Landslides of ash, gas and rock that flow out downhill during volcanic eruptions may be even more dangerous than scientists had realized.
Laboratory and field measurements show pulses of high pressure form within these slides, known as pyroclastic (火山碎屑的) flows. Those pressures can be far stronger, and more destructive, than disaster evaluations typically assume. “It’s not a small difference,” says Cert Lube, a volcanologist at Massey University in Palmerston North, New Zealand. Conventional disaster evaluations might suggest a certain flow will only burst windows, but he says, “When actually, the pressures are so strong, they knock down the walls of the building.”
Pyroclastic flows are the deadliest volcanic disaster, in part because of the pressures they cause. Due to their violent nature, researchers often have to evaluate average pressures in the flows using computer simulations (模拟) based on measurements of geologic deposits left by past flows.
At Massey University in Palmerston North, New Zealand, researchers freed mixtures of hot rock, ash and gas down a channel to copy volcanic landslides known as pyroclastic flows. These pyroclastic flows have an inner rhythm (节奏) that makes them especially destructive. To directly study the inner workings of these forces of nature, Lube and colleagues reproduced smaller versions of the flows in experiments, measuring the destructive power. That let the team calculate the pressures inside the flows. The researchers also analyzed the first measurements of pressures in natural flows, collected in 2019, when pyroclastic flows burst from the Whakaari volcano and swallowed a set of sensors.
To the researchers’ surprise, pressures in the flows shook rhythmically. These pressure pulses would successively damage barriers like blows from an electric drill, Lube says. The pulses sometimes smashed more than three times as hard as the average pressure evaluates typically suggested by conventional simulations.
【小题1】Why do researchers use computers to simulate pyroclastic flows?| A．To find out their inner rhythm. | B．To evaluate their violent nature. |
| C．To figure out their average pressures. | D．To copy the scene of volcanic landslides. |
| A．How to prepare simulation experiment. |
| B．How to carry out the simulation experiment. |
| C．Why to conduct the simulation experiment. |
| D．Why to measure the inner rhythm of pyroclastic flows. |
| A．Crashed. | B．Bombed. | C．Conflicted. | D．Increased. |
| A．A Well-known Landslide | B．The Deadliest Volcanic Disaster |
| C．More Destructive Pyroclastic Flows | D．A Pyroclastic Flows Simulation Experiment |
