Estimating Tsunami Travel Times

Want to know how long you have until a tsunami generated in Chile reaches your doorstep? To figure it out you need two things: the speed of the wave generated and the great circle distance between you and the location of tsunami origin.

Wave speed (c) is related to the depth (H) of the water body the wave is moving through:

c = √(gH)

 

where g is acceleration due to gravity = 9.8 m/s² and H is in meters. The average wave speed in open ocean is approximately 200 m/s. This is fine to use in back of the envelope calculations such as this.

 

To find the great circle distance between two points you need the radius of the earth (approximately 6370 km) and the spherical angle (ψ) between the points, given by: 

ψ = arcos [ sin(φ₁)sin(φ₂) + cos(φ₁)cos(φ₂)cos(θ₂ – θ₁) ]

where φ₁ and φ₂  are the latitudes of the starting and ending points respectively. θ₁ and θ₂ are the longitudes of the starting and ending points respectively.

From there, use the spherical angle and radius to find arc length (s): s=rψ. Once you have that, you can find the travel time of the tsunami: t = s/c. Keep in mind that this is very general and rough!

I've generated a Matlab script calculating the travel time for a tsunami generated in Santiago, Chile to reach Honolulu, Hawaii (~11.5 hrs according to my script). If you want to pick different starting or ending points, just mess with the latitudes and longitudes.

Interested in tsunamis? Check out these sites:
Violent Hawaii: Deadly Tsunamis
NOAA Tsunami Website
 

%Long Gravity Wavesclose all

clear all

c = 200; % speed of propagation (m/s)
r = 6370; % radius of Earth (km)
r2 = r*1000; % radius of Earth (m)

lat1 = -35.846; % Latitude of santiago, Chile -33
lat2 = 21.467; % Latitude of Honolulu, Hawaii 22
lon1 = -72.719; % Longitude of Santiago, Chile -71
lon2 = -157.983; %Longitude of Honolulu, Hawaii -158

cosangle = sin(lat1)*sin(lat2) + cos(lat1)*cos(lat2)*cos(lon2 - lon1);

angle = (acos(cosangle))*(180/pi); % angle in degrees

arclength = 2*pi*r2*(angle/360) % arclength between locations (m)

time = (arclength/c)*(1/60)*(1/60) % travel time (hr)

  

Mars is cool, stop whining about money and religion

I just watched this clip on NASA's Mars Exploration Rover Mission (MER) and my mind was sufficiently blown. How cool are we, how ingenious, that we can design a series of small robots to not only travel a distance of 55 million kilometers (that's seven long months of loneliness) but to also successfully hit an inconceivably small target and survive?



I guess I must be alone in that though. You know, the doe-eyed wonder at our ability to create? Yea apparently I'm the only one who's not jaded because just about every comment under this clip was either about the 'ridiculous' cost or how this video somehow affronts their religious views (you gotta love people like that, or where would The Daily Show be?).

I don't care how much it costs, this stuff is cool. For all those complaining about how our government is wasting money on something completely useless, stop for two seconds and think about all the useless stuff you bought in the past week. Stuffing your face with Doritos isn't solving world hunger and all that music you purchased on iTunes isn't curbing anthropogenic climate change. Until you start spending money more judiciously I suggest you sit down. So go right ahead, cast the first stone.

We do these things because that's what makes us human. We do it because we can. And you know what, we'll probably come up with a way to turn a profit on space exploration (or exploitation) sometime anyway. Baby steps guys.

And to all those who felt their religious views were somehow threatened by this video, how indescribably sensitive can you be? And how does that thought process work?

space exploration = science = thinking differently = blasphemy ???

We went to Mars. We didn't blow a hole through heaven, I promise. This huge fear of scientific thinking in religious communities is just silly. The two are not mutually exclusive. Just calm down and give everyone a hug or something.

AI forever

It doesn't matter how many times I watch this, it always make me tear up.

The Wandering Summer: Venice Beach

Wandering: Summer 2012

On July 13 I quit my job (yes I put in my two weeks notice, jeez) and hopped a flight to the mainland. I will be away from Hawaii for over a month, starting in California, then to Vegas, Indiana, Pennsylvania, and finally Vancouver for a Chondrythian conference. It all started out as a two week family vacation to California. When I found my dad was going to Indiana to visit his side of the family following our Cali venture, I decided to tag along. I haven't seen my grandparents in almost four years so I'm way past due. And they have no idea I'm coming. From there I'll be visiting my sister and her family in Dillsburg, PA. And to top it off I'll head to Canada to give a talk at a conference on deep sea sharks, skates, and rays. So this summer I'll be wandering.

 The California leg of the trip is already in full swing, so let me introduce you to the characters:

1) The Mom (Kiki) - planned this whole trip. Excites easily, and stresses way too much.
2) The Dad (Gramps) - just along for the ride. Cheesy and laid back.
3) The Younger Siblings - A younger sister (17), my dad in teenage girl form. A younger brother (20), thinks he's awesome. Dropped off the map about a year ago. This will be the first time the family's seen him in a while.
4) The Older Sister - happy and care-free. Lives in PA with her husband and two daughters. Basically awesome.
4) The Brother-in-Law - older sister's husband. Funny and outgoing. Kinda cheesy too.
5) The Girlfriend - Younger brother's gf. Knows what she likes and isn't shy to share it.
6) The Nieces - 5 and 8. The 5 year old is wild and hilarious, gets into lots of trouble. The 8 year old is smart and she knows it.

And finally there's me. I'm not nearly self-centered enough to describe myself, so I won't.

We touched down in LA on the 14th and headed to our first stop, Venice Beach. And the strange ramblings begin....

Kristen Stewart should stick to angsty teen movies

My sister and I saw Snow White and the Huntsman last night. We weren't impressed. While it was great visually, just about everything else, well, sucked.

Listen to our review:

The Volcom Fiji Pro is Pau. Please get over it.

I'm sick and tired hearing about the "controversy" over the lay day at the Volcom Fiji Pro 2012. For those of you chasing butterflies, there was a massive swell pummeling Cloudbreak, and I mean massive. After waiting for a couple hours to set up camera equipment, the contest was called on. But only the final two heats of Round 2 were completed before the contest was called off. Crazy wind seemed to be the predominant excuse for calling it quits. Unfortunately, about an hour later the wind died down and Tavarua gave us one of the most spectacular displays the surfing world has ever seen. Beautiful and terrifying, Cloudbreak delivered massive barrels wave after wave. With the contest officially called off for the day, big wave chargers from around the world descended upon the break. Cameras originally set up for the contest continued to roll, giving spectators a glimpse of one of the most amazing free surf sessions ever.

And now everyone and their moms are arguing over whether contest officials were right to call it quits.

I for one am over it. Who cares? The contest was great. We saw a little of everything from massive Cloudbreak to the never ending barrels of Restaurants. Plus we got to watch a crazy free surf session. That's all I need.

I'd love to say more about how everyone that keeps talking about that day are a bunch of whiny brats (on both sides) but the more I say the more I sound like one of them. So I'll finish with this. Please get over it. I won't survive two months of bickering until the Teahupoo contest. Let's argue about something else okay? Like who should be the next leader of the free world? I heard elections were coming up soon.

Mike Love

We toured the Garlic and Ginger Festival at Ward, Honolulu, HI, last night. Surrounded by garlic sandwhiches, garlic steak, garlic ahi poke, garlic garlic garlic! The sweets were thankfully embellished with the ginger half of the festival theme and included ginger cotton candy and (it seemed everyone's favorite) candied ginger bacon.

The entire place had run out of beer by the time we got there, so we got in line for some cocktails. No ginger or garlic themes here though. That would have been fun.

But the highlight of the night wasn't the garlic or the ginger. It was the music. Mike Love, a local reggae musician, was amazing as usual.

Here's a taste of his awesomeness:

Bad Branding: Blueberry Muffin Tops

I was walking through the grocery store the other day and stumbled upon a new gem of a cereal: Blueberry Muffin Tops. I stopped mid way down the aisle and gawked at this masterpiece of advertising. Really Malt-O-Meal? How did that slip through the marketing cracks?

Honestly, Google the phrase "Muffin Top" and the first site that pops up is a Wikipedia definition:

"'Muffin-top' is a generally pejorative slang term used to describe the phenomenon of overhanging fat when it spills over the waistline of pants or skirts in a manner that resembles the top of a muffin spilling over its paper casing."

Yum, can't wait to dig in! 

Gabriel Medina killed it. So can we stop saying he's only good at airs?

For the past two days, the Volcom Fiji Pro 2012 has delivered. Amazing barrels, ridiculous wipeouts, and classic power surfing. Josh Kerr surfing on a super taped-up sprained ankle. Cloudbreak offers a return to a raw, rough form of surfing, the kind we have always loved. It's a refreshing break from all those airs, not that we don't love those too. But I ramble. For the most part, the first two days of the contest have been awesome. Kelly Slater ousted in the last seconds of his heat by wildcard Mitch Coleborn. Don't worry Slater groupies, he won his next heat and is now safely into Round 3.

But Slater going down to a wildcard highlights a really important aspect of Cloudbreak: it's all about the wave. Like Pipeline or J-Bay, you can't force a score here. Catch a great wave and you'll get a great score... assuming of course you don't fall and test out the reef. It makes this contest unpredictable. That being said, just about everyone you'd expect to do well in heaving barrels did do well. Parko, Owen Wright, Mick Fanning, John John, Jordy.

Something you might not expect, and I've been guilty of this too, is that the Brazilian horde is killing it as well. Adriano de Souza, Heitor Alves, and Alejo Muniz all won their first round heats, getting to skip straight into Round 3. Although forced to surf in Round 2, Brazilians Gabriel Medina and Miguel Pupo rebounded and are also into Round 3. The only Brazilian to go down so far is Willian Cardozo and he lost to Taj Burrow (no shame there).

So now can I talk about him? I'm just going to say it. Gabriel Medina can surf. Period. He's not a one-trick pony. This kid does more than just insane airs. He can navigate barrels and destroy waves with beautiful power hacks. And with the contest's first perfect 10 point ride, he's proven it. So are you satisfied yet? Can we stop questioning whether all he can do are airs?

It's a bit of a paradox with Medina. Last year he was ridiculously hyped after making it onto the Pro Tour at the tender age of, what? 17? Anyway, really young. He then went on to - in his rookie year mind you - win two World Tour contests (The Quiksilver Pro France and The Rip Curl Search San Francisco). So, clearly he deserved the hype. What's weird is the excitement was extremely narrow. What I mean is, Medina was type-cast as this hot new kid who took to the air any chance he got. If anyone mentioned his power surfing skills it was only to degrade or at least express some level of concern. Every event he entered was punctuated with the question, "he's good at airs, but can he battle through these waves?" And just about every time he's proven himself. Even after placing 5th at the Pipeline Masters, commentators continued to question his skills outside launch ramps.

The media's views of him have been shaped by his youth, his size (tall, lanky - can those chicken legs really do power hacks?), but mostly his nationality. Brazilians have always had this stigma as choppy, ugly surfers with bad styles and even worst attitudes. While the recent crop of Brazos are working to overcome this wall, there are still years of bias. And that doesn't get overturned overnight. Which is why Gabriel's been so undersold. Ha, see the paradox? Over hyped yet undersold.

And, entering the Volcom Fiji Pro 2012, the questions continued. But Medina's perfect 10 in Round 2 was a game changer. Not even the cameraman thought he was making it out of that barrel. I think he's proven himself, so can we all just shut up now? I'll say it again, just one last time. Gabriel Medina can surf. Oh, and he does airs too.

Check it out: