The Kingdome in Seattle was destroyed on March 26, 2000. It was taken down to make room for a new stadium. The blast(爆破) from the falling building caused the earth to shake as if an earthquake had happened.
Scientists placed more than 200 earthquake recorders in the earth to measure the movement. They found which parts of the city shook the most. This information helped them know which parts of the city would be damaged in a real earthquake at an early time.
A real earthquake happened on February 28, 2001 in Seattle. The Nisqually earthquake was 6.8 on the Richter scale(里氏6.8级). It damaged the same parts of Seattle that scientists had predicted(预测) from the pulling down of the Kingdome. It was a plate quake. It started deep in the earth, 37 miles below the surface on the Juan de Fuca Plate. Sometimes, huge plates under the earth cause earthquakes when the plates move against each other suddenly.
Scientists have learned that deep earthquakes have very few aftershocks(余震). The Nisqually earthquake had only 4 ones. Another earthquake in California that was close to the surface had over 120 aftershocks. Scientists do not know why the deep earthquakes have fewer aftershocks.
Scientists plan to blast in the ground near Seattle with the purpose of testing the plate. The shockwaves from the blast will jump off the plate and give them an idea of where the plate is and how it is moving. This will give them more information in case another real earthquake hits the area.
72． According to the passage, ______ have the most aftershocks.
A．shockwave earthquakes B．shallow earthquakes
C．deep earthquakes D．earthquakes more than 6.8 Richter scale
73．What do scientists hope to learn from the blast above the Juan de Fuca Plate?
A．They hope to learn where the plate is and how it is moving.
B．They want to destroy the Kingdome.
C．They want to know which places are likely to have the most damage.
D．They hope to find out how many plates there are in the ground there.
74．Why were the scientists interested in the pulling down of the Seattle Kingdome?
A．They wanted to see which areas near the Kingdome would shake the hardest.
B．They wanted to predict what might happen in a real earthquake.
C．They wanted to measure the movement of the Earth with earthquake recorders.
D．All of the above.
75．What will happen after a deep earthquake according to the scientists?
A．There will be many aftershocks.
B．There will be very few aftershocks.
C．The Richter scale of the quakes will be a 6.8 or more.
D．There will be little damage.