An earthquake on Monday jolted the Big Island of Hawaii, which is already under a hurricane watch and a tropical storm warning.

The magnitude 5.3 temblor struck at 7:38 p.m. local time, about 25 miles south of Hilo, according to a preliminary report from the U.S. Geological Survey.

There were no reports of injuries, structural damage or a tsunami, though the quake caused a small landslide, according to Tom Brown, a spokesman for Hawaii County Civil Defense.

Earlier Monday, the weather service placed the Big Island under a hurricane watch and a tropical storm warning, as Hurricane Flossie approached. A flash flood watch was also issued for the island through Wednesday.

The Big Island is largely rural, with about 150,000 people, and most live in the west or northeast, not the southern portion expected to be hit hardest by the hurricane. Other islands are expected to get less of the storm's wind and rain.

Public schools were closed and Hawaiians were warned to have plenty of food and water on hand as Hurricane Flossie roared toward the state early Tuesday.

The eye of the Category 3 storm, with maximum sustained winds of 115 mph, was expected to pass fewer than 100 miles from the islands and bring strong winds and heavy rain.

The weather service placed the Big Island under a hurricane watch and a tropical storm warning.

Gov. Linda Lingle signed an emergency disaster proclamation, which activates the Hawaii National Guard. Mayor Harry Kim also declared a state of emergency Monday as a precaution. All 56 public schools, as well as private schools, on the Big Island also were closed for Tuesday.

At 5 a.m. EDT, Flossie was about 260 miles south-southeast of Hilo and 455 miles southeast of Honolulu, the Central Pacific Hurricane Center said. The storm was moving west-northwest at about 15 mph.

Hurricane force winds of at least 74 mph extended outward up to 40 miles from the center of the storm, while tropical storm force winds of at least 39 mph extend outward up to 155 miles.

Meteorologists cautioned that even a slight change of course in the unpredictable storm could take it closer to land.

"We're not out of it, but this is too close for comfort," said Maj. Gen. Robert Lee, state adjutant general and Hawaii National Guard commander.

The move also provides access to emergency money.

Forecasters earlier had said cooler weather would weaken the storm to a Category 1 hurricane, with sustained wind of at least 74 mph, by the time it passes about 90 miles south of the Big Island of Hawaii on Tuesday.

But on Monday forecasters said they now expected a Category 3 hurricane, with little change in strength when it passes the island. Earlier in the day, Flossie had been a Category 4 storm with maximum sustained winds of 140 mph.

"The intensity has remained stronger than what was originally forecast, but the track has been pretty much right on," said Jim Weyman, the National Weather Service's meteorologist in charge in Honolulu.

Officials strongly urged residents statewide to prepare, including having a supply of food, water and disaster plans.

"If Flossie misses us, that's great. But we're still in hurricane season," said Ray Lovell, spokesman for the state Civil Defense Agency.

Parts of the Big Island, home to one of the world's most active volcanoes in Kilauea, likely will experience tropical storm-level winds and at least 10 to 15 inches of rain, Weyman said.

The last time a hurricane hit Hawaii was in 1992, when Iniki ravaged Kauai, killing six people and causing $2.5 billion in damage.

Meanwhile, a tropical depression in the far Eastern Atlantic -- the fourth of the season -- was 855 miles west-southwest of the southernmost Cape Verde Islands and about 1,660 miles east of the Lesser Antilles. It had maximum sustained winds at 35 mph and was moving at 21 mph.

Hurricane season runs from June 1 to November 30. In May, forecasters said the Hawaiian Islands and the rest of the central Pacific faced a slightly below-average hurricane season, with just two or three tropical cyclones expected because of lower sea surface temperatures.