The Chilean Navy issued a tsunami warning while the U.S. Pacific Tsunami Warning Center said the aftershocks were too small to cause dangerous waves beyond Chile's central coast.
President Sebastian Pinera was inaugurated at a congressional building in coastal Valparaiso before the building was evacuated as a precaution. The seven aftershocks strongly swayed buildings, shook windows and sent frightened Chileans streaming into the street.
The magnitude-6.9 aftershock is the strongest since the day of the Feb. 27, magnitude-8.8 quake. It occurred along the same fault line, said geophysicist Don Blakeman at the U.S. Geological Survey in Golden, Colorado. The USGS initially estimated the aftershock's magnitude at 7.2.
"When we get quakes in the 8 range, we would expect to see maybe a couple of aftershocks in the 7 range," he said. Blakeman said Chile now can expect to feel "aftershocks of the aftershock."
"It's not a sign of anything different happening. But what does occur when you get these large aftershocks, typically we have a whole series of aftershocks again," Blakeman said.
Chile's navy issued a tsunami warning. The government's emergency office -- much criticized for failing to issue a tsunami alert that might have saved hundreds of lives from the towering waves that followed the initial quake -- urged Chileans to seek higher ground even though the epicenter of Thursday's biggest shock was inland.
At the inauguration, Bolivian President Evo Morales seemed briefly disoriented and Peru's Alan Garcia joked that it gave them "a moment to dance."
Outgoing President Michelle Bachelet says she's leaving Chile in good shape in the wake of the February quake, handing off the government to the first right-wing president to be elected in 52 years.
Pinera said he would go right to work. The billionaire investor, Harvard-trained economist and airline executive with little patience for bureaucracy planned a working visit Thursday to the coastal city of Constitution, where the tsunami destroyed the scenic downtown, and a late-night Cabinet session.
On election night, he had vowed to make Chile "the best country in the world," spending billions to accelerate economic growth, create a million jobs in four years and combat crime, among other things.
Now, reconstruction is his top priority.
Last month's earthquake -- the fifth-strongest since 1900 -- killed 500 identified victims and potentially hundreds of others, destroyed or heavily damaged at least 500,000 homes and broke apart highways and hospitals. Repairing infrastructure alone will cost $5 billion, and overall recovery costs could soar above $15 billion.
Pinera's victory ended a 20-year run for the leftist coalition that led Chile back to democracy after the dictatorship of Gen. Augusto Pinochet, and puts the country's relatively small business elite directly in power.
But Pinera's has promised to maintain social programs created by Bachelet, who leaves office with 84 percent approval ratings.
The new president lacks a legislative majority, so compromises with leftists will be a must, and restive unions have threatened crippling strikes if Pinera insists on his promise to privatize part of the state-run Codelco mining company, which provides much of the government's revenues.
Leaders of the center-left coalition, which earlier rejected the idea of a national unity government, have moderated their tone and promised legislative support for Pinera's reconstruction plans.