Elevated concentrations of sulphur dioxide gas venting from the Kilauea Volcano have prompted the closure of Hawaii Volcanoes National Park. About 2,000 visitors and park employees were ordered out of the park Tuesday, although park officials say there is "no immediate threat" to anyone's safety.

How soon the park reopens depends on where the prevailing winds blow the SO2.

Kilauea has been acting up since last summer, when officials noticed a change in the volcano's eruptions and the opening of new vents. Since late last year the volcano has been blowing out unusually high SO2 gases, and in early March an explosive eruption was noted for the first time since 1924.

Here's what USGS volcanologists had to say Tuesday:

Kilauea Volcano is active at two locations. At the summit, ash production and elevated sulfur dioxide emissions continued from the Halema`uma`u vent. Ash is being produced at decreasing rates; recent samples have contained mostly volcanic glass. Sulfur dioxide emission rates were still at elevated levels but have decreased from the high values in mid March. Seismic tremor levels continued elevated to several times background levels. At the coast, lava continued to flow from the east rift zone through tubes into the ocean at the Waikupanaha and Ki ocean entries.

The accompanying map, produced at 4:15 a.m. HST (or 8:15 a.m. MST), shows where winds were blowing the gas plumes. Green is good, yellow is a moderate health concern. For updates, check this site.