A tsunami watch issued early Tuesday for coastal areas from Washington state to California was canceled nearly three hours after a magnitude 7.9 earthquake struck the Gulf of Alaska and prompted precautionary calls to evacuate to higher ground in southern Alaska.
Tsunami watches were also canceled for the Canadian province of British Columbia and Hawaii, although a tsunami advisory remained in effect for southern Alaska after 3 a.m. local time (7 a.m. ET), according to the National Weather Service’s National Tsunami Warning Center.
There were no immediate reports of life-threatening waves or damage to property. The quake struck at 12:31 a.m. local time (4:31 a.m. ET) about 181 miles southeast of Kodiak, Alaska, at a depth of about 6.5 miles, the Alaska Earthquake Center said. The quake’s strength was later revised downward from an initial reading of 8.2 magnitude. read more…
A strong new earthquake shook Mexico on Saturday, causing new alarm in a country reeling from two powerful quakes this month that combined have killed nearly 400 people.
The U.S. Geological Survey said the new temblor was centered about 12 miles southeast of Matias Romero in the state of Oaxaca, which was the region most battered by a magnitude 8.1 quake on Sept. 7.
It swayed buildings and set off a seismic alarm in the capital, prompting civil defense officials to temporarily suspend rescue operations in the rubble of buildings downed by Tuesday’s magnitude 7.1 quake in central Mexico.
That quake dimmed activity in the stylish Condesa neighborhood, where young revelers typically spill out from dimly lit bars and restaurants on a Friday night. But the first weekend since the powerful quake toppled buildings just blocks away began on a somber note.
Instead of crowds gathered with beers, small handfuls of rescue workers still dressed in reflective vests took breaks from digging through the rubble. Entire restaurants with white linen tables were empty. Metal gates shuttered others.
“It feels lifeless,” said Mariana Aguilar, 27, a hostess at a bar and restaurant who stood waiting for guests yet to arrive. “I walk through these streets every day, and you never imagine something like this would happen.” read more…
In 1325, the Aztecs, until then a nomadic people, chose the site of their capital, Tenochtitlan, based on a prophecy that the location would be marked by an eagle eating a snake while perched on a cactus. That the cactus in question happened to sit on an island in a mucky lake did not, apparently, deter them from seeing it as a divine revelation; they went ahead and built a great city with grand temples and market squares on a tiny patch of land in a swamp. That metropolis is now Mexico City.
The cruel coincidence of there being a large earthquake in Mexico City on September 19th, the exact anniversary of the devastating magnitude-8.1 quake that killed at least five thousand people in the city in 1985, seems similarly preordained. But a closer look at the details partly dispels its statistical improbability. Neither quake was actually centered on Mexico City. The epicenter of the 1985 event was two hundred and twenty miles to the west, off the coast of Michoacán, while the recent quake was generated about seventy miles to the southeast, in the state of Puebla. Seismic waves emanate in all directions from their origins, and regions closer to these epicenters were hit harder than Mexico City. But, with a population of close to twenty million, the capital simply has more people and buildings likely to be affected—and the old lake sediments on which Tenochtitlan was built have an unfortunate tendency to magnify seismic waves, and sometimes to liquefy altogether.
A more interesting coincidence is the fact that the two large earthquakes that struck Mexico this month—the 7.1-magnitude Puebla event, on September 19th, and the 8.1-magnitude Gulf of Tehuantepec quake, twelve days earlier—were both exceptions to some general geophysical rules. Since the start of the new millennium, millions of Earthlings have been involuntary students in a rigorous experiential course on plate tectonics. There have been particularly punishing lessons about subduction zones, where old, dense ocean crust, often stuck in place for centuries, slides back into Earth’s mantle in a matter of seconds. The 9.1-magnitude Sumatra-Andaman earthquake, in 2004, and the 9.0-magnitude Tohoku quake, in Japan, in 2011, both of which spawned enormous tsunamis, occurred at such boundaries. The spectre of a similar catastrophe along the Cascadia subduction zone, in the Pacific Northwest, keeps many residents of Portland, Seattle, and Vancouver awake at night. read more…