A small aftershock hit Haiti's capital Friday morning sending some earthquake survivors into the streets.

The aftershock was less intense than the one that occurred late Thursday night, but residents struggling to regain a semblance of life in Port-au-Prince still found the quake unsettling.

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The U.S. Geological Survey did not immediately have a measurement of the Friday morning aftershock.

The USGS said the sequence of aftershocks "will continue for months, if not years," and warned that all rebuilding efforts must take into account the fragility of the island and its position along active fault lines between the U.S. and Caribbean.

"The frequency of events will diminish with time," the USGS report said, "but damaging earthquakes will remain a threat."

People in Port-au-Prince said the brief temblor Thursday night was not as strong as several others since the magnitude-7.0 earthquake that devastated the city Jan. 12. Ensuing aftershocks have reached as high as magnitude-5.9.

FOX News' Adam Housley and the Assosicated Press contributed to this article.