Story highlights John Vidale: Mexico's earthquake caused by crumpling from the downward bending of the sinking Cocos Plate deep within earth

He says cure for devastation: make buildings earthquake proof. Meantime Mexico's "earthquake early warning" appeared to do its job. US could use the same

John Vidale, a seismologist, is a professor of Earth Sciences at the University of Southern California and director of the Southern California Earthquake Center. Follow him on Twitter at @seismoguy. The opinions expressed in this commentary are solely those of the author.

(CNN) Another deadly earthquake struck deep under Mexico.

Shortly after noon on Tuesday, an earthquake violently shook the area around Mexico City, collapsing numerous buildings into dust, killing more than 100. The greatest impact was in densely populated Mexico City, but the shaking was even more intense in Puebla, closer to the epicenter.

The shaking energy was generated at the earthquake's source, 30 miles deep, for just 20 seconds, but the waves reverberated for much longer, up to a minute or two, in the mountain and valleys.

Plate tectonics was the engine behind the shaking, as is true for all major earthquakes. Along the coast of Mexico, the Cocos Plate slides underneath the North American Plate, moving about three inches per year. Tuesday's earthquake, however, was caused by crumpling arising from the downward bending of the sinking Cocos Plate, rather than directly by slippage between plates.

Photos: Deadly earthquake rocks central Mexico Relatives of missing people wait for news in front of a collapsed building in Mexico City on Friday, September 22. A magnitude 7.1 quake hit central Mexico three days earlier. Hide Caption 1 of 42 Photos: Deadly earthquake rocks central Mexico Rescue workers search for survivors Thursday, September 21, at a collapsed apartment building in Mexico City. Hide Caption 2 of 42 Photos: Deadly earthquake rocks central Mexico A religious statue is salvaged from a former convent that was heavily damaged in Tlayacapan, Mexico. This was the second earthquake to hit Mexico in two weeks. A magnitude 8.1 quake struck off the country's southern coast on September 8. Hide Caption 3 of 42 Photos: Deadly earthquake rocks central Mexico A wall is damaged at a home in Tlayacapan on Wednesday, September 20. Hide Caption 4 of 42 Photos: Deadly earthquake rocks central Mexico Volunteers organize donations in Mexico City on September 20. Hide Caption 5 of 42 Photos: Deadly earthquake rocks central Mexico Rescuers in Mexico City work to save a child trapped inside the Enrique Rebsamen elementary school on September 20. Rescue workers said they believed they'd made contact with a girl trapped in the rubble at the school. But by the next afternoon, navy official Angel Enrique Sarmiento said all the school's children had been accounted for and there was no student in the rubble. He apologized for the confusion. Hide Caption 6 of 42 Photos: Deadly earthquake rocks central Mexico Men carry beams of wood to offer help in Mexico City's Roma neighborhood on September 20. Hide Caption 7 of 42 Photos: Deadly earthquake rocks central Mexico Families prepare to sleep under tarps outside their quake-damaged building in Mexico City on September 20. Hide Caption 8 of 42 Photos: Deadly earthquake rocks central Mexico Rescuers and firefighters lower a corpse from a house in Mexico City on September 20. Hide Caption 9 of 42 Photos: Deadly earthquake rocks central Mexico Volunteers and rescue workers search for people trapped inside the Enrique Rebsamen school on September 20. Hide Caption 10 of 42 Photos: Deadly earthquake rocks central Mexico A volunteer in Mexico City asks for silence as a flattened building is searched for survivors on September 20. Hide Caption 11 of 42 Photos: Deadly earthquake rocks central Mexico Members of the Mexican Army nap September 20 after assisting in search-and-rescue missions in Mexico City. Hide Caption 12 of 42 Photos: Deadly earthquake rocks central Mexico People look for survivors in Mexico City on September 20. Hide Caption 13 of 42 Photos: Deadly earthquake rocks central Mexico A man walks his bike past a partially collapsed building in Jojutla on September 20. Hide Caption 14 of 42 Photos: Deadly earthquake rocks central Mexico Volunteers arrange food and other donated supplies at a distribution point in Mexico City on September 20. Hide Caption 15 of 42 Photos: Deadly earthquake rocks central Mexico Children's toys are seen in a damaged building in Mexico City on September 20. Hide Caption 16 of 42 Photos: Deadly earthquake rocks central Mexico A survivor is pulled out of rubble in Mexico City on September 20. Hide Caption 17 of 42 Photos: Deadly earthquake rocks central Mexico People sleep on the street next to damaged homes in Jojutla on September 20. Hide Caption 18 of 42 Photos: Deadly earthquake rocks central Mexico Soldiers remove debris from a collapsed building in Mexico City on September 20. Hide Caption 19 of 42 Photos: Deadly earthquake rocks central Mexico An injured person is carried away after being rescued in Mexico City on Tuesday, September 19. The earthquake happened on the anniversary of a 1985 quake that killed an estimated 9,500 people in and around Mexico City. Hide Caption 20 of 42 Photos: Deadly earthquake rocks central Mexico Rescue workers remove rubble from a Mexico City building on September 19. Hide Caption 21 of 42 Photos: Deadly earthquake rocks central Mexico Rescue workers in Mexico City search for people trapped inside the collapsed Enrique Rebsamen school on September 19. Hide Caption 22 of 42 Photos: Deadly earthquake rocks central Mexico A man comforts a student outside a school in Mexico City on September 19. Hide Caption 23 of 42 Photos: Deadly earthquake rocks central Mexico A police officer runs toward the site where a building collapsed in Mexico City on September 19. Hide Caption 24 of 42 Photos: Deadly earthquake rocks central Mexico Rescue workers and volunteers search a collapsed building in Mexico City on September 19. Hide Caption 25 of 42 Photos: Deadly earthquake rocks central Mexico A man is rescued under rubble in Mexico City's Condesa area on September 19. Hide Caption 26 of 42 Photos: Deadly earthquake rocks central Mexico Hide Caption 27 of 42 Photos: Deadly earthquake rocks central Mexico A woman's crushed body hangs from a collapsed building in Mexico City on September 19. Hide Caption 28 of 42 Photos: Deadly earthquake rocks central Mexico Recovery efforts take place at the collapse of a residential building in Mexico City on September 19. Hide Caption 29 of 42 Photos: Deadly earthquake rocks central Mexico The quake damaged the Jojutla Municipal Palace. Hide Caption 30 of 42 Photos: Deadly earthquake rocks central Mexico A search goes on at the scene of a collapsed building in Mexico City's Del Valle neighborhood on September 19. Hide Caption 31 of 42 Photos: Deadly earthquake rocks central Mexico Emergency workers remove debris as they search for survivors in Mexico City on September 19. Hide Caption 32 of 42 Photos: Deadly earthquake rocks central Mexico People react in Mexico City just after the quake hit. Hide Caption 33 of 42 Photos: Deadly earthquake rocks central Mexico People gather on a Mexico City street after office buildings were evacuated because of the quake. Hide Caption 34 of 42 Photos: Deadly earthquake rocks central Mexico A building is damaged in Mexico City on September 19. Hide Caption 35 of 42 Photos: Deadly earthquake rocks central Mexico A woman in Mexico City cries as she tries to reach people on her cell phone after the quake. Hide Caption 36 of 42 Photos: Deadly earthquake rocks central Mexico Patients from a Mexico City hospital receive treatment outside after the hospital was evacuated on September 19. Hide Caption 37 of 42 Photos: Deadly earthquake rocks central Mexico A woman in Mexico City reacts after the quake. Hide Caption 38 of 42 Photos: Deadly earthquake rocks central Mexico People remove debris off a building that collapsed in Mexico City. Hide Caption 39 of 42 Photos: Deadly earthquake rocks central Mexico A car is crushed by debris in Mexico City on September 19. Hide Caption 40 of 42 Photos: Deadly earthquake rocks central Mexico A woman receives medical assistance after she was injured in Mexico City on September 19. Hide Caption 41 of 42 Photos: Deadly earthquake rocks central Mexico People stand inside a Mexico City building that collapsed in the quake. Hide Caption 42 of 42

A similarly deep but much larger magnitude 8.1-earthquake struck two weeks ago, also from the crumpling of the Cocos Plate. It struck Mexico 400 miles to the southeast and offshore, not far from Guatemala, and killed dozens of people. It is not immediately clear whether Tuesday's earthquake was triggered by the earlier one or if it is unrelated -- usually aftershocks are not so distant in time.

Read More