5.9-magnitude earthquake jolts the Philippines

Scientists say a magnitude 5.9 earthquake has hit the northern Philippines but caused no damage or injuries.

The Philippine Institute of Volcanology and Seismology says the tremor struck at 1:15 a.m. Tuesday and was centered 19 miles (30 kilometers) under the sea about 22 miles (35 kilometers) off Iba township in Zambales province.

The institute has recorded at least three aftershocks with magnitudes 2.8 to 4.0. It says the quake was generated by the Manila Trench that runs north to south off the western coast of the main island of Luzon.

The United States Geological Survey (USGS) estimated that some 700,000 people may have felt moderate shaking, which could result in very light to light damage. More than 18.9 million people were estimated to have possibly felt light shaking, which would unlikely result in damage.

PHIVOLCS said it did not expect damage or casualties as a result of the earthquake but warned that aftershocks could follow. Three small aftershocks, ranging between 2.8 and 4.0 on the Richter scale, were recorded as of 6.30 a.m. local time.

The Philippines is on the so-called 'Pacific Ring of Fire', an arc of fault lines circling the Pacific Basin which is prone to frequent and large earthquakes. Volcanic eruptions also occur frequently in the region.

In July 1990, a powerful 7.8-magnitude earthquake struck the densely populated island of Luzon, killing at least 2,412 people and injuring thousands more. It was one of the most deadliest earthquakes in the Philippines in recent history.

Only more deadly was an enormous 8.1-magnitude earthquake in August 1976 which shook Mindanao island and had its epicenter in the Moro Gulf. It caused a destructive tsunami in the Celebes Sea, causing devastation in settlements along the coast of the Moro Gulf on Mindanao island and on the nearby Sulu Islands.

The 1976 earthquake was felt on all of the central islands of the Philippines Archipelago and in the southern part of Luzon. As a result of the earthquake and tsunami, more than 8,000 people were killed or left missing, 10,000 were injured, and 90,000 were left homeless.