Satellitic Shields

 

Approximately 50% of Hawaiian eruptions have no pyroclastic activity associated with them at all. Instead, lava is quietly erupted onto the surface.

 

This lava flows away in all directions forming a miniature shield volcano. These vents are called "satellitic" or "parasitic" shields, and produce tube-fed flows. Satellitic shields have diameters of 1-2 km, and can be ~100 m high with slopes of only a few degrees.

 

 

 

 

On the right is an image of Mauna Iki satellitic shield on the SW rift zone of Kilauea. Note the gentle slopes (similar to Kilauea as a whole). The distance from left to right on the horizon is about 5 km

 

While a satellitic shield eruption is going on, a lava pond usually exists at the summit of the shield. Overflows from the pond build the shield.

 

 

 

Kupa'ianaha lava shield and pond in September 1986 (~2 months after it formed). Notice the shape of the pond, with a large near-circular part and an elongate extension to the left. The main lava tube was fed from the end of the extension. When this photo was taken the pond was also overflowing to the right. A break-out low on the far side of Kupa'ianaha was feeding another surface flow that in this photo had almost reached the contact with 'a'a flows from Pu'u 'O'o (3 km uprift; at left).

 

There have been 4 major satellitic shields formed on since the arrival of Westerners (Mauna Iki 1919-1920, Mauna Ulu 1969-1974, Kupa'ianaha 1986-1992, and the presently-active vent 1992-who knows?). Including these, 16 satellitic shields have been mapped on Kilauea (Holcomb 1987).