When time allows, I'll post channel sets that I create to look at earthquakes on this "blog".

Instructions: To copy one of the channel sets on the iPad, press and hold your finger on part of the channel list. When you release you finger you will see text-selection handles. Select the channel set and choose copy. Then navigate to the seismogram settings tab and press and hold on the current channel list. When you release you will see text-selection options; choose Select All and then choose Paste to replace the current with a new set.

Sunday
Nov132016

13 November, 2016 - NNE of Amberley, New Zealand (M7.8)

A large, M7.8, earthquake occurred beneath the South Island of New Zealand. The aftershocks stretch across a zone along NE edge of the island for about 175-200 km.

 

You can watch the aftershocks on three stations near the rupture zone, SNZO in Wellington (to the north), KHZ near the middle of the aftershock zone), and RPZ (to the south). Here is the channel list

SIGNALPARAMETERS; 2016-11-13 15:23:58; -30;  10; 0.5; -4.0 
IU; SNZO; 00; BHZ; WELLINGTON, NEW ZEALAND (UP-DOWN)
IU; SNZO; 00; BH2; WELLINGTON, NEW ZEALAND (EAST-WEST)
IU; SNZO; 00; BH1; WELLINGTON, NEW ZEALAND (NORTH-SOUTH)
NZ; KHZ; 10; HHZ; KAHUTARA, NEW ZEALAND (UP-DOWN)
NZ; KHZ; 10; HHE; KAHUTARA, NEW ZEALAND (EAST-WEST)
NZ; KHZ; 10; HHN; KAHUTARA, NEW ZEALAND (NORTH-SOUTH)
NZ; RPZ; 20; BNZ; RATA PEAKS, NEW ZEALAND (UP-DOWN)
NZ; RPZ; 20; BNE; RATA PEAKS, NEW ZEALAND (EAST-WEST)
NZ; RPZ; 20; BNN; RATA PEAKS, NEW ZEALAND (NORTH-SOUTH)

Below is a view of the recent aftershocks on the three stations.


To look at the mainshock, you want to use the strong motion channels

IU; SNZO; 20; hnz; WELLINGTON, NEW ZEALAND (UP-DOWN)
IU; SNZO; 20; hn2; WELLINGTON, NEW ZEALAND (EAST-WEST)
IU; SNZO; 20; hn1; WELLINGTON, NEW ZEALAND (NORTH-SOUTH)
NZ; KHZ; 20; BNZ; KAHUTARA, NEW ZEALAND (UP-DOWN)
NZ; KHZ; 20; BNE; KAHUTARA, NEW ZEALAND (EAST-WEST)
NZ; KHZ; 20; BNN; KAHUTARA, NEW ZEALAND (NORTH-SOUTH)
NZ; RPZ; 20; BNZ; RATA PEAKS, NEW ZEALAND (UP-DOWN)
NZ; RPZ; 20; BNE; RATA PEAKS, NEW ZEALAND (EAST-WEST)
NZ; RPZ; 20; BNN; RATA PEAKS, NEW ZEALAND (NORTH-SOUTH)

The mainshock recordings to the north and to the south are shown below. The plots show the graound velocity and the numbers on the right are in miconrs/second, but the instrument response has not been removed. Only a gain correction applied. The ground velocities (particularly the S/Surface waves) are much larger towards the north than the south, consistent with a northward directed rupture, as indicated by the hypocenter, aftershocks, and early USGS finite fault model. But Rata Peaks is quite a bit farther south than Wellington is to the north. So distance plays some role in the comparison as well.

Sunday
Oct302016

30 October Central Italy (Norcia) Earthquake (M6.6)

A strong earthquake struck the mountainous Appenine region of central Italy this morning, part of a prolonged sequences of earthquakes that began in August and included several significant events. The map below shows large events from the last 30 days (data from the USGS).

The channels below correspond to the closest real-time seismic station (operated by MedNet), which is located in L'Aquila, about 50 km to the southeast. You should be able to monitor larger aftershock activity by watching that station.  

SIGNALPARAMETERS; 2016-10-30 06:40:09; 60;  10; 0.5; -4.0 
MN; AQU; --; BHZ; L'AQUILA, ITALY - UP-DOWN
MN; AQU; --; BHE; L'AQUILA, ITALY - EAST-WEST
MN; AQU; --; BHN; L'AQUILA, ITALY - NORTH-SOUTH

The image below shows the main shock signals (red dashed line is the origin time), followed by numerous aftershock signals.

The map below shows 3853 epicenter locations obtained from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) of Italy. The map includes earthquakes with M ≥ 2.0. Symbol areas are scaled logartihmically to show a representative size of the earthquakes. The maps includes earthquakes that occurred between August and this morning.

Each earthquake's symbol area is sized roughly to correspond with a "typical" rupture area of an earthquake of the corresponding magnitude. I used a simple forumula, but the area is generally within a factor of two of the actual area. Of course, large earthquake ruptures are not often circular in shape and the rupture may not be cetered on the epicenter.

Below is a projection of the earthquakes (from the INGV) from August through the present onto a plane strike 142N and dipping 42° to the southwest (the faults involved in this sequence are not well modeled by a single plane).

The lateral origin is the largest earthquake in August, events to the left are to the north and depth increases from top to bottom. The symbol sizes are scaled as in the map above - to crudely approximate the relative areas of the ruptures. The circles are centered on the hypocenter, but they may not have ruptures with that configuration.

The chart below is an Omori's Law diagram for the sequence thus far. The last day is only partly over - so the last bar will increase in height.

Below is a Gutenberg-Richter Diagram for the August-October activity. The corresponding "b" value is roughly 0.82. 

Again, these data are credited to Italy's INGV (http://www.ingv.it/en/) - they are doing a superb job sharing the data and results.

Sunday
Apr172016

16 April, 2016 Near Muisne, Ecuador - M 7.8

A large, damaging, and deadly earthquake struck the coast of Ecuador at 2016-04-16 23:58:37 (UTC). For details, please see the USGS event page.
Here is a channel list, for a nearby station from the Ecuador Seismic Network. The seismic stations are located within the volcanic belt, which about 200 km from the coast. Still, you can see the larger aftershock.
EC;CUIC;--;HHZ; CUIC, Ecuador, UP-DOWN
EC;CUIC;--;HHN; CUIC, Ecuador, NORTH-SOUTH
EC;CUIC;--;HHE; CUIC, Ecuador, EAST-WEST
EC;PULU;--;HHZ; PULU, Ecuador, UP-DOWN
EC;PULU;--;HHN; PULU, Ecuador, NORTH-SOUTH
EC;PULU;--;HHE; PULU, Ecuador, EAST-WEST
EC;CHSH;--;HHZ; CHSH, Ecuador, UP-DOWN
EC;CHSH;--;HHN; CHSH, Ecuador, NORTH-SOUTH
EC;CHSH;--;HHE; CHSH, Ecuador, EAST-WEST
EC;COHC;--;HHZ; COHC, Ecuador, UP-DOWN
EC;COHC;--;HHN; COHC, Ecuador, NORTH-SOUTH
EC;COHC;--;HHE; COHC, Ecuador, EAST-WEST
Or just the vertical channels
EC;CUIC;--;HHZ; CUIC, Ecuador, UP-DOWN
EC;PULU;--;HHZ; PULU, Ecuador, UP-DOWN
EC;CHSH;--;HHZ; CHSH, Ecuador, UP-DOWN
EC;COHC;--;HHZ; COHC, Ecuador, UP-DOWN
Not all the stations are available right now. Here is a what's recorded in the last 60 minutes.
Data source(s): Instituto Geofisico, Quito Ecuador; IRIS/NSF. 
SIGNALPARAMETERS; 2016-04-17 14:22:40; -60; 10; 0.5; -5
Here are the vertical recordings from the mainshock - most of the horizontals went off scale.
Friday
Apr152016

Kumamoto-shi, Japan, 15 April, 2016 - M 7.0

A sequence of deadly earthquakes struck Japan over the last few days (the sequence started earlier). The latest earthquake occurred in the shallow crust, near a large population center. The USGS PAGER Summary details the seriousness of such an earthquake.
Here is a nearby channel list, the closest station's data (JNU) are not available at the time of the mainshock, the more distance station, JSU, provides some of the foreshock and mainshock observations. JNU is up and running at present and you can see the aftershocks clearly.
JP;JNU;--;BHZ;Oita Nakatsue, Japan, UP-DOWN
JP;JNU;--;BHE;Oita Nakatsue, Japan, EAST-WEST
JP;JNU;--;BHN;Oita Nakatsue, Japan, NORTH-SOUTH
JP;JSU;--;BHZ;Kagoshima Suzuyama, Japan, UP-DOWN
JP;JSU;--;BHE;Kagoshima Suzuyama, Japan, EAST-WEST
JP;JSU;--;BHN;Kagoshima Suzuyama, Japan, NORTH-SOUTH

Here is a view of the last 30 minutes or so, the large aftershock near 18:03 is roughly a magnitude 5.5 (GFZ quick estimate).

Monday
Dec072015

Tajikistan, 07 December, 2015 - M 7.2

A major earthquake struck southeastern Tajikistan earlier today. The M 7.2 event occurred in a remote region, so hopefully few (or none) were affected.

Tajikistan has a good seismic network. The closest real-time station is at Manem, Tajikistan. You can observe the larger aftershocks on the signals recorded there (the station is about 80 miles or 128 km away from the mainshock epicenter). 

#SIGNALPARAMETERS; 2015-12-07 12:37:14; -60; *; -0.5; -4.0
TJ;MANEM;--;HHZ;MANEM, TAJIKISTAN, UP-DOWN
TJ;MANEM;--;HHE;MANEM, TAJIKISTAN, EAST-WEST
TJ;MANEM;--;HHN;MANEM, TAJIKISTAN, NORTH-SOUTH

The mainshock went off scale at this site. Here's a look at what's going on at the time of this post.

Wednesday
Sep162015

West of Illapel, Chile, 16 Sep, 2015 - Mw 8.3

A large earthquake struck the coast of Chile tonight.  The map below is an update from around 11:00 UTC on 17 September. You can find many details at the USGS event page.

 

There are many openly available seismic stations in Chile, including a station very near the source region. Here is the channel list for the station at the Tololo Observatory in Vicuna, Chile. 

 For the mainshock, look at the accelerometer, which stays on scale for large events:

C;GO04; --;HNZ;TOLOLO OBSERVATORY, VICUNA, CHILE - Up-Down
C;GO04; --;HNN;TOLOLO OBSERVATORY, VICUNA, CHILE - North-South
C;GO04; --;HNE;TOLOLO OBSERVATORY, VICUNA, CHILE - East-West
Here are the records from the mainshock (you can see one of the early, large aftershocks in the "coda" of the mainshock signals and one or two others a few minutes later). The second image shows some of the large early aftershocks recorded on the accelerometer.






To watch later aftershocks, the broadband sensors should perform better, but for now, they are not behaving too well (perhaps driven off scale by many of the large aftershocks that occurred early).

C;GO04; --;BHZ;TOLOLO OBSERVATORY, VICUNA, CHILE - Up-Down
C;GO04; --;BHN;TOLOLO OBSERVATORY, VICUNA, CHILE - North-South
C;GO04; --;BHE;TOLOLO OBSERVATORY, VICUNA, CHILE - East-West

 

Sunday
Apr262015

Nepal, 25 April, 2015 - Mw 7.9

The large earthquake and its aftershocks that struck beneath the Katmandu region of Nepal produced widespsread damage. The USGS page has the scientific information, and you can visit earthquake-report.com for updates. Here's a map of Mainshock and aftershock locations. The aftershock locations relative to that of the mainshock suggest that the rupture propagated about 140 km from NW to SE and extended beneath Katmandu.

There are not many openly available seismic stations in or near the source region. The two closest include LSA, Lhasa, Tibet, China (about 600 km away) and Shillong, Meghalaya, India (about 700 km away). The latency of data at both stations may be significant.

IC; LSA; 00; BHZ; Lhasa, Tibet, China (Vertical)
IC; LSA; 00; BH2; Lhasa, Tibet, China (East-West)
IC; LSA; 00; BH1; Lhasa, Tibet, China (North-South
IN; SHL; --; HHZ;  Shillong, Meghalaya, India (Vertical)
IN; SHL; --; HHE;  Shillong, Meghalaya, India (East-West)
IN; SHL; --; HHN;  Shillong, Meghalaya, India (North-South

Here is the mainshock at LSA on two different instruments at LSA. The top three channels show the strong-motion instrument and the lower three show the broad-band instrument. The strong-motion sensor has a better short-period response and does not go off scale, as did the broadband sensor. The broadband sensor would be better for detecting smaller aftershocks.

 

Right now the latency at SHL is low. Here's a recent aftershock plot (these observations are from several hundred km from the epicentral region). 

For reference, here's a map of the station locations:

Wednesday
Oct012014

The 2014 Mammoth Lakes Region Swarm

An earthquake swarm is underway near Mammoth Lakes, CA. Here is a map of the recent activity. Here's a CNN News summary. 

Here is a channel list from a nearby high-quality station:

CI; MLAC; --; BHZ;Mammoth, Mammoth Lakes, CA, USA (Vertical)
CI; MLAC; --; BHE;Mammoth, Mammoth Lakes, CA, USA (East-West)
CI; MLAC; --; BHN;Mammoth, Mammoth Lakes, CA, USA (North-South)

Here is a recent iamge of the seismograms from the station.

Sunday
Aug242014

Northern California, USA - 24 Aug, 2014 - M 6.0

A magnitude 6.0 earthquake occurred in northern California just north of San Francisco Bay this morning. Shaking in the epicentral region is estimated to be Intensity Level Vii (very strong, with the capability to produce moderate damage). 

 

Aftershocks:

Information is still coming in about the earthquake so you can check the latest results at the US Geological Survey site:

http://earthquake.usgs.gov/earthquakes/eventpage/nc72282711#summary

One of the closest easily accessible stations is located in Lucas Valley, about 30 km from the epicenter. The station has a quiet borehole sensor and aftershocks are readily apparent on B057 signals. The channel list:

PB; B057;--; EHZ; B057, LUCAS VALLEY, CA, USA (VERTICAL)
PB; B057;--; EH1; B057, LUCAS VALLEY, CA, USA (NORTH-SOUTH)
PB; B057;--; EH2; B057, LUCAS VALLEY, CA, USA (EAST-WEST)

To monitor aftershocks, use the above channel list and insert an asterisk in the Sample Rate field. To turn the filters off, insert negative numbers into the Low Corner and High Corner fields. The data sample rate is 100 samples per second, so don't use a duration that's too long. I've been using 30 minutes. Here is a plot of some early aftershock activity ("local time" in the seismogram plots is the app-user's local time, eastern time in the samples):

Here is a plot of the mainshock on more distant stations in the San Francisco Bay Area (channel list in popup):

and across the conterminous US (Conterminous US list in Channel-Lists popup menu):

Saturday
May242014

South of Kamariotissa, Greece - 24 May, 2014 - M 6.9

A large earthquake occurred about 20 kilometers south of Kamariotissa, Greece today. The event was shallow (about 10 km) and appears to be associated with strike-slip faulting in the northern Aegean Sea.

Here are seismograms from the mainshock (east-west is off clipped (off-scale).

The stations are operated by the National Observatory of Athens, Inst. of Geodynamics and the Geophysical Laboratory, University of Thessaloniki, Greece respectively.

SIGNALPARAMETERS; 2014-05-24 09:24:53; 4; *; -0.005; -0.05
# National Observatory of Athens, Inst. of Geodynamics
HL; RDO; --; HHZ; GRATINI, THRACE, GREECE (UP-DOWN)
HL; RDO; --; HHE; GRATINI, THRACE, GREECE (EAST-WEST)
HL; RDO; --; HHN; GRATINI, THRACE, GREECE (NORTH-SOUTH)
# Geophysical Laboratory, University of Thessaloniki, Greece
HT; ALN; --; HHZ; ALEXANDROUPOLIS, GREECE (UP-DOWN)
HT; ALN; --; HHE; ALEXANDROUPOLIS, GREECE (EAST-WEST)
HT; ALN; --; HHN; ALEXANDROUPOLIS, GREECE (NORTH-SOUTH)

Both these stations are close enough to watch the aftershock sequence (remove the SIGNALPARAMETERS line from the above list and choose real-time monitoring mode). Here's a look at what's going on at the time of this post.

Thursday
May152014

Crashes

If you are working with one of the earthquake feeds that includes small-magnitude events (and most of us do), you may have had epicentral+ crash recently. The crash is caused by a bad entry in the USGS list of earthquakes (specifically an earthquake with no magnitude value in the list of earthquakes that are supposed to have magnitudes greater than a specified value). I was contacted about the issue yesterday and submitted an app update to work around such entries last night. But it will take a while (at least days) for the update to work its way through the app store approval process.

For now, working with the 30-day "feed" that lists only larger (M>=4.5) earthquakes will allow the app to function. This is not ideal, because you won't have notifications of small events in US regions, but you will be able to use the seismogram streaming functions and to track larger events. You may need to delete and reinstall the app to clean out the corrupt data. You choose the "feed" using the Apple Settings app, and selecting epicentral+, then the earthquake feed selector.

Tuesday
May062014

Update on Oklahoma

The dramatic increase in the number of small earthquakes in Oklahoma during the last few years has been getting much attention from scientists and the media. The USGS and the Oklahoma Geological Survey issued a joint statement yesterday on the possibility of future damaging earthquakes.

Here are some updated plots showing the numbers (updating a previous post on 30 March). The increase in the number of events with magnitudes greater than 3.0 is quite impressive.

 

A common way to analyze the distribution of earthquakes by magnitude in seismology and earthquake science is a Gutenberg-Richter plot, where you plot the common logarithm of the number of earthquakes with a magnitude greater than a particular value versus the magnitude.  A plot of the events from the last 3 and a half years is shown below. The slope of the middle part of the gray line is -1.2 (we refere to the negative of the slope as the b-value).

 

The three markers for earthquakes with magnitudes 5.0 and above are one event, an Mw 5.6 earthquake that occurred near Prague, OK in 2011. Typical b-values are near unity, so this pattern is not too unusual, but the increase in the number of earthquakes shown above is extremely unusual.

The recent activity is believed to be related to fluid injection into the subsurface, which is known to trigger small-to-moderate size earthquakes (USGS page on induced earthquakes). You can follow the Oklahoma geological Survey (@OKearthquakes) and the USGS (@usgs) on twitter for updates.