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HomeNewsEXPLAINER: Why was Indonesia's shallow quake so lethal?

EXPLAINER: Why was Indonesia’s shallow quake so lethal?


JAKARTA, Indonesia — A 5.6 magnitude earthquake left greater than 260 useless and a whole lot injured as buildings crumbled and terrified residents ran for his or her lives on Indonesia’s essential island of Java.

Our bodies continued to be pulled from the particles on Tuesday within the hardest-hit metropolis of Cianjur, within the nation’s most densely populated province of West Java and a few 217 kilometers (135 miles) south of the capital, Jakarta. Quite a few persons are nonetheless lacking.

Whereas the magnitude would sometimes be anticipated to trigger gentle harm to buildings and different buildings, specialists say proximity to fault strains, the vanity of the quake and insufficient infrastructure that can’t face up to earthquakes all contributed to the harm.

Right here’s a more in-depth take a look at the earthquake and a few the reason why it induced a lot devastation:


The U.S. Geological Survey stated the quake late Monday afternoon measured 5.6 magnitude and struck at a depth of 10 kilometers (6.2 miles).

Quakes of this dimension often don’t trigger widespread harm to well-built infrastructure. However the company factors out, “There’s not one magnitude above which harm will happen. It is dependent upon different variables, reminiscent of the gap from the earthquake, what kind of soil you’re on, constructing development” and different components.

Dozens of buildings had been broken in Indonesia, together with Islamic boarding colleges, a hospital and different public services. Additionally broken had been roads and bridges, and components of the area skilled energy blackouts.


Consultants stated proximity to fault strains, the depth of the temblor and buildings not being constructed utilizing earthquake-proof strategies had been components within the devastation.

“Regardless that the earthquake was medium-sized, it (was) near the floor … and positioned inland, near the place folks dwell,” stated Gayatri Marliyani, an assistant geology professor at Universitas Gadjah Mada, in Yogyakarta, Indonesia. “The power was nonetheless massive sufficient to trigger vital shaking that led to break.”

The worst-affected space is near a number of recognized faults, stated Marliyani.

A fault is a spot with a protracted break within the rock that kinds the floor of the earth. When an earthquake happens on one in every of these faults, the rock on one aspect of the fault slips with respect to the opposite.

“The world most likely has essentially the most inland faults in comparison with the opposite components of Java,” stated Marliyani.

She added that whereas some well-known faults are within the space, there are a lot of different lively faults that aren’t nicely studied.

Many buildings within the area are additionally not constructed with quake-proof designs, which additional contributed to the harm, stated Danny Hilman Natawidjaja, an earthquake geology skilled on the Indonesian Institute of Sciences Geotechnology Analysis Heart.

“This makes a quake of this dimension and depth much more damaging,” he stated.


The nation of greater than 270 million folks is incessantly struck by earthquakes, volcanic eruptions and tsunamis due to its location on the arc of volcanoes and fault strains within the Pacific Basin generally known as the “Ring of Hearth.” The world spans some 40,000 kilometers (25,000 miles) and is the place a majority of the world’s earthquakes happen.

A lot of Indonesia’s earthquakes are minor and trigger little to no harm. However there have additionally been lethal earthquakes.

In February, a magnitude 6.2 earthquake killed at the very least 25 folks and injured greater than 460 in West Sumatra province. In January 2021, a magnitude 6.2 earthquake killed greater than 100 folks and injured practically 6,500 in West Sulawesi province.

A robust Indian Ocean quake and tsunami in 2004 killed 230,000 folks in a dozen nations, most of them in Indonesia.

The Related Press Well being and Science Division receives assist from the Howard Hughes Medical Institute’s Division of Science Schooling. The AP is solely accountable for all content material.



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