Why Was Indonesia’s 5.6 Magnitude Earthquake So Lethal?


JAKARTA, Indonesia — A 5.6 magnitude earthquake left greater than 160 useless and a whole lot injured as buildings crumbled and terrified residents ran for his or her lives on Indonesia’s major island of Java.

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

Whereas the magnitude would usually be anticipated to trigger gentle injury to buildings and different buildings, consultants say proximity to fault traces, the self-love of the quake and insufficient infrastructure that can’t stand up to earthquakes all contributed to the injury.

Right here’s a better have a look at the earthquake and a few explanation why it induced a lot devastation:

Was Monday’s Earthquake Thought of “sturdy”?

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

Quakes of this measurement normally don’t trigger widespread injury to well-built infrastructure. However the company factors out, “There may be not one magnitude above which injury will happen. It relies on different variables, reminiscent of the space from the earthquake, what sort of soil you’re on, constructing building” and different elements.

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

So why did the quake trigger a lot injury?

Specialists mentioned proximity to fault traces, the depth of the temblor and buildings not being constructed utilizing earthquake-proof strategies have been elements within the devastation.

“Although the earthquake was medium-sized, it (was) near the floor … and situated inland, near the place folks dwell,” mentioned Gayatri Marliyani, an assistant geology professor at Universitas Gadjah Mada, in Yogyakarta, Indonesia. “The vitality was nonetheless giant sufficient to trigger important shaking that led to break.”

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

A fault is a spot with a protracted break within the rock that types the floor of the earth. When an earthquake happens on one in all these faults, the rock on one facet 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,” mentioned Marliyani.

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

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

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

Does Indonesia normally have earthquakes like this?

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

Lots of Indonesia’s earthquakes are minor and trigger little to no injury. However there have additionally been lethal earthquakes.

In February, a magnitude 6.2 earthquake killed not less than 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 international locations, most of them in Indonesia.

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