Ok thank you for the correction. Im fine with being wrong in any case how much mass does maunloa carry over mauna kea? Something fun for me and my kids to learn about this week .
I don't remember the exact answer, but it is at least double (and that is probably understated by a factor of two). Mauna Loa means "Long Mountain" in Hawaiian. Perhaps that should be "Loooong Mountain". From certain directions, such as driving up the Saddle Road from the west, the two volcanoes appear to be of about the same size, but the crest of Mauna Loa is one long ridge. The profile of Mauna Kea is about the same in any direction, like that of Mt. Vesuvius (but not so steep because it is a shield volcano).
Wikipedia has a map that divides the island according to its five volcanoes. Mauna Loa is about half the projected area of the island (and more than that if one uses the surface areas of the individual mountains). Another way of putting this is that, if you wander randomly about the island (assuming you are are an expert climber), about half or more of the time you are standing on Mauna Loa lava.
en.wikipedia.org
I myself am not convinced that Kilauea (usually said to be the most "active" volcano in the world) should be considered independently of Mauna Loa, since it has no significant geographic prominence (i.e. no peak). It is more of bulge on the side of Mauna Loa. It is not therefore a separate and distinct mountain. This was an issue of dispute for many years, but volcanologists now seem to agree that Kilauea's underlying magma chamber is substantially independent of Mauna Loa's. Thus, it is classified as a separate volcano by them but not as a separate mountain by most geographers.
I raise this because the two islands discussed in the article might themselves be classified as distinct mountains by geographers, if measured from the ocean floor. That would depend on the depth of the saddle between them, which lies underwater. There is no universal agreement on the number that defines the required depth. The UIAA (a mountaineering society) says that a minimal descent of at least 300 meters (about 980 feet) as measured from the lesser peak defines two separate mountains. Otherwise the lesser peak is a just a sub-peak of a single mountain.
Does this mean they would also be separate volcanoes? Volcanologists apparently wouldn't care. They would ask if there were separate magma chambers for the two. This is nearly impossible to determine for extinct volcanoes, since the active magma chamber(s) is(are) long gone.
P.S. I am not a volcanologist, a geographer or a geologist. I'm just a retired chemist who lives on the island about two months of the year. If someone more expert wants to weigh in, have at it!