It would be nicer if we could add some useful labels to this instead
of just a raw seismogram. Perhaps getting some information about
this particular earthquake and the station it was recorded at. We
will use the IRIS
FDSNWS
station web service to get the station and channels and the USGS
FDSNWS
event web service to get the earthquake. Again, both of these
are asynchronous and so we will have to use promises. We first create
both the EventQuery
and StationQuery objects.
let queryTimeWindow = new seisplotjs.util.StartEndDuration('2019-07-01', '2019-07-31');
let eventQuery = new seisplotjs.fdsnevent.EventQuery()
.timeWindow(queryTimeWindow)
.minMag(7)
.latitude(35).longitude(-118)
.maxRadius(3);
let stationQuery = new seisplotjs.fdsnstation.StationQuery()
.networkCode('CO')
.stationCode('HODGE')
.locationCode('00')
.channelCode('LH?')
.timeWindow(queryTimeWindow);
Then we call their query
methods with a Promise.all()
which will wait until both of these return before calling the
then() function. We will also use the more powerful
POST method to get the seismograms. The
ChannelTimeRange works just like the
StartEndDuration but also hold the channel that the
time rage corresponds to. In this case they are all the same, but
might be different if we were using multiple stations and predicted
arrival times. Note that we use the event time as the start and
ask for a duration of 2400 seconds.
Promise.all([ eventQuery.query(), stationQuery.queryChannels()])
.then( ( [ quakeList, networks ] ) => {
let allChannels = seisplotjs.stationxml.extractAllChannels(networks);
let timeWindow = new seisplotjs.util.StartEndDuration(quakeList[0].time, null, 2400);
let seismogramDataList = allChannels.map(c => {
return seisplotjs.seismogram.SeismogramDisplayData.fromChannelAndTimeWindow(c, timeWindow);
});
let dsQuery = new seisplotjs.fdsndataselect.DataSelectQuery();
return Promise.all([ quakeList, networks, dsQuery.postQuerySeismograms(seismogramDataList) ]);
Because we have the
channel, we can also plot the seismograms corrected for overall
gain and in units of m/s. We also added a couple of
<span>
elements to hold the station codes and earthquake description.
}).then( ( [ quakeList, networks, seismogramDataList ] ) => {
let div = seisplotjs.d3.select('div#myseismograph');
let seisConfig = new seisplotjs.seismographconfig.SeismographConfig();
seisConfig.title = seismogramDataList.map(ctr => ctr.channel.codes());
seisConfig.doGain = true;
let graph = new seisplotjs.seismograph.Seismograph(div,
seisConfig,
seismogramDataList);
graph.draw();
seisplotjs.d3.select('span#stationCode').text(networks[0].stations[0].codes());
seisplotjs.d3.select('span#earthquakeDescription').text(quakeList[0].description);
}).catch( function(error) {
seisplotjs.d3.select("div#myseismograph").append('p').html("Error loading data." +error);
console.assert(false, error);
});
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