Sunday, February 28, 2010

A teachable moment - the Chile earthquake

The U.S Geological Survey has already issued an informative poster on the Chile earthquake, which can be downloaded here.

Here is the first part of the poster:
You can see the past earthquakes along the subduction zone (hatched line), where the Nazca plate on the left dives beneath the South American plate on the east. The epicenter of yesterday's quake (star) is not far from the largest earthquake ever measured, from 1960. The colors denote the depth of the hypocenters.

We'll look at other parts of the poster in upcoming posts.

Tsunami warning in Japan from Chile quake

Tsunamis can travel across the ocean at 1000 km/hr (600 mph), although they are barely felt until the wave amplitude builds up when the wave feels ocean bottom near the coast.  But given the 10,000 miles across the ocean from Chile to Japan (here is a nice Java applet to calculate geographic distances), that's 20 hours!

Here was the warning put out by the Japan Meteorological Agency:

Tsunami Warning/Advisory
Issued at 09:33 JST 28 Feb 2010

Major Tsunami and Tsunami have been issued.

Evacuate from the seashore immediately to the safe places near the above coasts.
Tsunami attentions are in effect at some of the other coasts now.

***********About Tsunami Forecast************

Tsunami height is expected to be 3 meters or more, Keep careful watch on tsunamis.

Tsunami height is expected to be up to 2 meters, Keep watch on tsunamis.

Tsunami height is expected to be about 0.5 meters, Pay attention to tsunamis.

Saturday, February 27, 2010

El Sismo en Chile

Here is the event report from the Servicio Sismologico, Department of Geophysics, University of Chile:

Blanco Encalada 2002 - Casilla 2777
Teléfonos: 9784298 - Fax 56-2-6873508
Dirección web :
E-ma il:



Fecha: 27 de Febrero del 2010 - Hora Local: 03:34


Hora UTC: 06:34:12 27/02/2010
Latitud:-36 12' 28''
Longitud:-72 57' 46''
Profundidad: 47.4 km
Magnitud:8.3 (Mw) GUC    
Fuente: Servicio Sismológico (U. de Chile)

REFERENCIA GEOGRAFICA:  63 km al SO de Cauquenes

Intensidades Teóricas Simuladas

Intensidades  (Escala de Mercalli)


Puerto MonttV
La SerenaIII

Note the maximum intensity of IX - "Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations"

Huge Chilean earthquake, magnitude 8.8

A huge earthquake struck offshore Chile Saturday 3:34 am local time.  The magnitude of 8.8 makes it one of the 5 or 6 largest earthquakes ever, according to the list from the NEIC:

Location Date UTC Magnitude Lat. Long. Reference
1. Chile 1960 05 22 9.5 -38.29 -73.05 Kanamori, 1977
2. Prince William Sound, Alaska 1964 03 28 9.2 61.02 -147.65 Kanamori, 1977
3. Off the West Coast of Northern Sumatra 2004 12 26 9.1 3.30 95.78 Park et al., 2005
4. Kamchatka 1952 11 04 9.0 52.76 160.06 Kanamori, 1977
5. Off the Coast of Ecuador 1906 01 31 8.8 1.0 -81.5 Kanamori, 1977
6. Rat Islands, Alaska 1965 02 04 8.7 51.21 178.50 Kanamori, 1977
7. Northern Sumatra, Indonesia 2005 03 28 8.6 2.08 97.01 PDE
8. Assam - Tibet 1950 08 15 8.6 28.5 96.5 Kanamori, 1977
9. Andreanof Islands, Alaska 1957 03 09 8.6 51.56 -175.39 Johnson et al., 1994
10. Southern Sumatra, Indonesia 2007 09 12 8.5 -4.438 101.367 PDE

There is a tsunami warning issued by the NOAA Pacific Tsunami Warning Center.

Below is the seismogram from my home institution of Franklin & Marshall College:

Click on the figure for a larger image.  The waves arrive a few minutes after 6:30, coordinated universal time (time scale on the right).

Thursday, February 25, 2010

News story on New Jersey quake

Small earthquakes in N.J. prompt calls to police, but no reported damages

By Alexi Friedman/The Star-Ledger

February 21, 2010, 8:05PM
SOMERSET COUNTY -- Two small earthquakes rattled northern New Jersey today, prompting scores of phone calls to police but no reported damage, authorities said.

The shocks began just before 9 a.m., when a 2.6-magnitude temblor struck in Gladstone, according to the U.S. Geological Survey. A smaller 2.3 magnitude quake, most likely an aftershock, hit the same area around 12:30 p.m.

Residents more than 30 miles from the epicenter reported feeling the earthquake, according to the geological agency. About 100 people in Bernardsville called police, said Sgt. John Remian, after a loud rumble was followed by what sounded like a boom.

"It was felt by everybody here," Remian said from police headquarters. "It felt like the whole room was shaking around us, and a loud explosion afterward."

Remian said the area, which sits on the Ramapo Fault, experienced a 1.5-magnitude earthquake in January. Though there has been no reported damage from today's earthquake, Remian said, "this was more substantial than the last one."

The county’s Office of Emergency Management was notified, he said, and Bernardsville police sent out an advisory through the town’s e-mail and text-messaging system.

According to an interactive online poll conducted by the USGS, most people near the epicenter reported "weak" shaking and no damage.

Paul Caruso, a geophysicist with the agency, said there was nothing unusual about the frequency of the earthquakes in the area.

"It’s pretty normal," he said. "We often see little earthquakes there."

The state rarely sees earthquakes with a high magnitude, Caruso said. The biggest one in the last decade — a 3.8 quake — struck in 2003 around 10 miles east of Phillipsburg.

Clifford Lisman said he felt today's quake and investigated, thinking a tree had fallen on his Bernardsville home.

"I went running through the house to make sure everything was okay," he said.
(This article made me wonder why most paragraphs had only one sentence.)

Staff writer Rohan Mascarenhas contributed to this report. 

(This article made me wonder why most paragraphs had only one sentence.)

Tuesday, February 23, 2010

New Jersey quakes

There have also been a couple of small earthquakes this week, on Feb. 21, in New Jersey:

MAG   TIME       LAT          LON     DEPTH      LOCATION
2.3    12:31:57  40.72N   74.68W    5.0    24 km WSW of Morristown,NJ
2.6    08:59:25  40.72N   74.66W    5.0    22 km WSW of Morristown,NJ


Monday, February 15, 2010

Small earthquakes near Albany

Just like a year ago, there has been a series of small earthquakes in the Albany, NY, area.

Here is the list of 8 events as of now, from the LCSN:

10/02/1509:08:04.142.584N74.156W20.01.70Mc34 km W of Albany, NY
10/02/1508:46:25.742.589N74.157W20.02.20Mc34 km W of Albany, NY
10/02/1411:36:58.942.584N74.139W19.01.90Mc32 km W of Albany, NY
10/02/1410:41:35.342.582N74.134W19.01.60Mc32 km W of Albany, NY
10/02/1405:52:47.742.584N74.133W18.01.50Mc32 km W of Albany, NY
10/02/1405:47:19.042.584N74.123W17.01.30Mc31 km W of Albany, NY
10/02/1403:23:32.842.582N74.158W22.01.70Mc34 km W of Albany, NY
10/02/1402:51:20.342.580N74.137W18.01.70Mc32 km W of Albany, NY

Here is a map from LCSN:
Notice the Albany quakes in the center of the map.

Friday, February 12, 2010

Munich Re - Hazard Insurance

In my sabbatical city of Munich lies the headquarters of Munich Re. According to Wikipedia, Munich Re (Munich Reinsurance Company), a is the world’s largest reinsurer. In 2008 the company's equity amounted to $30 billion. The group’s premium income for the year (gross premiums written) was $6 billion, with its consolidated profit amounting to $2 billion. Big business!  One of the main offices is down the street from my apartment, and the commanding presence of the 50-foot tall Walking Man, by the American artist Jonathan Borofsky, is right out front on Leopoldstrasse.

Munich Re has some very good web pages on natural disasters.  It states its interest in earthquakes:

"Underwriting aspects - There are many areas with high concentrations of values and population that are also located in zones of very high seismic activity. In highly exposed areas with, at the same time, a high concentration of values and high insurance penetration, the insurance industry is confronted with a major problem: the possible accumulation of losses which include the risk of financial ruin. This makes it all the more important to gain an objective impression of the exposure. Only with this as a basis can the most appropriate prevention measures be implemented, be they realistic premium calculations, accumulation controls, and the establishment of reserves, or structural improvements and land-use restrictions."

Here is a table from Munich Re on the costliest hazards in recent years (pre-Haiti):

Yes, that's $125 billion for Katrina!  No wonder insurers are interested in natural disasters.

More from Munich Re to come.

Sunday, February 7, 2010

Earthquakes far and near

Many local news outlets probably have had stories like the one in today's Lancaster newspaper, which compared the earthquake threat to Haiti (always significant) to that in Lancaster (small, but not zero).  I was asked via email about my own experience with earthquakes. As the article says, the only one I ever personally experienced was in Lancaster in 1984.  Charlie Scharnberger also comments.

Part of the full article is repeated below:

How safe are we?  Though not immune to earthquakes, Lancaster County is relatively secure compared to others areas of the United States.
Sunday News   Feb 07, 2010 00:12 ES
By JON RUTTER, Staff Writer

Shirley Riffle was celebrating her daughter's marriage in Reading when the walls of the reception hall started to flutter. The crystal lighting fixtures began to tinkle.

People looked up from their dinner, Riffle recalled. "We thought 'Oh my God.' "

An earthquake had been the remotest thing from their minds. But Riffle had good cause for alarm.

When she returned to her split-level in Spring Township, Berks County, she saw that half the chimney had toppled and a first-floor window had blown out. Some of her family's possessions, including a valuable Canterbury pottery collection, had been destroyed.

She's still paying off the roughly $30,000 in damage, she said. "We have cracks all over the walls to this day."

Riffle was singularly unlucky that bitterly cold weekend back in 1994. The epicenter of the 4.7 magnitude temblor that also buckled roads and pried open sinkholes happened to be under her house.

Last month's magnitude 7 quake in the Caribbean stirred painful memories for Riffle, who said her trauma was nothing compared to the massive death and destruction suffered by Haitians.

"I'm very lucky," said the mother of four. "I'm over it. I'm past it."

But 16 years is a geologic eyeblink.

Could a damaging earthquake again strike close to home? How secure is this place, anyway?

Even more of a mystery

Pretty secure, scientists say. But not entirely so.

There's simply too little known about the nether regions of the earth to rule out the big one.

Charles Scharnberger, a geophysicist and Millersville University professor emeritus, notes that the Spring Township quake was the strongest ever recorded in the immediate area.

He figures the odds of a local magnitude 6 quake happening in a given year to be one in 1,000.

By comparison, places like Haiti or California, which are perched on the slowly grinding junctions of tectonic plates, are at much greater risk of periodic, calamitous quakes.

The eastern United States sits squarely on the North American plate, which stretches about 2,000 miles seaward to the Mid-Atlantic Ridge.

Plate interiors are relatively placid geological zones, said Rob Sternberg [that's me, above] a Franklin & Marshall College geosciences professor who posts quake information on

On the other hand, many midplate quakes occur worldwide every year. Most are small. But some, even in the eastern U.S., have been severe.

Foremost in the lore is a trio of 1811-12 quakes in the Mississippi Valley, the strongest and noisiest of which was said to have shot sulfurous fumes into the air, awakened sleepers in Washington, D.C., and opened up fissures that swallowed seven Indians.

Reported one newspaper of the day: "The earth was so convulsed, as to tender it difficult for one to keep their perpendicular position."

An 1886 temblor estimated to have equaled 7.5 on the then-nonexistent Richter Magnitude Scale heavily damaged Charleston, S.C., and clanged bells in Boston, according to Scharnberger.

Saturday, February 6, 2010

Haiti earthquake and conspiracy theories

It came to my attention that there are some crackpot conspiracy theories about the cause of the Haiti earthquake. Yes, you thought it was due to the fact that it occurred on a major fault at a plate boundary, where earthquakes typically and inevitably happen.  Apparently, some folks think otherwise.

One such idea is that the earthquake was caused by HAARP, the High Frequency Active Auroral Research Program.  According to its web site, HAARP is a "scientific endeavor aimed at studying the properties and behavior of the ionosphere, with particular emphasis on being able to understand and use it to enhance communications and surveillance systems for both civilian and defense purposes."  The funding support by the U.S. Navy and Air Force further indicates that there is military interest in the results of this research.  But for some reason, HAARP has also been a lightning rod (atmospheric pun semi-intended) for conspiracy theorists.  Go ahead, do your own Google search. Or look at Arthur Goldwag's summary and Goldwag's follow-up.

Photo from HAARP photo gallery

Tuesday, February 2, 2010

Haiti aftershocks expected

I don't think this will get me an manyhits as the last Disaster Porn post.
Note again all the emphasis on probabilties!

From the USGS newsroom:

RESTON, Va.—The aftershock sequence of the magnitude-7 earthquake that struck near Port-au-Prince, Haiti, on Jan. 12, 2010, will continue for months, if not years. The frequency of events will diminish with time, but damaging earthquakes will remain a threat.

U.S. Geological Survey Director Marcia McNutt asked a team of USGS earthquake scientists to provide an evaluation of the earthquakes facing Haiti now and in the future. Here is the statement in its entirety from the U.S. Geological Survey:

Earthquake Hazard and Safety in Haiti and the Caribbean Region

The magnitude-7 earthquake of January 12, 2010, near Port-au-Prince, Haiti, has generated a sharp increase in concerns about the potential for future earthquakes in Haiti and the surrounding region. These concerns extend to understanding the causes of the earthquake hazard and learning what can be done to ensure seismic safety in the future. The purpose of this statement is to convey our best judgment on these subjects.

 Aftershocks: The aftershock sequence of a magnitude-7 earthquake will continue for months if not years in the affected area. The frequency of events will diminish with time, but damaging earthquakes will remain possible in the coming months. There is also a small chance of subsequent earthquakes larger than the initial shock. The sequence from the Port-au-Prince earthquake continues to be very strong and active. Based on this activity and the statistics of aftershock sequences, our estimate for aftershock activity during a 30-day period beginning January 21, 2010, is as follows:
  • The probability of one or more earthquakes of magnitude 7 or greater is less that 3 percent.
  • The probability of one or more earthquakes of magnitude 6 or greater is 25 percent.
  • The probability of one or more earthquakes of magnitude 5 or greater is about 90 percent.
  • Approximately 2 to 3 aftershocks of magnitude 5 or greater are expected within this time period.
These estimates will be updated as new information becomes available.

Precautions: Any aftershock above magnitude 5.0 will be widely felt and has the potential to cause additional damage, particularly to vulnerable, already damaged structures. Anyone living in Haiti or involved in relief work there must maintain situational awareness with regard to their personal earthquake safety. They should always be aware of what action they are going to take if the ground starts to shake. Open spaces are generally safe but running through falling debris to get to an open space may be dangerous. Only qualified engineers can determine if a damaged building is safe for reoccupation. Until engineering assistance arrives, a general rule to follow is: If it does not look safe, it probably is not safe. Entry into or reoccupation of obviously damaged structures should be avoided.

Near-term concerns: The geologic fault that caused the Port-au-Prince earthquake is part of a seismically active zone between the North American and Caribbean tectonic plates. The earthquake undoubtedly relieved some stress on the fault segment that ruptured during the event, but the extent of rupture along the fault is unclear at this time. Fault slip models, preliminary radar surface deformation measurements, and examination of satellite and airborne imagery for surface rupture suggest that the segment of the Enriquillo fault to the east of the January-12 epicenter and directly adjacent to Port-au-Prince did not slip appreciably in this event. This implies that the Enriquillo fault zone near Port-au-Prince still stores sufficient strain to be released as a large, damaging earthquake during the lifetime of structures built during the reconstruction effort. In historic times, Haiti has experienced multiple large earthquakes, apparently on adjacent faults. We shall continue to study this situation using radar, LiDAR, and photographic data taken from satellites and aircraft. Field studies and ground observations of fault offsets during this earthquake and past events are essential to evaluating the potential for future earthquakes in proximity to Port-au-Prince.   

Long-term concerns: It is essential that the rebuilding effort in Haiti take into account the potential for, indeed the inevitability of, future strong earthquakes. Haiti is cut by two major plate boundary fault zones. Over the past three centuries, earthquakes comparable to or stronger than the recent one have struck Haiti at least four times, including those in 1751 and 1770 that destroyed Port-au-Prince. Engineers and construction professionals know how to design and build structures that will not collapse in strong earthquake shaking. Seismic hazard assessments provide the basis for the development of appropriate building codes and the identification of regions at greatest risk. A thorough seismic hazard assessment of Haiti, as well as of other countries in the Caribbean, will provide the basis for establishing or improving building codes and strengthening building resilience over the long-term. Such assessments involve geologic investigations of faults and soil conditions, reoccupation of geodetic measurement sites to determine strain accumulation, and studies of recent and historic earthquakes and seismicity patterns and statistics. These assessments usually take several years but can be accelerated to provide results markedly better than what is currently available. From these investigations, we can assess the likelihood and nature of strong shaking and ground failure over various time frames. The development of more resilient structures and infrastructure is a long-term goal, particularly in the face of economic limitations. Over the short-term, it is critical that the rebuilding effort be undertaken with an awareness of the potential for subsequent damaging events during the next months and years. It is essential that structures such as hospitals, schools, and critical facilities be reconstructed with greater resilience for the preservation of life and functionality.

Regional concerns: The experience of the Port-au-Prince, Haiti, earthquake reveals a need for better understanding of the nature and extent of earthquake and tsunami hazard in the Caribbean region. The arc of islands that forms the Lesser Antilles and Greater Antilles generally outlines the contact zone between the Caribbean and North American plates. This entire region is seismically active due to the relative motion between the plates and is prone to damaging earthquakes: a small-scale “ring of fire” like that encircling the Pacific ocean. Historical earthquakes greater than magnitude 7 have occurred in Puerto Rico, Jamaica, Dominican Republic, Martinique, and Guadeloupe. Along the northern coast of Venezuela, the juncture of the Caribbean and South American plates has caused damaging earthquakes in the vicinity of Trinidad and Tobago. Earthquake safety policy, including building codes throughout the region, should be based on thorough seismic hazard assessments.

You can access a current map of aftershocks at the M7.0 Haiti Earthquake and Aftershocks Web site, and you can listen to podcast interviews at the USGS CoreCast Web site.