earthquakes – Membrane.com

Sea Serpents Washing Ashore

Posted on 2013/10/232013/10/23 by admin

CALIFORNIA — Two rare oarfish have washed up on California beaches. A dead 18-foot-long oarfish was found off Catalina Island on October. 13. A 14-foot-long oarfish carcass was found on Oct. 18 in Oceanside, CA.

Oarfish can grow to more than 50 feet in length and are considered the longest fish. Their appearance has led to many theories of sea serpents.

Japanese folklore believes the beaching of oarfish predicts earthquakes — “a notion that some scientists have speculated could be supported by the bottom-dwelling fish being more sensitive to seismic shifts.”

“It’s probably just a coincidence,” said Rick Feeney of the Natural History Museum of Los Angeles County. “We think that they come inshore to die actually because they’re in distress for some reason, but we don’t know what the reason is,” said Feeney, adding that the fish could have been starving or disoriented.

However, the one found off Catalina Island has been dissected and found to be healthy. “It looks good enough to eat – if you have a 13ft pan,” biologist Ruff Zetter said.

Northeastern Earthquakes

Posted on 2012/11/232012/11/23 by admin

Philadelphia, PA — There was an earthquake in Camden, NJ. In the past several years, the region has become aware of earthquakes.

The USGS says:

Tectonic Summary

EARTHQUAKES IN THE NEW YORK – PHILADELPHIA – WILMINGTON URBAN CORRIDOR
New York - Philadelphia - Wilmington urban corridor Since colonial times people in the New York – Philadelphia – Wilmington urban corridor have felt small earthquakes and suffered damage from infrequent larger ones. New York City was damaged in 1737 and 1884. Moderately damaging earthquakes strike somewhere in the urban corridor roughly twice a century, and smaller earthquakes are felt roughly every 2-3 years.

Earthquakes in the central and eastern U.S., although less frequent than in the western U.S., are typically felt over a much broader region. East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi).

FAULTS
Earthquakes everywhere occur on faults within bedrock, usually miles deep. Most bedrock beneath the urban corridor was assembled as continents collided to form a supercontinent about 500-300 million years ago, raising the Appalachian Mountains. Most of the rest of the bedrock formed when the supercontinent rifted apart about 200 million years ago to form what are now the northeastern U.S., the Atlantic Ocean, and Europe.

At well-studied plate boundaries like the San Andreas fault system in California, often scientists can determine the name of the specific fault that is responsible for an earthquake. In contrast, east of the Rocky Mountains this is rarely the case. New York City, Philadelphia, and Wilmington are far from the nearest plate boundaries, which are in the center of the Atlantic Ocean and in the Caribbean Sea. The urban corridor is laced with known faults but numerous smaller or deeply buried faults remain undetected. Even the known faults are poorly located at earthquake depths. Accordingly, few, if any, earthquakes in the urban corridor can be linked to named faults. It is difficult to determine if a known fault is still active and could slip and cause an earthquake. As in most other areas east of the Rockies, the best guide to earthquake hazards in the New York – Philadelphia – Wilmington urban corridor is the earthquakes themselves.

Earthquake Maps

Christchurch Earthquake

Posted on 2011/03/09 by admin

NASA writes about the religion of earthquakes:

It is a modern human tendency to focus on the number of an earthquake—specifically, the magnitude, or what people used to call the “Richter scale.” But the destruction from a quake usually has more to do with location and timing. Such was the case with the earthquake in Christchurch, New Zealand, on February 22, 2011.

A September 2010 earthquake centered 40 kilometers (25 miles) west of Christchurch, in the plains near Darfield, struck at 4:35 a.m., had a magnitude of 7.1, and caused some structural damage and one death (by heart attack). The earthquake in February 2011 occurred at 12:51 p.m. and just 10 kilometers (6 miles) from the center of Christchurch. It had a magnitude of 6.3, though was officially classified—scientifically speaking—as an aftershock of the 2010 quake. At least 166 people died, and the city of Christchurch was devastated structurally and emotionally. Many people are still missing.

The natural-color image above was captured on March 4, 2011, by the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite. Overlain on the map are seismological measurements of the ground shaking in the Christchurch area on February 22, as noted by the U.S. Geological Survey’s Earthquake Hazard Program.
The deeper the red color of the circle, the more intense the “peak ground acceleration,” or shaking of the earth. Note how intensity is highest right around the most densely developed areas of Christchurch. City officials and news accounts also described liquefaction—the softening and loosening of the soil due to shaking and groundwater penetration—that was 300 to 500 percent worse than during the September 2010 earthquake.

There are two forms of energy that cause the shaking in an earthquake. “P” or primary waves provide the initial, often vertical, jolt that lifts people and structures off the ground. “S” or secondary waves lead to horizontal shaking. Most structures collapse during the longer-duration S waves because buildings are not designed to handle this side-to-side motion. In Christchurch, the quake occurred so close by that the lag between P and S waves was a mere second.

References
GeoNet (2011, March 4) Christchurch badly damaged by magnitude 6.3 earthquake. Accessed March 8, 2011.
GNS Science (2011, February 25) February 22nd earthquake in Christchurch. Accessed March 8, 2011.
New Zealand Herald (2011, February ) Christchurch earthquake: Levels of liquefaction 300-500 pc worse. Accessed March 8, 2011.
U.S. Geological Survey (n.d.) Shake Map: South Island of New Zealand. Accessed March 8, 2011.
NASA Earth Observatory image by Robert Simmon, using ALI data from the EO-1 Team and USGS Earthquake Hazard Program. Caption by Mike Carlowicz.