Volcano Watch: Tiny changes at Mauna Loa’s summit hold big clues

  • Data plots showing some of the features mentioned in this week’s Volcano Watch article. The top panel is a histogram of seismicity on Mauna Loa’s west flank, showing an increase in activity in that region over the past month. The middle panel is a tilt record from a tiltmeter near Mokuʻaweoweo, the change in trend from March 23 to April 5 is the first time a tilt change at Mauna Loa could be ascribed to volcanic changes. The bottom panel show the change in distance across the summit caldera, as measured by GPS. Lengthening of the line indicate expansion of the volcano, and decreases indicate contraction. (USGS graphic)

Although Mauna Loa is Earth’s largest active volcano, it has lived in the shadow of Kilauea since it last erupted in 1984. The geologic record shows that Mauna Loa erupts every seven years on average; however, 37 years have passed since lava flows from the volcano’s Northeast Rift Zone came within 7 km (4 miles) of Hilo.