JDFEM.com		Juan de Fuca Emergency Management South coast of Vancouver Island BC, Canada
Earthquakes

Did an earthquake just happen? To you, or on the news?
How dangerous is your house?

Do you think you felt an earthquake?

1. Count the seconds of the shaking and you can make a guess about the magnitude

1 second jolt? Could be blasting or sonic boom. If longer than a second, and if hanging objects are swinging, it's more likely it could be a small quake. Click button >>

2. Check maps of current local quakes NOTE: Maps take time to update, and often are not available "Invalid URL" or "Not Found" -- Try again in a few minutes.

2A -- Live Map and List covering Vancouver Island and South BC Coast from Natural Resources Canada Times are in UTC (Greenwich / Universal Time 00:00 UT = 5:00 PM Pacific Daylight Time)

2B --- Maps of Current Quakes Southern Vancouver Island, Washington State, and the active Puget Sound region

Old style of maps -- great for a quick glance (Both maps are identical, but one or the other or both may not be available at various times.) These maps below are live

Maps usually update within 15 minutes . red square is within last 2 hours. Click on square to see detail

New style of map Click on map to see new-style website Awkward to get information off map. Move mouse over "Region Options" at left. < this map here is not live

Distant Quake You Heard About On The News?
These maps show quakes not usually felt in Victoria region. Click on map to go to source, then click on earthquake. You can get the time, magnitude, depth, and often maps of shaking, faults, etc. Map "Did you feel it" shows what people experienced = "Intensity" .
Japan	North America
	World
Did you miss a big quake on the news? Large quakes in last 24 hours on USGS Corvalis, Oregon Seismograph. Bottom Line is last hour 00:00 = 5 pm PDT

How Dangerous is Your House?

1. Test out your house on a computer simulator

Excellent educational feature from Earthquake Commission of New Zealand Change features and choose a magnitude of quake.Then click on furniture items to learn more.

2. Look at the soil under you. Houses on soggy wet lands will shake a lot (people frightened) Houses on well-drained soil will shake moderately Houses on rock will shake very little (people may not notice)

Liquefaction

When we shake a jar of beans, they settle in tighter. When wet sand is shaken by a quake, the sand also settles tighter. However, the water with the sand gets squeezed up, sometimes spouting up. The danger is that the rising water floats sand particles so they are not touching. This essentially makes quicksand, just as a spring bubbling up in sand makes natural quicksand (click on picture at right). A building on the spot would sink down into the sand, or tilt at an angle.

YouTube videos showing liquefaction Water flowing up out of holes, NZ - shaking settled sand, squeezing water up. In video, shaking stopped so okay to walk, but water still under pressure coming out of holes.

Cars sank into liquefied sand during shaking, now sand hard- NZ. Half-way into video is short clip of a car deeply buried.,

Amplification An orchestra conductor waving a whip will produce much more action than just waving a stiff baton. Earthquake waves will move soft ground much more than they will move bedrock. Buildings on wet ground -- especially lowlands around river deltas, bogs, ponds, and where loose fill has been dumped into water -- will tend to have much more damage than if built on rock. Wet lands should stay as farms and parks in earthquake country..

Hazard Maps of Victoria

BC Geologists tested the soil around Victoria to see whether it was safe or subject to liquefaction, amplification, or landslides. The maps are on line (click on pictures) , but are 2.5 MB pdf files.
If you live in a high hazard area -- high risk of building damage -- then make sure you have earthquake insurance, and follow proper guidelines about family safety and survival assuming your house may not be habitable after a quake
Liquefaction Wet sand acts like quicksand, and buildings can tilt MAP2.5MB -- Legend	Amplification Wet soils shake like jelly, which makes buildings shake more MAP 2.5MB-- Legend	Landslides Loose soil on slopes can collapse MAP 2.5MB-- Legend
HIGH RISK AREAS Unfortunately, the biggest areas of high-risk for amplification (red) are under the Victoria waterfront and CFB Esquimalt docks, both areas of great importance economically and strategically after a major earthquake. .

Estimate the magnitude by the time of shaking Impress your friends with a good guess...

Once you feel shaking that might be a quake, estimate the total seconds that you felt shaking. It won't normally be more than a few seconds. Then use this chart to get a very rough guess as to the magnitude. This only works for quakes as described. For close quakes

M 1  < 1 sec ----not felt M 2    ~ 1 sec ---- rarely felt unless shallow and close M 3    ~ 2 sec --- shaking of house, sometimes like a train coming in one end and quickly going out the other M 4   ~ 5 sec shaking, things fall off shelves M 5   ~ 10 sec shaking, some damage of weak structures, masonry

For quakes within distance of Seattle

M 6   ~ 10-20 sec shaking, some damage over large area M 7    ~ 20-30 sec shaking, significant damage in weak structures on wet soils with liquefaction or amplification (example: Haiti 2010) may cause local tsunami from underwater landslide

For quakes in Pacific NW

M 8    ~ 1 minute shaking, massive damage (example: San Francisco 1906) may cause local tsunami from underwater landslide

THE BIG ONE -- Megathrust subduction zone

M 9    ~ 4 minutes shaking (example: Japan 2011, Indonesia 2004, Alaska 1964, Pacific Northwest "Big One" 26 Jan 1700) Expect Big Tsunami with M9 quake . ~30 min to Port Renfrew ~3-5+ meters ~1 hour to Sooke ~1-2m ~1.5 hours to Victoria area ~1m+, higher inside Esquimalt and Victoria Harbours. Tsunamis repeat for many hours at varying heights -- stay away from shore for 24 hrs

JDFEM.com
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