Monday, July 27, 2009

Berkeley also blogs about moonquakes

See their story at Berkeley's Seismo Blog.

I couldn't have said it better myself.

Could those quakes be caused by a Man on the Moon?

Monday, July 20, 2009


I did think about an ode to the moon landing ... but there is just a little bit of that going on elsewhere.

But perhaps I should continue the thread of quakes on other heavenly bodies (no, I don't mean Brüno!).

According to a Stanford press release from last year:

"Scientists [my students inexplicably often write "scientist" in this kind of context, when they should use the plural - anyone else ever see that, or know why?] have shown for the first time that solar flares produce seismic waves, and gigantic seismic quakes, in the Sun's interior. Using data from the Michelson Doppler Imager onboard the European Space Agency/NASA Solar and Heliospheric Observatory (SOHO), Stanford and Glasgow scientists have tracked these seismic waves and found that "sun-quakes" closely resemble earthquakes on our planet.

"The researchers observed a flare-generated solar quake that contained about 40,000 times the energy released in the great earthquake that devastated San Francisco in 1906. The amount of energy released was enough to power the United States for 20 years at its current level of consumption, and was equivalent to an 11.3 magnitude quake on Earth."

Yikes, keep me away from that quake.

I'll be away in Europe on research for a few weeks. I'll be online from time to time, but maybe some of my colleagues would like to do some guest blogging.

Thursday, July 16, 2009

Apollo 11 - Moonquakes

It's 40 years today that Apollo 11 left Earth, and four days later humans first set foot on the Moon. I was a college lad, and I sat with friends around the tv to watch. What a stunning achievement - if only we could muster that same dedication, intelligence, creativity, and funding towards solving some of the critical issues that face us today.

From NASA: "Between 1969 and 1972, Apollo astronauts placed seismometers at their landing sites around the moon [as Buzz Aldrin is doing below]. The Apollo 12, 14, 15, and 16 instruments faithfully radioed data back to Earth until they were switched off in 1977."

"There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface, probably caused by tides; (2) vibrations from the impact of meteorites; (3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and (4) shallow moonquakes only 20 or 30 kilometers below the surface.

"The first three were generally mild and harmless. Shallow moonquakes on the other hand" could yield magnitude 5.5 tremors.

Seismograms from three types of moonquakes recorded at the Apollo 16 station. LPX, LPY, and LPZ are the three long-period components and SPZ is the short-period vertical component. The first column shows a deep-focus moonquake; the center column, a shallow moonquake; the third column shows records of the impact of meteoroid on the lunar surface. [From ETH website; courtesy of NASA].

Wednesday, July 15, 2009

Largest quake of year in New Zealand, m=7.8

USGS 2009 earthquake statistics

The largest quake of 2009 to date, magnitude 7.8, happened today off the southern tip of New Zealand.
New Zealand Earthquake Report - Jul 15 2009 at 9:22 pm (NZST)
Magnitude 7.8
Latitude, Longitude - 45.75°S, 166.58°E
Focal Depth - 12 km
100 km north-west of Tuatapere
100 km south-west of Te Anau
160 km north-west of Invercargill
300 km west of Dunedin

New Zealand Seismograph Drum - Wether Hill Road (WHZ), Southland, New Zealand
This image represents one day's recording of the seismometer located near Wether Hill Road, in Southland, about 150 km from the epicenter.

The timestamp shown at the top right of the seismograph drum shown below is the time when this image was last refreshed. Each horizontal line (or trace) represents 30 minutes, each vertical line is spaced 1 minute apart; 24 hours of recording are displayed in total. The most recent signal is drawn at the bottom right hand corner of the drum. Then read the traces from right to left, bottom to top, to get from the most recent to the oldest signals. The trace will appear red if the signals are very large; this means they have been clipped to stop them overwriting too much of the surrounding image.

Maximum Modified Mercalli intensities of VII were indicated.

A tsunami warning was issued, but has been canceled.

Tuesday, July 14, 2009

How wood you do in an earthquake?

Today, Bastille Day, a six-story condominium building was shaken with same type of the motions of the 1994 Northridge earthquake, but one and a half times as intense--more powerful than any quake California has experienced in modern times.

The capstone experiment of NSF's multi-year NEESWood (it was harder than it should be to find out that stands for Network for Earthquake Engineering Simulation Wood) project, the effort will test new ways to construct buildings that can withstand severe forces of nature.

Working with the Japanese government's National Research Institute for Earth Science and Disaster Prevention (NIED), as part of a broader partnership with NSF, the NEESWood engineers tested their structure at the E-Defense facility, located north of Kobe, which houses the world's largest shake table.

On June 30th, the entire, sensor-laden structure was subjected to two tests, one simulating earthquake forces that occur, on average, once every 72 years and a second that would occur similarly once every 475 years. On July 6th, the same tests were run, but the steel-frame components were locked down, so only the six-story, wood-frame, residential structure would be affected.

Today the wood-frame structure became the subject of the largest shake table test the world has seen to date, at a level that equates to an event that occurs, on average, once every 2,500 years.
See photos and movies at NSF.

Sunday, July 12, 2009

Terremoto in Peru

My son was vacationing in Alaska and now in Peru, and then will live near my other son in the Bay Area. I wonder if they are seismophilic?

The magnitude 6.0 earthquake he might have felt in Peru today (ok, he is 1,000 km away in Lima) had me looking at the website of the Instituto Geofísico del Perú .

Not a bad site if you want to learn about earthquakes in Spanish.

Wednesday, July 8, 2009

L'Aquila and the G8 Summit

NPR, a favorite news source, had a good story this morning on the G8 Summit meeting in Italy and reconstruction following the magnitude 6.3 shock on 6 April. And thanks to audio stories, I know how to actually pronounce L'Aquila. (I guess you could get this from tv news, but I don't watch "news" on tv.)

There are still 65,000 homeless, and 25,000 people living in tents, and serious damage to many cultural treasures. (Photo below from NPR.)

You can read more or listen on NPR.

Perhaps this crisis is what has driven Italian Prime Minister Berlusconi to vice? Well, I'll give him credit for one thing - he hasn't (as far as I know) whined at a press conference about soulmates and higher callings.

Sunday, July 5, 2009

Philly quake - Murphy's seismograph law?

Our seismograph is down due to a bad hard drive.

So of course there is an earthquake in the area.


Small earthquake shakes NJ, Delaware, Pa.
The Associated Press

NEWPORT, Del. - The National Earthquake Center says a small earthquake felt Wednesday in the Wilmington, Del. area had its epicenter in southern New Jersey.

The center says the earthquake measured 2.8 on the Richter scale, up from an earlier estimate of 2.7. That's big enough to feel, but too small to cause much damage.

The epicenter was near Mannington Township, near the Delaware River.

Salem County deputy administrator Robin Weinstein says he felt shaking in his emergency management office soon after the quake began at 9:46 a.m. No injuries or damage were reported.

A spokesman for PSE&G Nuclear, which operates three nuclear power plants in Salem County, says the quake was too minor to register on the plant's monitoring devices."

Thursday, July 2, 2009

Senior seismologist olympics: earth shaking

I can only say this because, age-wise, I would qualify for the senior olympics!

"Charles K. Scharnberger, left, Helen Delano of the Bureau of Topographic and Geologic Survey and others jump to test a seismograph buried in the backyard of a Dillsburg area home on Friday. Over the years, residents of Moodus, Conn. have come to accept their earthquakes; in Dillsburg and Carroll Township, scientists and residents are still trying to figure out exactly what's happening." (Daily Record/Sunday News -- Jason Plotkin)