The Earth Story

50 years ago right now this photo was taken. Original caption:

Hurricane Harvey fed off record warm Gulf of Mexico waters

This satellite shot captures Hurricane Harvey at the time it was a category 4 storm, just before it made landfall in Texas. The storm started off as a disturbance crossing the Yucatan Peninsula, but when it made it into the warm waters of the Gulf of Mexico it rapidly strengthened. Harvey became the second costliest disaster ever to hit the United States after it doused the city of Houston with record rainfall totals. A new analysis points squarely at the Gulf of Mexico as the main driving force behind the power of this storm.

Hurricanes feed off of warm temperatures in ocean waters. In the process, they remove heat from the ocean and leave the water behind it cooled off. However, other things can happen that affect ocean temperatures; for example, the winds blowing over the water could mix the shallow layer with deeper water, cooling the surface water by pushing the warm water deeper. As a consequence, it’s not easy for scientists to match up the energy of the storm with the energy of the ocean.

Harvey though represented a unique case. For much of the surrounding month it was the only major weather event in the Gulf of Mexico, and it traveled over areas that are well instrumented so that scientists could see how much heat it removed from the water. On top of that, scientists also have available the Global Precipitation Measurement Satellite system, which enabled estimates of Harvey’s rainfall over wide areas.

A team led by a scientist at the National Center for Atmospheric Research took these two measurements and converted them into total energy. The ocean cooled by a certain amount over a certain volume – that’s an energy measurement. Harvey produced a certain amount of rainfall over a certain area – that’s also an energy measurement. When they compared the number of joules pulled out of the Gulf to the energy released over land by Harvey – they were virtually identical, within 1% of each other. The energy that drove Harvey was the energy in the Gulf; basically every Joule of energy it pulled out of the Gulf, it dumped on Texas.

Harvey became such a disaster because it had an ample supply of energy in the shallow waters of the Gulf of Mexico. Prior to the storm, the waters of the Gulf were at their hottest temperature ever recorded, more than 1.5°C above the long term average. Those temperatures extended downwards, making the Gulf heat content also a record. When Harvey passed over these waters, it cooled them by 2°C. That extra 1.5°C in the Gulf of Mexico in 2017 was enough to almost entirely fuel the storm; had the Gulf not been at record temperatures, Harvey would not have had the energy to produce that rainfall.

Global ocean heat content has been rising steadily since the 1980s as the ocean takes up much of the extra heat kept in the atmosphere by greenhouse gases. The close match between energy taken out of the ocean and energy dumped by the storm verifies that the extra energy trapped in the atmosphere is feeding storms like Harvey. The extra heat in the Gulf of Mexico directly triggered flooding in Houston, and as ocean temperatures continue to increase, it will be able to continue powering devastating storms.

-JBB

Image credit: https://commons.wikimedia.org/wiki/File:Harvey_2017-08-26_0055Z.jpg

Original paper: https://doi.org/10.1029/2018EF000825

Today is the 117th birthday of the United States's 10th National Park, Montana's Glacier. A few decades after it opened, a single road called Going to the Sun road was constructed leading across the park from East to West. That road is consistently ranked as one of the most beautiful drives in the world. For the park's birthday, here's a brief clip.

It’s Asteroid Day!

On June 30, 1908 the largest asteroid impact in recent history occurred in Siberia. The asteroid hitting Earth was relatively small with about 40 meters across but devastated an unpopulated area about the size of a major metropolitan city.

In order to raise awareness and to learn about asteroids and what we can do to protect our planet Asteroid Day was created. Two years ago filmmaker Grigorij Richter and Dr. Brian May, astrophysicist and guitarist of the legendary band Queen, co-founded this annual event. So far over 100 astronauts, scientists, artists and technologists signed the Asteroid Day Declaration called “100X Declaration”.

The Declaration calls for increasing the asteroid discovery rate as we only have discovered about one percent of asteroids that have the potential to impact Earth. Early warning is essential for our planetary defense and at the current rate of discovery it would take more than a thousand years to find all the potentially threatening asteroids.

The event began as a scientifically-based declaration and grew to a global movement with more than 150 self-organized events around the globe. If you would like to find an event near you or sign the 100X Declaration, check out the link for Asteroid Day for further Information: http://asteroidday.org/

Happy Asteroid Day! Xandi

Image Credit: http://bit.ly/28ZCHiv

Second Largest Volcanic Eruption of the 20th Century

This week is the 25th anniversary of both the devastating Mount Pinatubo eruption, and of Typhoon Yunya hitting the Philippines. These two natural catastrophes struck the densely populated island of Luzon on June 15, 1991.

Prior to 1991, Pinatubo was a heavily forested lava dome that had been dormant for 500 years. Little was known about the stratovolcano. When it begin to show signs of life in March of 1991, first with earthquakes rumbling beneath it and then by relatively small ash explosions, scientists had very little information to predict what might happen next. Researchers quickly moved to install seismic monitors and survey the mountain. To their dismay, they discovered Pinatubo had a history of very large eruptions.

The mountain and the surrounding area were home to hundreds of thousands of people. An additional 15,000, US military personnel and their families, lived at Clark Air Force base. As seismicity, deformation of the mountain, and emission of small plumes increased, the people living on the mountain and those closest to it were evacuated in stages. Then on June 7, the first magma began to reach the surface. By June 9, over 50,000 locals had been ordered to leave. On June 10, all but 1,500 military personnel and the scientists monitoring Pinatubo were ordered to evacuate Clark.

At 8:51am on June 12 (Independence Day in the Philippines), Pinatubo erupted explosively, sending a column of ash and steam 19 kilometers (11 miles) into the air. It subsided after 40 minutes, but the earthquakes didn’t; the mountain wasn’t done. All residents within 20 kilometers of the mountain were told to evacuate. Another 600 at Clark were told to leave as well.

The morning of June 15, Typhoon Yunya struck Luzon even as the mountain continued to erupt with smaller explosions. Fortunately the storm was already dissipating into a tropical storm. Even so, it brought heavy rains and circular winds. Then, around 1:42pm local time, Pinatubo exploded with the second largest eruption in the 20th century. The explosion ejected 5 cubic kilometers (1 cubic mile) of material. Much of the mountain summit was removed by explosions or collapse, leaving a caldera 2.5 kilometers (1.6 miles) across. The ash cloud rose 35 kilometers (22 miles) into the air. At lower altitudes, ash that would’ve blown out to sea was caught in Yunya’s circulating winds, and then brought back down on Luzon by the rain. The heavy, wet ash came down like mud and accumulated on rooftops, collapsing many of them. Pumice, including some the size of apricots, began to fall on Clark and the nearby city of Angeles, in some cases causing injuries. Lahars and debris came down the mountain and filled some valleys 200 meters (660 feet) thick. Many people fled and more evacuations were ordered; all together, the eruption dislocated about 250,000 people.

Pinatubo continued to erupt for several days, but the worst was over and some people began to return to their homes. Ash continued to erupt and was reported to be 15-30 centimeters thick at Clark and some of the surrounding towns and cities. So much ash was expelled throughout the eruption that it would eventually cause a short-term global cooling of 0.5-degrees Celsius.

The eruption finally ended in September. Over 105,000 homes were damaged or destroyed, and the thick layer of ash over once fertile agricultural lands caused long-term hardship. There was so much ash that new lahars formed during monsoon seasons for several years after, in one case killing 60 people. In June of 1992, about 70,000 were still living in evacuation centers and resettlement areas. Clark was permanently abandoned.

Amazingly, the death toll was only about 725. The evacuations are believed to have saved the lives of 20,000 people.

Pinatubo begin to erupt again in July of 1992 from a caldera lake that now exists where the mountain summit used to be. It erupted again in February of 1993. Fortunately the eruptions were relatively small. The volcano finally went quiet, and, based on past history, probably won’t erupt again for hundreds of years.

Photo Credit: Richard P. Hoblitt, U.S. Geological Survey, http://bit.ly/1S0AQsa R.S. Culbreth U.S. Air Force, https://www.flickr.com/photos/kyngpao/8874135744/ USGS / Cascade Volcano Observatory, http://bit.ly/1rj2sDh E.J. Wolfe, http://bit.ly/1ZHrxU1 References: http://pubs.usgs.gov/fs/1997/fs113-97/ http://gsabulletin.gsapubs.org/content/117/1-2/195.full http://volcano.si.edu/volcano.cfm?vn=273083 http://bit.ly/1tuS3Go http://bit.ly/1SkSzjg Previous Earth Story Posts: http://bit.ly/1UnCM3S http://bit.ly/1ufd6VQ

Lateral Blast

Today, May 18th, is the 36th anniversary of the eruption of Mt. St. Helens in Washington State. This photograph of the volcano was taken earlier this month by astronaut Tim Peake from the International Space Station and although much of the surrounding landscape has recovered, the area damaged during the blast is still clearly outlined.

Mt. St. Helens’s 1980 eruption was a rare type known as a lateral blast. Most volcanic eruptions send material upward, in line with the direction of the plumbing system below. When those volcanoes produce pyroclastic flows and surges, they occur because of factors like the density and temperature in the ash cloud above. Mt. St. Helens was a different beast; the north side of the volcano collapsed, releasing stored pressure on the side of the volcano rather than at the top and sending a blast of debris out horizontally.

Both the location of the volcano in the United States (easily accessible to USGS scientists) and the unique style of eruption made the St. Helens eruption one of the best studied in the world. It is now recognized that lateral blasts, like St. Helens in 1980, occur globally about once every decade on average. They tend to be driven, as in the St. Helens case, by sector collapses and avalanches along one side of the volcano, or by the collapse of lava domes that similarly fall off to one side. In the case of St. Helens, the lateral blast did damage far beyond the limits of the evacuation zone since all the force of the eruption was in a single direction, so understanding the mechanics of eruptions like this one is important for understanding future volcanic hazards.

Mt. St. Helens, like many volcanoes, has continued its life since the 1980 eruption. Geologic investigation even shows that 1980 was not the first lateral blast in St. Helens’s lifetime; a smaller one occurred about a thousand years ago on this same damaged north slope. About a decade ago, the same magma that fed the 1980 eruption appeared at the summit and began slowly building a lava dome; since the magma had mostly degassed that eruption wasn’t explosive.

In the plumbing system beneath the volcano, earthquake pulses every few years show that molten rock continues entering the system, keeping it active. It could be years, decades, or even centuries until the next eruption; at present scientists don’t understand the conditions required to bring a volcano at the surface to life. Ongoing research suggests that these systems are complicated, constantly churning new batches of molten rock through their plumbing systems, mixing old and new batches together, and eventually this process creates the conditions required for a future eruption.

-JBB

Image credit: Tim Peake/ESA/NASA https://flic.kr/p/G2qATr

Recent St. Helens Science: http://www.sciencedirect.com/science/article/pii/S0377027306001879 http://pubs.usgs.gov/gip/msh/lateral.html http://www.wired.com/2016/05/mount-st-helens-recharging-magma-stores-setting-off-earthquake-swarms/

Local, on site news report from 36 years ago today - the eruption of Mt. St. Helens.

Videographer travels through Nepal to see how the country is recovering 1 year after the large Gorkha Earthquake.

Tohoku earthquake set off mega-landslide

This photo is one of the seemingly infinite number of shots showing damage after the great Tohoku earthquake and tsunami off the coast of Japan in March, 2011.

It was recognized shortly afterwards that the wave was very unusual. It was a “double” tsunami; two large, distinct waves were recorded by satellites and buoys throughout the Pacific, separated in time by several minutes. The presence of two waves greatly increased both the height of the waters onshore and the damage.

Consequently, scientists have spent the last few years trying to understand why there were 2 waves, in order to better prepare for future earthquakes. New research from the British Geological Survey presented at the 2013 meeting of the American Geophysical Union seems to have the answer.

The earthquake set off a landslide below the waters. Not just any landslide…an enormous one…almost beyond imagination in its scale.

Using sonar images, the scientists identified a piece of the ocean floor 40 kilometers wide, 20 kilometers long and 2 kilometers thick which slid downhill during the earthquake. That estimate means that 500 cubic kilometers of rock moved in this avalanche.

It’s actually hard to find anything to compare this volume to. The largest recorded slide on land was at the eruption of Mt. St. Helens, and that was about 3 cubic kilometers. An earthquake off of Newfoundland set off a slide with a volume of 200 cubic kilometers in 1929; that slide set of a tsunami that killed several dozen people.

500 cubic kilometers is roughly the amount of material erupted from the Long Valley caldera eruption 760,000 years ago. This slide was comparable in volume to a supervolcano that knocked a hole in the Sierra Nevada mountain range.

The scientists also used seismic data recorded during the earthquake to confirm the presence of this slide. Avalanches give a peculiar seismic signature and, within the data available on this earthquake, they located that fingerprint.

It’s impossible to say how much worse the devastation in Japan was because of this slide; there is no way to separate its damage from the other wave. However, over the last century, there are multiple examples of tsunami waves generated from submarine landslides, with the one in Japan likely being largest.

These mega landslides aren’t common, but they occur often enough that they are a major threat to civilization. They can occur in places thought safe from tsunami, making them a particular threat. These submarine landslides are in need of better scientific characterization soon, before another one contributes to or causes a mega-disaster in a populated area.

-JBB

Image credit: http://commons.wikimedia.org/wiki/File:Flickr_-Official_U.S._Navy_Imagery-Aerial_of_Wakuya,_Japan.%281%29.jpg

Press reports: http://www.theguardian.com/world/2011/dec/07/japan-double-tsunami-nasa-satellite http://blogs.agu.org/landslideblog/2013/12/17/tohoku-earthquake-landslide/ AGU Abstract: Tappin et al., 2013.

The harbor wave

On the morning of March 11, 2011, I turned on my television to see some of the most unbelievable footage I have ever watched. Helicopters flying over the fields in Northern Japan watched as a wave rolled across the fields and farmland of the Tohoku region, the northeastern part of Honshu Island.

That wave picked up cars, houses, boats, and washed away people. In places the wave literally caught fire – oil and gas ignited as stores of it spilled, and the wave carried the fire forward.

Although those images are still in my memory, they’re nothing compared to the memory of the people close to the event. I walked downstairs that day and saw that there was a group of Japanese nationals huddled around a television in silence, just watching the footage as it played again and again. Maybe they had relatives in that area; maybe they were just feeling pain for their country.

5 years ago today, the 4th most powerful earthquake in recorded history struck just off the coast of the Tohoku region. The quake and resultant tsunami were a massive disaster for Japan – with a total number of confirmed deaths in Japan of 15,891 and an estimated $300 billion (US dollars, 25 trillion yen) in economic losses.

The tsunami from this quake wrapped around the world. The waters of the oceans shook up and down for days as the energy dissipated. Debris from Japan, picked up by the wave and carried to sea, has migrated across the entire Pacific and still turns up on beaches to this day. The wave was powerful enough to cause casualties on the opposite side of the world, in a North American harbor. It even was powerful enough to dislodge icebergs from the coast in Antarctica.

Every superlative that one can apply to a disaster can be applied to this one; there is literally nothing I can do here to put the impact of this quake on the people of Japan, the people of this province, into words. But in the end, I can talk about some of the science that came from this quake, because that’s what I do, and that’s what brings me hope after these events.

This video is a simulation of the propagation of the Tohoku tsunami. Tsunami runup levels are complicated, depending on the angle of the wave to the shoreline, the shape of the shoreline, the angle of the shoreface, and the way the waves spread out over water. This quake and wave had several unique properties that weren’t well understood or predicted beforehand; better research will now save lives.

Many areas of the Tohoku province, including the destroyed Fukushima-Daiichi nuclear plant, had seawalls to protect against tsunami waves, but the seawalls were overtopped by the massive tsunami. Scientists knew the area had a tsunami risk but they underestimated the power this fault could release. The Tohoku quake in particular had several unique properties, including a “two pulse” tsunami that may indicate a large, submarine landslide was triggered – a landslide that could have contributed to the wave overtopping the tsunami defenses and a property the world is now better able to prepare for.

Since that quake, scientists have completed new maps of the area, new fault models relevant to the rest of the world, and new tsunami propagation models like this one that allow better forecasting of tsunami risk for the future. Scientists from Japan even conducted a drilling operation to directly sample the fault, better characterizing the physical properties that allowed such a large slip. They found unique properties on this fault – like a low friction layer due to a large amount of clay, and the first ever measurement of heat released during an earthquake.

But despite the scientific steps forwards, one final anecdote from a graduate student on the drilling mission stays with me to this day. When the drilling vessel Chikyu brought up the section of core that crossed the fault, the crew of the vessel crowded around the core in silence. They wanted to see the actual piece of rock that had done such damage to their country. That’s the part of the story to remember today.

-JBB

Video Credit: Pacific Tsunami Warning Center https://www.youtube.com/watch?v=jH3-hQjTGDQ&feature=youtu.be

References/More: http://bit.ly/1p2a388 http://bit.ly/1W378qQ http://bit.ly/1pu1HGX http://bit.ly/1OXuc4w http://bit.ly/1b2Ab4g http://on.doi.gov/1M2I2CM http://on.doi.gov/1UMYHRS

This clip is absolutely ridiculous. You can watch the wave build on a river/canal (not sure exactly what it is) with a seawall holding in place for about 6 minutes, it gets deeper, deeper, deeper, and then all hell breaks loose as the wave overtops the seawall. 

Helicopter video of the Tohoku tsunami as it came ashore. Take a look at how the ocean retreated before the main wave hit - a “low” part of the wave came in first before the first peak. Really remarkable to watch it - can literally see it demolish a whole community. The shots near the end of the tsunami marching across fields are the ones I remember most from this disaster.

Tohoku earthquake: lessons in tectonics.

As we remember the tragedy of the great (magnitude 9.0) Tohoku earthquake on its second anniversary, and the associated tsunami that devastated so much of coastal Japan near Sendai, it may be some small consolation that the events on that horrific day have led to a deeper understanding of how earthquakes and tsunamis occur. We heard, last week, how the infrasonic boom of the earthquake was detected on the day by a satellite orbiting 270 km above (http://tinyurl.com/atexxzw). Scientists have been busy trying to understand exactly what happened in the Japanese trench on 11th March 2011, and the first results from a number of investigations have been emerging over recent years.

Although not the largest recorded earthquake (that place goes to the great (Mw9.5) Chile earthquake of 1960), the Tohoku event resulted in the largest slip ever recorded in an earthquake. In 2012, Dan McKenzie and James Jackson highlighted the importance of the fact that the North American plate, overriding the Pacific plate not only shot 10m upwards (the response that was generally expected), but a whopping 50m east, in response to the earthquake. They explained that it was the energy from the overriding sediments in the wedge-shaped accretionary prism pushing down and out that led to the huge tsunami. “Let’s say you have something wedge-shaped on the floor and you jump on it, the wedge will shoot sideways,“ McKenzie explained. This observation led the group to look back at earlier quakes that had produced significant tsunamis, and the found that they all had this “pop out” of sediment in common. It had provided a way to identify those faults whose movements are more likely to be associated with tsunamis.

Since then, the first results have emerged from a rapid-response drilling mission, drilling into the fault at the trench. This has been conducted by scientists from the Integrated Ocean Drilling Program (IODP) and shed light on the stress state on the fault that controls the very large slip. Drilling, from a ship-based platform, down into the crust at the Japan trench, lying beneath nearly 7km of ocean, they have found that the stress on the fault has been completely relieved by the displacements. They are able to measure the stress in the crust through which they drill by looking for borehole breakouts – failures of the borehole wall during drilling. The way that such breakouts manifest themselves within the borehole can indicate the direction and magnitude of any stress field. The results of Weiren Lin and colleagues from Japan Agency for Marine-Earth Science and Technology (JAMSTEC) show that the present stress on the fault is near zero. Usually, residual stress remains on faults after earthquakes, but once again Tohoku reveals itself to be extraordinary, in showing this complete stress drop. The group hope that further measurements at the trench should reveal more details of exactly what happened, as they attempt to measure the energy release, expressed as temperature changes in rocks at the fault.

~SATR

Image: conceptual details of the IODP rapid-response drilling mission (credit: JAMSTEC/IODP)

Further links:

http://www.bbc.co.uk/news/science-environment-19366314 http://www.iodp.org/jfast-press-release-journal-science

Tohoku on TES: http://tinyurl.com/afrevrb http://tinyurl.com/atexxzw http://tinyurl.com/d3wrlat

The bouncing letters at the beginning are a bit much but this is eerie...you can literally watch the Tohoku tsunami approach. Keep an eye on the cars driving away as they go.

NATURAL DISASTER: TOHUKU EARTHQUAKE AND TSUNAMI

Today, March 11 marks the five year anniversary of the deadly Tohuku earthquake and tsunami. The earthquake was the strongest in Japanese recorded history, registering 9.0 on the Moment Magnitude scale, and one of the 5 strongest recorded in the world since 1900. The epicenter was located about 70 km (43 mi) off the coast of the Oshika Peninsula at a depth of 32 km (20 mi). Although the death toll and damage from the earthquake was severe, the greatest destruction was caused by the deadly tsunami that followed. The tsunami traveled inland up to 10 km (6 mi) in the Sendai area and reached an incredible height of 37.88 m (124 ft) in Miyako. The estimated death toll was 15,853, with at least 6.023 injuries and 3,282 missing. The infrastructure damage was severe, as well with 129,225 buildings collapsed, 254,204 half-collapsed and 691,776 partially damaged. Of great concern for weeks after the event was the damage to the Fukushima Daiichi nuclear reactor, which suffered a level 7 meltdown.

The earthquake was classified as a megathrust quake and occurred along a subduction zone, an area where the Pacific plate is sinking below the North America plate in the Japan Trench. Studies after the event indicate the seabed between the earthquake epicenter and the Japan Trench moved approximately 50 m (164 ft) east-southeast and rose about 7 m (23 ft). Many seismologists were surprised by the strength of the earthquake, as past modeling studies indicated subduction zone quakes in that are would not exceed magnitude 8.4. However, models were generated using data from short historical records. New work is being done to revisit models and include paleoseismic records, although even those events are limited. Several other subduction zone areas in the world may need to be studied and revised as potential 9.0 magnitude zones.

The tsunami generated by the earthquake was far more destructive than the initial quake. A tsunami occurs when the seafloor abruptly deforms, causing a vertical displacement in the water. A series of long-wavelength waves, or wave train, is formed as the water attempts to regain equilibrium. Although the government of Japan issued tsunami warnings after the earthquake, the loss of life was severe due to the unprecedented height of the waves. The tsunami waves inundated approximately 561 km2 (217 mi2) at heights over 9m (29 ft) in many coastal cities.

-Amy

Photo: Wave crashing over a street in Miyako City, Japan, courtesy of Mainichi Shimbun, Reuters

References and additional information:

http://mceer.buffalo.edu/infoservice/disasters/Honshu-Japan-Earthquake-Tsunami-2011.asp http://www.sciencedaily.com/releases/2013/01/130123133901.htm http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0001xgp/

This blog will feature a number of pieces on the science of this quake and reactions for the rest of the day.