A lost day? 

When I came to New Zealand I crossed the international dateline.  I “lost” January 19th the day that Obama was sworn into office.  Did I really lose that day?  I saw a live feed of it at the motel in Christchurch on the 20th in New Zealand.  Hmmmm?

While falling asleep last night I pondered how to explain the international dateline to 7th and 8th grade students.  If I jumped into the concept of the time zones I thought that would confuse.   So I am going to start with the definition of night and day. 

Time Zone Image from wwp.greenwichmeantime.co.uk/…/

24 hours is one day/night

In 24 hours our earth spins once on its axis.  The sun appears to rise and set.  It is just our perception we are really spinning towards and away from it into the darkness to return the next morning.   Depending on our latitude we experience different amounts of daylight.  By definition along the equator we receive equal amounts 12 hours of daylight and dark.   

24 hours spread around the world

It would make sense then that their would be 24 longitude lines with the zones inside representing 24 different time periods.  (Depending on how crazy you want to get with this you can start dividing each time period by 60 minutes then 60 seconds.  Wait that sounds like coordinates.  They are related.  Hmmmm! Disclaimer: Don’t read this unless you have good eyes and want to be really confused.  Some peppermint tea might help the nausea.) Now you are starting to understand how we created time and our clock.

The problem

If the earth remained still it could be January 19th all over the world at the same moment and it is for one second.  Then on that second after midnight it becomes the next day somewhere.  Uh oh!  So now what? 2 Date

Yeah!  The International Date Line

A line is drawn north south that indicates the new day.  That is basically it.  It is not mysterious just a way to try to capture time in a dynamic earth spin system.  Don’t forget time is nothing other than objects moving through space. 

In 1884 as people started to travel more quickly around the world a line was drawn exactly on the opposite side of the world from Greenwich, England (at 180 degrees). 

Image of International Timeline from-www.answers.com/topic/ international-date-line

The international time line is located out in the big Pacific and is altered to keep countries and other geographic/political entities on one day.  The tiny country of Kiribati had the line redrawn in 1995 so it wasn’t split.  Go Kiribati! 

Time Zones

Our country is broad enough to have four time zones.  Six if you include Alaska and Hawaii.   To reinforce our concept of the spinning earth, if you are on the east coast it is 6 PM and getting dark in the fall because it has already rotated away from the sun.  It will take four hours on the west coast for it to be pointing away from the sun and getting dark.  Looking at the map it would make sense that it is only 4 PM on the west coast. 

If you didn’t like my explanation try this one.

http://www.vistech.net/users/rsturge/dateline.html

Time Travel

For more on how the world would be without the timeline.

http://aa.usno.navy.mil/faq/docs/international_date.php

It is interesting to note that the time that I lost going west I will make back going east and I will be back to even with my minutes lived on the planet earth. 

If I don’t return would I be younger or older and would it depend where you were thinking about it?  

Introduction

I saw Mount Taranaki in the distance the day we saw the oil dereks.  I thought students would like to know a little bit more about the volcanoes on the North Island.   Cool fire and Magma!

Photo from

www.wanganui-city.school.nz

Taranaki

Lahars in my dreams

Traveling in 2004 we visited Tongariro National Park that is in the Taupo Volcanic Zone of the North Island 

I was a bit nervous staying at the Whakapapa Holiday park or campground that had an emergency escape route if the volcano erupted.  What posed the hazard was the melting of the snow causing a mud/water slide called a lahar.  Apparently this had happened in September of 1995 and the lahar’s path was right where we were staying.  I woke throughout the night listening for the siren.  Silly DT!

Why are there volcanoes on the North Island?

We studied the Ring of Fire during our 8th Grade geology unit.  In general we know that there is commonly subduction where two plates meet.  In New Zealand the Pacific Plate is being pushed under (subducted) to the north To the south of New Zealand the Indian-Australian Plate is being sub-ducted under the Pacific.   Mount Taranaki and Mount Tongariro are connected to the subduction of the Pacific Plate to the east.  The sub-duction causes heat and pressure and upwelling of magma at100 kilometers and greater under the ground.  The Taupo volcanic zone is a place of regional crust extension (pulling apart) with rates of 7-18 millimeters per year. This creates hot springs and other thermal features.

Diagram of the Taupo Volcanic Zone

diagram from www.gns.cri.nz

Taranaki the Young Strato-volcano

Taranaki is young 130,000 years and less.  It has one of the most symmetric cones in the world and it was used as a background for the movie “The Last Samarai,,” because it looks like Mount Fuiji.  It is a stratovolcano.  Stratovolcanoes are conical with many layers of strata.  The layers are lava flows, lahars, pyroclastic debris alternating.  Mount St. Helens is thought to be one. 

They are thought to be picturesque but deadly. 

For more on the different types of volcanoes check out:

http://www.geology.sdsu.edu/how_volcanoes_work/stratovolc_page.html

Using Seismic Monitoring to Predict Eruptions

Moderate activity of kicking ash out occurred in 1995 and 1996.  The last major eruption was around 1655.  The Taranake Regional Civil Defense organization has installed five seismometers designed to gather information around the volcano.  Weeks or even months of warnings could be apparent by looking at seismicity at different elevations.  As in Alaska with the Mount Redoubt volcano, seismometers can monitor more frequent and violent seismic activity that is a prelude to the eruption as the magma rises.

Remaining Question

Some people are wondering why Teranaki is there at all.  It is out of place not being in the direct line of subduction like the Ruapehu in the Taupo Volcanic Zone.

Check out this web site and specifically the area diagram showing off this discordance. 

http://www.goodschist.com/2008/02/24/mt-taranaki-hmmm/

Volcano on!  DT