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

******************Headline******************
Major Tsunami and Tsunami have been issued.
  PACIFIC COAST OF TOHOKU
  PACIFIC COAST OF HOKKAIDO
  JAPAN SEA COAST OF AOMORI PREF.
  KANTO
  IZU/OGASAWARA ISLANDS
  TOKAI
  PACIFIC COAST OF KINKI/SHIKOKU
  OKAYAMA PREF.
  ARIAKE SEA AND YATSUSHIRO SEA
  EASTERN PART OF KYUSHU
  KAGOSHIMA PREF.

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.

El Sismo en Chile

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

DEPARTAMENTO DE GEOFISICA UNIVERSIDAD DE CHILE Blanco Encalada 2002 - Casilla 2777 Teléfonos: 9784298 - Fax 56-2-6873508 Dirección web : http://www.sismologia.cl E-ma il: sismoguc@dgf.uchile.cl SANTIAGO - CHILE SERVICIO SISMOLOGICO INFORME DE SISMO Fecha: 27 de Febrero del 2010 - Hora Local: 03:34

---

HIPOCENTRO

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)

Fuente: ONEMI Y DIREMER

Concepcion IX Temuco VIII Talca VIII Rancagua VIII Santiago VIII

Valdivia VI Valparaiso VI Puerto Montt V Vicuna IV La Serena III

Copiapo III Antofagasta II Calama II

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).

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.)

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

From LCSN

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:

DATE ------	TIME ------	LAT ------	LON ------	DEPTH ------	MAG ------	Comments ----------
10/02/15	09:08:04.1	42.584N	74.156W	20.0	1.70Mc	34 km W of Albany, NY
10/02/15	08:46:25.7	42.589N	74.157W	20.0	2.20Mc	34 km W of Albany, NY
10/02/14	11:36:58.9	42.584N	74.139W	19.0	1.90Mc	32 km W of Albany, NY
10/02/14	10:41:35.3	42.582N	74.134W	19.0	1.60Mc	32 km W of Albany, NY
10/02/14	05:52:47.7	42.584N	74.133W	18.0	1.50Mc	32 km W of Albany, NY
10/02/14	05:47:19.0	42.584N	74.123W	17.0	1.30Mc	31 km W of Albany, NY
10/02/14	03:23:32.8	42.582N	74.158W	22.0	1.70Mc	34 km W of Albany, NY
10/02/14	02:51:20.3	42.580N	74.137W	18.0	1.70Mc	32 km W of Albany, NY

Here is a map from LCSN:

Notice the Albany quakes in the center of the map.