Everything in the world around us is built upon the Earth, grows on the Earth, or depends on the environment of the Earth in some way. Welcome to this world. Much of human history has been influenced directly or indirectly by earth science. Today as much as ever, major opportunities and problems are tied to Earth and to our understanding of it. 

In California, from before the Gold Rush days of the 49ers to the most recent earthquakes, the inhabitants have had an intimate relationship with geology, whether they have thought about it or not. Within its boundaries, this state contains examples of virtually everything geological.

The word "volcano" comes from the little island of Vulcano in the Mediterranean Sea off Sicily. Centuries ago, the people living in this area believed that Vulcano was the chimney of the forge of Vulcan -- the blacksmith of the Roman gods. They thought that the hot lava fragments and clouds of dust erupting form Vulcano came from Vulcan's forge as he beat out thunderbolts for Jupiter, king of the gods, and weapons for Mars, the god of war. In Polynesia the people attributed eruptive activity to the beautiful but wrathful Pele, Goddess of Volcanoes, whenever she was angry or spiteful. Today we know that volcanic eruptions are not super-natural but can be studied and interpreted by scientists.

EARTHQUAKES

One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible effects. An earthquake is a sudden movement of the Earth, caused by the abrupt release of strain that has accumulated over a long time. For hundreds of millions of years, the forces of plate tectonics have shaped the Earth as the huge plates that form the Earth's surface slowly move over, under, and past each other. Sometimes the movement is gradual. At other times, the plates are locked together, unable to release the accumulating energy. When the accumulated energy grows strong enough, the plates break free. If the earthquake occurs in a populated area, it may cause many deaths and injuries and extensive property damage. 

Today we are challenging the assumption that earthquakes must present an uncontrollable and unpredictable hazard to life and property. Scientists have begun to estimate the locations and likelihoods of future damaging earthquakes. Sites of greatest hazard are being identified, and definite progress is being made in designing structures that will withstand the effects of earthquakes. 

LAND SLIDES

Landsliding is a significant hazard along many hillslopes. Many factors contribute to slides, including geology, gravity, weather, groundwater, wave action, and human actions. Typically, a landslide occurs when several of these factors converge. 

For example, many slides on Puget Sound occur in a geologic setting that places permeable sands and gravels above impermeable layers of silt and clay, or bedrock. Water seeps downward through the upper materials and accumulates on the top of the underlying units, forming a zone of weakness. 

FLOODS

Floods kill people and destroy homes in many parts of the United States every year. Federal agencies estimate that an average of over 125 people die every year in the United States because of flooding, although losses vary widely from year to year. Property damage ranges into the billions each year, and has been rising in recent decades. 

Of course the live video of a family clinging to their car in a swollen river as rescuers winch down from a helicopter is so compelling that few viewers can change channels. But flooding is also worth covering because if people are informed, they can make decisions that will save lives and reduce property loss.