A volcanic eruption isn't over in an instant. People seem confused about that. ‘Huge' Explosion Rocks Caribbean Island of St. Vincent as Volcano Keeps Erupting
I don't know why it is that people refuse to get out of the way of natural disasters. Some come at you so fast, like a tornado, or a derecho, that you can't do much but take shelter. But people have been offered the chance to evacuate from the area impacted by this volcano, and some have refused. What's the worst that could happen? See below.
La Soufriere volcano fired an enormous amount of ash and hot gas early Monday in the biggest explosive eruption yet since volcanic activity began on the eastern Caribbean island of St. Vincent late last week, with officials worried about the lives of those who have refused to evacuate.
One of the latest explosions is said to have sent a pyroclastic flow down the volcano's south and southwest sides.
A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases. It occurs as part of certain volcanic eruptions. A pyroclastic flow is extremely hot, burning anything in its path. It may move at speeds as high as 200 m/s. [ref. National Geographic Resource Library]
A pyroclastic flow can be 1000℃ or about 1830℉. And 200 meters per second is not quite 450 miles per hour. You are not going to get out of the way of a pyroclastic flow in anything short of a jet airplane.
Richard Robertson, with the seismic research center, told local station NBC Radio that the volcano's old and new dome have been destroyed and that a new crater has been created. He said that the pyroclastic flows would have razed everything in their way.
“Anything that was there, man, animal, anything...they are gone,” he said. “And it’s a terrible thing to say it.”
As for people being confused by the fact that a volcano is still erupting a few days later...
The eastern Caribbean has 19 live volcanoes, 17 of those located on 11 islands. The remaining two are located underwater near Grenada, including one called Kick ’Em Jenny that has been active in recent years. The most active volcano of all is Soufriere Hills in Montserrat, which has erupted continuously since 1995, destroying the capital of Plymouth and killing at least 19 people in 1997. [My emphasis. Z-Deb]
There are other hazards of course. Some of the gas is acidic in nature and can cause you to loose consciousness from oxygen deprivation.
So, you can die of sufication, or you can be burned to a cinder by 1800 degree wind. You can have debris fall on you, though I haven't heard much about volcanic bombs or blocks, lava blobs or rocks larger than 2.5 inches, which can be thrown 100s of feet in the air or more, and land miles from the crater. I think I would get out of there.