President Michelle Bachelet placed the presidential sash on Pinera's shoulders shortly after midday in Chile's central city of Valparaiso.

    The ceremony was briefly delayed by the biggest aftershock measuring 7.2 on the Richter scale since the Feb. 27 earthquake.

    The aftershock, with its epicenter in Rancagua city, some 150 km south of the capital Santiago, had prompted a tsunami warning. The government later lifted the alert after ruling out possible high waves on its central and southern coast.

    Pinera is faced with a tough challenge to rebuild the country after the devastating quake that killed more than 500 people and left around 500,000 homeless.

    Pinera's team had estimated that Chile needs 30 billion U.S. dollars to recover from the Feb. 27 quake and the aftershocks. Pinera made his first journey as president to quake-affected regions on Thursday.

    In Constitucion, a town of 60,000 inhabitants and most affected by the quake, Pinera said his government will work day and night to tide over the emergency.

    "The challenge is very big... We will have to work together," Pinera said.

    Immediately after the inauguration, Pinera swore in a 22-member cabinet. The first measure of Pinera's government was the delivery of a subsidy of 80 U.S. dollars to each of the poorest 4.2 million victims.

    Pinera also announced changes in the 2010 budget to give more importance to relief efforts.

    Thanks to the preparedness of the South American country against earthquakes, the damage has been modest considering the magnitude of the quake.

    Chile was frequented by major earthquakes in history. The world's strongest quake ever recorded, which measured 9.5 on the Richter scale, occurred in southern Chile in 1960.

    Chile's buildings have strict construction codes and most of the cities close to the epicenter of the latest quake reported few building collapses, though power and sanitation services were interrupted.

    Meanwhile, its two pillar industries -- copper mining and financial services -- saw little damage.

    Chile has a tradition of frugality in its government. It has 11 billion dollars saved in a fund established in times when copper prices were high.

    Citizens in less affected regions are also ready to help. A telethon at the weekend raised close to 60 million dollars, and the money will be used to build shelters for the displaced people.