A subterranean event; Rapid, sheer slip across an approximately planar surface; Seismic waves

At plate boundaries; At seduction zones; Spatially clustered

8..........................................1

                        7...........................10-15 (12)

                        6...............................100-200

                        5.........................1,000-3,000

Given the G-R seismicity, 30 yrs., when will the next mag5 EQ occur?

                        Sometime in the next 30 yrs.

Given the G-R seismicity , 30 yrs., when will the next mag6 EQ occur?

Earthquakes are hazardous because...

Seismic waves in the epicentral region cause ground shaking

Our buildings fall down on us. They aren't as tough as we are.

Landslides can be triggered

Tsunamis can be generated

nearby, within a few hundred kilometers

7.8

            Ruptured ground surface along the San Andreas

            Ground shift of 4-5ft/sec.

$400 mil in property damage ($8 billion today)

            3000+ dead

            26 minutes

            Fires 90% of damage

            Fires burned for 3 days and 3 nights

            Firebreaks backfired 50% of damage

            Flames at the melting point of iron

            Fires essentially burned itself out

Insurance with fire only, so arson

            SEIC: first gvmt. Commissioned, scientific investigation into EQs

            Theory of Elastic Rebound= fault will become elastic and distort, then return to its original state?; faults cause EQs, rather than the reverse

            Building codes developed

Loma Prieta 1989 Facts

Santa Cruz Mountains of Cali

            15-20 sec.

            6.9 or 7.1?

            Caused by a 2 meter slip in the San Andreas fault

62 dead

            $6 billion

            San Francisco Bay Bridge unusable for 1 month

            Balls make lives?

            Fires cause most damage

            Most devastation occurred over 60 miles away in San Francisco

            First test of ATC-20

            Response time hindered by landslides that damaged highways 

Mercalli Intensity Scale

Attempts to use us and our surroundings to describe EQs

            Subjective

            People are unreliable about EQs

Great Hanshin EQ 1995 Facts

5:46 AM January 7, 1995

            7.2

            Shallow focus

            ìStrike-slip mechanismî

Over 5,000 killed

            Elevated highway collapse

            Older wood-frame houses as a liability because of the roof

            Seismic codes were mostly followed afterward

            90% of deaths occurred within 15 minutes

Most people were rescued by neighbors           

            Unexpected, so not many preparations

            Serious evacuation drills in schools since

            SRPA: not very successful

A place where molten rock reaches the Earth's surface

lava; molten rock

Volcano: flatter; Iceland, Hawaii

Convergent plate boundaries

            Pacific Ocean basic is surrounded by trenches

            Ring of Fire: 2/3 of world's active volcanoes

 : ranges from 0 to 8 according to volume of material ejected

: adjacent to subduction zones; thick, pasty lava

Andesite Line

Built by gentle outpouring

            When magma cools, it forms basalt

            Mostly oceanic

Lava Domes

Not all lava is created equal!

            Sometimes, it will be thick and move slowly

            New magma flows over cooled magma, making the dome gradually larger

            Magma that forms lava domes is usually rich in silicates

            Can be dangerous

            Build-up of pressure can lead to an explosion

Cinder Cones

Help begin the water cycle

            Help enrich soil

            Form the earth's valuable resources

            Shaping the earth 

Basalt:

            Andesite

            rhyolite

: rock dust in atmosphere changes weather and climate

yes, much can be done including some simple, inexpensive actions, such as vegetation and drainage control.

yes. An increasing number of landslides are caused or promoted by human activity.

sliding of a mass of loosened rocks or earth down a hillside or slope

Landslides are associated with hilly or mountainous landscapes. They are also common along coastlines and river valleys. Landslides occur most frequently in regions where climate and precipitation, bedrock and soil conditions, and slopes are susceptible to failure.

Zoning laws

            Control water

            Promotion: How? Construction