资料题：As used in this passage(para2), the word“devised" means（  ）。

Most earthquakes occur within the upper 15 miles of the earth' 8 surface.But earthquakescan and do occur at all depths to about 460 miles.Their number decreases as the depth increases.At about 460 miles one earthquake occurs only every few years.Near the surface earthquakesmay run as high as 100 in a month, but the yearly average does not vary much.In comparisonwith the total number of earthquakes each year, the number of disastrous earthquakes is verysmall.The extent of the disaster in an earthquake depends on many factors.If you carefully builda toy house with an erect set, it will still stand no matter how much you shake the table.But ifyou build a toy house with a pack of cards, a alight shake of the table will make it fl.An earthquake in Agadir, Morocco, was not strong enough to be recorded on distant instruments(设备), but it completely destroyed the city.Many stronger earthquakes have done comparativelylittle damage.If a building is well constructed and built on solid ground, it will resist an earthquake.Most deaths in earthquakes have been due to faulty building construction or poor building sites.A third and very serious factor is panic.When people rush out into narrow streets, more deaths will result.There is one type of earthquake disaster that little can be done about.This is the disastercaused by seismic(地震的) sea waves, or tsunamis.In certain areas, earthquakes take place beneath the sea.These submarine earthquakes sometimes give rise to seismic sea waves.The waves are not noticeable out at sea because of their long wave length.But when they roll into harbors, they pile up into walls of water 6 to 60 feet high.The Japanese call them”tsunamis" , meaning "harbor waves" , because they reach a sizable height only in harbors.Tsunamis travel fairly slowly, at speeds up to 500 miles an hour.An adequate warning system is in use to warn all shores likely to be reached by the waves.But this only enables people leave the threatened shores for higher ground.There is no way to stop the oncoming wave.