The Southeast Asian Ring of Fire

The famous Pacific Ring of Fire

The Pacific Ring of Fire (PRoF) the is famous association of volcanoes and earthquakes that broadly encircle the Pacific Ocean.

The western side of the ring is created by subduction of the Pacific plate beneath Asia and Australia.
The eastern part is created by subduction of a number of oceanic plates beneath North and South America; these plates are "siblings" of the Pacific plate, in the sense that they formed along the same oceanic spreading ridge system.
The southern edge of the Pacific Ring of Fire does not have volcanoes or large earthquakes because the plate boundaries with Antarctica are divergent, not convergent.

Southeast Asia does not belong to the Pacific Ring of Fire

When a large earthquake or volcanic eruption strikes anywhere in Southeast Asia, news reports almost invariably mention that the region lies along the Pacific Ring of Fire (see below).

However -

There is no Pacific Ocean or Pacific plate in this region, even in the east. The oceanic plate subducting beneath Taiwan and Japan is the Philippine Sea plate, not the Pacific plate.
The western half of of this area is defined by subduction of the oceanic crust of the Indian/Australian plates beneath Asia. The northward motion relative to Asia is different from the Pacific plate's east-west directed motions.
Many plate boundaries in this region are highly curved and complex, unlike most settings along the Pacific Ring of Fire where plate boundaries are longer and straighter.

News media say that Southeast Asia is on the Pacific Ring of Fire

News reports in the aftermath of earthquakes, tsunamis, and volcanic eruptions across Southeast Asia will almost invariably invoke the Pacific Ring of Fire. Repetition of phrases indicates that there is boilerplate text from newswire services being pasted in to many stories about this region.

A few recent examples... click to follow on to the original stories.

The list goes on and on.... try your own GOOGLE SEARCH for Indonesia and the Pacific Ring of Fire in the news.

What (and where) is the Southeast Asian Ring of Fire?

I propose that the Southeast Asian Ring of Fire can be defined as the seismically and volcanically active area stretching from Eastern Tibet to southwest Japan. This is where the Philippine Sea plate, Australian plate, and Indian plate are subducting beneath Southeast Asia.

The Pacific Ring of Fire diverges southward from Japan, running through the Marianas Trench to Papua New Guinea.

Why is the distinction important?

There are major differences between Southeast Asia and the circum-Pacific region that should be considered.

Large tsunamis from the Pacific Ring of Fire can travel across the Pacific Ocean, where they impact areas that are themselves seismically active.
Much of the population of Southeast Asia lives inside the circle of volcanoes and earthquakes, and are exposed to threats from multiple directions. In comparison, very few people live within the Pacific Ring of Fire - they mainly live outside of it, along its edges.
Ash from volcanic eruptions can cross the Southeast Asian Ring of Fire easily. In contrast, eruptions along the Pacific Ring of Fire do not generally have major impacts on the other side of the Ring due to the very large size of the Pacific Ocean.
The societies and communities in Southeast Asia have diverse relationships to hazard and risk, which are different in many ways to those found along the Pacific Ring of Fire.
Some of the largest countries along the Pacific Ring of Fire are already fairly resilient to seismic hazard (Chile, USA, Canada, Japan); no large country in Southeast Asia has attained the same level of resiliency.
Different social and environmental settings (typhoons, monsoons, inland seas, etc) set up hazard cascades that are different from what we usually see along the Pacific Ring of Fire.

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