s-waves travel only through solid and geologists found out that s-waves can travel only until the mantle because the outer core is liquid, bacause of this, earthquake are felt at a lower magnitude or not felt at all when you're distant enough from the focus and epicenter of the quake. hehe
ash, lapilli, lava blocks. there are many kinds of pyroclastic material ejected during a volcanic eruption. volcanic ash is so fine that it can be blown into the atmosphere and picked up by the jet stream where it can circle the earth for several years.