"As deflation continues, strong earthquakes in the area around Kilauea Volcano's summit are expected to continue and may become more frequent".
Kilauea's crater is located inside the National Park.
Earthquakes are damaging roads and buildings on Hawaii's Big Island on Wednesday as ash emissions stream from Kilauea volcano.
The Hawaii County Civil Defense Agency said: "This is a Civil Defense Message for May 17 at 5am. Shelter in place if you are in the path of the ash plume".
While the code red warning seemed to be staying for a while, USGS volcanologist Michelle Coombs mentioned in a video statement that the threat is very immediate.
A U.S. Geological Survey volcanologist described the pre-dawn explosive eruption at the summit of Kilauea as "short-lived" and not having a "widespread impact".
Even before Thursday morning's explosive eruption, the ash plume from the volcano could be seen from the International Space Station.
The Hawaii Fire Department reported "extremely risky air quality conditions due to high levels of sulfur dioxide gas in the evacuation area", civil defense officials said on Saturday. Accumulations were expected to be less than a quarter of an inch in the areas surrounding the summit of the volcano.
More than 1800 residents in Leilani Estates and Lanipuna Gardens had been ordered to leave their homes since Thursday, when public works officials first reported steam and lava erupting from fissures in a road, Ms Gabbard said. The volcano began erupting almost two weeks ago, and scientists say there's potential for larger eruptions to come. The park has remained closed since May 11.
Such an eruption could not only shroud large areas of the Big Island in volcanic ash and smog, but also other Hawaiian islands and potentially distant areas if the plume reaches up into the stratosphere and ash is carried by winds.
USGS geologists and staff were evacuated from the summit shortly before the blast and a webcam showed a gray plume of ash and chunks of magma known as pyroclasts that showered the volcano's slopes.