HONOLULU (AP) — The ground is shaking and swelling at Mauna Loa, the largest active volcano in the world, indicating that it could erupt. Scientists say they don’t expect that to happen right away but officials on the Big Island of Hawaii are telling residents to be prepared in case it does erupt soon. Hawaii volcanoes like Mauna Loa tend not to have explosive eruptions like Mount St. Helens in Washington state. That’s because Hawaii’s volcanoes have magma that’s hotter, drier and more fluid, and doesn’t trap as much gas. Volcanoes like Mount St. Helens have magma that traps more gas, making them more likely to explode upon eruption.