Tōhoku Japanese Earthquake Sculpture by Luke Jerram

About the piece:

This sculpture was made to contemplate the 2011 Tōhoku earthquake and tsunami in Japan. To create the sculpture a seismogram of the earthquake, was rotated using computer aided design and then printed in 3 dimensions using rapid prototyping technology. The artwork measures 30cm x 20cm and represents 9 minutes of the earthquake.

Look for it soon at the Jerwood Space in London for a show called Terra. The show will also include his fantastic virus sculptures.

Happy Birthday Inge Lehmann, Discoverer of Earth's Inner Core

In 1929 a large earthquake occurred near New Zealand. Danish seismologist Inge Lehmann “the only Danish seismologist,” as she once referred to herself—studied the shock waves and was puzzled by what she saw. A few P-waves, which should have been deflected by the core, were in fact recorded at seismic stations. 

Lehmann theorized that these waves had traveled some distance into the core and then bounced off some kind of boundary. Her interpretation of this data was the foundation of a 1936 paper in which she theorized that Earth’s center consisted of two parts: a solid inner core surrounded by a liquid outer core, separated by what has come to be called the Lehmann Discontinuity. Lehmann’s hypothesis was confirmed in 1970 when more sensitive seismographs detected waves deflecting off this solid core.

Born in Denmark in 1888, Lehmann was a pioneer among women and scientists. Her early education was at a progressive school where boys and girls were treated exactly alike. This was a sharp contrast to the mathematical and scientific community she later encountered, about which she once protested to her nephew, Niles Groes, “You should know how many incompetent men I had to compete with—in vain.” Groes recalls, “I remember Inge one Sunday in her beloved garden…with a big table filled with cardboard oatmeal boxes. In the boxes were cardboard cards with information on earthquakes…all over the world. This was before computer processing was available, but the system was the same. With her cardboard cards and her oatmeal boxes, Inge registered the velocity of propagation of the earthquakes to all parts of the globe. By means of this information, she deduced new theories of the inner parts of the Earth.”

A critical and independent thinker, Lehmann subsequently established herself as an authority on the structure of the upper mantle. She conducted extensive research in other countries, benefiting from an increased global interest in seismology for the surveillance of clandestine nuclear explosions. When Lehmann received the William Bowie medal in 1971, the highest honor of the American Geophysical Union, she was described as “the master of a black art for which no amount of computerizing is likely to be a complete substitute.” Lehmann lived to be 105.

Learn more about Lehmann and experience the power of earthquakes in the exhibition Nature’s Fury: The Science of Natural Disasters, now on view. 

Inge Lehmann [1888 - 1993]

Inge Lehmann was a Danish Seismologist who discovered the Earth’s inner core. In 1936 she postulated from existing seismic data that the Earth’s core is not a single molten sphere, but that an inner core exists, which has physical properties that are different from those in the outer core. This conclusion was quickly accepted by seismologists, who up to this time had not been able to propose a workable hypothesis for the observation that the P-wave created by earthquakes slowed down when it reached certain areas of the inner Earth.


The Most Dangerous City in the World

On the eastern edge of the Democratic Republic of Congo, the perilous Nyiragongo volcano towers 3470m over the city of Goma. The wildly erratic volcano is one of the most active on the planet, famous for the violent 200-metre-wide lava lake cradled in its vast summit crater, constantly emitting deadly gases and huge geysers of liquid rock. In 1977 and 2002, the volcano spewed deadly molten rock towards the million inhabitants of Goma, killing hundreds, forcing evacuations and destroying homes—but these were just small disturbances compared to what Nyiragongo is capable of unleashing. The volcano has an intricate ‘plumbing’ system like roots of a tree snaking deep underground, with vents not just at its summit but all around it, and so the threat to Goma is very immediate, and it has been dubbed ‘the most dangerous city in the world’ by researchers. The question is not if the volcano will erupt, but when. And yet, Nyiragongo is one of the least studied volcanoes in the world, because for the past twenty years, the Democratic Republic of Congo has experienced almost constant warfare. A deeper understanding of Nyiragongo must be gained in order to prevent a catastrophe, but serious research has only begun in the past few years. Until we can predict its activity, the question of when? will haunt scientists and seismologists alike, and will determine the fate of nearly one million people.

(Image Credit: Carsten Peter)

UC Berkeley’s Early Warning System Beat Napa Earthquake by 10 Seconds

Ten seconds before the San Francisco Bay Area started shaking early Sunday morning, an experimental system in a UC Berkeley lab sounded an alarm, counting down to the impending earthquake. The system works through an array of sensors near the fault line which calculate the severity of the quake and broadcast a warning.

It might not seem like much, but even a few seconds notice could allow utilities to shut off gas lines, elevators to let people off at the next floor, and trains to slow down. The USGS cites the benefits a warning could give to a doctor in the middle of performing surgery. In 2012, BART adopted an automatic braking system linked to the program, called Shake Alert.

Read more about UC Berkeley’s earthquake early warning system.



(CNN) – An 8.2-magnitude earthquake struck off the coast of northern Chile on Tuesday, generating a tsunami, authorities said.

The U.S. Geological Survey reported the quake, which hit at at 6:46 p.m. local time, was centered some 60 miles northwest of Iquique at a depth of 12.5 miles.

Chile’s National Emergency Office tweeted Tuesday night that it was asking everyone to evacuate the South American nation’s coast.  

A tsunami warning was in effect for Chile, Peru and Ecuador.

A tsunami watch was issued for Colombia, Panama and Costa Rica, according to the Pacific Tsunami Warning Center.

USGS National Earthquake Information Center

The April 1, 2014 M 8.2 earthquake in northern Chile occurred as the result of thrust faulting at shallow depths near the Chilean coast.

The location and mechanism of the earthquake are consistent with slip on the primary plate boundary interface, or megathrust, between the Nazca and South America plates. At the latitude of the earthquake, the Nazca plate subducts eastward beneath the South America plate at a rate of 65 mm/yr.

Subduction along the Peru-Chile Trench to the west of Chile has led to uplift of the Andes mountain range and has produced some of the largest earthquakes in the world, including the 2010 M 8.8 Maule earthquake in central Chile, and the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile.

NOAA Pacific Tsunami Warning Center

235 PM HST TUE APR 01 2014






With little warning Chile’s Calbuco volcano erupted with ferocity after 42 years of stability.

On April 22nd, plumes of ash began spewing from the volcano up to 10 kilometres in the air, and resulted in a large evacuation process as well as these powerful images. 

With warning of as little as 15 minutes for some residents, this eruption highlights the immense difficulty in forecasting volcanic eruptions. Chile has 400 or so active volcanoes - one of the highest amounts on the planet, yet there’s still little that can be done to efficiently predict these eruptions. 

The proximity of high population density near large volcanoes seen in countries like Chile, Malaysia and The US have experts in the field concerned about the measures taken to ensure safety. Volcanoes that have been dormant for hundreds or thousands of years can still spring to life, begging the question; what can we do to ensure safety of these populations?

(Nat Geo, Vox, Time)

So, about that earthquake advisory...

At this point, it seems that the whole internet has heard the story about how a swarm of earthquake activity near the Salton Sea in Imperial County, California, has raised the chances of a large earthquake on the San Andreas Fault, and an earthquake advisory was issued detailing all of this. If many headlines and reactions to them are to believed, the Big One is imminent, and large swathes of southern California are about to bite the big one.

So, how much of this is true? Do we need to worry?

Well, the raised probability aspect is, in fact, true - or it is according to our best understanding of how faults interact with each other. But we’re talking a raise to a maximum of a 1% chance in the next seven days. One percent! Or less! I don’t think I’ve ever seen a 1% chance of something bad happening get magnified into It Is Imminent And About To Happen, but that’s how this story is increasingly being spun. It’s misleading at best, and harmful at worst, when one major initial purpose of the earthquake advisory was simply to acknowledge that scientists are paying attention to what’s going on down there instead of just ignoring it.

Wait, but it did go up? How, then?

Faults are actually a lot like people. They undergo a lot of stress from day to day. For people, stress can come from a lot of things, but for faults, it mainly comes from the long-term motion of tectonic plates. People have a whole lot of different coping mechanisms to not break under the stress, but all faults share the same coping mechanism: friction. Just like you may have a breakdown when you can’t handle the stress in your life, faults break when the amount of stress they’ve accumulated is too much for friction to resist. That breaking process is an earthquake.

Most of the stress on a fault comes from plate motion, but other earthquakes on nearby faults can also add stress to the picture. The bigger the earthquake, the more stress it inflicts on everything around it. But, unlike stress accumulation from plate motions, the stress change from another earthquake is pretty instantaneous. It’s possible - and has happened - for an earthquake to set off another one within seconds, hours, or even a couple of days, but the longer you go since that earthquake, the more apparent it becomes that the stress change wasn’t enough to send any other faults into breakdown mode.

So - that increase in earthquake likelihood on the San Andreas, up to maybe as high as one percent last week, came from the stress changes from this earthquake swarm on top of the regular tectonic stresses. The odds are lowering again now that the swarm itself is slowing down.

But the bigger issue is - is that increase actually something to worry about?

I’d say not particularly, no, and I’m not alone among seismologists here.

Firstly - there are lots of swarms like this near the Salton Sea. They happen a couple of times per decade, and they tend to last for a few days. Swarms in this area in 2008 and 2012 had earthquakes with magnitudes in the low 5s; the largest one this time around has been a 4.3. These earthquakes all occur on faults that are not the San Andreas, and so far, there is zero historic precedent for one of these swarms directly preceding earthquake on the San Andreas, or any other fault. All of these swarms also raised stresses on the San Andreas, raised the odds of a larger quake to something like what they were last weak, just without a formal earthquake advisory issued - and nothing happened. This is enough precedent that, basically, if there IS a Big One soon, it was very close to happening anyway regardless of the current swarm. It’s entirely possible that a swarm event could eventually be the proverbial straw that broke the camel’s back, but there just isn’t enough energy involved in one of these swarms to bring the fault from Not Particularly Close to Big One. It won’t be the cause in and of itself.

Secondly - earthquakes that aren’t parts of swarms also affect stresses on nearby faults. The larger the earthquake, the more substantial the stress change, and the longer the period of increased hazard. Things like the 1992 M7.3 Landers or the 2010 M7.2 El Mayor Cucapah earthquakes kicked the San Andreas a lot harder than this week’s swarm of 4s did, but that didn’t set it off, either. If a similar earthquake advisories has been published after those, the percentages would’ve looked scarier than 1%. Earthquake scientists were actually pretty worried after Landers and its M6.4 aftershock near the San Andreas in Big Bear, and that’s not the case right now. We’re observing, but nobody’s particularly worried. Basically, faults affect each other all the time, it’s just that those effects are usually not the immediate triggering of another large earthquake.

Thirdly - the southern San Andreas is considered the highest hazard fault in the state already, but we’ve been living with it that way for a long time. The last earthquake on the part of the San Andreas was sometime in the late 1600s, and the average time between earthquakes on that section of the fault is more like 200 to 250 years. This is a section scientists have been saying is due for a while, which is what brings on the extra attention when there’s a swarm, and the extra nervousness. The most recent USGS statistical earthquake forecast - based on everything we know about every fault in the state - puts the odds of a M6.7 or greater on the southern San Andreas Fault at 19% within the next 30 years and the odds of a M7.5 or greater at 17.3%. That’s the baseline we’re living with, and this swarm hasn’t changed it by very much or for very long. And for another southern California point of comparison, your odds of getting into an accident on a Los Angeles freeway in any given year are higher than the yearly odds of a San Andreas earthquake, let alone your odds of being hurt in that earthquake.

So then…why issue a statement at all?

This kind of thing shows that scientists acknowledge the swarm, acknowledge it’s in an area that has already had media attention for being high hazard, and acknowledge that people are nervous. (Which, hooboy, the advisory did fail as an effective acknowledgment of nerves, looking at the reaction it’s caused.) It’s also some insurance against anyone who can claim later that “nobody said anything about the risk” if this becomes the unprecedented case where the swarm does lead to a damaging earthquake. That was the case with a swarm in central Italy in 2009 which eventually lead to a M6.4. The L’Aquila earthquake killed a bunch of people, and the scientists involved ended up on trial for manslaughter for ostensibly not acknowledging the change in risk. The whole L’Aquila situation was a huge mess of bad communication and bad policy, and that part of Italy didn’t have the precedent of lots of swarms without a bigger quake like the Imperial Valley does, but hey. It happened. We want to avoid that here in California.

Another important goal of advisories like that is to remind people, yes we’re on an active plate boundary and we have earthquakes. Yes, preparedness kits are a good idea. A lot of folks seem to misread “check your emergency kit” as “you’re gonna need it really soon” though, which is…a problem that may be hard to work around. But if you can’t use small earthquakes as a motivator to prepare for big ones, that’s a problem, too. If people are only motivated to prepare in hindsight after getting wrecked by a large earthquake, that’s not an effective mitigation strategy. I absolutely always tell people to use small ones as a reminder to prepare for big ones, but media storms like this are just a sign that scientists need to watch our phrasing, too…



  • PTWC’s near real-time animation for the tsunami from northern Chile on 1 April 2014 resulting from an offshore 8.2 magnitude earthquake in the region. The animation shows simulated tsunami wave propagation for 30 hours followed by an “energy map” showing the maximum open-ocean wave heights over that period and the forecasted tsunami run up heights on the coastlines.
  • Animación en tiempo casi real del PTWC para el tsunami en el norte de Chile el 01 de abril 2014 como resultado de un terremoto en alta mar 8.2 de magnitud en la región. La animación muestra la propagación de ondas de tsunami simulado durante 30 horas, seguido de un “mapa de la energía” que muestra las alturas máximas de olas de mar abierto durante ese período y la altura prevista de impacto en la costas del océano pacifico.

When tectonic plates collide, sometimes one plate sinks, or subducts, below another one. This can trigger an earthquake. When earthquakes cause the ocean floor to move, the water moves, too. Columns of water travel across the ocean and grow taller as they approach land, becoming a tsunami.

Scientists use computer models to predict whether a tsunami will occur. The model can forecast the wave’s speed, direction, and height as it approaches land. Local authorities can then warn communities that might be in danger.

Learn more about earthquakes and tsunamis.


Thingvellir National Park in Iceland is where the Vikings held their parliament meetings and the subsequent Icelandic government continued to use the sight to convene their general assembly from 930 to 1798. It’s also where the Eurasian and North-American tectonic plates meet, hence the huge fissure which is the result of earthquakes and seismic movement.


Don’t be shaken – Lucy’s not leaving us

Even as the dust was still settling with our nerves still quaking, for many of us in Los Angeles, one woman seemed to have all the answers. That was Lucy Jones, the doctor on-call when the earthquakes strike. 

Some have called her the Beyoncé of earthquakes. Well, she just announced she’s retiring from the U.S. Geological Survey. (But don’t panic. She’s not leaving California behind.)

There’s been a lot of love for Lucy on Twitter. One response I got asked the question many of us have: “Who else will come out in her bathrobe in the middle of the night to say it probably was not a precursor?”

As reporter Rosanna Xia put it: In her 33 years with the USGS, Jones has become a universal mother for rattled Southern Californians. After each quake, she turns fear of the unknown into something understandable.

While most of the earthquake guys aren’t remembered, Dr. Jones is certainly unforgettable to many of us who grew up in Southern California. In addition to making something complicated understandable (and a little less scary), she also helped to dramatically change the way we prepare for earthquakes across Southern California. 

“When the big one hits, people will be living because of the work that she has done." 

– Los Angeles Mayor Eric Garcetti  

What’s next for her? Helping to develop science-based policies on climate change. 

What’s next for us? Wondering who will be the one to settle our nerves with information when we are still quaking after the inevitable next temblor.  

You can read more about Dr. Lucy Jones and her work here. 


Photos by Los Angeles Times

Seeing with Seismic Waves

Earth is a rocky terrestrial planet, layered like a spherical, incredibly hot, completely unpalatable cake (so, not really like a cake at all). The outermost layer is the crust, followed by the molten mantle, then the metallic core, which is made mainly of iron and nickel but split into two parts: the outer core is churning liquid, and the inner core is a dense, rotating solid ball.

The deeper we go down, the hotter and more pressurised it becomes. The deepest hole humans have every drilled is only 12 kilometres down, not even deep enough to hit the mantle. So how do we know the structure and composition of the planet?

Our knowledge mainly comes from seismology, which allows us to study the planet’s interior based on how seismic waves travel through it. Seismic waves are produced by earthquakes, and they cause rock to either compress or to vibrate up and down. There are two types: P and S waves.

  1. P waves cause matter to move in a horizontal motion, compressing and stretching it like a spring. Sound waves are P waves, compressing and stretching the air in order to travel. These types of waves are much faster than S waves, and can travel through both solids and liquids.
  2. S waves cause matter to move up and down or side to wide, like the waves that travel up and down a jolted rope. They cause the most damage when earthquakes occur, as they physically displace the earth much more violently, even though they’re slower than P waves. However, they can’t travel through liquids.

(Image Credit)

The speed, size, and direction of these waves change depending on the density, composition, and temperature of the material they pass through. The fact that S waves can’t travel through liquid, for example, is vital to our knowledge of Earth’s interior. When an earthquake occurs in the crust, S and P waves are not only felt on the surface, but they also shoot down right through the Earth and can be detected on other parts of the planet. When seismologists measure these earthquake signatures around the world, they see a “shadow zones” where no waves have made it through. The key to this lies in the abrupt differences between the layers of the Earth.

Since S waves cannot travel through liquid, they can’t pass from the mantle and into the liquid outer core. Instead, they reflect off at an angle, leaving a huge shadow zone on the opposite side of the earth.  Meanwhile, P waves (which can travel through liquid) are able to pass through the core and emerge on the other side. Because of the way they bend as they pass through different mediums (from the dense core to the less dense mantle), they also create two, smaller shadow zones.

(Image Credit)

From this information about how waves reflect and refract, we’ve deduced the four main layers of our planet.

The cool thing is, these principles aren’t limited to the study of Earth’s interior. Similar instruments can be used on the surface of any solid planet—Apollo astronauts actually left seismometers on the Moon. The Moon isn’t broken into plates like the Earth, which collide and slip to cause earthquakes, so moonquakes are instead caused by tidal deformation. The Viking 2 lander attempted to use a seismometer on Mars, but the Martian winds prevented it from detecting any quakes. But studying seismology on Mars could help us understand fundamental questions about the planet’s geology, such as why its magnetic field decreased, and why it doesn’t have geological features similar to Earth’s, which could tell us more about the evolution of terrestrial planets.
Five myths about earthquakes

by renowned seismologist Susan Hough:

  1. Animals sense impending earthquakes: “Every pet owner understands that, say, cats and dogs sometimes behave strangely for no apparent reason; that’s what cats and dogs do. And if an earthquake had not subsequently struck, you can bet we would not be talking about strange animal behavior this week — because we wouldn't have noticed anything out of the ordinary.”
  2. The frequency of large-scale earthquakes has spiked: “The number of earthquakes greater than magnitude 7.0 has been somewhat high in recent years but well within the range throughout the 20th century.”
  3. Small earthquakes are helpful because they release pressure and prevent larger ones: “For each unit increase in magnitude (i.e., going from 5.5 to 6.5), the energy released rises by a factor of about 30. (…) If enough stress has built up on a fault to generate a magnitude-7.0 earthquake, say, it would thus take about 1000 earthquakes with a magnitude of 5.0 to release the equivalent energy. The Earth doesn't work that way. (…) If there is significant strain energy to be released, it must be released in large earthquakes.”
  4. “Don’t worry, it was just an aftershock.”: “The implication is that an aftershock is somehow a less worrisome event. Yet, as far as we understand, an aftershock of a certain magnitude is no different from an independent temblor of a similar magnitude. The shaking and rupture are the same; the energy released is the same. And aftershocks can be more damaging than larger "mainshocks” if they strike closer to population centers.“
  5. Earthquakes are a West Coast problem: "As millions of people on the East Coast were just reminded, less active does not mean inactive. By the end of the 19th century, two of the most notable temblors in the United States were the 1886 quake in Charleston, S.C., and a sequence of large events centered near the boot-heel along the New Madrid Fault of Missouri in 1811-1812. We don’t know exactly when or where the next Big One will hit the United States, but the central and eastern United States will inevitably experience large quakes in the future. (…) You have been warned.”
Inge Lehmann

Inge Lehmann was born on May 13, 1888 in Copenhagen, Denmark. Lehmann is best known for using seismic wave data to discover the Earth’s inner core. By studying Primary Waves, she came to the revolutionary conclusion that Earth had a solid inner core, which contradicted the scientific consensus of the time that Earth had a liquid core surrounded by a solid mantle. Upon its publication in 1936, Lehmann’s research was quickly accepted by the scientific community and in 1970, more advanced seismographs were used to prove her theory.

Inge Lehmann died in 1993 at the age of 104.