[EHPweb] NextGen EQMaps Beta

[David Oppenheimer]

Hi Mike,

 

The M<1 quake-issue arose with respect to Parkfield and Long Valley, where
the borehole networks enable us to detect/locate quakes much smaller than
1.0. The same is true at the Geysers where the 23-station Calpine network
drives the detection threshold down. The problem is that the coda duration
(Md) algorithm used in Earthworm (and AQMS) discards codas <7s because in
the previous analog world these short codas would generally be noise
glitches. So, M<1 quakes generally have indeterminate magnitudes. Still,
even with a "zero" magnitude, the P.I.'s monitoring these areas what to see
the smaller quakes on the recenteqs pages.

 

Now that the NCSN has complete metadata for all digital waveforms back to
1984, we can determine if the record is not clipped and, if so, compute
synthetic Wood Anderson seismograms for all quakes - even those recorded by
analog equipment. We can then calculate the peak amplitudes for use in
determining ML for these small quakes. 

 

We're in the discussion stages of how to do this. It will take a lot of
computation and careful calibration to get the Ml scale correct for M<3
quakes where the traditional ML scale was developed.

 

-David 

 

From: ehpweb-bounces at geohazards.usgs.gov
[mailto:ehpweb-bounces at geohazards.usgs.gov] On Behalf Of Michael Blanpied
Sent: Friday, December 03, 2010 12:12 PM
To: Lisa A Wald
Cc: Leith Bill; EHPweb
Subject: Re: [EHPweb] NextGen EQMaps Beta

 

Thanks, Lisa! Sorry to bother you about a resolved issue.

 

So the floor is now M=0? I assume that will satisfy folks. I actually have
no idea whether the network locates earthquakes M<0!

 

Mike

 

The omission of M<1 earthquakes was an error on our part.  We fixed that one
immediately.  If you take a look at the Beta maps now, you'll see all the
M<1 earthquakes on them already.

 

http://earthquake.usgs.gov/earthquakes/mapping/

 

- Lisa

------

 

 

 

 

On Dec 3, 2010, at 12:45 PM, Michael Blanpied wrote:

 

Lisa,

 

Thanks very much for the feedback and summary! It's great to know that
you're making progress on the new maps, and that you've found a suitable way
around the Google impediments.

 

One point that I don't see on your list is the question of M<1 earthquakes.
Our colleagues with interests in central California and in volcanic areas
are very keen to see the magnitude floor removed from the maps. This has
been brought to my attention a couple of times now, so I'd appreciate
hearing the status of that issue so that I'll know how to respond next time
it comes up.

 

Thanks again,

Mike

 

At 10:49 AM -0700 12/3/10, Lisa A Wald wrote:



Everyone-

 

Thank you for your feedback, comments, and suggestions about the Next
Generation Earthquake Maps for the EHP website.

 

The Web Team has compiled the various comments, weighted them according to
how many times we received the same comment, and we are currently addressing
all the comments starting with those with the highest priority.

 

Because of Google licensing issues with our high web traffic to the EQ Maps,
we are having to move to another client-side software, OpenLayers API.  I
think you'll agree that OpenLayers is every bit as good, if not better, than
Google Maps (and it doesn't preclude us from using Google Maps API in the
future if the licensing issue is resolved).

 

These are some of the tasks we're working on to address your concerns before
the Public Beta is launched in January:

 

1. Remove clustering algorithm, or allow user to turn it on and off; add
cluster symbol to map key.

2. Add links to event pages from event table below map; turn off dbl-click
on event symbol on map.

3. Implement full-page-size map.

4. Add magnitude to hover text.

5. Change labeling from "Event" to "Earthquake".

6. Add user guide for features that are not intuitively obvious.

7. Use our own basemaps, cities, list, etc instead of the build-in data
provided by Google Maps.

8. Other small changes such as scale bar, lat/lon of mouse position.

 

Additional features, such as faults with mouse-over info, volcano locations,
caldera boundaries, etc. will be added in the future, potentially before the
final public release.  We'll have a mechanism in place to receive comments
on the next beta version too.

 

Thanks for helping to make this an outstanding product!

- Lisa
--------------------------
Lisa Wald, Geophysicist

Web Team Manager/Project Manager
USGS Earthquake Hazards Program
Golden, CO
303-273-8543
 <mailto:lisa at usgs.gov> lisa at usgs.gov

--------------------------

 

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