Levels of U.S. aid to Pakistan have waxed and waned since the 1980s, according to American geo-political initiatives. Since 9/11, the country has received $19.34 billion in economic and military aid from the U.S. for its cooperation in the so-called âwar on terror.â.
There are three types of basalt lava flows: pillow, pahoehoe, and aa. Pillow Lava: Pillow lavas are volumetrically the most abundant type because they are erupted at mid-ocean ridges and because they make up the submarine portion of seamounts and large intraplate volcanoes, like the Hawaii-Emperor seamount chain.Pahoehoeâ and âaaâ are Hawaiian words that describe lava. Pahoehoe Lava: Pahoehoe is the second most abundant type of lava flow. Pahoehoe near the coast of Kilauea. Photo by Steve Mattox, 1989.
If the lava has low viscosity then the molten material will act fluidly and flow fast down the volcano flanks. As lava travels down the volcano sides, the surface of the flow will cool much more rapidly. The surface of the flow forms two different types called 'aa' and 'pahoehoe'. Aa lava (pronounced ah-ah) has a rough, jagged surface due to the gas explosions tearing apart the external crust. It looks like a pile of blocks and rock fragments but underneath lies molten lava. As the lava flow advances it is churned and folded over itself, allowing gas to escape.