Atlantic hurricane season starts/Bud may be following Aletta

With June 1st about 3 hours old in GMT, it is now officially the 2006 hurricane season in the Atlantic. Nothing looks imminent there, but the Eastern Pacific is already off to a strong start. Closely on the heels of Aletta, there is a tropical wave off the coast of Acapulco which the National Hurricane Center is monitoring. Should another storm develop from this wave, it would become Bud.

Aletta is gone

As of 2 PM Pacific Time earlier this afternoon, Aletta, which had already degenerated into a tropical depression, is gone. She brought about 2 inches of rain to Acapulco, and seems to have done more good than harm in her brief existance. Weak tropical storms like Aletta are often beneficial to areas needing moisture, as they are not much more than a really big rain storm. Wind damage from these small storms is not likely, but they can quickly alleviate drought conditions with the large amount of tropical moisture they contain.

Aletta Heads to Sea

The vague threat to the Mexican Riviera from this storm is over. She has made the turn short of the coastline, and will head west for the forseeable future. With increasingly hostile conditions, she's either going to fall apart due to shear, or eventually get nudged over cooler water and dissipate. North America won't see the first landfalling storm of 2006 for a while yet.

Aletta Stalls Out

Tropical Storm Aletta is wandering currently in the absense of strong steering currents. High pressure over Mexico is likely to keep Aletta at sea, and all the computer models are now in agreement that Aletta is no threat to make landfall. The environment around the storm isn't very hospitable, and it looks as though Aletta has very little chance of ever making hurricane strength.

Tongan Aftershock Arrives

After the M7.9 Tongan Earthquake earlier this month, I commented that there would likely be an aftershock between magnitude 6.5 and 6.9 in the first weeks after the initial earthquake. Looks like it just happened. Of course, I'm not claiming any special powers, just using what seismologists know about typical aftershock distributions.

UPDATE: The magnitude of this aftershock has been revised from 6.7 to 5.9. That's rather a larger change than is usual with this sort of reevaluation, so, oops, what I thought was a safe assumption has turned out wrong. The lack of a major aftershock above 6.5 is still somewhat anomalous, so I'll have to guess that there is still one in the works maybe a few months down the road.

Destruction in Java / First named storm of 2006 for North America

The destruction in Java from the earthquake yesterday is now evidentally much worse than was apparent last night. While the quake has been reassessed at magnitude 6.3, and some areas experienced MM Intensity VIII shaking, this was still not a gigantic quake in the overall scheme of things. The Northridge Earthquake, for instance was almost 6 times larger than this quake. The Great Northern Sumatra Earthquake of last year was nearly 3,000 times larger, yet struck a much less populated area. The reported death toll of over 3,000 shows that population density, building codes, and earthquake readiness have a greater affect on the deadliness of an earthquake than magnitude does.

Here in North America, the hurricane season is kicking off with the formation of Tropical Depression 1E. This disturbance is expected to intensify into Tropical Storm Aletta within the next 10 hours or so. There is a little disagreement in the hurricane models as to what will happen to it after that. The consensus has Aletta remaining a tropical storm off of the coast of Mexico and bringing maybe 3-5 inches of rain as it brushes along the shore. Some models show the storm making landfall around Acapulco as a category 1 hurricane, so further attention will have to be paid to it.

UPDATE: Aletta is here. Tropical Depression 1E has now strenghthened into Tropical Storm Aletta, with 40 mph winds.

Java quake

The city of Yogyakarta, Indonesia was hit by a magnitude 6.2 earthquake about 5 hours ago. The quake was centered about 15 miles out of the center of the city, and the Modified Mercalli Intensity experienced in Yogyakarta was reported around VII, indicating that significant damage has occurred. The quake appears to be from a strike-slip mechanism. Because the oceanic plate subducting below Java does not move precisely perpendicularly to the subduction fault, occasionally quakes like this must occur to relieve parallel stress that accumulates. Because of the mostly horizontal nature of this quake, and the location of the epicenter near land or beneath shallow water, no notable tsunami was generated by this earthquake. The location of this quake was also very close to Mount Merapi, which is currently erupting. It will be interesting to learn whether this quake has affected the eruptive pattern of the volcano.

10.5 Stupocalypse

I just finished watching this two-part stink-fest of ludicrous writing last night. This NBC made-for-TV movie (10.5 Apocalypse), and its ridiculous CBS twin Category 7: The End of the World were so hilariously ineptly beyond anything previously filmed that they have made me realize that a new calibration scale is in order. I call my new scale the Disaster Unbelievability Movie Magnitude (DUMM). It is an open-ended scale (unfortunately), and like the Richter Scale, it is logarithmic. Each increase of 1 in the DUMM represents approximately a 30-fold increase in the stupidity of the movie. Here is a quick guide. Remember that DUMM does not take into consideration the skill of actors or special effects technicians, just calibrates the overall premise of the movie.

DUMM 0
Description: Movies of DUMM 0 are your basic Hollywood disaster movies. Characters may act in stupid or cliched manners, the writing may be bad or uneven, and technical errors will be minor and not critical to the plot, but not to a greater extent than most other Hollywood movies. The disasters depicted remain firmly plausible, if not actual. Poor engineering and human hubris may be the main villains. The disaster depicted must be something that has actually happened, or which you would not be surprised to read in tomorrow's headlines: a volcano erupts, a building burns, etc. The laws of physics are at least recognizable.
Examples: Airport, The Towering Inferno, Dante's Peak
Characteristic Premise: That's what you get for using shoddy wiring!

DUMM 1
Description: The disaster faced, or the solution proposed, may be outlandish, but some attention is paid to technical detail. You could possibly believe that this could happen someday, even if it would not necessarily play out in the way depicted in the movie. The disaster at least still resembles the actual universe. Characters may attempt to use technology in some illogical or unbelievably sophisticated way. The ending may be a blatant deus ex machina in many cases.
Examples: Deep Impact, Twister
Characteristic Premise: FREAKIN' PEPSI CANS??

DUMM 2
Description: The laws of physics begin to lose their grip. The disaster being faced has only the loosest connection to reality. While a real phenomenon may be depicted, it is depicted in a way totally inconsistant with the real world. Far-fetched solutions are guaranteed to be deployed. Even though the laws of nature may have gone crazy, there's at least a bit of self-consistancy to the way they are developed, not unlike a lot of fantasy sci-fi.
Examples: Volcano, Armageddon, The Day After Tomorrow
Characteristic premise: Pointy asteroids the size of what??

DUMM 3
Description: We are in Wacky Land. Real jargon is constantly thrown about, but without regard to its actual meaning, and in quite nonsensical ways. Realism is nowhere to be found. The solution to the problem pretty much basically always must involve nuclear weapons in some way. The first word that springs to mind is "ludicrous". Major onscreen events begin to have little to no effect on other scenes because the directors and writers can't be bothered with maintaining continuity.
Examples: Asteroid, 10.5, Category 6: Day of Destruction
Characteristic premise: An *earthquake* is *chasing* the *TRAIN*?!?!

DUMM 4
Description: This magnitude can apparently only be achieved in sequels. Not only has reality gone out the window, but the movie is attempting to "one up" some previous movie to the extent that it almost feels like a parody. You can't believe that actual writers and directors were involved, and get the feeling that someone left it up to a bunch of 6-year-olds.
Examples: 10.5: Apocalypse, Category 7: The End of the World
Characteristic premise: Wait, Pangaea is coming back next week?!?!?!

I know of no movies yet that have achieved DUMM 5 or higher, but it's only a matter of time, I fear... Maybe when someone makes a movie about a hurricane that sucks up a school of fire-breathing sharks and hurls them into Denver, where they start massive brush fires...

Hong Kong may have dodged a bullet

The latest forecast for Typhoon Chanchu looks a lot better than it did yesterday. The storm was only briefly a super typhoon, and has now weakened somewhat with 140 mph winds. The storm should continue to slowly lose intensity as it moves north over the next two and a half days, and make landfall as a Category 3 storm. In addition, it looks to be taking a slightly more easterly track, which would put Hong Kong in the northwest quadrant of the storm, where the winds will be somewhat lower than the northeast quadrant. The impact is likely to still be major, but not catastrophic.

UPDATE: Chanchu has weakened a little further, with 130 mph winds at present. It is likely to lose more strength over the next two days, and make landfall as a Category 2 storm. The expected track keeps bending further eastward, and Hong Kong is now only on the very edge of the potential landfall zone. It looks as though the danger to the city has passed.

Welcome to hurricane season, North America

Hurricane season in the Eastern Pacific officially started today at midnight GMT. Hurricane season begins in the Atlantic 16 days later, on June 1st. While 2005 definitely showed that it's not impossible for hurricanes to form outside of the designated season, "hurricane season" is just the window of time when the NHC feels it is prudent to keep staff on 24-hour watch for developing storms. Nothing as yet looks to threaten the North American mainland, and it's likely to stay that way for several weeks. The Eastern Pacific basin forms far fewer hurricanes that can threaten land, because hurricanes in the northern hemisphere tend to start out moving westward, and only recurve eastward after gaining latitude by venturing north. The currents in the Pacific keep the temperatures much lower than the Atlantic in the latitudes that are likely to see eastward-moving hurricanes. Thus most East Pacific hurricanes simply move harmlessly out to sea, which is what is likely to happen to any storm that may happen to form there in the next two weeks.

Meanwhile, Chanchu has turned northward towards Hong Kong, and is now a Super Typhoon with sustained winds of 155 miles per hour. The terms "Super Typhoon" and "Category 5 Hurricane" are almost, but not entirely synonymous. A "Super Typhoon" is defined to have sustained winds of 151 mph or higher. A hurricane becomes Category 5 with sustained winds of 156 mph or higher. Thus for now, Chanchu is in that narrow band of storms that are Category 4 Super Typhoons.

Chanchu: Chinese Katrina?

The name "Chanchu", meaning "pearl" was submitted to the Western Pacfic typhoon name list by Macao, which is now looking to be hit by its full strength. Chanchu is currently a Saffir-Simpson Category 3 typhoon, with winds of 130 mph. By the time it reaches Hong Kong in 72 hours, it is projected to be a Category 5. It is now clear that this is rapidly becoming the worst case scenario for Hong Kong. For a preview of what is likely to occur there in three days there is a Discovery Channel miniseries episode airing tomorrow at 1 PM EST that explores this exact scenario. Of course, in some ways, Hong Kong is better off than New Orleans. For one, it does not have large sections that are below sea level. The higher terrain won't be as subject to the huge storm surge that the typhoon is certain to produce. However, typhoon wind strength rises with height, and the higher hills are likely to see even higher winds. The skyscrapers, likewise will sustain at least a lot of damage to glass facings. There hasn't been a direct hit by a Category 5 storm on such a built-up area before, so it's not really known how modern high-rise construction will fare. Landslides could also be a problem on steeper slopes due to the torrential rains expected. Hopefully a well-implemented civil defense/evacuation plan will keep the losses to a minimum.

Asian update: Volcano and Typhoon

The big geological and meteorological stories today are in Asia. In Indonesia, an Alert Level IV has been issued for the Merapi volcano, which overlooks the Yogyakarta region of Java. Evacuations are underway to move the population that might be threatened by any pyroclastic flows. The sides of the volcano are exceptionally steep, and as the lava dome builds, very hot chunks break off and flow down the mountain. As the rock particles and gases mix, they form a very dense and hot flow that incinerates anything in its path. Even without a large eruption, you do not want to be in the valley below the mountain when one of these collapses occurs.

Meanwhile, Typhoon Chanchu has crossed the Philippines, and is making a beeline for Hong Kong. It should arrive there in about 4 days, and is expected to be anywhere from Category 3 to Category 5 when it does.

Back to Indonesia, aftershocks of the Great Sumatra-Andaman Islands Earthquake are still continuing nearly 18 months later. Yesterday's magnitude 5.6 aftershock was felt at Banda Aceh, but caused no damage.

How to be a human seismometer

OK, so this is part of the blog where I divulge some of my deepest secrets. Have you ever wanted to impress people after an earthquake by making an eerily accurate estimate of the magnitude and epicenter? Here are my tips on how to do this.

Step 1: Know your surroundings

Before the ground starts shaking, look over some maps of your area, and be familiar with the seismic hazards you are likely to face. The USGS Quaternary Fault Database is a good starting point to familiarize yourself with the faults around you. Once you know the faults around you, and have a general idea of how they might behave, you are armed with the knowledge of some earthquake scenarios you can reasonably expect to experience at some point in the future.

Step 2: Know the Intensity

You won't be able to feel the magnitude of an earthquake, but you will feel the intensity. When the ground starts to move, you will need to be able to judge your Modified Mercalli Intensity. Here's my humorous version of it, if you can't make too much sense of the original:

I: Huh, look at that seismograph wiggle. (Only works if you're standing by a seismograph.)
II: Whoa, I feel dizzy. Why is that chandelier wobbling?
III: What the... Was that an earthquake?
IV: Wow! That was an earthquake!
V: Dude! Look at your bobblehead collection!
VI: Ah crap! There goes my bobblehead collection!
VII: Oh crap! Oh crap! This a big one!
VIII: Aaaaaaaaaaah!! Earthquake! Earthquake! AAAAAAAAH!!!
IX: Oh crap!!! We're all going to die!! We're all going to die!!
X: AAHHHHHHHH!!!!!! THE WHOLE DAMN STATE IS FALLING INTO THE OCEAN!!!!!!!
XI: AAAAAAAAAAAAAAAHHHHHHH!!!!!! WE'RE ALL DEAD!!!!!!!!!!!!!
XII: [nothing to say because everyone is actually dead]

Step 3: Direction

Now that the ground is actually shaking, you should be able to notice a distinctive direction to the motion. Once you have identified this direction, you have narrowed down the location of the quake to two small wedges, 180 degrees apart, centered on your location. The epicenter lies within one of these two wedges. The only exception to this is if this direction seems to change during the course of this earthquake. If it does, you know at that point you're dealing with a pretty major quake.

Step 4: Frequency

You can to a first approximation figure out the frequencies of the quake that you are experiencing. Do you hear rattling more than you feel a shaking? That's an indication of a high frequency seismic wave. You are either very close to a small quake, or you are experiencing the P-wave of a major quake. Do you feel a sharp shaking, or a gentle rocking like on a ship? Generally, the larger the quake, the lower frequencies you will notice. In very large quakes, you might notice everything moveable around you slowly rocking for several minutes after the quake.

Step 5: Duration

How long does the major shaking last? This will give you some idea of the magnitude. For a magnitude 3 quake nearby, you will feel a fairly intense shaking for only a few seconds. A magnitude 4 or 5 might last 10-20 seconds. If you feel shaking for over 30 seconds, you are dealing with a magnitude 6 or above.

Step 6: Synthesis

Once you have an idea of the intensity, direction, frequency and duration, you can begin to guess at magnitude and location. High frequency and short duration means a small quake, even if the intensity is high. A quake that lasts a minute or more, but is barely noticeable is likely a very large earthquake, but very far away. By knowing your surroundings, you can begin to guess at a location and magnitude. To get started I'll give a few examples of earthquakes that I've felt, and the results of my guesses according to these parameters:

Magnitude 3.1 about 4 miles away:
This minor earthquake occurred right below Portland back in January. The best description that I could think of for the motion was a "shiver". It was fairly high frequency, and felt like it was due south of my location. It lasted about 10 seconds. I guessed magnitude 3.5 near Scotts Mills. In reality, it was a magnitude 3.1 much closer to me than that. The USGS report showed that it was nearly due south from my location. I overestimated the magnitude because I thought the quake was more distant. I had neglected to take note of the recent increased activity on the East Bank Fault, where this earthquake occurred.

Distant magnitude 7.2:
Last June, we felt the very distant but very powerful Gorda Plate quake off the coast of California. This felt unlike any quake I had felt before, because of the great distance. The ground rocked like a ship's deck for about a minute or so, but there was no sharp shaking. I knew right away that this was a distant quake, and guessed a magnitude 7.1 near the Mendocino Triple Junction. This was probably my most accurate guess.

Deep magnitude 6.8:
The Nisqually Quake was one of the larger events to affect Portland recently. I was on a raised floor at work at the time of this quake, and didn't feel it firsthand. Based on reports from my coworkers that the quake had definitely come from the north, and lasted about 30 seconds, I guessed magnitude 7.0 near the Strait of Juan de Fuca.

Shallow magnitude 6.7:
I was about 16 miles from the epicenter of the Northridge Quake when it occured. I experienced very sharp shaking for about 40 seconds, with loose items flying everywhere off of shelves, but no real structural damage to my wood-frame apartment building. There was a definite WNW-ESE motion to the quake, and quite a bit of vertical motion as well. I knew this was a thrust quake immediately, but overestimated the magnitude at 7.0. I correctly located the epicenter as somewhere within the San Fernando Valley.

Somewhat distant magnitude 4.4:
This quake occurred during the aftershock sequence of Northridge, but I am mentioning it because the method of determining distance and direction allowed me to exclude it as a Northridge earthquake. The shaking was definitely not along the axis that I was used to feeling the Northridge aftershocks. It also lasted longer than I expected for the intensity: an indicator of greater distance. It turned out to be a Landers aftershock, and my perception of a difference from the Northridge shocks was vindicated.

JRO reopens

The Johnston Ridge Observatory reopened today after its usual closure for the winter. The Observatory is located about 5 miles from Mt. St. Helens, and is currently the closest that the public is allowed to get to the crater. There is some talk about reopening the mountain to climbing at some point during the summer, but this is unlikely to occur before the current eruption slows down just a bit. For now, the view from Johnston Ridge is the best available to those who aren't professional volcanologists.

Aftershock

Aftershocks of the Tonga quake are continuing, with the largest so far being magnitude 6.0. Most people will believe and tell you that earthquakes are completely random, unexpected and unpredictable, but this isn't strictly true. About a third of the total number of earthquakes that have ever been recorded have been predictable in many aspects, because they are aftershocks. The somewhat obvious reason that they are aftershocks is that they follow a larger mainshock. We know in general that the largest aftershock of an earthquake is usually around one Richter magnitude lower than the mainshock, and that the number of aftershocks will generally increase by about a factor of 10 for each magnitude below that. The aftershocks tend to become less frequent with time, but the individual aftershock magnitudes are more or less random as far as we know today. The strongest aftershock will generally occur close to the mainshock only because more aftershocks occur in the near timeframe than will occur later. However, there is no reason that the strongest aftershock has to be one of the first, so occasionally the largest aftershock can be weeks, months or years later. These relationships are so well known that the USGS turns them into a map of the current California aftershock hazard. This map is updated continuously and represents with "hot" colors areas of the state where damaging aftershocks may be expected to occur. Back to the Tonga quake, I would make a guess that an aftershock of magnitude 6.5 or higher is still in the works within the next few weeks. For more depth on the subject, it's hard to beat this discussion of aftershocks made available on the internet by Susan Hough of the USGS Pasadena.

Gotta start somewhere

OK, so I really only registered for this blog in order to be able to post comments on Internal Monologue but as long as I have this resource, I might as well use it occasionally. It's appropriate to start this blog today, on the day of the largest earthquake so far in 2006, a magnitude 7.9 quake off of Tonga. I give this about even odds of remaining the largest earthquake through the rest of the year. An expected tsunami was much smaller than anticipated (less than 2 feet tall). This probably indicates that the earthquake took place within the Pacific Plate as it moves below the Australian Plate, and the Australian Plate above didn't deform much. The quake was also remote enough not to cause much damage, but the power of one of these events is still staggering. The seismic energy released was over 3.4 megatons, the actual total energy released by the earthquake was almost 10,000 times larger. While this was about equivalent to the Great San Francisco Earthquake, the quake that caused the Indian Ocean tsunami was about 64 times larger.
Even though this earthquake was almost on the other side of the world from here, it still caused visible shaking for over an hour on seismographs here in Oregon.