Tuesdays quake was deeper than normal at China pu squishy toys Suppliers 32 miles below the surface, and deeper quakes are also associated with fewer aftershocks. New Zealand has been affected by similar issues in past quakes, he said.While the geology is not quite the same, Los Angeles, Seattle and the San Francisco Bay area have soft soil that can amplify seismic waves, according to US Geological Survey seismologist Oliver Boyd.This so-called "slab fault" quake usually has fewer aftershocks, like the relative quiet after a 2001 earthquake in Seattle. Instead, Tuesdays quake happened in the middle of the Cocos plate, the result of pressure built up as it slips under the North American plate.Geologists say the second quake was not an aftershock because it was too far away — about 400 miles — from the first. The first was a magnitude 8.The soft soil that lines the ancient lake bed that Mexico City is built on amplified the shaking from Tuesdays earthquake and increased its destructive force, seismologists say as they try to better understand the quake that has killed more than 200 people.

The soft sediments were the major cause of damage in Mexico Citys 1985 earthquake, according to Cornell University geophysicist Geoffrey Abers. Instead of cushioning the city from earthquakes, it exaggerates their effects, said James Jackson, a professor of geophysics at the University of Cambridge in England."Its like being built on jelly on top of something that is wobbling," Jackson said.1 quake that struck southern Mexico and killed at least 90 people.The vibrations, or seismic waves, from the hard rocks below are amplified by the soil and sediments above, making the surface — and the structures built on the surface — shake longer and more intensely. Usually an area can expect an aftershock one magnitude lower, which would be in the 6.Scientists are looking at other quirks of the magnitude 7.It was also not a release of stress generated by the far-off quake, Earle said. Sometimes they happen at the same time.Still, he said, seismologists will probe further to see if there might be some kind of link between the two — or not.Mexico City is built on deep, soft soil that was once the bottom of a lake.Unlike most earthquakes, it did not happen where two tectonic plates meet.Two in twelve daysTuesdays earthquake was the second in just 12 days in Mexico. "Sometimes they happen spaced out in time.Other Soft SpotsThe same deep soft soil effect worsened the deadly 2015 Nepal earthquake because Katmandu is also built on a dry lake bed, Jackson said.".1 range, he said — even though Tuesdays quake was a type that is usually accompanied by fewer aftershocks. Most aftershocks are within 62 miles, Earle said.1 earthquake, including the absence of aftershocks and if it is somehow related to a distant, even stronger, Mexican temblor that struck a dozen days earlier.Where are the aftershocks?Scientists have been unable to detect any aftershocks as of Wednesday afternoon, said USGS seismologist Paul Earle."Earthquakes are random," Earle said.

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