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Earthquakes Cross Political Boundaries

The earthquake that struck just south of the U.S.-Mexico border Sunday is a reminder that Earth's boundaries don't always follow political ones. And the result of the shaking, in addition to property damage and lives lost, could be better social and scientific ties, says one earthquake scientist.

"We will learn a lot about earthquakes in [the] California region, because this will have been well-recorded and will be well-studied, and it will strengthen social and scientific ties across the border, said J. Ramón Arrowsmith, a geologist at Arizona State University. "It is a reminder that California is a plate boundary system and the relative motion across that system is accommodated in a large part by earthquakes and so we should always be ready."

Cooperation between Mexican and U.S. scientists will be important moving forward, as they study the earthquake and put together emergency response systems to help affected residents, Arrowsmith said.

Some state and country boundaries follow rivers or other natural landmarks. Earth's fractures were of course all made by nature.

Our planet is made up of giant slabs of rocky material called tectonic plates that are constantly creeping along. Sometimes rather than a creep there's a jolt and the resulting energy sends out seismic waves that can be felt at Earth's surface. Yesterday's 7.2-magnitude temblor occurred roughly 40 miles (64 kilometers) south of the Mexico-U.S. border along the principal plate boundary between the North American and Pacific plates.  

However, the aftershock zone extends from the northern tip of the Gulf of California to the Mexico-U.S. border. And the effects of the initial quake along with aftershocks shook some 20 million people and could be felt as far north as Santa Barbara and in the Phoenix area, according to news accounts.

"The effects of the event crossed the border. Many of us have strong social connections across the border," Arrowsmith told LiveScience. "In terms of science, American scientists can't really do much until we have been invited officially. That is especially the case for any extensive response."

Arrowsmith added, "Fortunately, there are strong ties in place already from prior and ongoing collaborations on geological and geophysical investigations. I think people are already teaming up to put together an earthquake response.  It is going to be really important to make observations right away about what happened, especially in the source region so we can learn."