Aftershocks have been recorded for both earthquakes. On Dec. 8, Japanese authorities warned an even more powerful earthquake could strike within the next week and called on residents from the northernmost island of Hokkaido down to Chiba prefecture, east of Tokyo, to be on high alert.

The federal government and earthquake experts blamed a technical glitch for the alert that sent warnings hundreds of miles away last week.

Japan’s Meteorological Agency said a powerful earthquake hit off the Japanese northern coast Monday, triggering a tsunami alert.

A series of small earthquakes struck the San Ramon over the span of several hours on Monday in the latest swarm to hit the East Bay community over the past few weeks.

A shake alert went out over the U.S. Geological Survey's early warning system on Dec. 4, warning that a 5.9 earthquake near Carson City in western Nevada could produce heavy shaking in the region. But moments later, the survey announced the alert, which was sent to people as far west as San Francisco, was a false alarm.

A series of earthquakes rattled California’s Bay Area near Gilroy on Wednesday, according to the U.S. Geological Survey. The largest was a magnitude 4.0 quake centered about 8 kilometers east of Gilroy, followed by a magnitude 3.6 quake southeast of the city and a magnitude 2.7 event to the east.

Scientists say the answer is far more complex than a simple yes or no. Today, risk can be mapped, and early warnings can save lives.

Slow earthquakes have been discovered to exhibit anomalously slow, long-lasting and small slips, adjacent to regular earthquakes where we sometimes feel catastrophic vibration. However, no one knows the reason why slow earthquakes show such strange characteristics.

Glacial earthquakes are a special type of earthquake generated in cold, icy regions. First discovered in the northern hemisphere more than 20 years ago, these quakes occur when huge chunks of ice fall from glaciers into the sea.