[EHPweb] FW: M<1 earthquakes

[David Oppenheimer]

Hi Lisa,

 

Thanks for explaining the problem. Since the Google Maps is a prototype app,
we ask that the recenteqs on http://ncweb-north.wr.usgs.gov/, which is a
public facing server, be kept running indefinitely until we have a
satisfactory outcome of this issue.  Having said that, we're interested in
testing the Google Maps approach.

 

-David

 

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

David Oppenheimer                   office:650.329.4792

U.S. Geological Survey              fax:   650.329.4732

345 Middlefield Road.-MS 977    email: oppen at usgs.gov

Menlo Park, CA 94025

 

From: ehpweb-bounces at geohazards.usgs.gov
[mailto:ehpweb-bounces at geohazards.usgs.gov] On Behalf Of Lisa A Wald
Sent: Wednesday, May 19, 2010 11:55 AM
To: EHPweb; Dina Venezky
Subject: [EHPweb] M<1 earthquakes

 

Earthquake Maps and Lists for M<1 events


Background:
The EHP website has been listing and mapping all reent M1+ earthquakes in
the US.  The N. CA website has been listing and reporting all recent M0+
earthquakes.  When the Menlo website merged with the EHP website a couple of
weeks ago, the maps and lists of M<1 earthquakes were no longer available.
Subsequently, we learned that these smaller magnitude earthquakes are
monitored in specific locations by the Volcano Hazards Program (VHP) and by
the SAFOD group.  I'm also aware that some of the ANSS regional networks
still have their own maps and lists on their websites because they, too,
want to see all the smaller earthquakes.

Critical goal:
To restore the access to the recent maps and lists of earthquakes M<1 for
the VHP and SAFOD staff.  Being able to see the map and the list at the same
time is desirable.  VHP needs the caldera boundaries on the map.

Future goal:
To provide access to the recent M<1 earthquakes for the entire US and
eliminate the necessity for the ANSS regional networks to run their own
maps/lists system.

Issues:
The first instinct is to remove the M=1 threshold on the current recenteqs
system, but adding these on the EHP website doubles the number of
earthquakes in the system.  This has several consequences:

1) The addition of M<1 earthquakes on the lists will cause the lists to be
extremely long in some cases, making it difficult to see/find the larger
events in the list.

2) Every hour all the recenteq lists and maps are re-run to refresh the time
stamp and flush events that are older than 7 days.  This is a linear
operation with the list being updated first, then the maps being recreated,
and then last any new events that have come into the system during this
hourly process are added to the maps and lists.  This takes up to 5 minutes
currently, and could take up to 10 minutes if we added the M<1 events.  If a
new event occurred right after this process started on the hour, it may be
up to 10 minutes before it appeared on the EHP website.

3) The addition of M<1 earthquakes on the maps will obscure larger events
underneath them in some cases, making it difficult to access the information
on the larger event.

Note: Since event pages are created one at a time, these can easily be
created for ALL magnitude earthquakes, allowing access to all the products
for these smaller events.

Proposed Solution:
We already have an internal "proof of concept" Google map using the M1+ RSS
feed on the web development server.  We can add an RSS feed of ALL magnitude
earthquakes and plot these on the Google map.

Tasks for completion:

1) Turn on RSS feed for ALL earthquakes.

2) Start creating event pages for ALL earthquakes.

3) Obtain data for caldera boundaries.

4) Modify Google map to use "clustering" ??? which will plot a marker with
the number of earthquakes it is representing in locations where the
earthquakes are close together.  As you zoom in, the individual earthquakes
are individually plotted.  This will speed up the rendering of the Google
map which is really slow when plotting ALL magnitude earthquakes in the US.

5) Modify list below the Google map so that events are linked to their event
pages.

6) Deploy this on the master and backup servers for internal use.

This is the direction we would like to go in for our future recent eq maps,
so this would provide a convenient development and testing environment for
that longer term goal.  We intend to have this available sometime next week.

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

Web Team Manager
USGS Earthquake Hazards Program
Golden, CO
303-273-8543
lisa at usgs.gov

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

 

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