Natural Disasters Exam 2 (Quiz 3 & 4)

Angle of repose

the steepest angle that dry, granular material can be piled onto a flat surface without collapsing

How does DART stations work?

DART stations use pressure sensors on the seafloor to detect the pressure of a passing tsunami to send alerts when a tsunami is detected

The addition of water to soil on slope would ____.

destabilize the slope be reducing the frictional resistance to sliding

In comparing tsunamis to wind-driven waves…

tsunamis result from sudden movement os mass against water; wind shear produces wind-driven waves

Which type of mass wasting is characterized by rotational slide of soil and debris along a curves surface?

slump

What is the term used to describe the slow movement of soil and debris down a slope?

creep

Tsunami inundation limit describes

the maximum horizontal distance tsunamis encroach over land, relative to the shoreline

How does vegetation affect slope stability?

roots help stabilize slopes by holding regolith together and absorbing water

the mass flow process referred to as creep involves

low-velocity downslope displacement of regolith

what types of lithospheric plate displacement are most likely to result in the creation or alteration of relief

upward and downward displacement

Tsunamis that are generated by earthquakes occur most commonly at which type of tectonic plate margin?

convergement tectonic boundaries

The highest tsunami inundation elevation ever recorded was July 9, 1958, in Lituya Bay, Alaska, and reached 524 meters above sea level. The cause of the tsunami was…

a landslide that flowed into Lituya Bay that resulted from strike-slip fault displacement adjacent to Lituya Bay

Once a tsunami reaches its inundation limit, has the danger passed?

no, drawback returns water to the sea carrying much of the debris that was carried along in the advancing wave, and weakened structures are now subjected to dynamic forces in the opposite direction

do tsunamis pose a danger to ships at sea far from shorelines?

no, tsunamis exhibit small amplitudes in deep water and pose no danger to ships

Tsunamis are most often generated by

earthquakes

predicting the hazard potential for damage from tsunamis is in part related to the run-up elevation potential onto adjacent coastlines. Run-up potential is related to

elevation of the tsunami

One of the first signs of renewed volcanic activity of mount st. helens in march 1980 was…

a series of magnitude 3 earthquakes

the viscosity of melt is dependent on the temperature of the melt, its silica content, and its volatile content. What type of magma is the least viscous?

ultramafic