe small events.  Within eight minutes of the major earthquake's origin time, seismic activity within Long Valley caldera (400 km NNW of the epicenter) increased abruptly.  Of the >260 events located by the RTP system during the next three days, three were of M 3 or greater.

Ulawun Volcano (1983)
Volcano-seismic activity increased suddenly with the appearance of continuous harmonic tremor at 0200 on 24 December, less than 2 days after two strong regional earthquakes (ML 6.4 and 6.5, MM IV-V) about 150 km ESE of Ulawun Volcano (Papua New Guinea) at 0932 and 1102 on 22 December 1983.
 

Effects of volcano-tectonic earthquakes on Volcanoes

Earthquake Magnitude

Volcanic Result

7 +

Very large eruption

6-7

Strong eruption

5-6

Medium eruption

4-5

Small eruption