Revision summary
Earthquakes and volcanoes share plate belts; tsunamis follow submarine jerks or flank collapse. Subduction pairs volcanic arcs with megathrust quakes. Not every Himalayan quake is volcanic; the link is genetic, not universal. Eruptions come from decompression at rifts, flux melting at arcs, and hotspot plumes. Buoyancy and volatile overpressure drive magma through the crust. Glacier unload or a big quake may trigger a primed chamber, not create magma from nothing.
Model answer
Introduction
Volcanoes, earthquakes, and tsunamis are different surface expressions of the same restless lithosphere. They relate where plates grind, melt, or fail, but a tsunami is a water wave, an earthquake is a rupture, and a volcano is magma reaching the air—so the link is genetic, not identity.
Body
How the three hazards relate
- Convergent and transform plate edges store elastic strain; sudden slip is an earthquake, often in the same belts (Circum-Pacific, Alpine-Himalayan) that host volcanoes.
- Subduction both melts the downgoing slab’s fluids into magma, feeding volcanic arcs, and can rupture the megathrust, so Japan, Indonesia, and the Andes show paired quake-and-volcano geography.
- A submarine earthquake that jerks the seafloor, a coastal landslide, or a collapsing volcanic flank (Krakatau 1883, Anak Krakatau 2018) can displace the water column and launch a tsunami.
- Volcanic earthquakes (tremor, inflation) warn of magma; tectonic earthquakes can, rarely, shake a primed magma chamber. The relation is therefore: shared plate engine, occasional triggering, and tsunami as the marine messenger of either quake or volcano.
Possible causes of volcanic eruptions
- Decompression melting at divergent ridges and rifts lets hot mantle rise and melt as pressure drops, feeding Iceland- and East-African-type eruptions.
- Flux melting in subduction zones, where water and volatiles lower the melting point of the mantle wedge, feeds explosive andesite-dacite arcs.
- Hotspot or plume magmatism (Hawaii, Réunion, the Deccan’s deep past) punches through plates away from edges.
- Crustal thinning, continental rifts, and back-arc basins provide extra space and heat for magma to pond and then erupt.
- Magma ascent itself is caused by buoyancy, volatile exsolution (water, CO2), and chamber overpressure; a plug of viscous lava or a roof collapse can then open the vent.
- External triggers—glacier unloading, large tectonic quakes, or landslide unroofing—can add the last increment of pressure drop, but they act on magma already prepared.
Keeping the causes complete without confusion
- Not every earthquake makes a volcano, and Himalayan thrust quakes are largely non-volcanic; the Indian Ocean tsunami of 2004 was a megathrust, not a Deccan-style flood basalt.
- All plausible eruption causes therefore run from plate setting (rift, arc, plume) through magma physics (volatiles, buoyancy) to occasional external unroofing.
Flow diagram
flowchart TD P[Plate strain and melt] --> E[Earthquake rupture] P --> V[Volcano magma] E --> T[Tsunami seafloor jerk] V --> T V --> C[Rift arc plume volatiles]
Conclusion
- Volcano, earthquake, and tsunami meet at plate boundaries and at collapsing volcanic coasts: strain becomes a quake, melt becomes a volcano, and a jerked sea becomes a tsunami. Eruptions themselves are caused by decompression, subduction flux, plumes, rifting, volatile overpressure, and rarer external triggers.
Quick related
Students also ask
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Mention the factors responsible for the origins of ocean currents and name the currents of the Atlantic Ocean.
Next question in the 2018 paper (Q20). View answer →
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Can an earthquake always cause a volcanic eruption?
No. Most tectonic quakes do not tap magma. Only a chamber already close to eruption pressure is a candidate for seismic trigger.
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Is every tsunami volcanic?
No. Most great tsunamis are from submarine fault slip. Volcanic tsunamis are real but a smaller share of the global catalogue.
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