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DISSEMINATION When
seconds matter: improving early earthquake detection EU's "DG Environment News Alert Service" Presentations given during the 2nd SAFER annual meeting Internet Users as Seismic Sensors for Improved Earthquake Response EOS (vol. 89(25), pp. 225-226, 17.06.08) Remy Bossu, Gilles Mazet-Roux, Vincent Douet, Sergio Rives, Sylvie Marin and Muchael Aupettit Terremoti, studi made in Campania oltre l'Atlantico April 30, 2008 Il Sole 24 Ore California's earthquake warning system lags those in Europe, Japan December 11, 2007 San Francisco Chronicle and Times Record News by David Perlman Shake,
Rattle and Respond: Early Warning System for Earthquakes
December 11, 2007 Scientific American by David Biello Powerful Earthquakes Can Be Detected Within Two Seconds 12/05/2006 ScienceDaily Source Date December 5, 2006 More on Earthquakes,
Natural Disasters, Tsunamis, Construction, Wildfires, Earth Science
Powerful Earthquakes Can Be Detected Within Two Seconds Could a few
seconds warning of an impending strong earthquake be of practical
use in mitigating its effects? Scientists, engineers, and first responders
say yes, and now such warnings may be possible. Researchers in Italy
have analyzed seismic signals from over 200 moderate to strong earthquakes,
ranging from magnitude 4.0 to 7.4, and they conclude that the waves
generated in the first few seconds of an earthquake (the primary,
or P, waves) carry sufficient information to determine its magnitude
and destructive potential. Aldo Zollo and Maria Lancieri of the University
of Naples and Stefan Nielsen of the National Institute of Geophysics
and Vulcanology in Rome determined that the peak amplitudes of very
early seismic signals recorded in the vicinity of an earthquake source
correlate with the earthquake magnitude and may be used for real-time
estimation of the size of the event. Surprisingly, the researchers
say, earthquake magnitude can be estimated using just two seconds'
worth of signal from the first recorded P and S (secondary) waves,
that is, while the earthquake is still in progress and far from over.
The study will be published later this month in Geophysical Research
Letters. Primary waves travel around six kilometers [four miles] per
second, covering around 60 kilometers [40 miles] in 10 seconds. Secondary,
or S, waves, which are usually more destructive, travel more slowly,
around 3.5 kilometers [2.2 miles] per second, covering only around
17 kilometers [11 miles] in 10 seconds. Therefore, a city located
around 60 kilometers [40 miles] from an epicenter would have around
15 seconds of lead time to prepare for an earthquake's impact, the
time difference between the arrival of the first P wave at a recording
station near the epicenter and the arrival of the S wave at the city
itself. In the study, the researchers looked into the entire active
seismic belt of the Mediterranean region, which includes varying geological
and tectonic systems and faults. They compared signals from both P
and S waves from more than 200 earthquakes and found that stress release
and/or slip duration on the fault in the very early stage of seismic
fracture relates both to the observed peak amplitude of the early
P wave and to the elastic energy available for propagation of the
fracture. Although relatively few magnitude 7 earthquakes have hit
the study area in recent years, there have been many instances of
quakes in the magnitude 6 range. (A magnitude 7 earthquake is over
30 times more energetic than one of magnitude 6.) Zollo notes that
even magnitude 6 quakes can produce great damage, especially in urbanized
areas and places where old structures were not built to current standards;
this defines much of the Mediterranean basin and applies also in other
areas. The researchers say that installations as close as 50 kilometers
[30 miles] from the epicenter could receive an earthquake warning
10 seconds prior to the arrival of the main body wave of an earthquake.
Places further from the epicenter would have additional time, though
still measured in seconds. To take advantage of this brief warning
period, automated systems would have to be created that respond instantly
to notification alert signals, and they would have to be carefully
calibrated to avoid missed or false alarms. Engineers note that in
tall buildings, the higher floors sway much more than those near ground
level, so that even a moderate earthquake could cause severe damage
to a highrise, Zollo says. Therefore, even at 70-80 kilometers [40-50
miles] distance from its epicenter, a magnitude 6 quake could affect
hospital operating rooms and other critical installations. Closer
to the epicenter, a magnitude 6 or higher earthquake can damage critical
infrastructure, such as telephone lines, gas pipelines, highways,
and railroads, as well as airport runways and navigation systems.
These disruptions would have a domino effect in more distant areas,
which could be mitigated by an early warning alert system, based on
the earliest primary wave data to arrive at recording stations close
to the epicenter. The researchers note that earthquake early warning
systems can also help mitigate the effects of such earthquake-induced
disasters as fires, explosions, landslides, and tsunamis, which can
in many cases be more devastating than the earthquake itself. Systems
could be installed at relatively low cost in developing countries,
where moderate sized earthquakes can cause damage comparable to that
caused by much larger earthquakes in developed countries, they say.
The study was funded in part by the consortium Analisi e Monitoraggio
del Rischi Ambientali (AMRA) scarl through the European Union-Seismic
Early Warning for Europe (EU-SAFER) project. Conocen grado destructivo de sismo El poder destructivo de un terremoto puede conocerse
sólo dos segundos después de que se haya registrado,
según una investigación europea que ha estudiado 200
terremotos de entre 4 y 7,4 grados de magnitud en la escala Ritcher.
El trabajo, que publicará el próximo número de
la revista 'Geophysical Research Letters', concluye que las ondas
generadas en los primeros segundos de un terremoto (ondas primarias
o P) contienen suficiente información como para determinar
su magnitud y su potencial destructivo. Los investigadores Aldo Zollo
y María Lancieri, de la Universidad de Nápoles (Italia),
y Stefan Nielsen, del Instituto Nacional de Geofísica y Vulcanología
de Roma, han determinado los picos de amplitud de las primeras señales
sísmicas recogidas en el entorno del epicentro de un terremoto
y su correlación con la magnitud que acaba alcanzando. Tras
estudiar 200 terremotos sucedidos en los últimos años
en todo el Mediterráneo, una zona de gran variedad geológica
y tectónica, concluyen que la magnitud de un terremoto podría
estimarse utilizando sólo las señales recogidas durante
los primeros segundos del seísmo. Las ondas primarias (P) viajan
a una velocidad de 6 kilómetros por segundo, y, por lo tanto,
son capaces de llegar a 60 kilómetros del epicentro en 10 segundos.
Las secundarias, o S, que suelen ser las más destructivas,
viajan más despacio, alrededor de 3,5 kilómetros por
segundo, cubriendo alrededor de 17 kilómetros en 10 segundos.
Por tanto, una ciudad situada a unos 60 kilómetros del epicentro
tendría alrededor de 15 segundos para prepararse para el impacto
del seísmo, un tiempo resultado de la diferencia entre la llegada
de la primera onda P a la estación sismológica más
próxima al epicentro y la llegada de una onda S a una ciudad.
Aunque en los últimos años no se han registrado apenas
seísmos de magnitud 7 en el Mediterráneo, los temblores
de magnitud 6 pueden producir mucho daño, especialmente en
áreas urbanizadas y los lugares en donde abundan viejas estructuras
arquitectónicas, algo muy típico de la cuenca mediterránea.
Los investigadores observan que los sistemas de detección temprana
del terremoto pueden también ayudar a atenuar los efectos de
los desastres que provoca un terremoto, tales como los fuegos, las
explosiones, los derrumbamientos, y los tsunamis, que pueden en muchos
casos ser más devastadores que el terremoto en sí mismo.
El trabajo ha sido patrocinado por el consorcio Análisis y
Monitorización del Riesgo Ambiental (AMRA) en colaboración
con la Red de Alerta Temprana y la Unión Sísmica Europea
(EU-SAFER). Powerful Earthquakes Can Be Detected within
Two Seconds POWERFUL EARTHQUAKES CAN BE DETECTED WITHIN TWO
SECONDS, HELPING TO MITIGATE THEIR EFFECTS IN DISTANT CITIES Forecast just before earthquake possible Italian scientists say the effects of strong earthquakes
can be predicted seconds before the destruction occurs. The research
confirms a similar study announced by California researchers a year
ago. Researchers in Italy analyzed seismic signals from more than
200 moderate to strong earthquakes in the Mediterranean region, ranging
from magnitude 4.0 to 7.4. They found that the initial waves, called
primary or P waves, indicate what's to come from secondary or S waves.
Primary waves travel at about 4 miles per second, covering about 40
miles in 10 seconds. Secondary waves, which are typically more damaging,
move at about 2.2 miles per second. The conclusion Residents of a
city located 40 miles from an epicenter would have about 15 seconds
to prepare for impact if a sufficient automated warning system were
established, the scientists say. School children have long been advised
to dive under their desks when an earthquake strikes. People at home
are told to move to a strong doorway or get under a heavy desk to
protect themselves. Seconds can make all the difference. In the California
study last year, seismologist Richard Allen suggested cell phone towers
might be used to automatically transmit warnings. The new study, led
by Aldo Zollo and Maria Lancieri of the University of Naples and Stefan
Nielsen of the National Institute of Geophysics and Vulcanology in
Rome, will be published this month in the journal Geophysical Research
Letters. Among the potential beneficiaries, they say Hospitals, fire
departments and tsunami warning centers, all of which might be cut
off from communications by the damage caused shortly after a warning
is issued. In developing countries, where moderate temblors can cause
great damage, warning systems would be relatively cheap to install,
the scientists said. Detectan grado de destrucción de sismos Detectan grado de destrucción de sismos Internacional
- Lunes 4 de diciembre (12 35 hrs.) Podrá saberse la magnitud
de un terremoto dos segundos después de que se haya registradoLas
ondas de los primeros segundos de un temblor contiene la información
para determinar su potencia destructiva Powerful earthquakes can be detected within
two seconds, helping to mitigate their effects in distan Researchers in Italy have analyzed seismic signals
from over 200 moderate to strong earthquakes, ranging from magnitude
4.0 to 7.4, and they conclude that the waves generated in the first
few seconds of an earthquake (the primary, or P, waves) carry sufficient
information to determine its magnitude and destructive potential.
Aldo Zollo and Maria Lancieri of the University of Naples and Stefan
Nielsen of the National Institute of Geophysics and Vulcanology in
Rome determined that the peak amplitudes of very early seismic signals
recorded in the vicinity of an earthquake source correlate with the
earthquake magnitude and may be used for real-time estimation of the
size of the event. Surprisingly, the researchers say, earthquake magnitude
can be estimated using just two seconds' worth of signal from the
first recorded P and S (secondary) waves, that is, while the earthquake
is still in progress and far from over. The study will be published
later this month in Geophysical Research Letters. Primary waves travel
around six kilometers [four miles] per second, covering around 60
kilometers [40 miles] in 10 seconds. Secondary, or S, waves, which
are usually more destructive, travel more slowly, around 3.5 kilometers
[2.2 miles] per second, covering only around 17 kilometers [11 miles]
in 10 seconds. Therefore, a city located around 60 kilometers [40
miles] from an epicenter would have around 15 seconds of lead time
to prepare for an earthquake's impact, the time difference between
the arrival of the first P wave at a recording station near the epicenter
and the arrival of the S wave at the city itself. In the study, the
researchers looked into the entire active seismic belt of the Mediterranean
region, which includes varying geological and tectonic systems and
faults. They compared signals from both P and S waves from more than
200 earthquakes and found that stress release and/or slip duration
on the fault in the very early stage of seismic fracture relates both
to the observed peak amplitude of the early P wave and to the elastic
energy available for propagation of the fracture. Although relatively
few magnitude 7 earthquakes have hit the study area in recent years,
there have been many instances of quakes in the magnitude 6 range.
(A magnitude 7 earthquake is over 30 times more energetic than one
of magnitude 6.) Zollo notes that even magnitude 6 quakes can produce
great damage, especially in urbanized areas and places where old structures
were not built to current standards; this defines much of the Mediterranean
basin and applies also in other areas. The researchers say that installations
as close as 50 kilometers [30 miles] from the epicenter could receive
an earthquake warning 10 seconds prior to the arrival of the main
body wave of an earthquake. Places further from the epicenter would
have additional time, though still measured in seconds. To take advantage
of this brief warning period, automated systems would have to be created
that respond instantly to notification alert signals, and they would
have to be carefully calibrated to avoid missed or false alarms. Engineers
note that in tall buildings, the higher floors sway much more than
those near ground level, so that even a moderate earthquake could
cause severe damage to a highrise, Zollo says. Therefore, even at
70-80 kilometers [40-50 miles] distance from its epicenter, a magnitude
6 quake could affect hospital operating rooms and other critical installations.
Closer to the epicenter, a magnitude 6 or higher earthquake can damage
critical infrastructure, such as telephone lines, gas pipelines, highways,
and railroads, as well as airport runways and navigation systems.
These disruptions would have a domino effect in more distant areas,
which could be mitigated by an early warning alert system, based on
the earliest primary wave data to arrive at recording stations close
to the epicenter. The researchers note that earthquake early warning
systems can also help mitigate the effects of such earthquake-induced
disasters as fires, explosions, landslides, and tsunamis, which can
in many cases be more devastating than the earthquake itself. Systems
could be installed at relatively low cost in developing countries,
where moderate sized earthquakes can cause damage comparable to that
caused by much larger earthquakes in developed countries, they say.
The study was funded in part by the consortium Analisi e Monitoraggio
del Rischi Ambientali (AMRA) scarl through the European Union-Seismic
Early Warning for Europe (EU-SAFER) project.Could a few seconds warning
of an impending strong earthquake be of practical use in mitigating
its effects? Scientists, engineers, and first responders say yes,
and now such warnings may be possible. Grado destrucción seísmo puede
saberse 2 segundos después ocurrir Madrid, 4 dic (EFE).- El poder destructivo de un terremoto puede conocerse sólo dos segundos después de que se haya registrado, según una investigación europea que ha estudiado 200 terremotos de entre 4 y 7,4 grados de magnitud en la escala Ritcher. El trabajo, que publicará el próximo número de la revista Geophysical Research Letters, concluye que las ondas generadas en los primeros segundos de un terremoto (ondas primarias o P) contienen suficiente información como para determinar su magnitud y su potencial destructivo. Los investigadores Aldo Zollo y María Lancieri, de la Universidad de Nápoles (Italia), y Stefan Nielsen, del Instituto Nacional de Geofísica y Vulcanología de Roma, han determinado los picos de amplitud de las primeras señales sísmicas recogidas en el entorno del epicentro de un terremoto y su correlación con la magnitud que acaba alcanzando. Tras estudiar 200 terremotos sucedidos en los últimos años en todo el Mediterráneo, una zona de gran variedad geológica y tectónica, concluyen que la magnitud de un terremoto podría estimarse utilizando sólo las señales recogidas durante los primeros segundos del seísmo. Las ondas primarias (P) viajan a una velocidad de 6 kilómetros por segundo, y, por lo tanto, son capaces de llegar a 60 kilómetros del epicentro en 10 segundos. Las secundarias, o S, que suelen ser las más destructivas, viajan más despacio, alrededor de 3,5 kilómetros por segundo, cubriendo alrededor de 17 kilómetros en 10 segundos. Por tanto, una ciudad situada a unos 60 kilómetros del epicentro tendría alrededor de 15 segundos para prepararse para el impacto del seísmo, un tiempo resultado de la diferencia entre la llegada de la primera onda P a la estación sismológica más próxima al epicentro y la llegada de una onda S a una ciudad. Aunque en los últimos años no se han registrado apenas seísmos de magnitud 7 en el Mediterráneo, los temblores de magnitud 6 pueden producir mucho daño, especialmente en áreas urbanizadas y los lugares en donde abundan viejas estructuras arquitectónicas, algo muy típico de la cuenca mediterránea. Los investigadores observan que los sistemas de detección temprana del terremoto pueden también ayudar a atenuar los efectos de los desastres que provoca un terremoto, tales como los fuegos, las explosiones, los derrumbamientos, y los tsunamis, que pueden en muchos casos ser más devastadores que el terremoto en sí mismo. El trabajo ha sido patrocinado por el consorcio Análisis y Monitorización del Riesgo Ambiental (AMRA) en colaboración con la Red de Alerta Temprana y la Unión Sísmica Europea (EU-SAFER). Grado destrucción seísmo puede saberse
2 segundos después ocurrir Madrid, 4 dic (EFE).- El poder destructivo
de un terremoto puede conocerse sólo dos segundos después
de que se haya registrado, según una investigación europea
que ha estudiado 200 terremotos de entre 4 y 7,4 grados de magnitud
en la escala Ritcher. El trabajo, que publicará el próximo
número de la revista 'Geophysical Research Letters', concluye
que las ondas generadas en los primeros segundos de un terremoto (ondas
primarias o P) contienen suficiente información como para determinar
su magnitud y su potencial destructivo. Los investigadores Aldo Zollo
y María Lancieri, de la Universidad de Nápoles (Italia),
y Stefan Nielsen, del Instituto Nacional de Geofísica y Vulcanología
de Roma, han determinado los picos de amplitud de las primeras señales
sísmicas recogidas en el entorno del epicentro de un terremoto
y su correlación con la magnitud que acaba alcanzando. Tras
estudiar 200 terremotos sucedidos en los últimos años
en todo el Mediterráneo, una zona de gran variedad geológica
y tectónica, concluyen que la magnitud de un terremoto podría
estimarse utilizando sólo las señales recogidas durante
los primeros segundos del seísmo. Las ondas primarias (P) viajan
a una velocidad de 6 kilómetros por segundo, y, por lo tanto,
son capaces de llegar a 60 kilómetros del epicentro en 10 segundos.
Las secundarias, o S, que suelen ser las más destructivas,
viajan más despacio, alrededor de 3,5 kilómetros por
segundo, cubriendo alrededor de 17 kilómetros en 10 segundos.
Por tanto, una ciudad situada a unos 60 kilómetros del epicentro
tendría alrededor de 15 segundos para prepararse para el impacto
del seísmo, un tiempo resultado de la diferencia entre la llegada
de la primera onda P a la estación sismológica más
próxima al epicentro y la llegada de una onda S a una ciudad.
Aunque en los últimos años no se han registrado apenas
seísmos de magnitud 7 en el Mediterráneo, los temblores
de magnitud 6 pueden producir mucho daño, especialmente en
áreas urbanizadas y los lugares en donde abundan viejas estructuras
arquitectónicas, algo muy típico de la cuenca mediterránea.
Los investigadores observan que los sistemas de detección temprana
del terremoto pueden también ayudar a atenuar los efectos de
los desastres que provoca un terremoto, tales como los fuegos, las
explosiones, los derrumbamientos, y los tsunamis, que pueden en muchos
casos ser más devastadores que el terremoto en sí mismo.
El trabajo ha sido patrocinado por el consorcio Análisis y
Monitorización del Riesgo Ambiental (AMRA) en colaboración
con la Red de Alerta Temprana y la Unión Sísmica Europea
(EU-SAFER). Fast detection of strong earthquakes Could a few seconds warning of an impending strong
earthquake be of practical use in mitigating its effects? Scientists,
engineers, and first responders say yes, and now such warnings may
be possible. Researchers in Italy have analyzed seismic signals from
over 200 moderate to strong earthquakes, ranging from magnitude 4.0
to 7.4, and they conclude that the waves generated in the first few
seconds of an earthquake (the primary, or P, waves) carry sufficient
information to determine its magnitude and destructive potential.
Aldo Zollo and Maria Lancieri of the University of Naples and Stefan
Nielsen of the National Institute of Geophysics and Vulcanology in
Rome determined that the peak amplitudes of very early seismic signals
recorded in the vicinity of an earthquake source correlate with the
earthquake magnitude and may be used for real-time estimation of the
size of the event. Surprisingly, the researchers say, earthquake magnitude
can be estimated using just two seconds' worth of signal from the
first recorded P and S (secondary) waves, that is, while the earthquake
is still in progress and far from over. The study will be published
later this month in Geophysical Research Letters. Primary waves travel
around six kilometers [four miles] per second, covering around 60
kilometers [40 miles] in 10 seconds. Secondary, or S, waves, which
are usually more destructive, travel more slowly, around 3.5 kilometers
[2.2 miles] per second, covering only around 17 kilometers [11 miles]
in 10 seconds. Therefore, a city located around 60 kilometers [40
miles] from an epicenter would have around 15 seconds of lead time
to prepare for an earthquake's impact, the time difference between
the arrival of the first P wave at a recording station near the epicenter
and the arrival of the S wave at the city itself. In the study, the
researchers looked into the entire active seismic belt of the Mediterranean
region, which includes varying geological and tectonic systems and
faults. They compared signals from both P and S waves from more than
200 earthquakes and found that stress release and/or slip duration
on the fault in the very early stage of seismic fracture relates both
to the observed peak amplitude of the early P wave and to the elastic
energy available for propagation of the fracture. Although relatively
few magnitude 7 earthquakes have hit the study area in recent years,
there have been many instances of quakes in the magnitude 6 range.
(A magnitude 7 earthquake is over 30 times more energetic than one
of magnitude 6.) Zollo notes that even magnitude 6 quakes can produce
great damage, especially in urbanized areas and places where old structures
were not built to current standards; this defines much of the Mediterranean
basin and applies also in other areas. The researchers say that installations
as close as 50 kilometers [30 miles] from the epicenter could receive
an earthquake warning 10 seconds prior to the arrival of the main
body wave of an earthquake. Places further from the epicenter would
have additional time, though still measured in seconds. To take advantage
of this brief warning period, automated systems would have to be created
that respond instantly to notification alert signals, and they would
have to be carefully calibrated to avoid missed or false alarms. Engineers
note that in tall buildings, the higher floors sway much more than
those near ground level, so that even a moderate earthquake could
cause severe damage to a highrise, Zollo says. Therefore, even at
70-80 kilometers [40-50 miles] distance from its epicenter, a magnitude
6 quake could affect hospital operating rooms and other critical installations.
Closer to the epicenter, a magnitude 6 or higher earthquake can damage
critical infrastructure, such as telephone lines, gas pipelines, highways,
and railroads, as well as airport runways and navigation systems.
These disruptions would have a domino effect in more distant areas,
which could be mitigated by an early warning alert system, based on
the earliest primary wave data to arrive at recording stations close
to the epicenter. The researchers note that earthquake early warning
systems can also help mitigate the effects of such earthquake-induced
disasters as fires, explosions, landslides, and tsunamis, which can
in many cases be more devastating than the earthquake itself. Systems
could be installed at relatively low cost in developing countries,
where moderate sized earthquakes can cause damage comparable to that
caused by much larger earthquakes in developed countries, they say.
The study was funded in part by the consortium Analisi e Monitoraggio
del Rischi Ambientali (AMRA) scarl through the European Union-Seismic
Early Warning for Europe (EU-SAFER) project. An Early Warning System for Earthquakes Dec. 4, 2006 - What if an earthquake were coming,
and you had just a little bit of warning? It might be only 15 seconds,
maybe 30 - but it might be enough time to take cover under a table,
or find the safety offered by a door frame. Italian scientists say
they have figured out a way to measure the shock waves from a quake
just two seconds after they begin, and, from that, calculate the earthquake's
strength, location, and potential for damage in populated regions.
American researchers have been at work on this as well, hoping to
set up an early warning system in California and other earthquake-prone
areas. Faster Than a Speeding P-Wave If researchers succeed, they
might be able to place seismometers up and down fault lines, and measure
the P-waves — the primary shock waves from an earthquake —
several critical seconds before they reach the places where people
live. P-waves may be useful for warnings; they are not nearly as strong
as secondary vibrations — known as S-waves — that do most
of the damage. It typically takes about 10 seconds for P-waves to
spread 40 miles. S-waves travel about half as fast. But a warning
signal, transmitted electronically from a seismometer near the epicenter,
would spread at the speed of light. That could mean extra time for
gas companies to close automatic valves on their supply pipes, electric
companies to isolate the vulnerable sections of their grid and people
to run for cover. Earthquakes are, by nature, chaotic. Many geologists
have been skeptical that the first P-waves can tell very much about
the strong vibrations to follow. But the new research suggests they're
reliable for setting off warnings. "We can determine the magnitude
within a couple of seconds of initiation of rupture and predict the
ground motion from seconds to tens of seconds before it's felt,"
said Richard Allen, an assistant professor of earth and planetary
science at the University of California, Berkeley, when he and colleagues
published a paper on early warnings last year in the journal Nature.
ElarmS Allen is part of a team that has been at work on a project
called ElarmS — short for Earthquake Alarms Systems. They calculate
that in the worst earthquakes, a well-designed system could give San
Francisco, for instance, an extra 20 seconds to put systems in safe
mode. That is, if the warnings are accurate. Nobody wants a very expensive
system that constantly gives false alarms. ElarmS has been held up
by political arguments over its cost effectiveness. That's where the
Italian researchers come in. Writing in an upcoming issue of the journal
Geophysical Research Letters, they report that in just the first two
seconds after a major earthquake, they can get enough data for an
accurate picture of where it will spread, and how violent it will
be. They say they tested their calculations on more than 200 earthquakes
in the Mediterranean Basin, and found that the early P-waves were
very reliable as indications of the stronger S-waves to follow. "The
earthquake size can be, therefore, estimated," they write, "while
the rupture itself is still propagating and rupture dimension is far
from complete." Could all this make a difference when a major
earthquake strikes? Science has been frustrated in its attempts to
predict when one will happen, so, as many geologists argue, every
nanosecond's warning will help. |