The volcanic activity that began building Haleakala occurred about 2 million years ago. Haleakala is listed as a moderate threat volcano, and scientists say it’s not a matter of if but when ...

By comparison, Kilauea’s threat score was 263. Haleakala, rising more than 10,000 feet from sea level, erupts every 200 to 500 years, according to the USGS Hawaiian Volcano Observatory.