Reference no: EM13977913

PROBLEM SET #1- GEOMAGNETISM

Part A: Some planets have magnetic fields, some don't. What characteristics are required in order for a planet to have a Dipole Magnetic Field? We have already looked at the magnetic field's of Earth and Mars in some detail through the pdfs from Module 2, Part 1A and video from Module 2, Part 1B. In addition, these sources talk about how learning about our magnetic field has provided tools to learn about the Earth's tectonic history. But what about Venus and Mercury... how do they compare?

https://connect.ubc.ca/bbcswebdav/pid-3340896-dt-content-rid-15458639_1/courses/SIS.UBC.EOSC.310.99C.2015WC.55232/Hawaii-EmperorChain%281%29.pdf

Work through Questions 1 - 5 in the file to help address these queries.

Part B: I've attached an image of the Hawaiian seamount chain. It shows the current location of the hotspot plume under Hawaii with the age there shown as 0 My. In other words, there is lava erupting there that is creating brand new rock. Some of that igneous rock (primarily basalt) was erupted today! So some of the volcano has an age of ~0 My. The entire enormous volcanic edifice has formed within only a couple of million years (very quick from a geological perspective). Further down the Hawaiian-Emperor Chain, there are two more dates given. One at the bend (42.4 Ma) and one towards the northern end (64.7 Ma). [Ma means 'Million years ago', My means 'Million years']

Question 1. If a planet has a dipole magnetic field now, what does that say about its internal structure, composition, and rheology? If a planet used to have a dipole magnetic field but doesn't now, what does that mean? No research is really needed for this one. Try to use the criteria we think is required for Earth to have a dipole field. Feel free to use the other terrestrial planets (and our Moon) for comparisons (SHORT ANSWER QUESTION)

Question 2. The MESSENGER probe has made three passes and moved into orbit around Mercury in March 2011. Catherine Johnson, from the Earth and Ocean Science Department at UBC, and her research group are part of the MESSENGER team... One of the primary goals is to learn about Mercury's magnetic field.

Which of the answers below best describes Mercury's Dipole and Magnetic Field[Use the MESSENGER websites to answer this question (e.g., JPL main, JPL Mission Goal and NASA site

A) Mercury has neither a dipole field nor a magnetic field.
B) Mercury has a dipole field but definitely does not have a magnetic field.
C) Mercury has a dipole field and may have a weak magnetic field.
D) Mercury has a dipole field and may have a strong magnetic field.

Question 3. What is one current hypothesis to explain why Venus has no dipole magnetic field?

[Use the Course Readings and NASA site to answer this] https://www.nasa.gov/mission_pages/messenger/main/index.html

A) Venus is too small.
B) Venus is not magmatically active.
C) Venus does not rotate.
D) Venus does not have enough heat removal from the mantle to cause sufficient convection in the outer core metal.

Question 4. What is the declination of the magnetic field preserved in the most recently erupted rocks on Hawaii? [Check Part B of the Instructions for this Problem for specific instructions and resources for Questions 4 - 6. Also, use the maps in the pdf files. You can also use one of the online Geomagnetic Field Calculators that are provided by groups like NOAA.] Choose the closest number; remember that the number varies a bit over time due to Secular Variation of Earth's Magnetic Field.

A) 9 degrees 29 minutes west
B) 16° 23' degrees east
C) 16° 23' degrees west
D) 9 degrees 29 minutes east

Question 5. What is the inclination of the magnetic field preserved in the most recently erupted rocks on Hawaii? [Check Part B of the Instructions for this Problem for specific instructions and resources for Questions 4 - 6. Also, use the maps in the pdf files. You can also use one of the online Geomagnetic Field Calculators that are provided by groups like NOAA.] Choose the closest number; remember that the number varies a bit over time due to Secular Variation of Earth's Magnetic Field. Look at this cartoon of the Earth's dipole field to get the 3D 'image' of what the field looks like. Probably easier than looking at a flat map: Magnetic field shape. https://architectureideas.info/wp-content/uploads/2008/10/magnetic-field.jpg

A) 53 degrees, 18 minutes up
B) 53 degrees, 18 minutes down
C) 36 degrees, 42 minutes down
D) 36 degrees, 42 minutes up

Question 6. Lets assume that the hot spot plume under Hawaii is 'stationary'. That means it doesn't move relative to the Earth's core. The hot rock rises up from the lower mantle, heated from a stable, but anomalously hot area associated with the Earth's core. Therefore, although the plates can glide around over the surface of the planet, the plume is stationary.Based on this and your knowledge of the geomagnetic field over time, what would you expect to find if you went to the northern end of the chain and tested the paleomagnetic field locked into those rocks (that solidified 64.7 million years ago)? In other words, what inclination/declination would you expect them to have?

A) declination about 4 degrees east; inclination about 60 degrees down

B) declination and inclination similar to that preserved in the rocks that are forming at time '0' today but not quite the same

C) can't say as the dipole magnetic field was not operating that long ago

D) The same declination and inclination as the rocks that are forming at time '0' today.

PROBLEM SET #2- EARTHQUAKES

Instructions

After a long, grueling semester taking UBC online courses, you decide to head to the southern hemisphere to relax and do some hiking. Throwing a dart at the map, it lands near Valparaiso, Chile. So, that's where you go!

Worn out from learning to make animatronic sandcastles, you are lying on the beach and you feel an earthquake. Not too big, but it knocks your friend's Pisco cocktail drink over in the sand. Since you are an expert on these things, your friends want you to explain to them what is going on! You decide that you can do that best by examining the following resources and then answering the 'Questions' in the next folder.

Resources: pdf files, textbook, USGS earthquakes webpage, IRIS earthquakes website and maps of plate boundaries. There are maps of plate boundaries in the pdf files and textbook. And lots on the web.https://earthquake.usgs.gov/
https://ds.iris.edu/seismon/

Question 1. Is the principal kind of fault motion occurring thrust, normal or strike slip? (pick-one) (Type either "thrust", "normal" or "strike slip" in the space below - do not include the quotes around the word)

Hint: You can look at a Historic Seismicity map on the USGS website for quakes near Valparaiso.

Question 2. How big do you think the earthquake could have possibly been (maximum amplitude)?

A) M6
B) M7
C) M8
D) M9
E) M9.5

Question 3. Why did you choose the answer you did for question 2 and what additional information if any would help you narrow down the earthquake's possible magnitude? (SHORT ANSWER)

Question 4. Should you be moving to higher ground? [In other words, is a tsunami possible?] (Type either "yes" or "no" in the space below - do not include the quotes around the word)

PROBLEM SET # 3-TSUNAMIS

https://connect.ubc.ca/bbcswebdav/pid-3348710-dt-content-rid-15458613_1/courses/SIS.UBC.EOSC.310.99C.2015WC.55232/seismomap.jpg
https://www.pac.dfo-mpo.gc.ca/science/oceans/tsunamis/medium-tsunami-moyenne-eng.htm
https://www.pac.dfo-mpo.gc.ca/science/oceans/tsunamis/coarse-tsunami-faible-eng.htm

You and your friends decide to take a seakayaking trip. The plan is to begin at Tofino, on the West Coast of Vancouver Island, and paddle over to Hot Springs Cove (see attached map).

Fortunately, the weather and sea conditions were useable, so you were able to go around the outside of Vargas and Flores Islands. Whales galore - both humpbacks and greys! You even had some good surfing on the big beach on Vargas. But with the weather closing in, it was time to head for Hot Springs Cove. The hot springs are soooo good. Even more so because you haven't bathed in 3 days!

Almost dozing off, you are jolted alert by a strange bump. Then, some time later (close to a minute...) a strong earthquake! Then after things calmed down, another longer round of shaking. Really quite strong! Rocks tumble down the slope across the creek and everyone gets out of the hot springs, a little nervous that the water might get hotter. You are also concerned about a possible tsunami. To be safe, you and your friends grab your camping gear and hike up a nearby ridge to get well above sea level.

Once you are up high, you try to figure a few things out.

The first thing you are worried about is whether or not there will be a tsunami. You brought your iPod with you, and you just happened to have loaded the latest DFO (Department of Fisheries & Oceans) tsunami model on it... Tsunamis can be modelled quite accurately - all you need to know is where the rupture of the seafloor is (i.e. the trench in a subduction zone) and a detailed map of the seafloor topography. Then it is possible to compute how fast the tsunami wave will move and what the wave height will be as it travels toward land.

You can see computer models done by Fisheries and Oceans Canada here: DFO Cascadia Tsunami Models. In particular, look at the ON-LINE 2D Coarse Resolution model (about half way down the page).

Feel free to look at the other models too if you like. The red colour indicates the crest (height in cm) - where the water is bulged up. The blue indicates the trough of the wave (depth in cm). Note the timescale: 00:00:00 indicates hours:minutes:seconds. [Warning: This needs a pretty fast connection to work well. Give the model time to load before you try to run it. It often takes a while. Once it is loaded up, it runs quite well.]

You are now able to answer a few questions for your friends, using your observations from this model. (Using the model, answer questions 1-5 in the 'Questions' file directly below in this folder. Question 6 is a separate question which you will answer using your notes and the information given in the Problem itself.)

[Note: The tsunami models are pretty interesting. They are very accurate. One variable is how large the rupture at the trench will be. That controls the amplitude of the wave - and that of course influences how far it goes inland. But as long as you have detailed seafloor bathymetry, you can model how the wave refracts and reflects and then grows in shallower water. This is done all the time in the global tsunami warning systems.]

Question 1. If a tsunami was generated by the earthquake you felt, how long will you have before the first big wave arrives?

A) About 5 minutes
B) About 20 minutes
C) About 1 hour
D) About 2 hours

Question 2. Will the water recede first? Or will a wave just build up before it surges in towards you? (Type either "recede" or "build up" in the space below - do not include the quotes around the word)

Hint: Check the amplitude (min/max sea levels) in the first few frames of the model

Question 3. How long will it take for the first wave to hit Victoria?

A) 20 minutes
B) 50 minutes
C) 80 minutes
D) 110 minutes

Question 4. Will it be very large by the time any of the wave energy gets to UBC?

(Type either "yes" or "no" in the space below - do not include the quotes around the word)

Question 5. Will it be one wave or several wave pulses?

(Type either "one" or "several" in the space below - do not include the quotes around the word)

Question 6. Now that you know how much time you have before a possible tsunami rolls in and have moved to the safest place you have available, you just have to sit and wait. However, you are wondering if you can figure out whether or not there will actually be a tsunami!

You wonder:

* Was the earthquake along the subduction thrust fault (along the plate interface) and did it break the seafloor at the trench? That would be the tsunami scenario! Or...

* Was the earthquake in the upper, overriding plate (no tsunami in this case)?

* Or was the earthquake deeper, and within the downgoing plate (no tsunami in this case either).

Hmmm. You definitely felt 3 pulses of waves. So... a small bump from the arriving P wave, and then pretty strong S waves arriving, and then surface waves arriving. You think it was probably 45 seconds or even one minute between when you felt the first bump (P waves) and when the S waves hit. Those rumbled around for a while - then another substantial gap of quiet before the surface waves rolled in.

Fortunately, you have a map with you that shows the plates offshore and where the subduction zone is (see the attachment to the Problem 3 Instructions). If the plate interface ruptured offshore of you, you know the distance to the trench - and you can also estimate how deep that interface is directly below you (below Hot Springs Cove). It would have ruptured there too.

Question: Is it likely that there will be a tsunami? Explain why/why not.

This sounds tricky to figure out... but it is actually pretty easy to estimate (it would be much harder to calculate exactly).

Think about:

* how fast the different waves travel, and how long they will take to reach you after the quake. Relate that to the difference in arrival times of P and S waves that you measured! Estimate how far away the quake was.

* where the plate interface would have to rupture in order to generate a tsunami that could affect Hot Springs Cove.

* What is your conclusion? Is a tsunami likely or unlikely?

Note: You cannot answer this problem using the model. Instead, you should answer this question using your notes and information given here, in the problem itself. (SHORT ANSWER)

PROBLEM SET #4- VOLCANOES

Instructions

For reading week, you decide to travel to the Cascades area of Washington State (USA) to check out the skiing south of the border. You spend a couple of days on Mount Baker, then head south to Olympia to visit a friend.

Your friend works for the USGS and offers to let you join a trip to service instruments monitoring the Mount St Helens volcano so you jump at the chance! You know that the volcano was erupting off and on since 1980 and you've never been close to a really active volcano... Later, hanging out back in Vancouver you tell your friends about your trip. They've heard of Mount St Helens but don't know much more about it. You answer their questions by working through the question set 'Volcano Questions' shown below.

Hint: You often hear about or read in the media about an earthquake or volcanic eruption happening somewhere. If you know the tectonic setting you should be able to make a good educated guess as to what is going on!

For a volcanic eruption, if you know (or look up using a map with plate boundaries) the tectonic situation there, you should be able to deduce things like:

* what type of volcano it is (shield, ridgecrest, composite cone)

* what is the range of magma chemistry that built the volcano (and that could be erupting now)

* the source of that magma

* what the likely hazards are from that volcano (this is a strong motivation to understand all the previous points!)

This shouldn't take a long time to do. Once you figure out the tectonic setting, then the rest really just drops out of the pdf slides. You don't need to do any research at all. You can if you like, but you can find the location of the volcano (on the web) and then just look at the maps of plate motions/speeds in the Plate Tectonic pdf files to help you deduce the tectonic setting.

Question 1. What type of volcanoes (shield, ridgecrest, composite cone) are the ones in that area (including Mount St Helens)? (Type either "shield", "ridgecrest" or "composite cone" in the space below - do not include the quotes around the word)

Question 2. What type of tectonic setting or plume (hotspot) formed this volcano?

A) divergent margin
B) convergent margin
C) transform margin
D) hotspot

Question 3. From what you know about the volcanic and crustal setting there, what would you expect to be the range of magma chemistry that has built the volcano?

A) mafic
B) intermediate
C) felsic
D) intermediate and felsic
E) all of the above

Question 4. Where did the magma that sometimes erupts likely form in the mantle/crust? Why? [Hint: perhaps more than one location is possible?] (SHORT ANSWER)

Question 5. What are the likely hazards from the local volcanoes here in the Pacific Northwest? (choose all that apply)

extensive faulting

lahars

tsunami

pyroclastic flows

gas

tephra fall

explosion

lava flows

climate change

impact damage