JAKARTA, Indonesia (CNN) -- A powerful earthquake shook buildings and caused panic on the densely-populated Indonesian island of Java, but there have been no reports of injuries and no tsunami alert.
Shaken residents stand outside an apartment building in Kunigan, South Jakarta
The quake, measured at magnitude 7.5 by the U.S. Geological Survey, struck shortly after midnight in a part of the sea dotted with oil rig platforms, Financial Times journalist John Aglionby told CNN International.
He described feeling the quake in his house in a suburb of the Indonesian capital.
"I was just getting into bed on the second floor of my house. You rarely feel these things in Jakarta so I knew something was wrong immediately," he told CNN. Watch Aglionby describe what he felt »
According to CNN's Kathy Quiano, the shaking caused many in the capital to flee their homes. "We felt the earthquake in Jakarta, it was pretty strong and went on for at least a minute," Quiano said.
The Pacific Tsunami Warning Center said there was no threat of a tsunami, because the quake was too deep.
According to the U.S. Geological Survey, the quake was centered 100 kilometers (62 miles) east of Jakarta, at a depth of 289 kilometers (180 miles). It occurred about 32 kilometers (20 miles) from shore.
"Earthquakes of 7.5 and over happen approximately 18 times a year," said John Bellini of the USGS, "and in the area around Indonesia that varies. You might see one or two a year, or you might not see any."
About 15 minutes after the quake struck, Quiano drove through Jakarta, and said she saw no signs of damage. She said residents -- especially those living in high-rises, ran from their homes when they felt the quake, but returned fairly quickly.
"The earthquake went on for at least a minute here. It was pretty strong and scary," Quiano said. "People are shaken, that's for certain."
And Aglionby said there were still concerns for the many oil rigs exploiting the resource rich waters off the north coast of Java. E-mail to a friend
All About Jakarta
Location of earthquake shown by blue star.
According to the United States Geological Survey (USGS) a powerful magnitude 7.5 earthquake struck Indonesia's main island, Java, at 5:05 p.m. UTC, which is just after midnight locally.

The epicenter was located 100 kilometers (65 miles) east of Jakarta and was at a depth of 289.2 km (179.7 miles). The Pacific Tsunami Warning Center said that no tsunami is expected as the depth of the quake exceeded 280 km.

There are no reports of damage, injuries or deaths.

"No reports of damage or casualties have been received at this time. Because this earthquake is located about 290 km below the surface of the earth, it will have been felt strongly over a wide area, but is not likely to cause severe damage. We have received reports that the earthquake was felt in much of Java and in parts of Malaysia", said a statement posted on the USGS website.