Earthquake Hazard Investigator

Investigation Question

How can earthquake data help communities prepare when scientists cannot predict the exact time of an earthquake?

1
Collect Read three seismograms.
2
Locate Triangulate the epicenter.
3
Analyze Find hazard patterns.
4
Recommend Choose a mitigation strategy.

Event Controls

Create a mystery earthquake

All map locations and historical records are simulated for learning.

Scenario Magnitude 5.2 Focus depth 12 km Guided mode Shows broad P- and S-wave arrival zones.

Event status Ready for a new event

Selected magnitude M 5.2

Selected depth 12 km

Epicenter estimate Not placed

Student Guide

How to locate the earthquake

You do not need to memorize the process. Follow these steps for each station, and the model will check your work.

1
Trigger an earthquakeWait for all three records to finish.
2
Pick P and S arrivalsP is the first small motion. S is the later, larger motion.
3
SubtractS time − P time = the S–P gap.
4
MultiplyS–P gap × 8.4 = distance in kilometers.
5
TriangulateApply three circles and click their closest overlap.

Worked example

P arrival: 18 seconds

S arrival: 30 seconds

Step 1: 30 − 18 = 12 seconds

Step 2: 12 × 8.4 = 100.8, or about 101 km

In this model, every 1 second of S–P gap represents about 8.4 km of distance from the station.

Current task

Trigger an earthquake

Choose a scenario, magnitude, and depth, then start the recording.

Regional Seismic Network

Triangulation map

Historical events

Apply all three distance circles. An estimate marker will then appear; drag it to the closest overlap of the circles.

Seismic station Community Fault zone Historical event Your estimate

Place an estimate after triangulating.

Your estimate is scored by its distance from the hidden epicenter.

Field Notes

What to look for

P waves arrive first

Look for the first small change from the quiet baseline.

S waves arrive later

Look for the later section with larger side-to-side motion.

The time gap matters

A larger S–P time gap means the station is farther from the earthquake.

Two calculations

1. S–P gap = S time − P time 2. Distance = S–P gap × 8.4 km Each station card provides answer boxes and checks both steps. The model uses constant wave speeds and a simplified Earth.

Triangulation progress 0 of 3 circles

Seismic Records

Read, calculate, and check each station

On each graph, click the first small P wave and then the later, larger S wave. The model automatically switches from P to S. Next, check the picks, complete the calculations, and apply the circle.

Northwest Station

Bedrock sensor

Waiting

Trigger an earthquake to record data.

Click the graph twice: first on the P-wave start, then on the S-wave start.

P arrival: —
S arrival: —
S–P gap: —
Distance: —

Distance calculation Check your wave picks first

1 S–P gap

S time − P time = ?

2 Distance

S–P gap × 8.4 = ?

Correct calculations will unlock the distance circle.

Northeast Station

Valley sensor

Waiting

Trigger an earthquake to record data.

Click the graph twice: first on the P-wave start, then on the S-wave start.

P arrival: —
S arrival: —
S–P gap: —
Distance: —

Distance calculation Check your wave picks first

1 S–P gap

S time − P time = ?

2 Distance

S–P gap × 8.4 = ?

Correct calculations will unlock the distance circle.

Southern Station

Foothill sensor

Waiting

Trigger an earthquake to record data.

Click the graph twice: first on the P-wave start, then on the S-wave start.

P arrival: —
S arrival: —
S–P gap: —
Distance: —

Distance calculation Check your wave picks first

1 S–P gap

S time − P time = ?

2 Distance

S–P gap × 8.4 = ?

Correct calculations will unlock the distance circle.

Hazard Pattern Analysis

What does the regional history suggest?

Patterns can estimate locations and likelihoods. They do not predict an exact date or time.

Filter the simulated records

Minimum magnitude M 2.5 Time window

Events shown 0

Largest magnitude —

Near fault —

Pattern question

Which zone contains the greatest number of filtered earthquakes?

Events by map zone

Count of earthquakes that match the current filters

Simulated event count

North

Central

South

Select the zone best supported by the filtered data.

Community Decision

Recommend a risk-reduction plan

Evidence required

Priority community Mitigation technology or action Evidence from the model 0/240 characters

Use the map, zone graph, and community information as evidence.

Ridgeview

Older buildings · Firm rock · Moderate population

Riverbend

Soft river sediment · Dense utilities · High population

Pine Junction

Newer buildings · Firm rock · Lower population

NGSS

Standards Alignment

MS-ESS3-2 · Earth and Human Activity

Analyze and interpret data on natural hazards to forecast future catastrophic events and inform the development of technologies to mitigate their effects.

Science & Engineering Practice Analyzing and Interpreting Data

Students compare locations, magnitudes, and frequencies in the simulated earthquake record.

Disciplinary Core Idea ESS3.B · Natural Hazards

Historical patterns and geologic forces help estimate where future hazards are more likely.

Crosscutting Concept Patterns

Students use mapped and graphed patterns as evidence for a hazard forecast and mitigation recommendation.