In volcano: Lava flows …smooth to ropy surface; and aa (or a’a), a more viscous flow whose surface is covered by thick, jumbled piles of loose, sharp blocks. Both types have the same chemical composition; the difference seems to be in the eruptive temperature and the speed of movement of the flow.

2022年10月26日 · The three types of lava flow are pahoehoe, a’a, and pillow lava. Most lava flow is mafic or basaltic. Pahoehoe is smooth, a’a is rough, and pillow lava is rounded and only forms under water.

‘A‘ā (pronounced "ah-ah") is a Hawaiian term for lava flows that have a rough rubbly surface composed of broken lava blocks called clinkers. The incredibly spiny surface of a solidified ‘A‘ā flow makes walking very difficult and slow.

1999年5月27日 · In an ‘a‘ā flow, widespread fracturing of the exterior of the flow allows the steady advance of the whole front as a single unit. In a pāhoehoe flow, more localized cracking of the crust occurs, allowing the flow to advance by the propagation of individual toes or lobes.

2023年8月12日 · There are six lava flow types or morphologies: pahoehoe, aa, blocky lava, pillow lava, sheet flow, and lobate. The first three are subaerial, and the last three are subaqueous (submarine, subglacial, and other subaqueous environments).

2023年8月1日 · Aa is a subaerial lava flow whose surface is characterized by sharp and rough or jagged irregular blocks/rubbles known as clinkers or spinose. These loose, broken, contorted, spiny, or angular fragments or clinkers have sharp edges, making them dangerous to …

2010年5月6日 · Aa lava flows tend to be relatively thick compared to pahoehoe flows. During the early episodes of the current eruption of Kilauea volcano, aa flows up to 36 feet (11 m) thick surged through the Royal Gardens subdivision at rates as great as 108 ft/min (33 m/min).

Map of the 1859 Mauna Loa "paired" lava flow. The 'a'a flow (orange) was active for 16 days, advanced at an average flow-front velocity of 133 meters/hour, and erupted at a volumetric flow rate of 208 cubic meters/sec.

2023年8月2日 · Pahoehoes have continuous, smooth, ropy, or hummocky glassy surfaces, while aa lava flows have a surface with sharp, rough, angular clinkers.

When volcanoes do produce lava flows they are classified as either Pahoehoe or Aa. The lava is identical in both pahoehoe and aa lava flows, the difference comes from the amount of lava erupted and the speed of cooling.