### Elevation with USGS

  use Geo::WebService::Elevation::USGS;

  my $eq = Geo::WebService::Elevation::USGS->new();
  my $alt =
    $eq->elevation( $event->{location}->{lat}, $event->{location}->{lon} )
    ->{Elevation};

  $logger->info("USGS elevation is $alt ft");

### compare values

  my $percent = percent_error( $feet, $alt );
  $logger->info("Percent difference is $percent");

### home cooked distance
  my $d = distance(
    $prev_lat, $prev_long,
    $event->{location}->{lat},
    $event->{location}->{lon}, "M"
  );
  $logger->info("distance is $d miles");


### distance with GPS::Point
  use GPS::Point;
  my $gps = GPS::Point->new( lat => $prev_lat, lon => $prev_long );
  my $dist =
    $gps->distance( $event->{location}->{lat}, $event->{location}->{lon} );
  my $feet2 = 3.28084 * $dist;
  my $miles = $feet2 / 5280;

  #$logger->info("distance is $feet2 feet");
  $logger->info("distance is $miles miles");
 

### compare values

  my $percent2 = percent_error( $d, $miles );
  $logger->info("Percent difference is $percent2");