Question 1

How is Taiwan’s seismic intensity scale classified (including 5-weak/5-strong, 6-weak/6-strong)?

Accepted Answer

The Central Weather Administration (CWA) introduced a refined seismic intensity scale that subdivides levels 5 and 6 into "5-Weak / 5-Strong" and "6-Weak / 6-Strong" (10 levels in total).

Intensities 1 to 4 are determined primarily by Peak Ground Acceleration (PGA), while levels 5 and above incorporate Peak Ground Velocity (PGV) to better correlate with structural damage in buildings. Scale Levels: 0, 1, 2, 3, 4, 5-Weak, 5-Strong, 6-Weak, 6-Strong, 7 Strong Shaking: Levels 5+ incorporate PGV (kine) for building damage correlation

Question 2

What is a "Very Shallow" earthquake, and why does it cause intense shaking?

Accepted Answer

Earthquakes with a focal depth under 30 kilometers are categorized as "Very Shallow Seismicity."

Because the hypocenter is so close to the ground surface, seismic energy undergoes minimal attenuation before reaching populated areas, resulting in acute, sudden ground shaking near the epicenter. Depth Categories: Very Shallow (<30km), Shallow (30-70km), Intermediate (70-300km), Deep (>300km)

Question 3

What is the difference between "Significant Felt" and "Local Felt" earthquake reports?

Accepted Answer

Significant felt earthquakes typically exhibit larger magnitudes and affect multiple administrative counties; they receive unique official report numbers (e.g., 115058) and shakemaps.

Local felt events are smaller or geographically isolated tremors felt only in select townships (officially designated with event number 115000). OpenViz combines both datasets without truncation. Significant Felt: Dataset E-A0015-001 with individual report numbers and shakemaps Local Felt: Dataset E-A0016-001 covering localized tremors

Question 4

How frequently is OpenViz earthquake data updated, and is this raw seismometer telemetry?

Accepted Answer

OpenViz periodically syncs official earthquake reports published by the CWA Open Data Platform.

Once the CWA seismic observation network computes the event parameters and publishes the official bulletin, OpenViz processes and visualizes it immediately. These represent verified official reports rather than uncalibrated raw instrument waveforms. Source: Central Weather Administration Open Data Platform (E-A0015-001, E-A0016-001)

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