A Tale of Two Earthquakes

On August 24, 2016, at 3:36 a.m. local time, a magnitude 6.2 earthquake struck Central Italy, taking 296 lives. On the same day, a few hours later at 5:06 p.m. local time, a magnitude 6.8 earthquake rattled the country of Myanmar, also known as Burma. While the magnitude was much stronger, only 4 people died in that quake even though many buildings were damaged and a priceless cultural heritage site destroyed.

The big differences? Geographical location, depth of the epicenter, and type of building construction.

The Central Italy quake hit near a densely populated area at a shallow depth of only 10km (6 mi.) under villages that still had very old stone and brick buildings never retrofitted to earthquake safe standards. The shallow quake, rated IX, or violent, on the intensity scale, shook the older buildings apart, burying almost 300 people in rubble as they slept. The town of Amatrice and surrounding villages were filled with tourists who had come for a festival that was to start that same day.

The Central Italy earthquake zone in the Apeninne Mountains, where three tectonic plates meet, is a complex area geologically. The Africa Plate is still converging (shoving into) the Eurasian Plate, while the Adriatic Plate is pulling away from the Eurasian Plate, creating a spreading zone down the Po Valley. When the pulling apart released long-stored fault line tension, one side of the fault line dropped suddenly, creating the shockwave.

The Myanmar quake epicenter was located in a thinly populated area of Central Burma, at a depth of 84km (52 mi). The maximum intensity of the quake was rated VI, or strong, but not severe or violent. As a result, a few buildings near the epicenter collapsed and others were damaged, but loss of life and major damage were held to a minimum.

This earthquake was located on a strike-slip fault line marking the convergence of the India Plate and the Eurasian Plate. The India Plate is moving briskly north in geological terms, against the Eurasian Plate moving slowly south. As the two plates bump together and try to slide past each other, horizontal stress builds up until some weaker point in the fault line gives way. The sudden release of tension causes sideways slippage triggering the shaking motion. This fault line is similar in structure to the San Andreas Fault that runs the length of California.

Whether an earthquake is caused by Normal Faulting as in Central Italy, or a strike-slip fault, or a megathrust that occurs in ocean trenches and can reach magnitude 9.0 and higher, the amount of resulting damage depends on what a real estate agent would call location location location.